WO2015177237A1

WO2015177237A1 - Rolled tube having a double row of channels

Info

Publication number: WO2015177237A1
Application number: PCT/EP2015/061163
Authority: WO
Inventors: Christian Riondet
Original assignee: Valeo Systemes Thermiques
Priority date: 2014-05-23
Filing date: 2015-05-20
Publication date: 2015-11-26
Also published as: FR3021398B1; FR3021398A1; DE112015002443T5

Abstract

The present invention relates to a method for manufacturing a tube, which includes a step of extruding a tubular profile section in a longitudinal direction of said profile section by means of a die, and a later step of flattening said profile section in the longitudinal direction.

Description

Laminated tube with double row of channels

-1 -

The present invention relates to the technical field of heat exchangers for a motor vehicle, and relates more specifically to a tube for such an exchanger. The heat exchanger tubes concerned are intended to be used for example in cooling radiators or condensers of air conditioning circuit of vehicles.

FR2996296 already discloses a tube for a motor vehicle heat exchanger extending in a longitudinal direction and having a cross section, the tube comprising in its interior a plurality of longitudinal channels for circulation of a fluid in which at at least a part of the channels is distributed in the cross-section of the tube so as to define two distinct rows of channels.

The fact of arranging said channels in two rows in the tube improves the thermal performance of the tube, without increasing the pressure losses. Thus, a heat exchanger of imposed dimensions comprising such tubes sees its thermal performance improved.

Another way to improve the performance of such an exchanger would be to increase the number of tubes despite the imposed dimensions of the exchanger.

Also, in order to accommodate a greater number of tubes in the exchanger, the trend has therefore been to seek to design a die that allows for the extrusion of a tube whose thickness is reduced compared to that of a tube of the prior art.

It is specified that the tubes in question are flat tubes provided with two external flanks and that the thickness of the tube is the distance between the outer flanks of the tube.

To increase the number of tubes, the inventors of the present invention have devised a surprising alternative solution which avoids having to modify the type of die commonly used for the manufacture of these double-row tube tubes. The present invention is intended in particular to provide a method of manufacturing a dual channel heat exchanger tube whose thickness is smaller than that of a tube of the prior art.

For this purpose, the subject of the invention is a method of manufacturing such a tube comprising:

a step of extruding a tubular section in a longitudinal direction to said profile using a die; and

- A subsequent step of crushing said tubular section in the longitudinal direction.

The above method may further include one or more of the following features, taken alone or in combination.

Advantageously, it can be provided that the crushing step is carried out by rolling by means of rolling rolls.

Alternatively, the crushing step may be performed by pressing with a press.

It is also possible to provide a stretching step subsequent to the crushing step.

The invention also relates to a flat tube for a motor vehicle heat exchanger, the tube comprising in its interior a plurality of longitudinal channels for circulation of a fluid and having a cross section provided with external flanks, each channel comprising several parallel edges defining internal faces of the channel, at least a portion of the channels being distributed in the cross section of the tube so as to define two distinct rows of channels, a distance d of less than 2 mm separating the outer flanks, at least one of the faces internal features a relief in the sense that a point located at the top of the relief is at a distance of at least 0.05 millimeters from a plane passing through the edges of said face.

Two edges are considered parallel if a line perpendicular to one is perpendicular to the other. In the case where the edges are curved, for example because of a particular extrusion process, it is considered that on a very small length of the channel section, the edges are rectilinear. Thus, even in this particular case, there is always a plane passing through the edges of the face.

Advantageously, the above double-row channel exchanger tube has a thickness which is reduced in comparison with that of a double-row tube of the prior art. This is particularly advantageous because the reduction in thickness of the tube makes it possible to improve the heat exchange properties and to reduce the size of the tube. Also, as the tube according to the invention is less bulky, it becomes possible to accommodate a larger number of these tubes inside a heat exchanger whose dimensions are imposed. This results in an improvement of the heat exchange efficiency of an exchanger equipped with such tubes. The heat exchanger tube as defined above may further include one or more of the following features, taken alone or in combination.

- The relief exists on at least 90% of the length of the tube.

- The channels of one of the rows are aligned in pairs with the channels of the second row.

- The channels of one of the rows are mainly staggered with respect to the channels of the second row.

- The channels have an inner thickness, taken perpendicular to the axis of a row, which is between 0.1 and 0.7 mm.

- The channels have a length taken parallel to the axis of a row which is between 0.5 and 5 mm.

- Two neighboring channels are separated by a distance between 0.2 and 0.4 millimeters.

- A distance between an outer side of the tube and a side of a channel adjacent to said outer side is between 0.2 and 0.4 millimeters.

The various additional characteristics described above have the advantage of improving the efficiency of the heat exchange of the proposed tube and not to increase the pressure drop of the tube too much. The invention further relates to a heat exchanger for a motor vehicle comprising a plurality of tubes, the tubes extending substantially parallel to each other, the pitch of the tubes being between 6 and 10 millimeters, preferably between 6 and 8 millimeters.

The invention will be better understood on reading the appended figures, which are provided by way of examples and are in no way limiting, in which:

- Figure 1 is a schematic cross-sectional view of an example of a tube obtained by the method according to the invention;

- Figure 2 is a schematic cross-sectional view of another example of a tube obtained by the method according to the invention; and

- Figure 3 is a schematic cross-sectional view of a tube obtained by the method according to the invention wherein the channels of a row are arranged staggered with respect to those of the other row.

With reference to the figures, there is shown a flat tube 10 intended to be arranged in a motor vehicle heat exchanger. It will be understood that a flat tube has an oblong cross section provided with external flanks 12, rectilinear and parallel to one another, and two rounded lateral edges 14.

For the rest of the description, it is specified that the longitudinal direction is the direction which extends parallel to the longitudinal axis of the tube 10, the longitudinal axis of the tube generally corresponding to the direction of flow of the fluid inside. of the tube. The cross section of the tube is defined by the intersection of the tube with a plane perpendicular to the longitudinal direction. The plane of the cross section, or transverse plane, merges with the plane of the figures.

The tube 10 has in its interior a plurality of longitudinal channels 16 for circulating a fluid, each channel 16 having a plurality of ridges 18 parallel to each other and delimiting internal faces 20 of the channel.

The two outer flanks 12 of the tube are separated by a distance of less than 2 millimeters. Thus, the external cross section of the tube is delimited by a thickness d which is less than 2 millimeters. According to the cross section, a majority of the channels 16 is distributed so as to define two distinct rows 21 of channels 16. Each row 21 is substantially perpendicular to the longitudinal direction of the tube. The two rows 21 are parallel to each other and the channels 16 of one of the rows 21 are aligned in pairs with the channels 16 of the second row 21.

For each channel 16, at least one of the internal faces 20 has a relief 22 in the sense that a point S situated at the top of the relief 22 is at a distance of at least 0.05 mm from a plane P passing through the edges 18 of the inner face 20.

In the example, the relief 22 of a face 20 of a channel 16 is present along the entire length of the channel 16. However, it is possible for the relief 22 of a channel 16 to have discontinuities such that the relief 22 is present on most of the face of the channel 16, for example on 90% of the length of the channel 16.

In the cross section of the tubes 10, the channels 16 of a row 21 have a generally rectangular shape. Each channel 16 of a row 21 has a long side corresponding to a length L taken parallel to the direction T and between 0.5 and 5 millimeters, and a small side corresponding to an internal thickness I taken in the perpendicular direction of the row 21 which is between 0.1 and 0.7 millimeters.

The tube 10 has two end channels 24, which are adjacent to the lateral edges 14. These end channels 24 have a rounded wall whose profile corresponds to the profile of the lateral edges 14 of the tube, their section forming a D. that these end channels 24, which bite each on the two rows 21, are not part of the channels defining the rows 21. In other words, the rows 21 are imaginary lines composed solely of the juxtaposition of channels similar to the channels 16, without including the end channels 24.

The distance d ₂ separating two adjacent channels 16 is between 0.2 and 0.4 mm. The distance d ₃ between an outer flank 12 of the tube and a face of an adjacent channel of this outer flank 12 is also between 0.2 and 0.4 mm. We will now describe the method of manufacturing a double-row tube of channels as presented above. In a first step, there is carried out a step of extruding a tubular section in a longitudinal direction to said profile using a die. Then we proceed to a subsequent step of crushing said profile in the longitudinal direction.

According to a first embodiment, the crushing step is carried out by rolling by means of rolling rolls. The method presented here also includes a stretching step subsequent to the crushing step. This is achieved by using at least one roll whose rotational speed is faster than the speed of rotation of the rolling rolls. Referring to Figure 2, there is shown an exchanger tube 10 always obtained by the same method of crushing the tubular section. In this example, each channel 16 comprises at least two faces 20 forming reliefs 22 whose respective vertices S are oriented towards the inside of the channel 16 and are at a distance of at least 0.05 millimeters from a plane P passing through the edges 18 of a channel 16.

There is shown in Figure 3 a tube in which the channels 16 of one of the rows are mainly staggered with respect to the channels of the second row. Here, the faces 20 which are substantially parallel to the longitudinal direction have reliefs 22 whose S vertices are oriented towards the inside of the channel. Such a staggered conformation means that the channels are not aligned in pairs with the channels of the second row, which makes it possible to optimize the mechanical strength and the thermal efficiency of the tube. The invention is not limited to the embodiments presented and other embodiments will become apparent to those skilled in the art.

Claims

1. Flat tube (10) for a motor vehicle heat exchanger, the tube (10) having in its interior a plurality of longitudinal channels (16) for circulating a fluid and having a cross section provided with external flanks (12), each channel (16) having a plurality of parallel ridges (18) delimiting internal faces (20) of the channel, at least a portion of the channels (16) being distributed in the cross-section of the tube (10) so as to define two distinct rows of channels (16), a distance (d) of less than 2 mm separating the external flanks (12), characterized in that at least one of the internal faces (20) has a relief (22) in the sense that a point (S) situated at the top of the relief (22) is at a distance of at least 0.05 millimeters from a plane (P) passing through the edges of the face.

2. Tube according to the preceding claim, wherein the relief (22) exists over at least 90% of the length of the tube.

The tube (10) according to any one of claims 1 or 2, wherein the channels (10) of one of the rows (21) are aligned in pairs with the channels (10) of the second row.

4. Tube according to any one of claims 1 or 2, wherein the channels

(10) of one of the rows (21) are mainly staggered with respect to channels (10) of the second row (21).

5. Tube (10) according to any one of claims 1 to 4, wherein the channels have an inner thickness (I), taken perpendicularly to the axis of a row (21), which is between 0 , 1 and 0.7 mm.

6. Tube (10) according to any one of claims 1 to 5, wherein the channels have a length (L) taken parallel to the axis of a row which is between 0.5 and 5 mm.

7. Tube according to any one of claims 1 to 6 wherein two adjacent channels are separated by a distance (d ₂ ) between 0.2 and 0.4 millimeters.

8. Tube according to any one of claims 1 to 7, a distance (d ₃ ) between an outer side of the tube and a side of a channel adjacent said outer side is between 0.2 and 0.4 millimeters.

9. Heat exchanger for a motor vehicle comprising a plurality of tubes according to any one of claims 1 to 8, the pitch of the tubes being between 6 and 10 millimeters, preferably between 6 and 8 millimeters.

10. A method of manufacturing a tube (10) according to any one of claims 1 to 8, characterized in that it comprises:

a posterior step of crushing said tubular section in the longitudinal direction.

1 1. A method of manufacturing a tube (10) according to the preceding claim wherein the crushing step is carried out by rolling by means of rolling rolls.

12. A method of manufacturing a tube (10) according to claim 10 wherein the crushing step is performed by pressing with a press.

13. A method of manufacturing a tube (10) according to any one of claims 10 to 12 comprising a drawing step subsequent to the crushing step.