Clamping collar with retaining fingers

A clamping system for connecting a first and a second tube whose opposite ends have clamping surfaces protruding from the cylindrical outer surface of said tubes. The system comprises a collar which comprises a belt able to be clamped around said clamping surfaces, the belt having a first and a second flank between which an internal recess able to receive the clamping surfaces is delimited. The collar carries at least one retaining finger which has a free end portion protruding axially beyond the edge of the first flank, said free end portion having a retaining edge configured to be retained outside the belt by a radially protruding element.

BACKGROUND

The present disclosure relates to a clamping system for connecting a first and a second tube whose opposite ends have clamping surfaces protruding from the cylindrical outer surface of said tubes.

A clamping system of this type is known, for example from European patents EP 1 4514 498 and EP 2 598 785.

In such a system, the collar comprises a belt able to be clamped around the clamping surfaces of the tubes. The belt has flanks between which an internal recess is delimited in which the clamping surfaces of the tubes are disposed to carry out the clamping. The tubes are thus retained clamped relative to each other. As indicated in the aforementioned patents, it may be useful to pre-mount the clamping system on the end of at least one of the tubes before carrying out the clamping.

In order to allow a pre-mounting on the two tubes, EP 2 598 785 recommends that the clamping system comprise a washer, retained relative to the collar by fastening lugs, and comprising first and second pre-mounting lugs able to respectively cooperate with the first and the second tube to retain the washer, and therefore the entire clamping system, relative to the respective clamping surfaces of the tubes before the clamping. These pre-mounting lugs in this case comprise short lugs extending back above the frustoconical annular shape of the washer to cooperate with the clamping surface of the tube whose clamping surface is disposed between the belt and the washer. These pre-mounting lugs also include long lugs, which extend from the top of the washer in the opposite direction to the washer to cooperate with the clamping surface of the other tube.

In EP 2 598 785, the lugs of these two categories are elastically deformable. This device is generally satisfactory, but, for some applications, it is important to improve reliability of the retention of the lugs relative to the clamping surfaces, particularly as regards the long lugs. Indeed, concerning particularly long lugs, it may be difficult to ensure the right range of elastic deformation for some clamping diameters, particularly large diameters on the order of 5 cm or more. On the one hand, it is necessary to ensure that the modulus of elasticity of these lugs is sufficiently high so that they have the desirable elasticity for elastically recovering, after having been deformed upon engagement of the tube in the clamping system, a position ensuring the pre-mounted retention of this tube. They must then have the elastic responsiveness necessary in order not to be too easily deformed if traction is exerted on the tube in the direction of its disengagement from the clamping system. However, this elastic retention is useful only in the pre-mounted state, before the clamping. In the clamped state, it is on the contrary desirable that the lugs are deformed to be pressed inside the belt of the collar, without affecting the quality of the clamping. However, if the elastic modulus of the lugs is high, this latter property may be difficult to achieve in some cases, particularly for large-diameter collars. In addition, if the elastic modulus is too high, the engagement pushing force required for the clipping of the lugs on the clamping surface of the tube can be high, and difficult to achieve in a context of final mounting.

Thus, even though the system of EP 2 598 785 is satisfactory for a large number of applications, it is desirable to propose another solution allowing pre-mounting of the clamping system at the end of the first tube substantially free from the aforementioned drawbacks, particularly for the large-diameter collars.

EP 1 451 498 proposes a system allowing a pre-mounting relative to a tube, using pre-mounting lugs also carried by the belt via a washer itself carried by the belt. The same problems as those mentioned above can arise for a pre-mounting relative to a single tube.

Other clamping systems are also known comprising a collar and a washer carried by the collar, the washer having internal lugs, able to grip inside one of the tubes, for pre-mounting the clamping system at the end of this tube. It may be useful to complete this system to also allow a pre-mounting relative to the other tube. For that, it is possible to use the long lugs proposed by EP 2 598 785 but, particularly for large-diameter collars, there is a need for another solution, substantially free from the abovementioned drawbacks.

SUMMARY

Generally, there is a need for a clamping system allowing controlled retention in the pre-mounted state relative to the clamping surface of one of the tubes it is intended to clamp.

Thus, the disclosure relates to a clamping system for connecting a first and a second tube whose opposite ends have clamping surfaces protruding from the cylindrical outer surface of said tubes, the system comprising a collar which comprises a belt able to be clamped around said clamping surfaces, the belt having a first and a second flank between which an internal recess able to receive the clamping surfaces is delimited, the collar carrying at least one retaining finger, which has a free end portion protruding axially beyond the edge of the first flank, said free end portion having a retaining edge configured to be retained outside the belt by a radially protruding element.

Thus, the retaining finger is naturally on standby to cooperate, when the first tube is fitted into the clamping system, with an element radially protruding therefrom. The implementation of the retention therefore does not require any particular manipulation once the first tube has been fitted into the clamping system.

Optionally, the clamping system comprises centering surfaces located axially outside the edge of the first flank.

Optionally, the centering surfaces comprise at least one centering surface formed on the retaining finger.

Optionally, the collar carries at least one centering finger protruding axially beyond the edge of the first flank and in which the centering surfaces comprise at least one centering surface formed on the centering finger.

Optionally, the retaining finger has a ramp at the end of its free end portion.

Optionally, the retaining finger has at least one reinforcing rib.

Optionally, the centering finger has a ramp at the end of its free end portion.

Optionally, the centering finger has at least one reinforcing rib.

Optionally, the clamping system comprises a washer supported by the collar, the washer comprising an annular part disposed inside the belt and carrying the retaining finger.

Optionally, the washer also carries the centering finger.

Optionally, the retaining edge is formed on a pin cut out in the retaining finger and deformed radially.

The disclosure also relates to a clamping system according to the disclosure and a first tube having, in the vicinity of its free end, a clamping surface protruding from its cylindrical outer surface, the first tube further having a retaining protrusion located on the other side of its clamping surface relative to its free end, the retaining edge cooperating with said retaining protrusion when the first tube is fitted into the collar.

Optionally, the retaining protrusion is formed on a transverse blade which has a fastening portion through which it is fastened to the first tube, and a retaining portion, straightened radially relative to the fastening portion.

Optionally, the blade has two retaining portions and the collar carries two retaining fingers configured to cooperate with said retaining portions.

Optionally, the retaining protrusion is configured to define an angular wedging of the clamping system relative to the first tube.

Optionally, the blade has two shoulders forming a radial stop for the retaining fingers.

The present disclosure will be clearly understood and its advantages will appear better upon reading the following detailed description of one embodiment represented by way of non-limiting example.

DETAILED DESCRIPTION

FIGS.1and2are described at first. It can be seen in these figures that the clamping system comprises a collar10, of the same type as the one described in EP 2 598 785 and a washer28, which cooperate to assemble two tubes2,4.

In the following, “radially internal” elements will refer to the elements that are directed towards the axis A of the two tubes placed end to end and that are closest to this axis A relative to other elements referred to as “radially external” elements, the “radially external” elements also being those that are directed away from the axis A. It is also considered that the axis A of the two tubes is also the axis of the collar, more specifically the axis of the collar belt, the latter being wound on itself.

Furthermore, it will be considered that a second element is “external” or “axially external” to a first element, if the second element is located next to the first one, that is to say outside the axial slice occupied by the first element.

The collar comprises a belt12which delimits a recess14in which the bearing surfaces, respectively18belonging to the first tube2and20belonging to the second tube4can be inserted. This recess and these bearing surfaces have shapes such that the clamping of the belt of the collar forces the ends of the tubes2and4to come close to each other. The recess14is delimited between a first and a second flank13A and13B of the belt12, these flanks defining in this case the branches of a V seen in axial section. Thus, the belt12has an advantageously V-shaped axial section, while the bearing surfaces18and20have a diameter which increases progressively towards the opposite free ends of the tubes and have for example a frustoconical shape.

The belt12has ends respectively12A and12B, which are straightened substantially radially so as to form bearing lugs. These lugs are pierced so as to allow the passage of the rod24A of a clamping screw24through these lugs. The head24B of the screw is wedged relative to one of the bearing lugs, in this case the lug12B, while a nut26is retained relative to the other bearing lug12A. It is understood that the rotation of the nut in the direction of screwing brings the bearing lugs closer to each other and therefore reduces the inner diameter of the collar, that is to say it allows clamping the strip. Of course, other ways of clamping the strip can be envisaged, for example hooking systems, as described in particular in patent application FR 3 008 160.

The clamping system comprises a washer28which is secured to the collar. The washer may particularly be of the type described in EP 1 451 498.

This washer28has a frustoconical annular portion30which can be inserted between the opposite ends of the two tubes2and4when they are engaged in the clamping system. Indeed, the washer28is retained relative to the belt, in this case relative to its second flank13B, by fastening lugs so that an annular space is arranged between the second flank and the washer. The free end of the second tube4carrying its bearing surface20is inserted into this annular space inside the recess14, while the free end of the first tube2carrying its bearing surface18is inserted on the opposite side of the annular space relative to the washer, that is to say against the internal face of the frustoconical portion30of the washer28.

In this case, the end of the tube4is a female flared part, the internal periphery of its bearing surface20forming a flared part. On the other hand, the free end of the first tube2is a male end which, beyond its bearing surface18, has an outer periphery23whose diameter gradually decreases towards the termination of the free end. The end part23thus formed can therefore be inserted, substantially in a form-fitting manner, inside the flared part formed at the end of the tube4. The frustoconical annular portion30of the washer28may have annular deformations32forming a seal between the internal surface of the flared part19and the external periphery23.

The fastening of the washer28of the collar10and/or the pre-mounting of the clamping system comprising the collar and the washer on the tube4can be ensured in the same way as in EP 1 451 498, by fastening lugs and/or pre-mounting lugs34with which the washer is equipped, these lugs serving to hook the washer on the second flank13B of the belt, while arranging the abovementioned annular space, as described in EP 1 451 498.

Other modes of fastening the washer to the collar can be used. For example, the washer may have a retaining loop in which the shank of the screw24can be engaged, as well as one or several retaining lugs which can be retained on the edge of the belt, for example by hooking or by pinching. Likewise, other modes of pre-mounting the clamping system relative to the tube4can be used, for example, by equipping the washer with internal lugs or studs engaged in the tube4to cling on the internal surface of the tube4.

The collar carries retaining fingers40that have free end portions protruding axially beyond the edge of the first flank13A. For each retaining finger, the free end portion has a retaining edge42configured to be retained outside the belt by a radially protruding element. As will be seen below, this radially protruding element is particularly a retaining protrusion secured to the first tube2. The internal surfaces43of the common portions of the retaining fingers form centering surfaces that extend axially beyond the edge of the first flank13A, while being radially comprised in the diametrical dimensions of this edge. Considered together, the different centering surfaces define diametrical dimensions comparable to those defined by the top of the clamping surface18of the first tube2, so as to carry out a centering of this first tube upon its insertion into the clamping system. It is seen that the collar also carries centering fingers50that are similar to the retaining fingers, except that they do not have a retaining edge. However, as for the retaining fingers, their internal surfaces53form centering surfaces. It can be seen that the retaining fingers and the centering fingers have ribs48that are oriented axially and that stiffen these fingers. Thus, the retaining fingers and the centering fingers have a radial responsiveness, that is to say they are relatively not very flexible and can be elastically deformed radially over a small radial displacement by having a strong tendency to elastic return. The retaining fingers and the centering fingers also have flared ramps49at the end of their free ends. These flared ramps promote the insertion of the first tube into the clamping system.

In this case, the retaining fingers40and the centering fingers50are carried by the washer28which is itself supported by the collar10as indicated. More specifically, the retaining fingers and the centering fingers are carried by the annular part30, in this case frustoconical annular part, of the washer which is disposed inside the belt12of the collar. The retaining fingers and the centering fingers extend forwardly from the front edge of this annular part. Within the meaning of the present disclosure, the forward direction is the one which goes from the second flank13B toward the first flank13A. Thus, the retaining fingers and the centering fingers extend forwardly beyond the front edge of the flank13A. The forward direction is indicated by the arrow F inFIG.1. In the unclamped state of the collar, the retaining fingers and the centering fingers can extend substantially axially forwardly from the front edge of the annular part30of the washer28. Particularly, at least in their common portions between their ends, they can extend parallel to the axis A. They can, however, in their part of attachment to the washer28, be slightly corrugated radially outwardly to get closer to the bottom of the recess14of the belt12. In addition, the reinforcing ribs can start only at a short distance from the connection of the retaining fingers and the centering fingers to the washer, so as to allow a certain flexibility in this connection portion between the lugs and the washer, while ensuring the responsiveness mentioned previously, it being noted that the radially external faces of the fingers can cooperate with the edge of the first flank to contribute to the elastic return of these fingers radially inwardly. It is understood that, upon clamping of the collar, while the two tubes are connected, these parts for connecting the fingers to the washer are deformed by being pressed against the bottom of the recess by the clamping surface18.

As seen inFIGS.1and2, the first tube has a retaining protrusion62which is radially protruding on its outer surface and which is located on the other side of the clamping surface18relative to the free end2′ of this first tube2. More specifically, the retaining protrusion62is formed on a transverse blade60which has a fastening portion60A through which it is fastened to the first tube, and a retaining portion which forms the retaining protrusion62and which is straightened radially relative to the fastening portion60A. Indeed, the fastening portion is connected to the retaining portion by a step60B. In this case, the transverse blade60has the shape of a flat blade whose thickness is measured radially and whose width is measured parallel to the axis A of the collar. More specifically, in the example represented, the transverse blade has two similar retaining portions62which, in this case, are disposed at its two ends between which its fastening portion60A extends.

It can be seen inFIG.2that each of the two retaining fingers40cooperates, through its retaining pin42, with one of these retaining portions62. InFIG.2, the two tubes are pre-assembled, the clamping system being both pre-mounted at the end of the second tube4and at the end of the first tube2. In this situation, it suffices to clamp the collar to finalize the assembly of the two tubes. In doing so, as indicated above, the retaining and centering lugs deform under the effect of the clamping without hampering the latter.

With reference toFIGS.3to5, a variant will now be described. The clamping system itself is unchanged compared to that ofFIGS.1to2. What changes in this variant is the fact that the system, combined with the first tube, allows an angular wedging of the clamping system relative to this first tube. Indeed, the transverse blade70carried by the first tube2and on which the retaining portions72forming the retaining protrusions are formed, differs slightly from the blade60previously described, in that these retaining portions72are connected to its fastening portion70A by steps70B extended radially outwardly by ears70C protruding radially. These ears are made simply by a fold of the transverse blade. As seen inFIG.5, the angular spacing of the ears70C is adapted so that, in the pre-assembled state, the ears extend between the two retaining fingers40and are retained by their pins42on the front edges of the retaining portions72. This allows ensuring the angular wedging of the second tube relative to the clamping system.

The shaping of the transverse blade60or70allows a particularly effective pre-assembly. Indeed, as indicated, the thickness of the blade is oriented radially while its width is oriented axially. The retaining fingers are retained on the front edge of the retaining portions of this blade, that is to say the edges that are furthest from the free end of the first tube. Any forces to detach the first tube from the locking system operate parallel to the width of the transverse blade. It is therefore a direction in which this blade is unlikely to be deformed. Thus, the pre-assembly is particularly effective. The ears70C of the blade70form shoulders in the form of a radial stop for the retaining fingers40.

For the mounting of the assembly comprising the two tubes and the clamping system, the free end of the tube4is first engaged in the annular space arranged between the washer28and the second flank13B of the belt so as to pre-mount the clamping system around this free end, then the free end of the tube2in the clamping system is engaged, until reaching the position represented inFIGS.3and5.

The centering surfaces allow, during the fitting of the first tube into the clamping system, cooperating with the top of the clamping surface of this first tube to center it relative to the clamping system. This promotes the correct pre-mounting of the clamping system on the first tube and therefore the centering of the two tubes relative to each other. The centering surfaces can be formed on the retaining finger(s), by being possibly completed by one or several centering surfaces formed on the centering fingers if they are provided. The retaining edge of the retaining finger can be made in a very simple manner by a simple partial cutout in this finger releasing a tab which is folded back to form a pin42folded radially inwardly. This pin is very simple to manufacture, without addition of material, while forming an effective claw so that the retaining finger grips on the radially protruding element on the external periphery of the first tube.

FIG.6Aschematically represents the first tube2, the second tube4, the belt12of the collar, the washer28and the transverse blade40. The frustoconical portion30of the washer28is located between the internal face of the bearing surface20of the second tube4and the external face of the frustoconical end part23of the first tube2. The clamping system is, on the one hand, pre-mounted on the second tube4, pre-mounting lugs34of the washer hooking on the one hand the washer on the belt12of the collar and on the other hand bearing on the external face of the clamping surface20. On the other hand, the clamping system is also pre-mounted on the first tube, the retaining finger40being retained on the retaining portion72of the blade70, the pin42being retained against the front edge of the retaining portion. In this example, as in that of the previous figures, the finger passes radially above the retaining portion72until hooking against its front edge.

FIG.6Billustrates a variant, which differs from that ofFIG.6Aby the fact that the retaining finger40′ passes radially under the retaining portion, which in this case is similar to the retaining portion62. Indeed, the retaining finger40′ extends axially forwardly from the frustoconical portion30of the washer while remaining in diametrical dimensions which allow it to pass radially under the retaining portion62during insertion of the end of tube2in the clamping system. Thus, the retaining pin42′ of the finger42, which is directed radially outwardly, can hook on the front edge of the retaining portion62. The ramp49′ formed at the free end of the finger40′ is directed inwardly. The retaining finger40′ may also be similar to the retaining finger40of the previous figures and, particularly, have a centering surface and a reinforcing rib.

As indicated, the retaining protrusion can be formed on a transverse blade fastened to the first tube. This blade is a geometric element which is very simple and therefore easy to manufacture. Its fastening can however be extremely resistant because of the possible contact surface between the first tube and this blade. The transverse orientation of this blade promotes effective retention because the possible detachment forces operate axially, therefore perpendicularly to the main direction of the blade, direction in which this blade is not very deformable.

The clamping belt and the washer as well as the fingers are preferably made of metal. Concerning particularly the washer, this can be made in a stainless steel strap of the austenitic type, and having particularly a thickness comprised between 0.1 mm and 0.5 mm, or even between 0.2 and 0.4 mm.