Rohrkupplung

Abstract

Arrangement of a pipe coupling and a pipe element (16), wherein the pipe coupling has the following elements: a connector body (14) along the axial direction of which a through-opening (12) is formed and which has an external thread (22) and a shaft section (32) at one end side, and a nut element (20) with an insertion opening (18) through which the pipe element (16) is inserted, and with an internal thread (42) for thread engagement with the external thread (22), wherein annular projections (40) are formed on an outer circumferential surface of the wave section (32) and wherein the pipe element (16) is gripped with a section with an increased diameter between the annular projections (40) and an inner circumferential surface of the nut element (20), characterized in that a first conical surface (34) is attached to one end of the shaft section (32), that a second conical surface (66), which extends outwards in a direction towards the external thread (22), is formed at one end of the shaft section (32) on a side near the external thread (22), that a third conical surface (68) is formed on an inner circumferential surface of the nut element (20) at a position facing the second conical surface (66), and that the pipe element (16) with enlarged diameter is held between the second conical surface (66) and the third conical surface (68).

Description

Background of the invention; Field of the invention

[0001] The present invention relates to a pipe coupling with which a pipe element, for example a hose or the like, can be connected to a fluid device in a liquid-tight or airtight manner in order to simplify the routing of a high-purity liquid or ultrapure water used in a production process, for example in the manufacture of semiconductor devices, the production of medical equipment and pharmaceuticals, food processing and processes in the chemical industry. State of the art

[0002] A pipe coupling of this type is known in which one end of a pipe element is held in a gap between a connector base body and a nut element that is screwed onto or to the connector base body.

[0003] For example, Japanese patent JP 3251196 B2 describes a pipe coupling in which an opening edge of a through-hole of the pipe coupling is arranged opposite a rear wall of a nut element. A stepped section, extending from a general outside diameter section to a section of the pipe element with an expanded diameter, is positioned in a gap between the rear wall and the opening edge of the through-hole. When the nut element of the pipe coupling is screwed in or out, the gap between the rear wall and the opening edge of the through-hole narrows, and a projecting ridge formed on the opening edge section presses the stepped section of the pipe element against the rear wall.Accordingly, gaps formed between the protruding burr, the stepped section of the pipe element, and the rear wall are closed, and a sufficiently firm contact between these elements is achieved. Furthermore, since the protruding burr bites into the stepped part of the pipe element, separation or unintentional removal of the pipe element is prevented.

[0004] DE 103 54 360 A1 describes a device for joining pipe elements. The device comprises a first element and a second element. The pipe element is pushed onto the first element. The first element has clamping sleeve sections. The second element is screwed onto the first element and deforms the clamping sleeve sections in a radial direction. This secures the pipe element and forms a tight seal with the device.

[0005] US 5,622,393 A describes a device for joining pipe sections. It describes several sawtooth-shaped elements that serve both as a seal and as a fixing element. The pipe section is slid onto the device. A nut that can be screwed onto the device secures the pipe section by means of several annular projections that deform the pipe section and press it against the sawtooth-shaped elements.

[0006] JP 2011 - 12691 A describes a device for connecting pipe elements. The device comprises a first element and a second element. The first element has a conical section and an annular section. A circumferential element is arranged on the annular section. A pipe element is slid onto the first element and secured by the second element, which is screwed onto the first element. The pipe element is thereby secured and sealed in the area of ​​the circumferential element. Furthermore, the pipe element is secured and sealed on the conical section by annular elements of the second element.

[0007] JP H06 - 159 574 A describes an arrangement for connecting pipe elements. The pipe element is slid onto a first element, which has a conical surface and an outer circumferential surface. An annular element is arranged on the outer circumferential surface. A second element is positioned over the pipe element mounted on the first element and screwed to the first element. The annular element presses the pipe element against the second element, thereby fixing and sealing it. Summary of the invention

[0008] However, if the nut element of the pipe coupling according to Japanese patent JP 3 251 196 B2 loosens due to external factors or a decrease in tension, the sealing capacity diminishes and fluid leakage can occur. Furthermore, there is a risk that the pipe element may detach or be unintentionally removed.

[0009] The present invention was made taking into account the problems mentioned above and aims to propose a pipe coupling in which the sealing capability is reliably maintained even in the event that a nut element loosens due to external factors or a reduction in load, and loosening or unintentional removal of the pipe is reliably prevented.

[0010] This problem is essentially solved by the invention through the features of claim 1.

[0011] Advantageous embodiments of the invention are set out in the dependent claims.

[0012] The pipe coupling according to the present invention comprises a connector body in which a through-opening is formed along an axial direction and which has an external thread and an elongated shaft section at one end, and a nut element with an insertion opening through which a pipe element is inserted and with internal threads formed therein, which are screwed to the external thread. Annular projections are formed on an outer circumferential surface of the shaft section, and the pipe element, the diameter of which is increased, is held between the annular projections and an inner circumferential surface of the nut element.

[0013] Since the pipe element is held between the annular projections and the inner circumferential surface of the nut element in the pipe coupling described above, the seal between the distal ends of the annular projections and the inner circumferential surface of the pipe element, as well as the holding force of the pipe element, are maintained even if the nut element loosens due to prolonged use. This results in a stable seal and reliably prevents the pipe element from loosening or being unintentionally removed.

[0014] In the pipe coupling described above, a first tapered, particularly conical, surface can be formed at one end of the shaft section. An annular locking section can be formed at an edge of the insertion opening near the first conical surface.

[0015] An inner wall surface of the pipe element with the expanded diameter can be pressed against the first tapered surface, and the annular locking section of the nut element can be positioned to rest against an outer wall surface of the pipe element with the expanded diameter. Since, according to this feature, the pipe element is held between the first tapered surface of the shaft section and the annular locking section of the nut element, the sealing capability is further improved and loosening of the pipe element can be prevented even more reliably.

[0016] Furthermore, a second tapered, particularly conical, surface, widening outwards in the direction of the external thread, can be formed at one end of the shaft section on a side near the external thread. A third tapered, particularly conical, surface can be formed on an inner circumferential surface of the nut element at a position facing the second conical surface. In this case, the pipe element with its increased diameter is held between the second conical surface and the third conical surface. Because, according to this feature, the pipe element is held between the second conical surface of the shaft section and the third conical surface of the nut element, loosening of the pipe element is reliably prevented.

[0017] Furthermore, projections that regulate the tightening force of the nut element on the connector body are preferably formed on an end face of the nut element. This feature prevents overtightening of the nut element.

[0018] Several curved grooves are preferably formed on the connector body opposite the projections, the multiple curved grooves having widths that allow the projections to be inserted into the grooves. The projections and the multiple curved grooves are preferably arranged on a common circumference (viewed in the axial direction). This feature of the invention allows a worker using the pipe coupling to easily ascertain that the nut element is sufficiently tightened.

[0019] Furthermore, annular projections can be formed on the inner circumferential surface of the nut element on the nut side, such that these projections press against the pipe element with its enlarged diameter towards recesses formed between adjacent annular projections. Since, according to this feature, the pipe element is held between the annular projections on the nut side and those on the shaft section, the sealing capacity and holding force can be further enhanced. Moreover, because the annular projections on the nut side and those on the shaft section are arranged alternately, deformation of the pipe element can be carried out smoothly.

[0020] Furthermore, annular projections can be formed on the inner circumferential surface of the nut element on the nut side, such that these projections press against the pipe element with the increased diameter in the direction of the annular projections. Since, according to this feature, the pipe element is held between the annular projections on the nut side and the annular projections formed on the shaft section, the sealing capacity and the holding force are further improved. Because the annular projections on the nut side and the annular projections formed on the shaft section are opposite each other, the force with which the pipe element is held is further increased.

[0021] With the pipe coupling according to the present invention, a stable sealing capability is achieved even in the event that the nut element loosens due to external factors or a reduction in load, and the falling off or unintentional removal of the pipe element is reliably prevented.

[0022] Further developments, advantages, and possible applications of the present invention will become even clearer from the following description in conjunction with the accompanying drawings, in which preferred embodiments of the present invention are illustrated by way of example. All features described and / or illustrated, individually or in any combination, constitute the subject matter of the invention, irrespective of their compilation in the claims or their cross-references. Brief description of the drawings Fig. Figure 1 is a longitudinal section along an axial direction of a pipe coupling not according to the present invention; Fig. Figure 2 is an enlarged longitudinal section of a section A of the pipe coupling according to Fig. 1; Fig. Figure 3 is a perspective exploded view of the pipe coupling according to Fig. 1; Fig. Figure 4 is a longitudinal section along an axial direction of a pipe coupling according to an embodiment of the present invention; Fig. 5 is a section along line VV of the pipe coupling according to Fig. 4; Fig. Figure 6 is an enlarged longitudinal section of section B of the pipe coupling according to Fig. 4; Fig. Figure 7 is an enlarged partial longitudinal section through a pipe coupling according to a second embodiment of the present invention; Fig. Figure 8 is an enlarged partial longitudinal section through a pipe coupling according to a third embodiment of the present invention; and Fig. Figure 9 is an enlarged partial longitudinal section through a pipe coupling according to a fourth embodiment of the present invention. Description of preferred embodiments

[0023] Preferred embodiments of pipe couplings according to the present invention are described in detail below with reference to the accompanying drawings.

[0024] A pipe coupling 10, which is not designed according to the invention, is described with reference to the Fig. 1 to 3 described.

[0025] The pipe coupling 10 comprises a substantially cylindrical coupling or connector body 14 with a through-opening 12, which serves as a fluid passage and is formed in a straight line along an axial direction, and an insertion opening 18, which has a circular cross-section and into which a pipe (pipe element) 16 is inserted. The pipe coupling 10 also comprises a nut element 20, which holds the pipe 16 by being placed on the connector body 14. The connector body 14, the nut element 20, and the pipe 16 can be made of plastic, in particular a fluoropolymer.

[0026] The connector body 14 has a first external threaded section 22 with threads having a substantially trapezoidal cross-section on its outer circumferential surface near one end of the connector body 14, and a second external threaded section 24 with threads having a serrated cross-section on the outer circumferential surface of another end of the connector body 14. At one end of the first external threaded section 22 near the second external threaded section 24, an annular projection 28 is formed, which projects radially outwards over an annularly stepped portion 26 formed by a flat surface circumscribing the connector body 14, and a polygonal portion 30 is formed between the annular projection 28 and the second external threaded section 24.The polygonal part 30 has a hexagonal cross-section so that a tool, for example a wrench (not shown) or the like, can engage with the connector body 14.

[0027] At one end of the connector body 14, a small-diameter shaft section 32 is formed. The small-diameter shaft section 32 has a through-opening 12 extending axially therein. A section 16a with an enlarged diameter of the tube 16 can be placed onto the shaft section 32. A first conical surface 34, the diameter of which gradually widens in the direction in which the tube 16 is inserted, is provided at the end of the shaft section 32. A small annular projection 36, which has the cross-sectional shape of a rafter or sawtooth, is formed on the first conical surface 34 such that it projects from the first conical surface 34 (see Figure 1). Fig. 2) In a transition area between the first conical surface 34 and the through-opening 12, a first chamfered or rounded section 38 is formed to prevent the occurrence of liquid accumulation.

[0028] Several annular projections 40, which abut an inner wall surface of section 16a with an increased diameter of the tube 16, are provided on an outer circumferential surface of the shaft section 32 and transition into the first conical surface 34. The cross-section of the circumference of the several annular projections 40 is semicircular. Several annular projections 40 are arranged side by side in the axial direction, with defined distances between them. In the Fig. In the example shown, five such annular projections are provided. The height of the annular projections 40 is essentially the same. Furthermore, the annular projections 40 do not necessarily have to be provided multiple times; it is also possible to provide only one such annular projection 40.

[0029] An internal threaded section 42, which can be screwed onto the first external threaded section 22 of the connector body 14, is formed on an inner circumferential surface of the nut element 20. An annular projection 44 is formed on an outer surface of the nut element 20 adjacent to the insertion opening 18. The projection 44 serves a protective function for the tube 16 by preventing it from breaking or buckling as it protrudes outwards from the insertion opening. The outward widening diameter of the distal end of the projection 44 simplifies the insertion of the tube 16.

[0030] An annular locking section 46, designed as an acute angle in cross-section, is formed on an inner side of the nut element 20 next to the insertion opening 18. The annular locking section 46 engages with the inclined outer circumferential surface of the tube 16 and presses the tube 16 against the first conical surface 34 of the connector body 14 when the nut element 20 is tightened on the connector body 14.

[0031] An annular press section 48 is formed on an inner circumferential surface of the nut element 20 between the annular locking section 46 and the internal threaded section 42. This press section is pressed against an outer wall surface of the section 16a with an increased diameter of the tube 16. The annular press section 48 has a cylindrical surface with a substantially uniform inner diameter. A second chamfered or rounded section 50, having a defined radius of curvature, is formed at one end of the annular press section 48 near the internal threaded section 42. A defined gap or space is provided between the annular press section 48 and all annular projections 40 of the shaft section 32 of the connector body 14.The distances between the respective ends of the annular projections 40 and the annular press section 48 are essentially equivalent to each other, so that, as will be described later, at the time when the section 16a with enlarged diameter of the tube 16 is formed, the distance between the annular projections 40 and the annular press section 48 is less than the thickness of the section 16a with enlarged diameter.

[0032] Accordingly, by tightening the nut element 20 on the connector body 14, the section 16a with the expanded diameter of the tube 16 is held and gripped between the several annular projections 40 and the annular press section 48. This keeps the inner wall surface of the section 16a with the expanded diameter in close contact with the several annular projections 40, and a first seal is formed between the respective distal ends of the annular projections 40 and the inner wall surface of the section 16a with the expanded diameter.

[0033] By increasing the tightness with which the nut element 20 is tightened onto the connector body 14 (tightening depth), the tube 16 is engaged between the annular locking section 46 of the nut element 20 and the first conical surface 34 of the shaft section 32 of the connector body 14. This holds the first conical surface 34 of the shaft section 32 in close contact with the inclined inner wall surface of the tube 16 by means of the annular locking section 46, and a second seal is formed between the first conical surface 34 of the shaft section 32 and the inclined inner wall surface of the tube 16.

[0034] The pipe connector 10 is essentially constructed as described above. Next, the operating principles and advantages of the pipe connector 10 will be described.

[0035] First, the tube 16 is inserted along the insertion opening 18 of the nut element 20, so that the end of the tube 16 is positioned on the inside of the nut element 20 to a specified length.

[0036] Next, the shaft section 32 of the connector body 14 is inserted into the nut element 20 from the side of the internal thread section 42, and the internal thread section 42 of the nut element 20 is screwed along the first external thread section 22 of the connector body 14.

[0037] When the nut element 20 is tightened, the tube 16 expands in diameter from its distal end along the first conical surface 34 of the shaft section 32. Furthermore, the annular press section 48 of the nut element 20 and the shaft section 32 of the connector body 14 gradually overlap in the axial direction, with several of the multiple annular projections 40 of the shaft section 32 being positioned opposite the annular press section 48 from the side closest to the first inclined surface 34. The annular press section 48 facing the annular projections 40 presses the outer wall surface with the expanded diameter of the tube 16 against the annular projections 40.Specifically, after its diameter has been expanded, the tube 16 is deformed, being compressed from the side closest to the first inclined surface 34, and the inner wall of the expanded-diameter section 16a is compressed in its areas that are in contact with the respective annular projections 40. On both sides of these areas, the inner wall expands diametrically inwards and is inserted into the spaces between the adjacent annular projections 40.

[0038] When this is done, the section 16a with the enlarged diameter of the tube 16 is formed and the section 16a with the enlarged diameter is held between the several annular projections 40 of the shaft section 32 and the annular press section 48 of the nut element 20. Accordingly, a seal, namely the first seal, is achieved between the distal ends of the several annular projections 40 and the inner wall surface of the tube 16.

[0039] When the nut element 20 is tightened further and the distal end of the nut element 20 comes into contact with the annular stepped section 26 of the connector body 14, the annular locking section 46 of the nut element 20 engages with the inclined outer circumferential surface of the tube 16 and presses the tube 16 against the first conical surface 34 of the connector body 14. This holds the tube 16 between the first conical surface 34 of the shaft section 32 and the annular locking section 46 of the nut element 20, and a seal, namely the second seal, is formed between the first conical surface 34 of the shaft section 32 and the inclined inner wall surface of the tube 16.

[0040] Once the fastening of the nut element 20 is complete, a strong sealing capability can be achieved accordingly, since a seal is achieved by both the first seal and the second seal.

[0041] Even if a force is applied to pull out the tube 16 in a direction opposite to the direction in which the tube 16 was inserted, the tube 16 can still be reliably prevented from being pulled out of the connector body 14. This is because the tube 16 is held between the annular press section 48 of the nut element 20 and the respective annular projections 40 of the shaft section 32 of the connector body 14, and also between the annular locking section 46 of the nut element 20 and the first conical surface 34 of the shaft section 32 of the connector body 14. Furthermore, the small annular projection 36, which is formed on the first conical surface 34, bites into the inner wall surface of the tube 16, preventing the tube 16 from loosening or being unintentionally removed.

[0042] Even if the fastening force decreases due to prolonged use over an extended period and the nut element 20 detaches from the connector body 14, the respective annular projections 40 of the shaft section 32 of the connector body 14 are held at a defined distance and in opposition to the annular press section 48 of the nut element 20. Since a state is maintained in which the section 16a with the increased diameter of the tube 16 is held between the annular press section 48 and the several annular projections 40, at least the sealing force at the first seal is maintained and a stable sealing capability can be continuously achieved.Furthermore, the force that holds the pipe 16 between the respective annular projections 40 and the annular press section 48 is maintained, so that there is no danger of the pipe 16 separating from the connector body 14.

[0043] A pipe coupling 60 according to an embodiment of the invention is now described with reference to the Fig. Sections 4 to 6 are described. Those components that are the same as those of the pipe connector 10 described above are designated with the same reference numerals. In this respect, reference is made to the description above.

[0044] The pipe coupling 60 according to the embodiment differs from the pipe coupling 10 in that the pipe coupling 60 has means for limiting the tightness with which the nut element 20 is tightened (tightening depth) and that a worker using the pipe coupling 60 is informed when a specified tightening depth has been reached. Furthermore, the pipe coupling 60 has means for further gripping the pipe 16 at a distal end of the section 16 with an increased diameter.

[0045] On an end face of the nut element 20, adjacent to the internal threaded section 42, several cylindrical, post-shaped end face projections 62 are integrally formed. The end face projections 62 extend a defined length from the end face of the nut element 20. On the other hand, several curved grooves 64 are provided on an annular projection 28 of the connector body 14, opening onto the annularly stepped section 26. The multiple curved grooves 64 each have the same shape and a width greater than the diameter of each of the end face projections 62. They are arranged uniformly around the entire circumference of the connector body 14. Viewed along the axial direction, the respective end face projections 62 are positioned on the same circumference as the circumference on which the multiple curved grooves 64 are arranged.In the illustrated example, two end-surface projections 62 are formed on diametrically opposite sides, while six curved grooves 64, each with a length corresponding to a central angle of approximately 45°, are provided. Furthermore, the end-surface projections 62 need not necessarily be multiple; a single end-surface projection 62 may also be provided.

[0046] At one end of the shaft section 32, on a side near the first external threaded section 22 of the connector body 14, a second conical surface 66 is formed, which spreads outwards in one direction towards the first external threaded section 22. A third conical surface 68, which spreads outwards in one direction towards the internal threaded section 42, is formed between the internal threaded section 42 and the annular press-fit section 48 of the nut element 20. The second conical surface 66 of the connector body 14 and the third conical surface 68 of the nut element 20 have substantially the same angle of inclination, so that when the nut element 20 is tightened onto the connector body 14, both conical surfaces face each other, with a defined gap between them.

[0047] The pipe coupling 60 according to the present embodiment is essentially constructed as described above. Next, the operating principles and advantages of the pipe coupling 60 will be explained.

[0048] First, the tube 16 is inserted along the insertion opening 18 of the nut element 20. Then, the shaft section 32 of the connector body 14 is inserted on the side of the internal thread section 42 of the nut element 20, and the internal thread section 42 of the nut element 20 is rotated and screwed along the first external thread section 22 of the connector body 14.

[0049] When the nut element 20 is tightened, the tube 16 expands in diameter from its distal end, and the annular press section 48 of the nut element 20 and the shaft section 32 of the connector body 14 gradually overlap in the axial direction. Accordingly, the section 16a with the expanded diameter of the tube 16 is engaged between the respective annular projections 40 of the shaft section 32 of the connector body 14 and the annular press section 48 of the nut element 20.

[0050] As the nut element 20 is tightened further, the respective end-surface projections 62, which are formed on the end surface of the nut element 20, move towards the annular stepped section 26. Combined with the screwing movement of the nut element 20, and after the respective end-surface projections 62 have moved past the flat surface of the stepped section 26 and entered the respective curved grooves 64 (viewed along the axial direction), the respective end-surface projections 62 collide with the inner side walls of the respective curved grooves 64 when the respective end-surface projections 62 reach positions where they are about to exit the respective curved grooves 64. This regulates further tightening of the nut element 20 beyond this position.The operator is informed that the tightening of the nut element 20 has reached a specified level by the sound and the feeling of resistance when the end surface projections 62 collide with the inner side surfaces of the curved grooves 64. In other words, the nut element 20 is sufficiently tightened.

[0051] Essentially at the same time as the respective end-surface projections 62 collide with the inner side surfaces of the respective curved grooves 64, or at a time shortly before this collision, the annular locking section 46 of the nut element 20 engages with the inclined outer circumferential surface of the tube 16. The tube 16 is then pressed towards the side of the first conical surface 34 of the connector body 14. Furthermore, the distal end face of the section 16a with the increased diameter of the tube 16 is engaged between the second conical surface 66 of the connector body 14 and the third conical surface 68 of the nut element 20.

[0052] When the tightening of the nut element 20 has been carried out appropriately, the tube 16 is engaged between the respective annular projections 40 of the shaft section 32 of the connector body 14 and the annular press section 48 of the nut element 20, between the first conical surface 34 of the shaft section 32 of the connector body 14 and the annular locking section 46 of the nut element 20, and between the second conical surface 66 of the connector body 14 and the third conical surface 68 of the nut element 20. Even if a force is applied to pull the tube 16 out in a direction opposite to the direction in which the tube 16 was inserted, this reliably prevents the tube 16 from being pulled out of the connector body 14.

[0053] A pipe coupling 10 according to a second embodiment is now referred to in relation to the Fig. 7 described. The pipe coupling according to the present embodiment differs from the pipe coupling 60 according to the first embodiment only with regard to a part of the structure of the annular press section 48 of the nut element 20. Fig. Figure 7 is a view corresponding to the partially enlarged longitudinal section of the pipe coupling 60 according to the second embodiment, which is shown in Fig. 6 is shown.

[0054] Several annular projections 80 are formed on the nut-side of the annular press section 48 of the nut element 20. These projections bear against the outer wall surface of the section 16a with the increased diameter of the tube 16. The annular projections 80 on the nut side have essentially the same height and a semicircular cross-section and are arranged along the axial direction with defined intervals between them. The annular projections 80 on the nut side are smaller than the annular projections 40 formed on the shaft section 32 of the connector body 14. When the nut element 20 is tightened onto the connector body 14, the respective annular projections 80 on the nut side are positioned centrally between an annular projection 40 formed on the shaft section 32 and an adjacent annular projection 40.

[0055] When the section 16a with the increased diameter of the tube 16 is inserted over the shaft section 32 of the connector body 14 and the nut element 20, which is loosely placed on the tube 16, is tightened, the section 16a with the increased diameter of the tube 16 is gripped between the multiple annular projections 40 formed on the shaft section 32 and the multiple annular projections 80 on the nut side formed on the annular press section 48. Therefore, the seal between the multiple annular projections 40 and the inner wall surface of the tube 16 is further increased, and the force with which the tube 16 is held is further improved.

[0056] Because the multiple annular projections 40 and the multiple nut-side annular projections 80 are arranged alternately, the section 16a with the increased diameter of the tube 16 bulges radially inwards on both sides of each of the annular projections 40, being pressed through the nut-side annular projections 80, and is thus deformed so that it enters the spaces between the adjacent annular projections 40. This simply deforms the section 16a with the increased diameter of the tube 16 into a corrugated shape.

[0057] Next, a pipe coupling according to a third embodiment is described with reference to Fig. 8 described. The pipe coupling according to the present embodiment differs from the pipe coupling 60 according to the first embodiment and from the pipe coupling according to the second embodiment only with regard to a part of the structure of the annular press section 48 of the nut element 20. Fig. Figure 8 is a view corresponding to the partially enlarged longitudinal section through the pipe coupling 60 according to the first mixing shape, which is shown in Fig. 6 is shown.

[0058] Several annular projections 90 are formed on the nut-side of the annular press section 48 of the nut element 20. These projections bear against the outer wall surface of the section 16a with the increased diameter of the tube 16. The annular projections 90 on the nut side have essentially the same height, a semicircular cross-section, and are arranged along the axial direction at defined intervals. The annular projections 90 on the nut side are smaller than the annular projections 40 formed on the shaft section 32 of the connector body 14. When the nut element 20 is tightened onto the connector body 14, the annular projections 90 on the nut side are positioned exactly opposite each of the annular projections 90 formed on the shaft section 32.

[0059] When the section 16a with the expanded diameter of the tube 16 is placed onto the shaft section 32 of the connector body 14 and the nut element 20, which is loosely placed on the tube 16, is tightened, the section 16a with the expanded diameter of the tube 16 is gripped between the multiple annular projections 40 formed on the shaft section 32 and the multiple annular projections 90 on the nut side formed on the annular press section 48. This further improves the seal between the multiple annular projections 40 and the inner wall surface of the section 16a with the expanded diameter of the tube 16, and further increases the force with which the tube 16 is held.

[0060] Since the respective annular projections and the respective nut-side annular projections 90 are arranged in positions that are directly opposite each other, the force with which the tube 16 is held by the respective annular projections 40 and the respective nut-side annular projections 90 is further increased.

[0061] Next, a pipe coupling according to a fourth embodiment is described with reference to Fig. 9 described. The pipe coupling according to the present embodiment differs from the above-described, non-inventive pipe coupling only with regard to parts of the structure of the shaft section 32 of the connector body 14 and the annular press section 48 of the nut element 20. Fig. Figure 9 is a view corresponding to the partially enlarged longitudinal section through the pipe coupling 10, which is shown in Fig. 2 is shown.

[0062] Several annular projections 92, which abut an inner wall surface of the section with the enlarged diameter of the tube 16, are formed on an outer circumferential surface of the shaft section 32 adjacent to the first inclined surface 34. Each of the annular projections 92 has a sawtooth cross-section and comprises, on one side near the distal end of the shaft section 32, an inclined surface that has a slightly increasing angle relative to the axial direction of the shaft section 32. It also has an inclined surface formed by a steeply increasing angle relative to the axial direction of the shaft section 32 on a side furthest from the distal end of the shaft section 32. Thus, the several annular projections 92 together have a sawtooth shape.Furthermore, the heights of the several ring-shaped projections 92 increase as their positions move further away from the distal end of the wave section 32.

[0063] The annular press section 48, which abuts the outer wall surface of the section with the enlarged diameter of the tube 16, comprises a conical surface 94, the diameter of which widens towards the side of the second chamfered or rounded section 50, and a cylindrical surface 96 with a uniform inner diameter. Fig.A line runs along 9, connecting the tips of the several annular projections 92, essentially parallel to the line defining the conical surface 94. When the nut element 20 is tightened onto the connector body 14, those of the several annular projections 92 that are closest to the distal end of the shaft section 32 are opposite the cylindrical surface 96, although the majority of the several annular projections 92 are opposite the conical surface 94.

[0064] Since the section with increased diameter of the tube 16 is gripped between the sawtooth-shaped annular projections 92, which are formed on the shaft section 32 of the connector body 14, and the annular press section 48 of the nut element 20, the force with which the tube 16 is held is increased in particular.

[0065] The pipe coupling according to the present invention is not limited to the embodiments described above. It is understood that various alternatives or additional designs can be provided without departing from the scope of the invention. For example, the annular projections 80, 90 on the nut side of the nut element 20 can be modified to project in a helical or spiral shape. Furthermore, the section 16a with an increased diameter of the pipe 16 can be formed by a separately provided press die after the pipe 16 has been inserted through the insertion opening 18 of the nut element 20, but before the nut element 20 has been placed onto the connector body 14.

Claims

[1] Arrangement consisting of a pipe coupling and a pipe element (16), wherein the pipe coupling has the following elements: a connector body (14) along the axial direction of which a through-opening (12) is formed and which has an external thread (22) and a shaft section (32) at one end side, and a nut element (20) with an insertion opening (18) through which the pipe element (16) is inserted, and with an internal thread (42) for thread engagement with the external thread (22), wherein annular projections (40) are formed on an outer circumferential surface of the wave section (32) and wherein the pipe element (16) is gripped with a section with an increased diameter between the annular projections (40) and an inner circumferential surface of the nut element (20), characterized by , that a first conical surface (34) is attached to one end of the wave section (32), that a second conical surface (66), which extends outwards in a direction towards the external thread (22), is formed at one end of the shaft section (32) on a side near the external thread (22), that a third conical surface (68) is formed on an inner circumferential surface of the nut element (20) at a position facing the second conical surface (66), and that the pipe element (16) with enlarged diameter is held between the second conical surface (66) and the third conical surface (68). [2] Arrangement according to claim 1, characterized by, that an annular locking section (46) is formed on an edge of the insertion opening (18) near the first conical surface (34), that an inner wall surface of the pipe element (16) with an enlarged diameter is pressed against the first conical surface (34), and that the annular locking section (46) rests against an outer wall surface of the pipe element (16) with an enlarged diameter. [3] Arrangement according to any one of the preceding claims, characterized by , that projections (62) which regulate the strength of the tightening of the nut element (20) relative to the connector body (14) are formed on an end surface of the nut element (20). [4] Arrangement according to claim 3, characterized by, that several curved grooves (64) are formed on the connector body (14) opposite the projections (62), that the several curved grooves (64) have widths that allow the projections to be inserted into the grooves (64), and that the projections (62) and the several curved grooves (64) are provided on a common circumference as seen in the axial direction. [5] Arrangement according to any one of the preceding claims, characterized by , that annular projections (80) are formed on the inner circumferential surface of the nut element (20), and that the nut-side annular projections (80) press the pipe element (16) with enlarged diameter in the direction of recesses formed between adjacent annular projections (40). [6] Arrangement according to any one of claims 1 to 4, characterized by, that annular projections (90) on the nut side are formed on the inner circumferential surface of the nut element (20), and that the annular projections (90) on the nut side press the pipe element (16) with enlarged diameter towards the annular projections (40).

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