Connection arrangement for a pipe fitting

Abstract

Connection arrangement comprising a pipe section (1), a connecting body (2) and a union nut (3) for connecting the pipe section (1) to the connecting body (2), wherein - the connecting body (2) has a first cylindrical bore (21) for receiving the pipe section (1) and a second cylindrical bore (22) with a reduced diameter adjoining the first cylindrical bore (21), wherein a contact surface (23) is provided on the end face transversely to the first cylindrical bore (21), - the union nut (3) has a first cylindrical bore (31) for receiving the pipe section (1), to which a second bore (32) with an increased diameter is connected, wherein an internal thread (33) is arranged for screwing onto an external thread (24) arranged for this purpose on the connecting body (2), - the pipe section (1) has a circumferential outwardly projecting section (11) spaced apart from its end, characterized in that the second bore (32) of the union nut (3) with increased diameter is cylindrical, thereby forming a stop surface (34) positioned transversely to it, and that the outwardly projecting section (11) is formed by a folding of the pipe section (1) and has two parallel, opposing contact surfaces for contact with the stop surface (34) of the union nut (3) on one side and with the end face contact surface (23) of the connecting body (2) on the other, between which the section (11) is clamped in the assembled state.

Description

[0001] The invention relates to a connecting arrangement for connecting a cylindrical, thin-walled pipe section to a connecting body according to claim 1.

[0002] Pipe fittings can essentially be divided into three types: cutting ring fittings, pipe forming system fittings, and compression fittings. In many hydraulic applications today, traditional cutting ring fittings are being replaced by pipe forming systems, as described, for example, in EP 2 162 662 B1. As with a cutting ring system, a 45° cone is formed on the pipe, which interacts with a 45° bevel in the adjacent nut to fix the pipe in the fitting body. Since the well-known pipe forming system is a general hydraulic system that is also used in high-pressure applications, it is designed for thick-walled hydraulic pipes. The stability of these pipes allows the required, sometimes high, torques to be applied to ensure the function and tightness of the fitting.

[0003] During the manufacture of railcars and carriages for trains, trams, and subways and commuter trains, long pipelines are installed beneath and within the railcars and carriages. These pipelines are required to supply and transmit fluids to the braking, air conditioning, and hydraulic systems within a train. The pipelines used extensively for braking systems in particular are operated with air at a low pressure of 12 bar. A growing requirement in the equipment of vehicles, especially railway carriages, is weight reduction to save energy. Due to the low pressure, the use of very thin-walled pipes is therefore possible. Cutting ring and clamping ring bolts are primarily used in this area.The tube forming system in its known design has only limited stability due to the very small wall thicknesses, which leads to an undesirable high degree of compliance when applying the torques.

[0004] This is where the present invention comes in. The invention is based on the object of providing a connecting assembly for connecting a cylindrical, thin-walled pipe section to a connecting body, which is designed to minimize weight and in which compliance when torque is applied is avoided. According to the invention, this object is achieved by a connecting assembly having the features of claim 1.

[0005] The invention provides a connecting arrangement for connecting a cylindrical, thin-walled pipe section to a connecting body, which is designed to be lightweight and in which compliance when torque is applied is avoided. Because the outwardly projecting section is formed by a fold in the pipe section, whereby the union nut has a 90° contact surface - in contrast to the 45° contact surface present in the prior art - good support of the pipe is achieved, which is clamped with its outwardly projecting section between this contact surface and the front contact surface of the connecting body. The connecting body can be designed either as a connecting piece for two pipes or in the form of a T-piece. The connections for the further (when designed as a connecting piece) orThe other pipes (when designed as T-pieces) can be designed in the same way or in a known way, for example as a threaded connection.

[0006] In a further development of the invention, the outwardly projecting section (11) is arranged orthogonally to the pipe axis of the pipe piece, wherein the transition between the outer circumferential surface of the pipe piece and the contact surface of the outwardly projecting section facing the stop surface of the union nut has a circular arc-shaped cross-section with a radius R, wherein the transition from the first bore to the enlarged-diameter second bore has a circular arc-shaped cross-section with a radius substantially corresponding to the radius R. This achieves a flat, continuous contact between the contact surface of the outwardly projecting section and the pipe section adjoining it, thereby further increasing the stability of the connection. A particularly good flat contact can be achieved by selecting the largest possible radius of the transition. This avoids, in particular, notch effects.

[0007] In an embodiment of the invention, the connecting body (2) has a conical bore extending from its contact surface, which is adjoined by the first cylindrical bore and aligned with it. Advantageously, a space is defined between the pipe section and the conical bore, in which a preferably soft-sealing sealing ring is arranged. The oblique guidance of the conical bore ensures uniform compression of the sealing ring during assembly, thereby achieving a uniform sealing effect.

[0008] In a further embodiment of the invention, the union nut has an outer polygonal section, in particular an outer hexagonal section, which is adjoined by a hollow cylindrical guide section with a reduced outer diameter. The outer polygonal section serves as a tool engagement point. The adjoining, reduced-diameter hollow cylindrical guide section provides extended guidance and thus improved support for the pipe section being held, while simultaneously reducing weight.

[0009] Further developments and refinements of the invention are specified in the remaining subclaims. An embodiment of the invention is illustrated in the drawings and described in detail below. They show: Fig. 1: the schematic representation of a connection arrangement in longitudinal section and Fig. 2: the detailed view of section A in Fig. 1.

[0010] The connection arrangement chosen as an example is based on a pipe screw connection of a thin-walled pipe section with a connecting body according to Fig. 1 explained.

[0011] The connection arrangement comprises a thin-walled pipe section 1, a connecting body 2 and a union nut 3 for connecting the pipe section 1 to the connecting body 2.

[0012] The pipe section 1 is hollow-cylindrical and has, adjacent to its end, a circumferential outwardly projecting section 11 which is formed by a folding of the pipe material (cf. Fig. 2). The transitions on both sides of the outwardly projecting section 11 to the outer surface of the pipe section 1 each have an arcuate shape.

[0013] The connecting body 2 is essentially hollow-cylindrical and has a first cylindrical bore 21, which is adjoined by a second cylindrical bore 22 of reduced diameter, forming a stop 26. On the end face of the connecting body 2, there is a contact surface 23 that is positioned transversely to the first cylindrical bore 21. The contact surface 23 is delimited by a conical bore 25 that merges into the first cylindrical bore 21 and is aligned with it. At the end, the connecting body 2 has an external thread 24 in the area of ​​the conical bore 25.

[0014] The union nut 3 is essentially designed as a hexagon nut and has a cylindrical bore 31 for receiving the pipe section 1, which is adjoined by a second cylindrical bore 32, which has a larger inner diameter than the first bore 31, thereby forming a stop surface 34 positioned transversely to the second bore 32. The transition from the stop surface 34 to the first bore 31 is rounded, forming an arcuate cross-section with a radius R.

[0015] In the second cylindrical bore 32, an internal thread 33 is arranged for screwing onto the external thread 24 of the connecting body 2.

[0016] The hexagonal section 35 of the union nut 3 is followed by a substantially hollow-cylindrical guide section 36 through which the first bore 31 is guided and whose outer diameter is smaller than the outer diameter of the hexagonal section 35.

[0017] A sealing ring 4 is pushed onto the end of the pipe section 1, which rests laterally against the outwardly projecting section 11. The pipe section 1, thus provided with the sealing ring 4, is pushed into the first cylindrical bore 21 of the connecting body, with the outwardly projecting section 11 resting against the contact surface 23 of the connecting body 2. In this position, the sealing ring 4 is arranged in a sealing manner in the space defined between the pipe section 1 and the conical bore 25 of the connecting body 2.

[0018] The union nut 3 is pushed onto the pipe section 1, with the stop surface 34 resting against the outwardly projecting portion 11 of the pipe section 1. The pipe section 1 is guided in the guide section 36 of the union nut. The union nut 3 is screwed with its internal thread 33 onto the external thread 24 of the connecting body 2, whereby the outwardly projecting portion 11 of the pipe section 1 is clamped between the contact surface 23 of the connecting body 2 and the stop surface 34 of the union nut 3.

[0019] The radius R of the transition between the stop surface 34 of the union nut and the first bore 31 is selected such that it essentially corresponds to the radius R of the transition between the outwardly projecting section 11 and the outer surface of the pipe section 1, as a result of which the pipe section 1 also rests against the union nut 3 in this area. The pipe section 1 is thus well supported within the union nut 3 and also by the guide section 36. This achieves maximum support for the thin-walled pipe section 1 and thus optimizes its ability to withstand alternating bending loads. For this purpose, the outer diameter of the pipe section 1 essentially corresponds to the inner diameter of the first cylindrical bore 31 of the union nut, which preferably essentially corresponds to the inner diameter of the first cylindrical bore 21 of the connecting piece 2 into which it is inserted.

[0020] In this way, a solid, massive transition is formed between the union nut 2, the folded pipe 1 and the connecting body 2. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 162 662 B1

[0002]

Claims

[1] Connection arrangement, comprising a pipe section (1), a connecting body (2) and a union nut (3) for connecting the pipe section (1) to the connecting body (2), wherein - the connecting body (2) has a first cylindrical bore (21) for receiving the pipe section (1) and a second cylindrical bore (22) of reduced diameter adjoining the first cylindrical bore (21), wherein a contact surface (23) is provided on the end face which is arranged transversely to the first cylindrical bore (21), - the union nut (3) has a first cylindrical bore (31) for receiving the pipe section (1), which is followed by a second bore (32) of enlarged diameter, wherein an internal thread (33) is arranged for screwing onto an external thread (24) arranged for this purpose on the connecting body (2), - the pipe section (1) has a circumferential outwardly projecting section (11) spaced from its end, characterized bythat the enlarged-diameter second bore (32) of the union nut (3) is cylindrical, whereby a stop surface (34) is formed transversely thereto, and that the outwardly projecting section (11) is formed by a fold of the pipe section (1) and has two mutually parallel, opposite contact surfaces for contact with the stop surface (34) of the union nut (3) on the one hand and with the frontal contact surface (23) of the connecting body (2) on the other hand, between which the section (11) is clamped in the assembled state. [2] Connecting arrangement according to claim 1, characterized byin that the outwardly projecting section (11) is arranged orthogonally to the pipe axis of the pipe piece (1), wherein the transition between the outer circumferential surface of the pipe piece (1) and the contact surface of the outwardly projecting section (11) facing the stop surface (34) of the union nut (3) has a circular arc-shaped cross-section with a radius R, wherein the transition of the first bore (31) to the diameter-enlarged second bore (32) has a circular arc-shaped cross-section with a radius substantially corresponding to the radius R. [3] Connecting arrangement according to claim 1 or 2, characterized by that the connecting body (2) has a conical bore (25) extending from its contact surface (24), to which the first cylindrical bore (21) is connected and with which it is aligned. [4] Connecting arrangement according to claim 3, characterized bythat between the pipe section (1) and the conical bore (25) a space is defined in which a sealing ring (4) is arranged. [5] Connecting arrangement according to one of the preceding claims, characterized by that the union nut (3) has an external polygonal section, in particular an external hexagonal section (35), to which a hollow cylindrical guide section (36) with a reduced outer diameter is connected.

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