Tube connection

Abstract

A tube connection for connection to a tube includes: a body having a through hole with a central axis, a first end, a second end, and an internal thread arranged close to the first end and coaxial with the central axis. The internal thread has a constant pitch diameter. A maximum diameter of the internal thread increases in an axial direction from the first end towards the second end. A minimum diameter of the internal thread decreases in the axial direction from the first end towards the second end.

Claims

1. A tube connection for connection to a tube, comprising: a body having a through hole with a central axis, a first end, a second end, and an internal thread arranged close to the first end and coaxial with the central axis, wherein the internal thread has a constant pitch diameter, wherein a maximum diameter of the internal thread increases in an axial direction from the first end towards the second end, and wherein a minimum diameter of the internal thread decreases in the axial direction from the first end towards the second end.

2. The tube connection according to claim 1, wherein the maximum diameter and minimum diameter are equal at a start of the thread.

3. The tube connection according to claim 1, wherein the minimum diameter decreases at an angle of 1°-5°.

4. The tube connection according to claim 1, wherein the body comprises a hexagonal prism shape, and wherein an axis of the hexagonal prism shape is coaxial with the central axis.

5. A tube connection for connection to a tube, comprising: a body having a through hole with a central axis, a first end, a second end, and an internal thread arranged close to the first end and coaxial with the central axis, wherein the internal thread has a constant pitch diameter and starts at a distance from the first end such that a cylindrical surface is provided in the through hole between the first end and the thread, wherein a maximum diameter of the internal thread increases in an axial direction from the first end towards the second end, and wherein a minimum diameter of the internal thread decreases in the axial direction from the first end towards the second end.

6. The tube connection according to claim 5, wherein a diameter of the cylindrical surface is equal to a pitch diameter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:

(2) FIG. 1 shows an embodiment of a tube connection according to the invention and a tube end in exploded view.

(3) FIG. 2 shows the embodiment of FIG. 1 in assembled state.

DETAILED DESCRIPTION

(4) In an embodiment, the present invention reduces or even removes the above mentioned disadvantages.

(5) In an embodiment, the present invention provides a tube connection, which is characterized in that the maximum diameter of the thread increases in axial direction from the first end towards the second end and wherein the minimum diameter of the thread decrease in axial direction from the first end towards the second end.

(6) As the thread of the tube connection has a constant pitch diameter, while the maximum diameter increases and the minimum diameter decreases, a tube, which is inserted in the tube connection by rotation, will have an end being flared outwardly. This is caused by the minimum diameter of the thread which will deform the material of the tube when rotated inwardly in the through hole. The deformed material will be pushed into the space provided by the increasing maximum diameter of the thread.

(7) The resulting shape of the tube end will be flared outwardly, while the shape of the internal thread in the through hole is conical, widening from the first end inwardly toward the second end. As a result a shape defined connection between the tube connection and the tube is provided, which is not only dependent on a single turn of the thread like in U.S. Pat. No. 4,488,738.

(8) An additional advantage of the invention is that the tube connection can be made without any specialized tools. As long as sufficient torque can be generated to rotate a straight tube end into the tube connection, a reliable connection can be achieved.

(9) To ensure a leak tight connection, a special glue can be provided between the tube end and the tube connection, or a soft seal or thermoplastic seal could be arranged in the area of the tube end.

(10) In a preferred embodiment of the tube connection according to the invention the thread starts at a distance from the first end, such that a cylindrical surface is provided in the through hole between the first end and the thread.

(11) The cylindrical surface provides support for the tube end, such that insertion of the tube end is facilitated, but also for withstanding bending stresses exerted on the tube end. With the cylindrical surface, the bending stresses are exerted on a part of the tube end distal from the part of the tube end provided with the thread, such that the part provided with the thread is virtually only subjected to axial forces.

(12) Preferably, the diameter of the cylindrical surface is equal to the pitch diameter. This allows for a smooth transition from the cylindrical surface towards the threaded part.

(13) In a further preferred embodiment of the tube connection according to the invention, the maximum diameter and minimum diameter are equal at the start of the thread.

(14) This ensures that the thread starts with a thread depth of zero and a tube end with a diameter corresponding to the pitch diameter can be inserted into the tube connection. Then by rotating the tube end and further inserting the tube end into the through hole, the desired flared out shape of the tube end is provided by the internal thread of the tube connection.

(15) In yet a further preferred embodiment of the tube connection according to the invention the minimum diameter decreases at an angle of 1°-5°.

(16) An angle of 1°-5° allows for a tube end to be screwed into the tube connection without additional axial force and no additional specialized tools.

(17) In still a further preferred embodiment of the tube connection according to the invention, the body comprises a hexagonal prism shape, wherein the axis of the hexagonal prism is coaxial with the central axis.

(18) With the hexagonal prism shape a typical wrench or spanner can be used to connect the tube connection of the invention with a tube end.

(19) FIG. 1 shows a tube connection 1 with a body 2 having a through hole 3. The first end of the through hole 3 is provided with a cylindrical part 4 followed by an internal thread 5.

(20) On the second end, the body 2 is provided on the outer surface 6 with a hose connection. Furthermore, a hexagonal prism shape 7 is provided on the body 2 to allow engagement of a wrench or spanner.

(21) The thread 5 has a constant pitch diameter D.sub.p, while the minimal diameter D.sub.min decreases from the cylindrical part 4 towards the second end of the body and the maximal diameter D.sub.max increases from the cylindrical part 4 towards the second end.

(22) The minimum diameter D.sub.min decreases at an angle α, which is preferably between 1° and 5°, such that no additional axial force is required when a tube end 8 is screwed into the tube connection 1.

(23) The maximum diameter D.sub.max increases in the same amount as the minimum diameter decreases D.sub.min. This ensures that the pitch diameter D.sub.p is constant, but also ensures that the amount of material deformed by the minimum diameter D.sub.min can be pushed towards the expanding space as a result of the increasing maximum diameter D.sub.max.

(24) The tube end 8 inserted into the tube connection 1 and shown in exploded view in FIG. 1 has a normal diameter D.sub.norm. Due to the shape of the thread 5, the end of the tube end 8 flares out to an expanded diameter D.sub.exp, which provides a shaped defined connection of the tube end 8 with the tube connection 1.

(25) FIG. 2 shows the tube end 8 and the tube connection 1 is assembled state. The normal diameter D.sub.norm corresponds to the pitch diameter D.sub.p of the thread. The end of the tube end 8 is flared out to the expanded diameter D.sub.exp, which is almost identical to the maximum diameter D.sub.max at this position of the thread 5.

(26) While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.

(27) The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.