JP2008121934A - Plate fin tube heat exchanger and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate fin tube heat exchanger and its manufacturing method causing neither failure in appearance, nor degradation of heat exchange performance by positively preventing fin pitch disorder, nor a pairing phenomenon caused by the enlargement of a tube. <P>SOLUTION: The plate fin tube heat exchanger comprises a large number of laminated plate fins 3 forming fin collars 5 around a tube hole 4 inserted through the tube 2, and the tube 2 inserted through the tube hole 4 and enlarged to stick to each plate fin 3. Each plate fin 3 is formed in umbrella shape enlarged from the tube hole 4 toward the formed side of the fin collar 5, and a slant face of the umbrella shape inclines by 8-30° with respect to a plane perpendicular to the tube 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plate fin tube heat exchanger suitable for, for example, a power steering pipe for automobiles and a method for manufacturing the same.

  Conventionally, as shown in FIG. 4, the plate fin tube heat exchanger 101 is formed by laminating a large number of planar plate fins 103 formed with a fin collar 105 around a tube hole 104 through which the tube 102 is inserted. After the tube 102 is inserted, a tube (not shown) whose outer diameter is slightly larger than the inner diameter of the tube 102 is pushed in from the fin collar 105 side to expand the tube 102 so that the tube 102 and the plate fin 103 are fixed. It was.

  However, at the time of fixing the pipe expansion, as will be described in detail later in the embodiment, two kinds of bending moments in the opposite directions are generated in the fin, and the magnitude relationship changes depending on the extent of the pipe expansion. However, there is a problem that the Abek phenomenon in which adjacent fins are in close contact with each other and the fin pitch are disturbed easily, resulting in poor appearance and reduced heat exchange performance.

  Therefore, conventionally, various measures have been proposed to solve the above problems.

  For example, Patent Document 1 discloses a plate fin in which a flange portion is formed at a tip end portion of a fin collar around a tube hole, and a protruding portion wider than the flange portion area is formed on a flat surface of the fin. As a result, the sectional moment of the protrusion is increased to increase the deformation resistance, thereby preventing the Abeck phenomenon and the like.

  Further, in Patent Document 2, the plate fin is made of a fin material having a friction coefficient of 0.15 or more without oil coating, and a compression force is applied from the side where the fin collar portion of the plate fin is not formed with the fin collar. The manufacturing method of the plate fin tube heat exchanger which adds and expands a tube in the state is indicated. Thereby, it is said that disturbance of the fin pitch can be prevented by sharpening and deforming the color root angle of the fin.

  Further, in Patent Document 3, a plate using plate fins formed on a strip-shaped plate fin having a plurality of tube holes so that a bent molded portion extending in a direction crossing the longitudinal direction is positioned between adjacent tube holes. A finned tube heat exchanger is disclosed. All the plate fins are deformed in the same direction by being deformed so that the bent portion is bent at the time of tube expansion, and the occurrence of the Abeck phenomenon can be prevented.

  However, in the inventions described in Patent Documents 1 to 3, basically, since flat plate fins are used, the direction in which the fins incline is not constant at the time of tube expansion, and the pitch disturbance is completely prevented. This is assumed to be difficult and has not yet been put into practical use.

Furthermore, the invention described in Patent Document 3 can be applied when the plate fin has a plurality of tube holes (for example, when the tube is U-shaped), but has a single tube hole (the tube is a straight line). There are some problems that cannot be applied.
Japanese Patent Application Laid-Open No. 9-119792 [Claims] JP-A-10-277679, [Claims] JP-A-10-166088, [Claims]

  Accordingly, the present invention provides a plate fin tube heat exchanger and a method for manufacturing the same, which do not cause poor appearance or decrease in heat exchange performance by reliably preventing fin pitch disturbance and Abeck phenomenon caused by tube expansion. The purpose is to provide.

  According to the first aspect of the present invention, a plate fin formed by forming a fin collar around a tube hole through which a tube, which will be described later, is inserted, and a plate fin inserted through the tube hole and fixed to the plate fins. A plate fin tube heat exchanger having a tube expanded in a tube shape, and all the plate fins are formed in an umbrella shape extending from the tube hole toward the fin collar forming side. The plate fin tube heat exchanger is characterized in that the inclined surface of the plate is inclined by 8 to 30 ° with respect to a plane perpendicular to the tube.

  A second aspect of the present invention is the plate fin tube heat exchanger according to the first aspect, wherein a rib is provided on each of the plate fins so as to ensure an interval between adjacent plate fins.

  According to a third aspect of the present invention, a fin collar is formed around a tube hole through which the tube is inserted, and is formed into an umbrella shape that extends from the tube hole toward the fin collar forming side. A step of laminating a large number of plate fins whose inclined surfaces are inclined by 8 to 30 ° with respect to a plane perpendicular to the tube, a step of inserting the tube into the tube hole, and formation of the fin collar in the tube And a step of expanding the tube from the inside by pushing a plug having an outer diameter slightly larger than the inner diameter of the tube from the side, and fixing the plate fin and the tube. It is a manufacturing method of an exchanger.

  According to the present invention, since the plate fin is formed in an umbrella shape that is inclined backward by a predetermined angle (8 to 30 °) with respect to the plug push-in direction, the collar root angle of the fin is always sharpened and deformed when the pipe is fixed. The plate fin tube heat exchanger and its manufacturing method can be put into practical use, which can reliably prevent the fin pitch disturbance and the Abeck phenomenon, and does not cause the appearance defect or the heat exchange performance to deteriorate.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

Embodiment
FIG. 1 shows a plate fin tube heat exchanger according to an embodiment of the present invention. The plate fin tube heat exchanger 1 is inserted into the tube hole 4 and the plate fin 3 formed by forming the fin collar 5 around the tube hole 4 through which the tube 2 is inserted, which are stacked, as in the conventional product. The tube 2 is expanded so as to be fixed to each plate fin 3.

  However, the plate fins 3 according to the present invention are all formed in an umbrella shape that spreads from the tube hole 4 toward the formation side of the fin collar 5 as shown in FIG. Thus, it is assumed that the umbrella-like slope 6 is inclined by 8 to 30 ° with respect to a plane perpendicular to the tube 3.

  A large number of such umbrella-shaped plate fins 3 are stacked, and the tube 2 is inserted into the tube hole 4, and then a plug (not shown) having an outer diameter slightly larger than the inner diameter of the tube 2 is pushed in from the fin collar 5 side. By expanding the tube 2, the tube 2 and the plate fin 3 are fixed, and the plate fin tube heat exchanger 1 shown in FIG. 1 is manufactured.

  Here, at the time of fixing the tube expansion, when a plug having a slightly larger outer diameter than the inner diameter of the tube 2 is pushed in, a pressing force Fr acts on the fin collar 5 in the tube expansion direction as shown in FIG. Since the pressing force Fr and the plate thickness center of the plate fin 3 are decentered, a moment Mr is generated, and the plate Mr 3 bends to the opposite side to the fin collar 5 side by the moment Mr as shown by a broken line. Further, when the plug is pushed into the tube 2, the tube 2 is contracted in the axial direction, and the fin collars 5 are pressed against each other. As shown in FIG. 3B, the axial load is applied to the fin collar 5. Fz acts. Due to the moment Mz generated based on this axial load Fz, the plate fin 3 bends to the same side as the fin collar 5 side as indicated by the broken line (see paragraphs [0007] to [0008] of Patent Document 3).

  Here, the moment Mr is constant because the pressing force Fr is constant as the pipe expands (that is, the amount of pushing of the plug increases), but the axial load Fz is increased by increasing the amount of contraction in the axial direction. The moment Mz increases to increase. Therefore, the magnitude relationship between the moment Mr and Mz varies depending on the extent of tube expansion (that is, the amount of push-in of the plug), and the bending direction of the plate fin 3 becomes the same side as the fin collar 5 side or the opposite side. It becomes becoming.

  For this reason, when the conventional planar plate fin 103 (see FIG. 4) is used, the plate fin 103 is inclined to the same side as the fin collar 105 side, or is inclined to the opposite side to the fin collar 105 side. The fin pitch was disturbed and the Abek phenomenon was likely to occur.

  On the other hand, when the umbrella-shaped plate fin 3 according to the present invention is used, since the plate fin 3 is previously bent to the same side as the fin collar 5 side by a predetermined angle (8 to 30 °), the moment Mr Even if the bending direction of the plate fins 3 changes due to the magnitude relationship between Mn and Mz, all the fins 3 are not inclined to the opposite side to the fin collar 5 side, and are always inclined to the same side as the fin collar 5 side. Since they are in the same state (if they are reduced, they are sharpened and deformed), the fin pitch is not disturbed and the Abeck phenomenon does not occur.

  Here, the reason why the inclination angle of the plate fin 3 is set to 8 to 30 ° is as follows. That is, when the angle is less than 8 °, as shown in the examples described later, some of the fins 3 are inclined to the side opposite to the fin collar 5 side, and fin pitch disturbance and Abeck phenomenon occur. On the other hand, if the angle exceeds 30 °, the fin pitch disturbance or Abeck phenomenon does not occur, but the gap between the plate fins 3 (that is, the air flow path) becomes excessively narrow and the heat exchange performance decreases. is there. A preferable range of the inclination angle of the plate fin 3 is 8 to 15 °, and a more preferable range is 8 to 12 °.

  The plate fins 3 are preferably formed so that the outer periphery thereof is a perfect circle, so that when laminating a large number of plate fins 3, there is no need to worry about the assembly direction, and assembling workability is eliminated. Is significantly improved.

  In addition, as shown in FIG. 2, it is preferable to provide ribs 7 on all the plate fins 3 for ensuring a space between the adjacent plate fins 3. For example, the rib 7 has a trapezoidal cross section as shown in FIG. 5B, and the height of the rib 7 is substantially the same as the height of the fin collar 5, so that the rib 7 and the fin collar 5 are adjacent to each other. It is possible to keep the interval between the plate fins 3 to be constant more reliably. It should be noted that a plurality of ribs 7 are preferably provided in the circumferential direction of the plate fins 3, but the work is performed with the smallest possible probability that a plurality of ribs 7 overlap each other between adjacent plate fins 3 and do not serve as ribs. In order to improve the property, for example, as shown in FIG. 2 (a), if six pieces are provided in the circumferential direction, the circumferential interval is not fixed at 60 °, but 58 °, 60 °, It is recommended to provide it by deliberately shifting such as 62 °.

  Regarding the plate fin tube heat exchanger for car coolers using the heat transfer medium in the tube as oil, the influence of the inclination angle of the plate fin was investigated.

  The plate fin is made of an aluminum alloy (A1050) having an outer diameter of 30 mm and a thickness of 0.3 mm. The inner diameter of the tube hole is 11.6 mm, the height of the fin collar is 2 mm, and a trapezoidal cross section (bottom surface 6 mm, upper surface 2 mm, height). 2 mm) ribs are intentionally shifted in the circumferential direction such as 58 °, 60 °, and 62 ° (see FIG. 2). And what changed the inclination-angle of the umbrella-shaped slope sequentially between 5-15 degrees was produced.

  The plate fin is manufactured by forming ribs, tube holes, and fin collars in order on a flat plate of an aluminum alloy (A1050), then deforming it into an umbrella shape around the tube holes, and finally the entire outer diameter. This was done by punching out a circle.

  The tube used was an aluminum alloy (A6063) having an outer diameter of 11.4 mm and a thickness of 1 mm.

(1) Measurement of the fixing force of the plate fin First, for each inclination angle of the umbrella-like slope of the plate fin, only one plate fin is inserted into the tube, and the fin collar forming side (that is, the umbrella-like slope is inclined) The plug having a maximum tip diameter of 10.2 mm was pushed into the tube from the side where the tube and the plate fin were fixed. Then, to measure the fixing force of the plate fin to the tube, for each of the five samples at each inclination angle of the umbrella-like slope of the plate fin, the plate fin is pulled out from the tube to the fin collar forming side. The required force was measured, and the average value was taken as the fixing force of the plate fin.

(2) Investigation of the frequency of occurrence of Abeck phenomenon and fin pitch disturbance Next, for each inclination angle of the umbrella-like slope of the plate fin, 200 plate fins are placed on the tube, and the inclination directions of the umbrella-like slope are all the same direction. As in (1) above, insert a plug with a maximum diameter of 10.2 mm into the tube from the fin collar formation side to expand the tube and fix the tube and plate fin in the same manner as in (1) above. It was. Then, for each of the inclination angles of the umbrella-shaped slope of the plate fin, the presence or absence of occurrence of the Abeck phenomenon or fin pitch disturbance was visually examined for five samples.

(3) Investigation of effects on heat exchange performance
[Invention Example]
As shown in FIG. 5 (a), 100 circular plate fins with an umbrella-like slope having an inclination angle of 15 ° are fixed to each straight portion of the curved tube having the same material and diameter as the straight tube. The plate fin tube heat exchanger was manufactured by inserting a spring for heat transfer promotion into the tube and reducing the diameter so that the end of the tube could be connected to the low pressure rubber hose. And the low pressure rubber hose was connected to the tube both ends of this plate fin tube heat exchanger, and it filled with oil, and formed the cooling circuit.

[Comparative example]
As shown in FIG. 5 (b), 100 pieces of rectangular fins having a flat shape of 25 mm × 70 mm (without ribs) and having two tube holes along the longitudinal direction at a pitch of 2 mm (same pitch as the above-described invention example). Each tube is fixed to the same curved pipe tube as in the above invention example, and the heat transfer promotion spring is inserted into this tube, and the end of the tube is reduced in diameter so that it can be connected to the low pressure rubber hose. It processed and produced the plate fin tube heat exchanger. And the low pressure rubber hose was connected to the tube both ends of this plate fin tube heat exchanger, and it filled with oil, and formed the cooling circuit.

[Method and conditions of heat exchange performance evaluation experiment]
While circulating oil at each flow rate of 4, 6, and 8 L / min in each cooling circuit of the above invention example and comparative example, for each plate fin tube heat exchanger, with a fan in a direction perpendicular to the paper surface in FIG. The air velocity was changed and normal temperature air was blown, and the cooling performance (W) at that time was measured. The wind speed is measured by an anemometer installed in the vicinity of the plate fin tube heat exchanger, and the cooling performance (W) is measured by measuring the oil temperature on the inlet side and the outlet side of the plate fin tube heat exchanger. It calculated | required by calculating the thermal radiation amount.

(Experimental result)
The experimental results of the above (1) and (2) are shown in Table 1 below.

  As shown in Table 1 above, the fixing force of the plate fin tends to decrease rapidly when the inclination angle of the plate fin is 13 ° or more, because the component force in the direction in which the plate fin tightens the tube decreases. In the range of this experiment (15 ° or less), the fixing force (120 N or more) required for the plate fin tube heat exchanger is sufficiently secured.

  Also, when the plate fin inclination angle is less than 8 °, the Abeck phenomenon and the fin pitch disturbance occur frequently. On the other hand, when the plate fin inclination angle exceeds 8 °, the Abeck phenomenon and the fin pitch disturbance occur. It turns out that it does not occur at all.

  The results of the heat exchange performance evaluation experiment (3) are shown in FIG. Although the invention example had a smaller total plate fin area than the comparative example, as shown in the figure, the cooling performance (W) was almost the same, and it was found that the heat exchange performance could be sufficiently secured.

It is a longitudinal section showing a plate fin tube heat exchanger concerning an embodiment of the present invention. It is the (a) front view showing the plate fin concerning the embodiment of the present invention, and the XX line sectional view in (b) and (a). It is sectional drawing explaining the deformation | transformation behavior of the plate fin at the time of pipe expansion, (a) is based on pressing force, (b) is based on an axial load. It is a longitudinal cross-sectional view which shows the conventional plate fin tube heat exchanger. It is a front view which shows the structure of the plate fin tube heat exchanger used for heat exchange performance evaluation experiment, (a) shows an invention example, (b) shows a comparative example. It is a graph which shows the relationship between a wind speed and cooling performance in a plate fin tube heat exchanger.

Explanation of symbols

1: Plate fin tube heat exchanger 2: Tube 3: Plate fin 4: Tube hole 5: Fin collar 6: Umbrella slope 7: Rib

Claims (3)

  A plate fin formed by forming a fin collar around a tube hole through which a tube, which will be described later, is inserted, and a tube that is inserted through the tube hole and expanded to be fixed to each plate fin. It is a plate fin tube heat exchanger, and all the plate fins are formed in an umbrella shape extending from the tube hole toward the fin collar forming side, and this umbrella-shaped inclined surface is a surface perpendicular to the tube. A plate finned tube heat exchanger that is inclined by 8 to 30 °.   The plate fin tube heat exchanger according to claim 1, wherein a rib for ensuring a space between adjacent plate fins is provided on all of the plate fins.   A fin collar is formed around a tube hole through which the tube is inserted, and is formed in an umbrella shape extending from the tube hole toward the fin collar forming side, and this umbrella-shaped inclined surface is a surface perpendicular to the tube. A step of laminating a large number of plate fins inclined by 8 to 30 °, a step of inserting the tube into the tube hole, and a slightly larger inner diameter of the tube from the fin collar formation side in the tube A method of manufacturing a plate fin tube heat exchanger, comprising: a step of expanding the tube from the inside by pushing a plug having an outer diameter to fix the plate fin and the tube.

Images