JP2006038286A - Multitubular heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multitubular heat exchanger capable of inhibiting the rotation of tubes 1 around an axis in accompany with expanding, and preventing resonance fracture of the tubes on the basis of the rotation, with respect to the multitubular heat exchanger constituted by bending a number of tubes of circular cross-section into the waveform, inserting both end parts of the tubes into holes of a header, and expanding and fixing openings of the tubes 1. <P>SOLUTION: Swelling parts 3 having non-circular outer periphery are formed on outer peripheries of the end parts of the tubes 1, a number of tubes 1 are penetrated to a plane of the header 2, the tubes 1 adjacent to each other are partially kept into contact with each other only at their swelling parts 3, and the rotation around the axis of the tubes can be inhibited by the contact. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multi-tube heat exchanger that is optimal as an exhaust gas recirculation device (EGR).

  In the conventional multi-tube type EGR cooler, as described in Patent Document 1 below, a plurality of rows of straight tubes having a circular cross section are arranged apart from each other, both ends of the tubes communicate with the header, and the communication portion is expanded. After opening, it was airtightly fixed by welding or brazing. A high-temperature exhaust gas is circulated inside the straight tube, and an air flow for cooling is circulated on the outer surface side to cool the internal exhaust gas.

Next, there is Japanese Patent Application No. 2003-145967 proposed by the following Patent Document 2 or the applicant of the present invention as a compact multi-tube heat exchanger in which the axis of the tube meanders in a waveform.
This is because each tube is bent into a waveform in one plane, and both ends of the tube are made straight in the axis, and are arranged in parallel to each other so that the phases of the respective waves coincide with each other. .

JP 2002-168586 A WO-00 / 29517

In order to improve the heat exchange performance and realize a compact heat exchanger, an example in which the pipe is bent into a corrugated shape can be considered as shown in FIG. As shown in FIG. 6A, the axis of the circular tube is bent into a waveform except for both ends.
Note that this example is related to the above-mentioned proposal by the applicant, and a gap t is formed between the axis d of both ends of the tube and the center line c of the corrugated bent portion. By providing such a shift t, it becomes easy to arrange a large number of manufactured tubes 1 in the same direction. That is, in FIG. 3A, when the pipe 1 is supported in a free state at a point E between a pair of bent portions, all the pipes 1 are aligned in the same direction by their own weight. Therefore, both ends of the pipe 1 can be inserted into the pair of headers 2 while maintaining the aligned state, and the portions can be joined by welding or the like after being expanded. In the aligned state, each tube 1 is formed as shown in FIG.

However, when an expansion jig is inserted into both ends of each pipe 1 from the state shown in FIG. 3B and is expanded so that the outer periphery of the pipe 1 is in close contact with the hole edge of the header 2, In some cases, the tube 1 rotates around its axis as shown in FIG. Then, the bent portions of the tube 1 come into contact with each other, and there is a possibility that resonance destruction occurs at the contact portion. That is, if vibration is generated during use of the heat exchanger and the vibration coincides with the resonance vibration, the pipes may repeatedly collide and be destroyed at the intermediate portion of the pipe.
Then, this invention makes it a subject to provide the multi-tube type heat exchanger which can keep the bending direction mutually parallel without the bending parts of each pipe | tube 1 contacting with a simple structure.

The present invention as set forth in claim 1 includes a plurality of circular tubes (1) having an axial line bent in a waveform in one plane except for both ends thereof;
A multi-tube heat exchanger having a pair of headers (2) in which both ends of each pipe penetrate and the through-holes are hermetically fixed so that the bending directions of the respective pipes (1) coincide with each other In
A bulging portion (3) having a non-circular outer periphery is formed on the outer periphery of the end of each tube (1),
Each pipe (1) is attached to the plane of the header (2) in a staggered manner, and adjacent pipes (1) are in contact with only a part of each of the bulging portions (3), and the respective contacts are caused by the contact. It is a multi-tube heat exchanger configured to prevent the rotation of the pipe (1) around the axis line.

The present invention according to claim 2 is the method according to claim 1,
The bulge portion (3) is a multi-tube heat exchanger in which the outer periphery of the bulge (3) has an elliptical cross section and adjacent tubes (1) are in contact with each other on the outer periphery on the long axis side.

In the multi-tube heat exchanger of the present invention, a bulging portion 3 having a non-circular outer periphery is formed on the outer periphery of the end portion of the tube 1, and the bulging portions 3 of adjacent tubes 1 are in contact with each other. Since the tube 1 is configured to prevent rotation around the axis, even if the tube 1 is bent into a waveform in one plane except for both ends, the waveform portions may come into contact with each other and be damaged by resonance. Absent.
That is, there is a possibility that the tube 1 whose both ends are straight and whose middle is bent into a waveform is rotated around the axis when the end is inserted and fixed in the header. Then, the corrugated bent parts of the adjacent pipes 1 come into contact with each other, and the contact parts may be resonantly broken due to vibration during use.
However, in the present invention, the bulging portions 3 are in contact with each other at the root portion of the tube 1 to prevent the rotation around the axis line, so that the contact of the intermediate portion of the tube 1 is prevented and resonance destruction is prevented. In addition to preventing the heat exchange, the tubes 1 can be evenly spaced from each other.

  In the said structure, the cross section of the outer periphery of the bulging part 3 can be made into an ellipse, and it can comprise so that the adjacent pipe | tubes 1 may contact in the outer periphery of the major axis side. In that case, the bulging portion 3 can be easily molded and the effect of preventing rotation around the axis can be reliably performed.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view and a side view of a tube 1 used in the multi-tube heat exchanger of the present invention. Moreover, FIG. 2 is a principal part sectional view and a BB arrow sectional view of the multitubular heat exchanger.
The tube 1 used in this heat exchanger has a circular cross section in which the axis is bent into a waveform in one plane except for both ends thereof. And there exists a gap t between the center line c of the corrugated bent portion 1a and the axis d of the straight portion 1b.
The reason why the center line c and the axis line d are shifted in this way is that, as described above, after manufacturing a large number of the tubes 1 having the same shape, they are aligned in the same direction by their own weight.

  A feature of the present invention in such a tube 1 is that a bulging portion 3 having a noncircular outer periphery in cross section is formed at least at one end thereof. The bulging portion 3 is formed in an annular shape, leaving a slight straight line portion at one end portion of the tube 1, and the outer periphery of the cross section is formed in an elliptical shape as shown in FIG. That is, in this example, the bulging portion 3 has a major axis in the vertical direction and a minor axis in the horizontal direction in the drawing. As shown in FIG. 2 (A), each tube 1 formed in this way has its end inserted through a circular hole previously drilled in the header 2, and the bulging portion 3 contacts the edge of the hole. To do. Thereby, the axial direction of each pipe 1 is positioned with respect to the header 2.

  At this time, the bending directions of the respective tubes 1 are arranged in parallel to each other. In this state, as shown in FIG. 2B, the bulging portions 3 of the adjacent pipes 1 are in contact with each other on the long axis side of the bulging portion 3. The tube 1 located in the central portion comes into contact with the bulging portion 3 of the tube 1 located in the four circumferences thereof, thereby preventing the tube 1 from rotating around its axis. That is, when the tube 1 tries to rotate, the bulging portions 3 of the adjacent tubes 1 interfere with each other, and the rotation is prevented. Therefore, even if an expansion jig is inserted into the opening end of the tube 1 in the state of FIG. 2A and the tube is expanded, the tube 1 itself rotates around its axis during the expansion. There is nothing. Therefore, the wave bending directions of the respective tubes 1 are positioned in parallel to each other. Next, the end of the tube 1 and the header 2 are fixed by welding.

2A, when one end of the tube 1 is positioned in the axial direction by the bulging portion 3, even if the bulging portion 3 does not exist at the other end of the tube 1, its length If the length is constant, the other end is also positioned at a normal position with respect to the header surface.
Therefore, when the bulging portion 3 does not exist on the other end side in this way, the side where the bulging portion 3 exists is first expanded with an expansion jig, and then the side where the bulging portion 3 does not exist The pipe end can be fixed to the circular hole of the header 2 by expanding.
In the above-described embodiment, the case where the axis c of the waveform bent portion 1a and the axis d of the straight portion 1b do not coincide has been described, but the present invention is applied to the case where both coincide.

The front view and side view of the pipe | tube 1 which are used for the multi-tube type heat exchanger of this invention. The longitudinal cross-sectional view which shows the principal part of the same heat exchanger, and BB arrow sectional drawing. The longitudinal cross-sectional view and explanatory drawing which show the principal part of the heat exchanger of a comparative example.

Explanation of symbols

1 Tube 1a Waveform bend 1b Straight line 2 Header 3 Swelling c Centerline d Axis t Displacement E Point

Claims (2)

A number of circular tubes (1) whose axes are bent in a waveform in one plane except for both ends;
A multi-tube heat exchanger having a pair of headers (2) in which both ends of each pipe penetrate and the through-holes are hermetically fixed so that the bending directions of the respective pipes (1) coincide with each other In
A bulging portion (3) having a non-circular outer periphery is formed on the outer periphery of the end of each tube (1),
Each pipe (1) is attached to the plane of the header (2) in a staggered manner, and adjacent pipes (1) are in contact with only a part of each of the bulging portions (3), and the respective contacts are caused by the contact. A multi-tube heat exchanger configured to prevent the pipes (1) from rotating around the axis. In claim 1,
A multi-tube heat exchanger in which a cross section of the outer periphery of the bulging portion (3) is formed in an elliptical shape, and adjacent tubes (1) are in contact with each other on the outer periphery on the long axis side of the ellipse.

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