FLAT TUBE FOR HEAT EXCHANGER

Abstract

A tube (10) for a motor vehicle heat exchanger exhibits a cross section comprising two opposite longitudinal walls (12), each provided with at least two concave portions (14).

Claims

1. A tube for a motor vehicle heat exchanger exhibiting a cross section comprising two opposite longitudinal walls, wherein each wall is provided with at least two concave portions.

2. The tube as claimed in claim 1, wherein two concave portions are separated by a convex portion.

3. The tube as claimed in claim 2, wherein the convex portion is of such a size that the internal perimeter of the section has a value that is at least 2% greater than the section of a tube in which the walls are straight.

4. The tube as claimed in claim 1, wherein the walls of the tube are connected to one another by end sections which are substantially circular in shape.

5. The tube as claimed in claim 4, exhibiting, according to the cross section of the tube, a length L.sub.Tube denoting the greatest distance between the sections with a substantially circular shape on the outside of the tube, a width I.sub.Tube denoting the smallest distance between the two walls of the tube on the outside of the tube and a flatness ratio T.sub.f of the tube defined by the relationship: $T_f=\frac{l_{\mathrm{Tube}}}{L_{\mathrm{Tube}}}$ where the flatness coefficient Tf is strictly lower than 0.20 to 0.01.

6. A fin comprising at least one substantially oblong opening, wherein the opening comprises an edge provided with two opposite longitudinal walls, each provided with at least two convex portions.

7. The fin as claimed in claim 6, in which two convex portions are separated by a concave portion.

8. A heat exchanger provided with at least one fin as claimed in claim 7 and comprising at least one tube for a motor vehicle heat exchanger exhibiting a cross section comprising two opposite longitudinal walls, wherein each wall is provided with at least two concave portions.

9. An assembly of at least one tube for a motor vehicle heat exchanger exhibiting a cross section comprising two opposite longitudinal walls, wherein each wall is provided with at least two concave portions and at least one fin as claimed in claim 6, wherein the tube is configured to be introduced into the inside of an opening in the fin with play existing between the tube and the opening.

Description

[0019] The invention will be easier to understand on reading the attached figures, which are provided by way of example and are in no way limiting in nature, in which:

[0020] FIG. 1 is a sectional view of a tube according to the invention;

[0021] FIG. 2 is an elevation of a portion of a fin intended to receive a tube in FIG. 1.

[0022] With reference to FIG. 1, a tube 10 according to the invention is depicted prior to its shaping by deformation. Said tube exhibits a substantially oblong cross section comprising longitudinal walls 12 facing one another, each wall being provided with at least two concave portions 14. In other words, viewed from the outside of the tube, the tube 10 comprises two hollow forms 14 which are substantially curved.

[0023] The two longitudinal walls 12 are connected to one another by two end sections 16 which are circular in shape. In the example, a convex portion 18 is arranged between the two concave portions 14 of each longitudinal wall 12. Hence, viewed from the outside, each wall 12 of the tube exhibits a raised section arranged between the two hollow shapes 14.

[0024] The tube 10 is produced from a metal alloy adapted to be easily deformed and has a wall with a substantially constant thickness e.

[0025] Along the cross section, the tube has a length L.sub.Tube denoting the greatest distance separating the two end sections 16 which are substantially circular in shape on the outside of the tube and a width I.sub.Tube denoting the shortest distance between the two walls 12 of the tube on the outside of the tube. A flatness ratio T.sub.f of the tube can be defined by the relationship:

[00002]$T_f=\frac{l_{\mathrm{Tube}}}{L_{\mathrm{Tube}}}$

[0026] where the flatness coefficient T.sub.f is strictly smaller than 0.20 to 0.01.

[0027] With reference to FIG. 2, a fin 20 which is generally rectangular in shape comprises a plurality of holes 22 disposed in a row along axis N. The holes 22 in a fin 20 are separated in twos by louvered rows 24 well known to the person skilled in the art, the function of which is to increase the heat exchange of the fins 20.

[0028] Each opening 22 exhibits a cross section which is substantially oblong in shape, comprising two longitudinal edges 26 facing one another, each edge 26 being provided with at least two convex portions 28. The two convex portions 28 of an edge 26 of the opening 22 are separated by a concave portion 30. Viewed from the inside of the opening, each longitudinal edge exhibits one hollow section and two raised sections.

[0029] Each opening 22 in a fin 20 therefore has a shape that is substantially identical to that of a tube 10, but its dimensions are smaller, in order to allow the tube to be threaded inside the opening 22 prior to shaping. Hence, each opening is configured to receive a tube as previously described, in such a manner that an assembly formed by an opening provided with a tube exhibits play J between the tube and the receiving opening that matches it.

[0030] There follows a description of a method of shaping a tube 10 according to the invention in a plurality of fins 20 of a heat exchanger. In a first stage, the tube 10 is positioned in an opening 22 of at least one fin 20, in such a manner that the tube 10 is positioned to create play J between the tube and the opening, said play J not having a consistent value over the entire periphery of the tube. The tube is then made to press against the inside of the opening 22 in the fin due to the expansion of its walls.

[0031] The tube and the fin that are presented are not limited to the embodiment described above and other embodiments will appear clearly to the person skilled in the art.