Torque limiter fitting
The connector system with a base nut, clamping member, and compression spring ensures precise and reliable pipe tightening to a set torque, addressing the cumbersome nature of torque wrenches and ensuring consistent connection quality.
Patent Information
- Application Number
- FR2023014002
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2022-12-13
- Filing Date
- 2023-12-12
- Publication Date
- 2025-01-17
- Estimated Expiration
- 2043-12-12
AI Technical Summary
Existing pipe connection methods using torque wrenches are cumbersome and do not guarantee precise tightening to a set torque, especially in constrained environments.
A connector system featuring a base nut, clamping member, compression spring, and preloading nut that ensures precise tightening to a predetermined torque without the need for a torque wrench, using complementary hooking rings and Belleville springs to limit torque transmission.
Guarantees precise and reliable tightening to a set torque, preventing over-tightening and simplifying the installation process, especially in confined spaces.
Smart Images
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Abstract
Description
Title of the invention: Torque limiter connection FIELD OF THE INVENTION
[0001] The present invention relates to a connector for joining two pipes with a predetermined tightening torque comprising a first end piece fixed to a first pipe, a second end piece fixed to a second pipe to be joined, the first end piece provided with a tool grip collar being terminated by a thread and a sealing surface, the second end piece has a collar terminated by a sealing surface intended to be applied against the sealing surface of the first end piece, a nut freely engaged on the second end piece behind its collar and screwed onto the threaded end of the first end piece by pulling the collar to apply its sealing lip against the sealing surface of the first end piece and achieve sealing with a determined stress. STATE OF THE ART
[0002] It is known to tighten connections of two pipes or conduits with a torque wrench allowing tightening with a determined tightening torque.
[0003] However, compliance with the tightening torque is not always guaranteed and the torque wrench is very cumbersome for tightening a fitting in a constrained environment.
[0004] PURPOSE OF THE INVENTION
[0005] The aim of the present invention is to develop a tightening means making it possible to guarantee tightening precision with a set torque without using a torque wrench.
[0006] DISCLOSURE AND ADVANTAGES OF THE INVENTION
[0007] For this purpose, the invention relates to a connection of the type defined above, characterized in that it comprises a base nut in the form of a sleeve having: at one end, a thread for screwing onto the threaded segment of the first end piece, a bearing surface following the thread for pushing the collar of the second end piece and pressing its lip against the bearing surface of the first end piece, an external attachment crown, a bearing and, a threaded segment at its end, a tightening nut coming onto the smooth bearing to rotate freely there and having on its face facing the crown of the base nut - a second crown intended to come against the first crown of the base nut, on its opposite face a bearing surface, a compression spring element applied against the bearing surface of the tightening nut,a preload nut screwed onto the threaded segment of the base nut to press the clamping nut against the attachment ring of the nut with a determined preload, base via the compression spring element, the second latching ring being connected to the first latching ring to transmit by contact the tightening torque of the nut on the first end piece up to a set torque adjusted by the tightening of the compression spring element elastically clamping the two latching surfaces.
[0008] The connection according to the invention has the advantage of allowing two pipes to be connected with a set tightening torque that is fixed and precisely adjusted.
[0009] The connection is in fact supplied to the installer with the factory-preset torque setting and therefore precisely adjusted and verified, an adjustment on which the installer cannot intervene.
[0010] The installer can only tighten the fitting to the limit of the set torque without being able to exceed this limit.
[0011] This connection thus offers an important guarantee for serial work requiring rapid, repeated intervention on multiple connections and which must not be subject to the vagaries of tightening even if this is done with a torque wrench.
[0012] According to another advantageous characteristic, the first attachment ring comprises a set of peripheral ramps and the second attachment ring comprises a set of peripheral ramps, the two rings are complementary so as to transmit the tightening torque exerted by the tightening nut up to the set torque.
[0013] According to an advantageous characteristic, the base nut has a threaded segment after the plain bearing receiving the clamping member,
[0014] The prestressing member is screwed onto the threaded segment to be secured to the base nut and,
[0015] The compression spring is between the prestressing member and the bearing face opposite that of the second attachment ring.
[0016] According to another advantageous characteristic, the base nut has a collar whose face facing the face of the clamping member forms a bearing surface and this bearing surface and the bearing surface of the clamping member receive the compression spring between them,
[0017] The other face of the collar carries a first attachment ring and the clamping member has a return and passes around the compression spring and the collar, this return coming against the attachment ring of the face of the collar.
[0018] This form of connection has the advantage of being particularly compact due to the grouping of the compression spring, notably formed by a stack of Belleville springs.
[0019] According to another characteristic, the return of the clamping member is a removable ring secured to the clamping member after placement on the smooth part of the clamping nut and the installation of the pre-stressed spring between the face of the clamping member and the face of the collar.
[0020] According to another characteristic, the sealing surface of the second end piece is a sealing lip or a conical surface and the sealing surface of the first end piece is a flat surface or a conical surface.
[0021] According to another advantageous characteristic, the clamping member is in the form of a cap nut whose tool-engaging surface covers the compression spring element and the preloading member. This protects these elements and also prevents any direct intervention by a tool in the gap between the compression spring element and the preloading nut.
[0022] Furthermore and advantageously, the preloading nut has a tool gripping surface which is not accessible to a usual tool but a tool specially designed for this particular application to avoid any intervention on the setting of the set torque of the subassembly formed by the base nut, the clamping member, the compression spring element and the preloading nut which is crimped after adjustment on the threaded part of the sleeve. It is advantageous to be able to check the correct execution of the tightening since it is sufficient for the person checking the tightening to tighten the tightening nut again.
[0023] This protection is essential to guarantee the reliability of this connection, that is to say the conformity of the connection to its sign parameters.
[0024] According to another advantageous characteristic, the compression spring element is a Belleville spring or a Belleville spring stack. Brief description of the drawings
[0025] The present invention will be described below in more detail with the aid of an embodiment of a connector shown in the accompanying drawings in which:
[0026] [Fig-1] side view and an axial sectional view of the connection according to the invention,
[0027] [Fig.2] axial half-section view of the components of the connection according to the invention,
[0028] [Fig.3] side view and perspective view of a basic nut,
[0029] [Fig.4] perspective view along two diametrically opposite directions of the clamping nut,
[0030] [Fig.5] axial sectional view of a second embodiment of the connection,
[0031] [Fig.6] exploded axial half-section view of the connection of [Fig.5],
[0032] [Fig.6A] assembled axial half-sectional view of the connection of [Fig.5],
[0033] [Fig.7] axial sectional view of a variant of the second embodiment,
[0034] [Fig.8] isometric view of the connection of the second embodiment.
[0035] DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
[0036] According to Figures 1 and 2, the invention relates to a connector 100 intended to join two pipes C1, C2 with a predetermined tightening torque (set torque CS).
[0037] This connection 100 of axis XX consists of a first end piece 1 intended to be fixed to a first pipe C1 and a second end piece 2 intended to be fixed to the other pipe C2 to be joined by the connection and further comprising a base nut 3 and a clamping member 4.
[0038] The base nut 3 is fitted onto the second end piece 2 and it carries the clamping member 4 to drive the base nut 3 with the second end piece 2 and tighten the latter against the first end piece 1 with a setpoint tightening torque CS; the tightening torque applied to the clamping member 3 cannot exceed this setpoint torque.
[0039] The first sleeve-shaped end piece 1 is provided on its outer surface with a nut crown 11 forming a tool-gripping surface, for example, a faceted hexagonal profile 111, as is customary for screw-in elements.
[0040] This first end piece 1 ends at its other end with a thread 12 and a sealing surface 13 in a plane perpendicular to the axis XX.
[0041] The base nut 3 is intended to be screwed onto the end piece 1 by pulling and pressing the second end piece 2 by its collar 21 to press its lip-shaped sealing surface 211 against the sealing surface 13 of the first fitting 1.
[0042] The base nut 3 is formed of two cylindrical sleeves 3a, 3b connected by a crown 3c. The sleeve 3a intended to be screwed onto the end piece 1 has an internal diameter corresponding to the external diameter of the first end piece 1.
[0043] The sleeve 3b intended to cover the second end piece 2 has an internal diameter corresponding, apart from the clearance, to the external diameter of the end piece 1 on which it is fitted.
[0044] The difference in the diameters of the base nut 3 corresponds to the relief formed by the collar 21 of the end piece 2 and to the thickness of the end piece 1 forming the bearing surface 13.
[0045] The meeting of the two inner surfaces of the sleeves 3a, 3b forms a conical or flat bearing surface 32 corresponding to the shape of the side 212 of the collar 21 against which the nut 3 pushes.
[0046] The junction 3c of the two sleeves 3a, 3b overlaps the bearing surface 32 and carries a hooking ring 33. Beyond this hooking ring 33, the sleeve 3b has a smooth surface forming a bearing 34 and then a threaded segment 35.
[0047] The clamping member 4 intended to cooperate with the base nut 3 is wheel-shaped with a central orifice 41 to rest on the bearing 34 of the base nut 3. On its face facing the nut 3, it has a hooking crown 42 to cooperate with the first hooking crown 33 of the base nut 3; the outer edge of the clamping member 4 is a tool-gripping surface 43, for example, faceted for a contour hexagonal tool grip.
[0048] The surface of the clamping member 4, opposite that of the (second) hooking ring 42, is a bearing surface 43 for a compression spring 5 surrounding the bearing 34 of the nut 3.
[0049] The compression spring element 5 is sandwiched between the bearing surface 43 and a prestressing member 6 to be screwed onto the threaded segment 35 of the base nut 3 and tighten the spring 5 against the clamping member 3 and thus the second latching ring 41 against the first latching ring 33.
[0050] The preload nut 6 is protected and does not have a tool grip surface other than the special tool grip, not shown, used for setting the set torque CS in the factory. The nut can be immobilized by crimping or other mechanical solution after factory adjustment.
[0051] As shown in the sectional view of part B of [Fig.l], the tightening nut 4 is a cap nut which covers both the compression spring 5 and the preloading nut 6 so as to prevent any misadjustment of the set tightening torque.
[0052] The operation of the preloading nut 6 requires a tool with a particular grip, for example, a pin wrench which engages in two diametrical holes made in the external face of the preloading nut 6.
[0053] The subassembly 100a of the connector 100 comprising the nut 3, the clamping member 4, the compression spring 5 and the preloading nut 6 is preset to the set tightening torque CS. The assembly of the pipes C1, C2 by the connector 100 consists of fixing the two end pieces 1, 2 to the respective end of the pipes C1, C2 then screwing the subassembly 100a (fitted onto the end piece 2 before fixing the latter to the pipe C2), onto the threaded segment 12 of the end piece 1. The first end piece 1 is held by a tool applied to its tool gripping surface 11 and the subassembly 100a is maneuvered using its tool gripping surface 43. The screwing movement continues until the radial hooking rings 33, 42 slip and no longer transmit torque greater than the set tightening torque CS.Advantageously, the teeth formed by the hooking crowns allow loosening without torque limitation since in the direction of unscrewing the tightening nut, the teeth are driven by the notches formed by the vertical faces of the teeth.
[0054] The tightening of the connection 100 is done by screwing the base nut 3 onto the threaded segment 12 of the first end piece 1, being driven in rotation for its screwing by the clamping member 4 mounted freely in rotation on a bearing 34 and cooperating by its hooking surface 42 with the first hooking surface 33 of the base nut 3. The clamping member 4 is pushed against the base nut 3 by the compression spring element 5 itself pushed by the preloading nut 6 screwed by its thread 61 onto the base nut 3. The tightening of the compression spring 5 by the adjusted screwing of the preload nut 6 allows the setting torque CS to be adjusted up to which the tightening nut 4 drives the base nut 3 for its screwing onto the first end piece 1.
[0055] The tightening of the base nut 3 on the end piece 1 can be done until the set torque fixed by the preload nut 6 and the compression spring 5 is reached.
[0056] For this tightening, the end piece 1 is held with a tool applied to its tool gripping surface 11, for example, as shown, a hexagonal surface with facets 111 or flats. As shown in part A of [Fig.l], the end of the base nut 3 with its faceted crown 36 carries the hooking crown.
[0057] It should be noted that nut 4 allows loosening.
[0058] The first end piece 1 comprises a collar with a peripheral tool gripping surface 11, for example, a faceted hexagonal structure 111.
[0059] [Fig. 3] shows, in a side view and a perspective view, the structure of the base nut 3 and its various parts visible from the outside such as the sleeve 3a provided with the thread 31, on one side of the crown 36 with facets 361 carrying the attachment crown 33; this is followed by a smooth surface forming the bearing 34 and then by a threaded segment 35.
[0060] The hooking surface 33 is composed of identical facets 331, in the form of ramps leaving between them radial surfaces forming unscrewing notches 332.
[0061] [Fig.4] shows in its two views A and B the shape of the clamping member 4 which has a tool gripping surface 41 in the form of a faceted hexagonal nut 431. This member 4 is placed on the bearing surface 34. This position shows the face of the member 4 has a hooking crown 43 constituted by a succession of elements in the form of a ramp 431, with an opposite slope in the axial direction XX to that of the hooking crown 33 of the base nut 3. The projecting ends of the ramps 431 terminate in radial surfaces forming notches 432 cooperating with those of the ramps of the hooking crown 33 for unscrewing. When the clamping member 4 is turned clockwise, the sliding of the ramps 431 on the ramps 331 of the base nut 3 results in a thrust from right to left which drives the collar 21 of the second end piece 2 and pushes its sealing lip 211 against the bearing surface 13 of the first end piece 1.
[0062] The loosening of the connection can be done by contact of the notches 432 of the ramps 431.
[0063] According to an advantageous variant, the facets 361 of the crown 36 and that 431 of the tightening nut 4 are provided with marks, the association of which makes it possible to visually check that the connection 100 is properly tightened. It is particularly advantageous that in the tightened position of the connection 100, a facet 361 provided with a mark coincides with a facet 431 with a mark.
[0064] Figures 5 and 6 show a second embodiment of the connector 100', intended to join two pipes with a predetermined tightening torque (set torque CS).
[0065] This connection 100' of axis XX consists of a first end piece 1' fixed to a pipe and a second end piece 2' fixed to another pipe and comprising a base nut 3' and a clamping member 4'.
[0066] The base nut 3' fitted onto the second end piece 2' carries the clamping member 4' to drive the base nut 3' with the second end piece 2' and tighten the latter against the first end piece 1' with the set tightening torque CS.
[0067] The first sleeve-shaped end piece 1' is provided on its outer surface with a nut crown 11' forming a tool gripping surface, for example, a faceted hexagonal profile.
[0068] The first end piece 1' terminates at its other end with a thread 12' and a sealing surface 13' in a plane perpendicular to the axis XX.
[0069] In more detail, according to the exploded view of [Fig.6], the base nut 3' is screwed onto the end piece 1' by pulling and pressing the second end piece 2' by its collar 21' to press its lip-shaped sealing surface 211' against the sealing surface 13' of the first fitting 1'.
[0070] The base nut 3' is formed of two cylindrical parts 3'a, 3'b carrying a collar 36'. The part 3'a is screwed onto the end piece 1'.
[0071] The part 3b' covering the second end piece 2' has an internal diameter corresponding, within the clearance, to the external diameter of the end piece.
[0072] The junction of the two inner surfaces of the parts 3'a, 3'b forms a surface support 32' corresponding to the shape of the side 212' of the collar 21' against which the nut 3' pushes.
[0073] The base nut 3' has a collar 36' with a hooking crown 33' on one face and a face facing the face 43' of the clamping member 4' forms a bearing surface 6'; the bearing surfaces 6', 43' receive the spring 5' between them.
[0074] Before the collar 33', the nut has a smooth surface forming a bearing 34' to receive the clamping member 4' on one side; the clamping member 4' has a central orifice 41' to rest on the smooth bearing 34' and form a bearing surface 43' for the spring 5' which is a stack of Belleville washers with the diameter of the smooth bearing 34' to freely occupy the space between the sleeve of the clamping member 4' which forms the gripping surface 44' for example, a hexagonal surface.
[0075] The end of this sleeve, opposite the central orifice 41', forms a return 45'. The return 45' is a ring detached from the sleeve of the member 4' but which is secured in the assembled state to the clamping member 4' on the sleeve formed by the nut 3' beyond the collar 36'.
[0076] The ring 45' has a hooking ring 42' facing the hooking ring 33' of the collar 36' to cooperate with it in the direction of screwing the base nut 3' onto the thread 12' of the end piece when the clamping member 4' is driven in the screwing direction. This connection between the crowns 33742' when the clamping member is turned in the opposite direction is released and allows loosening.
[0077] The compression spring 5' formed by the stack of Belleville washers rests between the side 43' of the clamping member 4' and the side 6' of the collar 36'.
[0078] The non-detailed hooking surfaces of the hooking rings 33742' are ramps like those of the first embodiment ([Fig.3]). The tightening of the connection up to the set tightening torque CS takes place as in the first embodiment. The same applies to loosening.
[0079] Towards the end of tightening, the tightening nut 3' remains almost fixed, but the continuation of the screwing, more precisely of the pivoting of the tightening member 4' causes the ramps of the hooking ring 42' to rise on those of the hooking ring 33' so that the hooking ring and the ring 45' secured to the tightening member 4' pull the ring 45' towards the collar 36' and compress the spring 5'. When the torque exerted attempts to exceed the set torque CS, the ramps of the hooking ring 42' escape and slide on those of the hooking ring 33' which cuts off the transmission of the torque from the tightening member 3'.
[0080] The operation is the same as that of the first embodiment, except that the mechanism formed by the hooking rings 33742' is inside the clamping member 4' whereas in the first embodiment, it is outside.
[0081] The second embodiment is more compact and reduces the diameter of the assembly.
[0082] In the first embodiment, the compression spring 5 pushes the clamping member 4 to lock the hooking rings 33, 42 together, whereas in the second embodiment, the compression spring 5' pulls the clamping member 4' to lock the hooking rings 33742' together; in both cases, for the setpoint tightening torque CS, the ramps of the hooking rings slide over each other and compress the spring 65' until the screwing torque reaches the setpoint torque and compresses the compression spring 5, 5' sufficiently to open the connection between the hooking rings 33', 42'.
[0083] [Fig.7] shows a variant of the second embodiment relating to the shape of the contact surfaces of the two end pieces 1”, 2”. The references to [Fig.7] are limited to the differences, i.e. the contact surfaces 13” of the end piece 1” and 211” of the end piece 2”. The subassembly 100'a is unchanged.
[0084] The isometric view of [Fig.8] shows the connection 100' without the clamping member 4' revealing the Belleville washers of the spring 5', the collar 7' of the clamping member 3 and the ramps of the attachment rings 33', 42'.
[0085] In conclusion, the subject of the invention is a connector 100 for joining two pipes with a predetermined tightening torque comprising a first end piece 1 fixed to a first pipe C1, a second end piece 2 fixed to a second pipe C2 to be joined, the first end piece 1 provided with a tool gripping collar 11 being terminated by a thread 12 and a sealing surface 13, the second end piece 2 has a collar 21 terminated by a sealing surface 211 intended to be applied against the sealing surface 13 of the first end piece 1, a nut freely engaged on the second end piece 2 behind its collar 21 and screwed onto the threaded end 12 of the first end piece 1 by pulling the collar 21 to apply its sealing surface 211 against the sealing surface 13 of the first end piece 1 and to achieve sealing with a determined stress, connector characterized in that it comprises:
[0086] A) a base nut 3 in the form of a sleeve having: at one end, a thread 31 for screwing onto the threaded segment 12 of the first end piece 1, a bearing surface 32 following the thread 31 for pushing the collar 21 of the second end piece 2 and pressing its sealing surface 211 against the sealing surface 13 of the first end piece 1, a first attachment ring 33, a bearing 34,
[0087] B) a clamping member 4 coming onto the smooth bearing 34 to rotate freely there and having:
[0088] a second crown 42 intended to come against the first crown 33 of the base nut 3, and on its opposite face, a bearing surface 43,
[0089] C) a compression spring 5 applied against the bearing surface 43 of the clamping member 4,
[0090] D) a prestressing member 6 on the base nut 3 for pressing the clamping member 4 against the hooking ring 33 of the base nut 3 by means of the compression spring 5,
[0091] E) the second attachment ring 42 being connected to the first attachment ring 33 to transmit by contact, the tightening torque to the nut 3 screwing onto the first end piece 1 up to a set torque CS elastically tightening the two attachment surfaces 42 / 33.
[0092] In this connection, the first attachment ring 33 comprises a set of peripheral ramps 331 and the second attachment ring 42 comprises a set of peripheral ramps 421, the two rings 33, 42 are complementary so as to transmit the tightening torque exerted by the tightening nut up to the set torque CS.
[0093] According to one characteristic, the base nut 3 has a threaded segment 35 after the plain bearing 34 receiving the clamping member 4, the prestressing member 6 is screwed onto the threaded segment 35 to be secured to the base nut 3, the compression spring 5 is between the prestressing member 6 and the bearing face 43 opposite that of the second hanging crown 42.
[0094] According to another interesting characteristic, the base nut 3' has a collar 36' whose face 6' facing the face 43' of the clamping member 4' forms a bearing surface, the bearing surface 6' and the bearing surface 43' of the clamping member 4' receiving between them the compression spring 5',
[0095] - the other face 32' of the collar 36' carries the first attachment ring 33',
[0096] - the clamping member 4' having a return 45' and passing around the control spring pressure 5' and the collar 36' to come against the attachment crown 33' of the face 32' of the collar 36'.
[0097] According to another advantageous characteristic, the return 45' of the clamping member 4' is a ring removable from the clamping member 4', secured to this clamping member 4' after the clamping nut 3' has been placed on the smooth part 34' and the spring 5' has been placed in prestress between the face 43' and the face 6' of the collar 36'.
[0098] According to another advantageous characteristic, the sealing surface of the second end piece 2, 2' is a sealing lip 211 or a conical surface 211' and the sealing surface of the first end piece 1, 1' is a flat surface 13 or a conical surface 13'.
[0099] Advantageously, the clamping nut 4 is in the form of a cap nut whose tool-gripping surface 43 covers the compression spring element 5 and the preloading nut 6.
[0100] In particular, the compression spring element 5 is a Belleville spring.
[0101] According to another characteristic, the first end piece 1 has a tool gripping collar 11 provided with facets 111 and at least one of the facets comprises a tightening mark, the tightening member 4 comprises a tool gripping surface 43 provided with facets 31 of which at least one comprises a mark whose position at the end of tightening of the connection corresponds to the mark of the facet 111 of the collar of the first end piece.
[0102] NOMENCLATURE OF MAIN ELEMENTS
[0103] (without references with “prime” except exception)
[0104] 100 Connection
[0105] 100a Fitting subassembly
[0106] 1 First tip
[0107] 11 Tool gripping surface / tool gripping flange
[0108] 111 Facet
[0109] 12 Threaded segment
[0110] 13 Sealing surface [YES] 2 Second tip
[0112] 21 Collar
[0113] 211 Sealing lip / sealing surface
[0114] 212 Conical bearing surface
[0115] 3 Base nut
[0116] 3a Sleeve
[0117] 3 ' a Sleeve part
[0118] 3 ' b Sleeve part
[0119] 3b Sleeve
[0120] 3c Junction of sleeves 3a, 3b
[0121] 31 Tapping
[0122] 32 Support surface
[0123] 33 First hanging crown
[0124] 331 Ramps
[0125] 332 Unscrewing notches
[0126] 34 Plain bearing
[0127] 35 Threaded segment
[0128] 36 Faceted Crown
[0129] 361 Facet
[0130] 4 Clamping member
[0131] 41 Central orifice
[0132] 42 Second attachment crown
[0133] 421 Ramp
[0134] 43 Support surface
[0135] 431 Facets
[0136] 432 Unscrewing notches
[0137] 44 Tool gripping surface
[0138] 5 Compression spring
[0139] 51 Central orifice
[0140] 6 Preloading member / preloading nut
[0141] 61 Tapping
[0142] Cl Driving
[0143] C2 Driving
[0144] XX Axis of the connection
Claims
Claims
1. A connector (100) for joining two pipes with a predetermined tightening torque comprising - a first end piece (1) fixed to a first pipe (Cl), - a second end piece (2) fixed to a second pipe (C2) to be joined, - the first end piece (1) provided with a tool grip collar (11) being terminated by a thread (12) and a sealing surface (13), - the second end piece (2) has a collar (21) ending in a sealing surface (211) intended to be applied against the sealing surface (13) of the first end piece (1), - a nut freely engaged on the second end piece (2) behind its collar (21) and screwed onto the threaded end (12) of the first end piece (1) by pulling the collar (21) to apply its sealing surface (211) against the sealing surface (13) of the first end piece (1) and achieve sealing with a determined stress, connection characterized in that it comprises: A) a sleeve-shaped base nut (3) having: - at one end, a thread (31) for screwing onto the threaded segment (12) of the first end piece (1), - a bearing surface (32) following the tapping (31) for pushing the collar (21) of the second end piece (2) and pressing its sealing surface (211) against the sealing surface (13) of the first end piece (1), - a first attachment crown (33), - a landing (34), B) a clamping member (4) coming onto the plain bearing (34) to rotate freely there and having: - a second crown (42) intended to come against the first crown (33) of the base nut (3), and - on its opposite face, a support surface (43), C) a compression spring (5) applied against the bearing surface (43) of the clamping member (4), D) a pre-stressing member (6) on the base nut (3) for pressing the clamping member (4) against the hooking ring (33) of the base nut (3) by means of the compression spring (5), E) the second attachment ring (42) being connected to the first attachment ring (33) to transmit by contact, the tightening torque to the nut (3) screwing onto the first end piece (1) up to a setpoint torque (CS) elastically tightening the two gripping surfaces (42 / 33), exceeding the setpoint torque detaching the gripping surface (42) from the gripping surface (33) which is no longer driven.
2. Connection (100) according to claim 1, characterized in that the first attachment ring (33) comprises a set of peripheral ramps (331) and the second attachment ring (42) comprises a set of peripheral ramps (421), the two rings (33, 42) are complementary so as to transmit the tightening torque exerted by the tightening nut (4) up to the set torque (CS).
3. Connection (100) according to claim 1, characterized in that - the base nut (3) has a threaded segment (35) after the plain bearing (34) receiving the clamping member (4), - the prestressing member (6) is screwed onto the threaded segment (35) to be secured to the base nut (3), - the compression spring (5) is between the prestressing member (6) and the bearing face (43) opposite that of the second attachment ring (42).
4. Fitting (100) according to claim 1, characterized in that the base nut (3') has a collar (36') whose face (6') facing the face (43') of the clamping member (4') forms a bearing surface, the bearing surface (6') and the bearing surface (43') of the clamping member (4') receiving between them the compression spring (5'), - the other face (32') of the collar (36') carries the first attachment ring (33'), - the clamping member (4') having a return (45') and passing around the compression spring (5') and the collar (36') to come against the attachment ring (33') of the face (32') of the collar (36').
5. Connection (100) according to claim 4, characterized in that the return (45') of the clamping member (4') is a ring removable from the clamping member (4'), secured to this clamping member (4') after the clamping nut (3') has been placed on the smooth part (34') and the spring (5') has been placed in prestress between the face (43') and the face (6'). of the collar (36').
6. A fitting (100) according to claim 1, characterized in that the sealing surface of the second end piece (2, 2') is a sealing lip (211) or a conical surface (211') and the sealing surface of the first end piece (1, 1') is a flat surface (13) or a conical surface (13').
7. Connection (100) according to claim 1, characterized in that the clamping member (4) is in the form of a cap nut whose tool gripping surface (44) covers the compression spring (5) and the prestressing member (6).
8. A fitting (100) according to claim 1, characterized in that the compression spring element (5) is a Belleville spring or a Belleville spring stack.
9. A fitting (100) according to any one of claims 1 to 8, characterized in that the first end piece (1) has a tool gripping collar (11) provided with facets (111) and at least one of the facets has a tightening mark, the tightening member (4) has a tool gripping surface (43) provided with facets (31) of which at least one has a mark whose position at the end of tightening of the fitting corresponds to the mark of the facet (111) of the collar of the first end piece.