Pipe connection arrangement for a fluid line of a motor vehicle

Abstract

Pipe connection arrangement for a fluid line of a motor vehicle, comprising a pipe (20) which has a clamping section (22) at one end, a union nut (30) which has a thread (32), and a connection component (40) which has a mating thread (34) corresponding to the thread (32) of the union nut (30). In the assembled state of the pipe (20) on the connection component (40), the clamping section (20) of the pipe (20) is clamped between the union nut (30) and the connection component (40) in the longitudinal direction of the pipe (20). The pipe (20), the union nut (30), and the connection component (40) are manufactured in such a way that the friction coefficient (u1) between the pipe (20) and the union nut (30) is smaller than the friction coefficient (u2) between the union nut (30) and the connection component (40).

Description

[0001] The invention relates to a pipe connection arrangement for a fluid line of a motor vehicle, comprising a pipe which has a clamping section at one end, a union nut which has a thread, and a connecting component which has a counter-thread corresponding to the thread of the union nut, wherein the clamping section is clamped in the assembled state of the pipe on the connecting component between the union nut and the connecting component in the longitudinal direction of the pipe.

[0002] Such pipe connection assemblies are generally known from the prior art. The pipe connection assemblies comprise a pipe, a union nut, and a connecting component. The union nut is typically slipped onto the pipe and has an external thread. The front end of the pipe is designed as a flange, with the flange forming a clamping section such that the union nut rests against the clamping section in the longitudinal direction of the pipe. The connecting component typically has a blind bore with a fluid channel branching off from the center. An internal thread corresponding to the external thread of the union nut is arranged on the inner circumferential surface of the blind bore.When the pipe is mounted on the connecting component and thus when the union nut is screwed into the connecting component, the clamping section is clamped in the longitudinal direction of the pipe between the union nut and the connecting component, whereby the surface pressure between the pipe and the union nut and between the union nut and the connecting component depends on the tightening torque with which the union nut was tightened. To ensure a functionally reliable connection, sufficiently high clamping forces or surface pressures are required under all operating conditions. When screwing in the union nut, the frictional forces between the union nut and the pipe are already so high that there is a risk that the pipe will rotate with the union nut when the union nut is screwed in.The rotation of the pipe, which is already secured to another component at an opposite end, causes torsion, which preloads the pipe in the direction of rotation. This torsion or preload creates an undesirable back torque, which can lead to uncontrolled and undesired loosening of the pipe connection assembly.

[0003] To prevent such a loosening of the connection of the pipe connection arrangement, the friction coefficients between the pipe and the union nut and between the pipe and the connecting component are typically specifically influenced by a coating or a washer. The attempt is made to reduce the friction coefficient between the union nut and the pipe such that the friction coefficient between the pipe and the union nut is lower than the friction coefficient between the pipe and the connecting component. Such a pipe connection arrangement is disclosed, for example, in DE 20 2013 012 239 U1. Alternatively, a washer is arranged in the longitudinal direction of the pipe between the pipe and the union nut. Such a pipe connection arrangement is disclosed, for example, in EP 1 624 183 A1.

[0004] A disadvantage of both designs is that at least one additional component and / or at least one additional process step, in particular a coating process step or an assembly process step, is required, which increases the manufacturing and assembly effort and the manufacturing costs.

[0005] The object of the invention is therefore to provide a pipe connection arrangement by means of which, in a simple and reliable manner, rotation of the pipe when mounting the union nut on the connection component and thus loosening of the connection between the pipe and the connection component can be prevented.

[0006] The problem is solved by the features of claim 1.

[0007] Because the pipe, union nut, and connection component are manufactured in such a way that the friction coefficient between the pipe and the union nut is lower than the friction coefficient between the union nut and the connection component, rotation of the pipe and thus loosening of the pipe connection assembly can be prevented in a simple and cost-effective manner. No additional components or additional process steps are required during the manufacture and assembly of the pipe connection assembly.

[0008] When the union nut is screwed into the connection element and the clamping section is clamped between the union nut and the connection component, the clamping section adheres to the connection component due to the higher coefficient of friction between the clamping section and the connection component, while the union nut slides off the clamping section due to the lower coefficient of friction. The frictional force acting between the connection component and the clamping section of the pipe during the screwing-in process or clamping is higher than the frictional force between the union nut and the clamping section of the pipe.

[0009] Preferably, the tube, union nut, and connecting component are each made exclusively from a single material. For example, the tube is made of copper, the connecting component is made of aluminum, and the union nut is made of steel. Thus, the tube, union nut, and connecting component are formed in one piece and without a coating or the like, so that the different friction coefficients between the tube and union nut and between the tube and connecting component are provided by the base material of the tube, union nut, and connecting component.

[0010] In a preferred embodiment, the contact surfaces between the clamping section and the connecting component, and between the clamping section and the union nut, have a surface roughness such that the coefficient of friction between the pipe and the union nut is lower than the coefficient of friction between the union nut and the connecting component. To achieve the different surface roughnesses, the contact surfaces can be specifically machined. The contact surfaces can be either roughened or ground.

[0011] An embodiment of the invention is explained in more detail with reference to the drawing.

[0012] Figure shows schematically a pipe connection arrangement in cross section.

[0013] The figure shows a pipe connection assembly 10 for a fluid line, for example, a brake line, for a motor vehicle. The pipe connection assembly 10 comprises a pipe 20, a union nut 30, and a connection component 40.

[0014] The tube 20 has a clamping section 22 at one end, which is designed as a flange. Such a clamping section 22 is produced by forming, in particular by a flanging tool, in which an end section of the tube 20 is formed from the inside to the radial outside.

[0015] The union nut 30 is pushed onto the pipe 20, i.e. the union nut 30 radially surrounds the pipe 20, wherein the outer diameter of the clamping section 22 of the pipe 20 is larger than the inner diameter of the union nut 30. As a result, the union nut 30 and the clamping section 22 of the pipe 20 form a first contact pairing K1 in the assembled state of the pipe connection arrangement 10. The first contact pairing K1 is formed by a first contact surface A1 on the union nut 30 and a second contact surface A2 of the clamping section 22, wherein in the assembled state of the pipe connection arrangement 10, the contact surfaces A1, A2 bear essentially axially against one another. The union nut 30 has an external thread 32 on an outer circumferential surface.

[0016] The connecting component 40, for example a valve block, has an internal thread 42 on an inner circumferential surface of a receiving bore into which the pipe 20 can be inserted. This internal thread 42 is complementary to the external thread 32 of the union nut 30. In the assembled state of the pipe connection arrangement 10, the pipe 20 rests against the connecting component 40 at its end, so that the connecting component 40 and the pipe 20 or the clamping section 22 of the pipe 20 form a second contact pairing K2. The second contact pairing K2 is composed of a third contact surface A3 of the pipe 20 and a fourth contact surface of the connecting component 40.

[0017] In the assembled state and during assembly of the pipe connection arrangement 10, the clamping section 22 rests against the union nut 30 via the second contact surface A2 and against the connection component 40 via the third contact surface A3, wherein the clamping section 22 is clamped into the connection component 40 during the screwing-in process of the union nut 30. Thus, a surface pressure is already present on both contact pairs K1, K2 when the union nut 30 is turned or screwed into the connection component 40.

[0018] According to the invention, the pipe 20, the union nut 30, and the connecting component 40 are manufactured such that the friction coefficient u1 between the pipe 20 and the union nut 30 is smaller than the friction coefficient u2 between the union nut 30 and the connecting component 40. In other words, the frictional force acting on the first contact pair K1 during the screwing-in process is smaller than the frictional force on the second contact pair K2. As a result, the clamping portion 22 adheres to the connecting component 40 during the screwing-in process, and the union nut 30 slides along the clamping portion 22 in the direction of rotation.

[0019] Such friction coefficients u1, u2 are achieved by a coordinated selection of materials between the tube 20, the union nut 30, and the connecting component 40. For example, the tube 20 is made entirely of copper, the union nut 30 entirely of steel, and the connecting component 40 entirely of aluminum. Steel, copper, and aluminum also include associated alloys. The friction coefficient between copper and steel is lower than the friction coefficient between copper and aluminum. As a result, the friction coefficients u1, u2, which prevent the tube 20 and the union nut 30 from rotating during the screwing-in process, are established solely through the selection of materials for the tube 20, the union nut 30, and the connecting component 40. A coating of the components 20, 30, 40, or the like, is not required.Alternatively or additionally, the surface roughnesses of the contact surfaces A1, A2, A3, A4 can be specifically influenced, in particular by mechanical processing, so that the desired friction coefficients u1, u2 are achieved or the difference between the friction coefficients u1, u2 is increased.

[0020] This reduces the risk of the pipe 20 with the union nut 30 rotating during the assembly process in a simple and cost-effective manner, whereby no additional coating process or additional components are required. 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] DE 20 2013 012 239 U1

[0003] EP 1 624 183 A1

[0003]

Claims

[1] Pipe connection arrangement for a fluid line of a motor vehicle, comprising a pipe (20) having a clamping section (22) at one end, a union nut (30) having a thread (32), and a connecting component (40) having a mating thread (34) corresponding to the thread (32) of the union nut (30), wherein, in the assembled state of the pipe (20), the clamping section (20) of the pipe (20) is clamped between the union nut (30) and the connecting component (40) in the longitudinal direction of the pipe (20). characterized by , that the pipe (20), the union nut (30) and the connecting component (40) are manufactured such that the coefficient of friction (u1) between the pipe (20) and the union nut (30) is smaller than the coefficient of friction (u2) between the union nut (30) and the connecting component (40). [2] Pipe connection arrangement according to claim 1, characterized by, that when the union nut (30) is screwed into the connecting element (40) due to the coefficients of friction (u1, u2) the union nut (30) moves in the direction of rotation relative to the pipe (20) and adheres to the connecting component (40). [3] Pipe connection arrangement according to claim 1 or 2, characterized by that the pipe (20), the union nut (30) and the connecting component (40) are each made exclusively from a single material. [4] Pipe connection arrangement according to claim 3, characterized by , that the pipe (20) is made of copper, the connecting component (40) is made of aluminium and the union nut (30) is made of steel. [5] Pipe connection arrangement according to one of the preceding claims, characterized by, that the contact surfaces (A3, A4) between the clamping section (22) and the connecting component (40) and the contact surfaces (A1, A2) between the clamping section (22) and the union nut (30) have such a surface roughness that the coefficient of friction (u1) between the pipe (20) and the union nut (30) is smaller than the coefficient of friction (u2) between the union nut (30) and the connecting component (40).

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