JP6789019B2 - Corrugated fins and heat exchanger - Google Patents

Description

The present invention relates to corrugated fins and heat exchangers equipped with the corrugated fins.

For example, a power conversion device that switches by a semiconductor element is used for various applications such as control of a drive motor mounted on a hybrid vehicle or an electric vehicle. The power conversion device includes a heat exchanger for cooling a semiconductor element and a heating element such as an electronic component that constitutes a power conversion circuit together with the semiconductor element. The heat exchanger has a jacket on which a heating element is mounted on the outer surface and inner fins housed inside the jacket. From the viewpoint of improving the performance and production efficiency of the heat exchanger, the inner fins are usually joined to the jacket by brazing.

As the inner fin, corrugated fins, which are relatively easy to manufacture and can be manufactured at low cost, are often used. Further, the corrugated fin is often made of an aluminum plate material (including an aluminum plate and an aluminum alloy plate; the same applies hereinafter) which is relatively lightweight and has good thermal conductivity.

Further, the corrugated fin may be provided with a slit extending in the fin height direction for the purpose of improving the cooling performance. For example, Patent Document 1 describes corrugated fins arranged inside a flat heat transfer tube for cooling EGR (exhaust gas recirculation) gas.

Japanese Unexamined Patent Publication No. 2006-64345

In the heat exchanger incorporated in the power conversion device, the heat generated from the heating element is transferred to the corrugated fin via the jacket. In this case, if the corrugated fins are thin, the heat conduction in the corrugated fins deteriorates, resulting in a decrease in cooling performance. On the other hand, when the plate thickness is thick, the pressure loss when the cooling medium is circulated increases and the manufacturability deteriorates. Therefore, in this type of heat exchanger, corrugated fins having a plate thickness of 0.30 mm or less are used from the viewpoint of balancing cooling performance and pressure loss while ensuring manufacturability.

However, in order to cope with the increase in the output of the power converter in recent years, it is strongly required to further improve the cooling performance of the heat exchanger. In such a situation, it is necessary to ensure the required cooling performance even if a certain increase in pressure loss is allowed.

The present invention has been made in view of this background, and is a corrugated fin capable of achieving significantly higher cooling performance than before while suppressing an increase in pressure loss, and a heat exchanger provided with the corrugated fin. Is intended to provide.

One aspect of the present invention is a corrugate made of an aluminum plate, in which a flat plate portion erected in the fin height direction and a connecting portion connected to the end portion of the flat plate portion in the fin height direction are alternately connected. It ’s a fin,
The fin height of the corrugated fin is 5 to 10 mm.
The corrugated fin has a plurality of slits provided over the entire flat plate portion and one of the connecting portions of the pair of connecting portions connected to the flat plate portion.
The slit has a rectangular shape when viewed from the fin width direction.
The thickness of the aluminum plate is 0.4 to 1.0 mm.
The width of the upper Symbol slit and S [mm], in the above flat plate portion, the distance between the adjacent said slit is taken as L [mm], satisfies the following relationship formula (1) to (4), corrugated It's in the fins.

0.5 <S <5.0 ... (1)
L> 1.0 ・ ・ ・ (2)
S ≦ 0.625L + 0.125 ・ ・ ・ (3)
S ≦ -0.88571L + 7.5 ・ ・ ・ (4)

Another aspect of the present invention includes the corrugated fin of the above aspect and
It is in a heat exchanger having a jacket that houses the corrugated fins.

The corrugated fin is made of the aluminum plate material having a plate thickness in the specific range. Further, the width S of the slits provided on the flat plate portion and the distance L between the adjacent slits satisfy the relationship of the above formulas (1) to (4).

As the corrugated fin, the heat conduction in the corrugated fin can be improved by using the aluminum plate material having a thicker plate thickness than the conventional one. Further, by providing the slit in the flat plate portion so as to satisfy the relationship of the formulas (1) to (4), the flow of the cooling medium passing through the corrugated fin is disturbed, and heat exchange with the corrugated fin is performed. Can be promoted. Then, the effect of the thickness of the aluminum plate and the effect of the slit act synergistically to realize a significantly higher cooling performance than before.

Further, by providing the slit in the flat plate portion so as to satisfy the relationship of the above formulas (1) to (4), it is possible to realize high cooling performance and avoid an excessive increase in pressure loss. ..

As described above, in the corrugated fin, the width S of the slits and the distance L between the adjacent slits are adjusted to the optimum range in which high cooling performance can be realized while avoiding an excessive increase in pressure loss. Therefore, the corrugated fin can realize a significantly higher cooling performance than the conventional one while suppressing an increase in pressure loss within an acceptable range.

Further, the heat exchanger has the corrugated fin and a jacket for accommodating the corrugated fin. Therefore, it has a much higher cooling performance than the conventional one while suppressing an increase in pressure loss within an acceptable range.

FIG. 5 is a perspective view of corrugated fins in which slits are arranged at equal intervals in the first embodiment. It is a side view of the corrugated fin in Example 1. FIG. It is explanatory drawing which summarized the comprehensive evaluation in Example 1. FIG. 2 is a perspective view of corrugated fins having different slit spacings in the second embodiment. It is sectional drawing which shows the main part of the corrugated fin provided with the flat surface at the top of the connection part in Example 3. FIG.

The flat plate portion of the corrugated fin is erected in the fin height direction. As a result, the number of flat plate portions included in the corrugated fin can be increased, and the cooling performance can be improved.

The connecting portion connects the ends of adjacent flat plate portions in the fin height direction. The cross-sectional shape of the connecting portion in the longitudinal direction of the fin can be, for example, an arc shape. In this case, when brazing with the jacket, the contact portion between the connecting portion and the brazing material tends to be linear. Therefore, it is possible to suppress the generation of voids at the joint portion after brazing as compared with the case where the connecting portion and the brazing material are in contact with each other in a planar manner. As a result, the heat conduction from the jacket to the corrugated fin can be further improved, and thus the cooling performance can be further improved.

Further, the connecting portion has a curved portion connected to the end portion of each flat plate portion in the fin height direction and a top surface portion connecting the curved portions to each other, and the top surface portion is flat outward in the fin height direction. It may have a face. That is, the cross-sectional shape of the connecting portion in the longitudinal direction of the fin may have an arc shape with a flat top surface portion. In this case, the area of the contact portion between the top surface portion and the brazing material can be narrowed when brazing with the jacket, as compared with the case where the cross-sectional shape of the connecting portion in the longitudinal direction of the fin is rectangular. it can. Therefore, the generation of voids at the joint portion after brazing can be suppressed as compared with the case where the cross-sectional shape of the connection portion is rectangular. As a result, the heat conduction from the jacket to the corrugated fin can be further improved, and thus the cooling performance can be further improved.

As the aluminum plate material constituting the corrugated fin, a known aluminum plate or aluminum alloy plate can be adopted depending on the required strength, corrosion resistance, and the like.

The plate thickness of the aluminum plate material is 0.4 to 1.0 mm. If the plate thickness is less than 0.4 mm, the heat conduction in the corrugated fins deteriorates, which may lead to a decrease in cooling performance. On the other hand, if the plate thickness exceeds 1.0 mm, the workability of corrugated processing deteriorates, which may lead to deterioration of the manufacturability of corrugated fins. Further, in this case, the number of flat plate portions included in the corrugated fin is reduced, which may lead to a decrease in cooling performance. From the viewpoint of improving the cooling performance, it is preferable that the thickness of the aluminum plate is 0.6 to 0.9 mm.

The fin length and fin width of the corrugated fins can be appropriately set according to the shape of the jacket of the heat exchanger. On the other hand, the fin height is 5 to 10 mm. If the fin height is excessively high, the cooling performance may be deteriorated. Further, if the fin height is excessively low, the pressure loss may increase. By setting the fin height within the above-mentioned specific range, these problems can be easily avoided.

The distance between the adjacent flat plates is preferably 0.9 to 1.0 mm. If this interval becomes excessively narrow, foreign matter tends to be clogged between adjacent flat plates. Further, in this case, the processability of the corrugated process is deteriorated, which may lead to the deterioration of the manufacturability of the corrugated fin. On the other hand, if the distance between the adjacent flat plates is excessively wide, the number of flat plates contained in the corrugated fins is reduced, which may lead to deterioration of cooling performance. By setting the distance between the adjacent flat plates to 0.9 to 1.0 mm, these problems can be easily avoided.

A plurality of slits are formed in each flat plate portion, and the width S [mm] of the slits and the distance L [mm] of the adjacent slits satisfy the relationship of the following formulas (1) to (4). ..
0.5 <S <5.0 ... (1)
L> 1.0 ・ ・ ・ (2)
S ≦ 0.625L + 0.125 ・ ・ ・ (3)
S ≦ -0.88571L + 7.5 ・ ・ ・ (4)

The width S of the slit is more than 0.5 mm and less than 5.0 mm. If the width S of the slit is 5.0 mm or more, the pressure loss may increase.

On the other hand, when the width S of the slit is 0.5 mm or less, it is difficult to form the slit in the flat plate portion. Further, in this case, the function of the slit may be caused by troubles such as the brazing being filled in the slit when the corrugated fin and the jacket are brazed, or foreign matter being clogged in the slit when the cooling medium is circulated. It may be damaged. These problems can be avoided by making the width S of the slit larger than 0.5 mm, preferably larger than 0.9 mm.

The distance L between adjacent slits is 1.0 mm or more. When the slit spacing L is 1.0 mm or less, it is difficult to form slits in the flat plate portion.

Further, the relationship between the slit width S and the slit spacing L satisfies the above equations (3) and (4). If the relationship between the two does not satisfy the above equation (3), the pressure loss will be excessively increased. Further, if the relationship between the two does not satisfy the above equation (4), the cooling performance becomes insufficient.

As described above, the corrugated fin has a pressure because the slit width S [mm] and the adjacent slit spacing L [mm] satisfy all the relationships of the above formulas (1) to (4). It is possible to achieve much higher cooling performance than before while suppressing the increase in loss within an acceptable range. In these relational expressions, two parameters, the slit width S [mm] and the adjacent slit spacing L [mm], are the cooling performance and pressure loss from among many parameters related to the dimensions of the corrugated fin. As a result of finding that it has a great influence by the present inventors, it was possible to obtain it.

In order to obtain the above-mentioned effects, it is sufficient that all the slits provided in the corrugated fin satisfy the above formulas (1) to (4). For example, within the range satisfying the above formulas (1) to (4), the widths of all the slits may be the same, or the widths of some slits may be different from those of other slits.

From the viewpoint of further improving the cooling performance of the corrugated fins, the relationship between the width S [mm] of the slits and the distance L [mm] of the adjacent slits in at least some of the slits is further expressed by the following equation ( It is preferable to satisfy the relationship of 5).
S ≦ −0.015L ² + 0.5253L −1.5511 ・ ・ ・ (5)

From the viewpoint of further improving the cooling performance of the corrugated fins, the relationship between the width S [mm] of the slits and the distance L [mm] of the adjacent slits in all the slits is determined by the above formula (5). It is even more preferable to satisfy the relationship.

Further, all the slits may be arranged at equal intervals within the range satisfying the above equations (1) to (4), or the intervals of some slits may be different from the intervals of other slits. ..

For example, the corrugated fin has an upstream portion arranged at one end in the fin longitudinal direction and a downstream portion arranged at the other end in the fin longitudinal direction and connected to the upstream portion, and is adjacent to each other in the upstream portion. The distance between the slits may be wider than that of the downstream portion. In this case, it is possible to suppress an increase in pressure loss in the upstream portion where the slit spacing is relatively wide. Further, in the downstream portion where the distance between the slits is relatively narrow, the slits can disturb the flow of the cooling medium and promote heat exchange between the cooling medium and the corrugated fins. As a result, it is possible to improve the cooling performance in the downstream portion while suppressing the increase in pressure loss.

A heat exchanger can be configured by accommodating the corrugated fin in the jacket. As the jacket, a jacket known for heat exchangers can be adopted. The heat exchanger having the corrugated fins can be used for various purposes, and can be particularly preferably used for a power conversion device.

Examples of the corrugated fins will be described with reference to the drawings. The mode of the corrugated fin according to the present invention is not limited to the mode of the embodiment, and the configuration can be appropriately changed as long as the gist of the present invention is not impaired.

(Example 1)
This example is an example of corrugated fins 1 in which slits 4 are arranged at equal intervals. The corrugated fin 1 of this example is made of an aluminum plate material, and as shown in FIG. 1, is connected to a flat plate portion 2 erected in the fin height direction and an end portion of the flat plate portion 2 in the fin height direction. The connected connection portions 3 are alternately connected. The plate thickness of the aluminum plate material is 0.4 to 1.0 mm. The flat plate portion 2 has a plurality of slits 21 extending in the fin height direction. Further, as shown in FIG. 2, the corrugated fin 1 has the following formula (when the width of the slit 21 is S [mm] and the distance between the adjacent slits 21 in each flat plate portion 2 is L [mm]. The relationships 1) to (4) are satisfied.

0.5 <S <5.0 ... (1)
L> 1.0 ・ ・ ・ (2)
S ≦ 0.625L + 0.125 ・ ・ ・ (3)
S ≦ -0.88571L + 7.5 ・ ・ ・ (4)

As shown in FIGS. 1 and 2, the corrugated fin 1 of this example has a plurality of slits 21 arranged at equal intervals. Further, in this example, the slit 21 is formed over the entire surface of the flat plate portion 2 and one of the connecting portions 3 (3a, 3b) connected to the flat plate portion 2.

The cross-sectional shape of the connecting portion 3 in the longitudinal direction of the fin is arcuate.

In this example, the thickness of the aluminum plate is 0.6 mm, the distance between the adjacent flat plates 2 is 0.9 mm, the fin height is 6 mm, and the width S of the slit 21 and the distance L between the adjacent slits 21 are shown in Table 1. Corrugated fins (test bodies A1 to A28) modified in various ways as shown in the above were actually manufactured, and the manufacturability was evaluated. As a result, when it was possible to manufacture, the symbol "A" was described in the column of "manufacturability" in Table 1, and when it could not be manufactured, the symbol "B" was described.

In addition, thermo-fluid analysis was performed on those corrugated fins that could be manufactured, and the cooling performance and pressure loss were evaluated. The thermo-fluid analysis was performed by the following method. First, a box-shaped jacket having a pair of wall portions facing each other and having a refrigerant inlet / outlet port and a wall portion having a fin longitudinal end surface and a refrigerant inlet / outlet port facing each other are housed in the jacket. A structural model with corrugated fins was created. Next, a 1000 W heating element was placed on the outer surface of the outer wall of the jacket in contact with the connecting portion. Then, the cooling medium was made to flow into the jacket from the refrigerant inlet / outlet on the upstream side, and the maximum temperature Tmax [° C.] of the jacket in the steady state and the pressure loss ΔP [kPa] were calculated. The cooling medium was LLC (Long Life Coolant) at 60 ° C., and the flow rate was 10 L / min.

As an index of the cooling performance, the value of the thermal resistance Rth [K / W] calculated by the following formula (6) was used. Further, the pressure loss ΔP [kPa] was defined as the difference between the pressure of the cooling medium at the refrigerant inlet / outlet on the upstream side and the pressure of the cooling medium at the refrigerant inlet / outlet on the downstream side. These values were as shown in Table 1.
Rth = (Tmax-60) / 1000 ... (6)

Further, for comparison with corrugated fins having slits, the thermal resistance Rth [K / W] and pressure loss ΔP [kPa] when corrugated fins without slits (Table 1, Specimen R) are used. It was calculated by the same method as above.

Based on these values, the quality of the corrugated fin performance was judged. The cooling performance was determined based on the ratio of the values of the thermal resistance Rth of the test bodies A1 to A28 to the value of the thermal resistance Rth when the test body R was used. When the thermal resistance Rth of the test bodies A1 to A28 is 0.9 times or less with respect to the test body R, the symbol "A" is displayed in the "judgment" column in Table 1, and when it exceeds 0.9 times, The symbol "B" is described. Then, the case of the symbol "A" in which the cooling performance was sufficiently improved was determined to be acceptable.

The pressure loss was determined based on the ratio of the pressure loss ΔP of the test bodies A1 to A28 to the value of the pressure loss ΔP when the test body R was used. When the pressure loss ΔP of the test bodies A1 to A28 is 2 times or less with respect to the pressure loss ΔP, the symbol “A +” is displayed in the “judgment” column in Table 1. When "A" is larger than 3 times, the symbol "B" is described. Then, the cases of the symbol "A +" and the symbol "A" that could sufficiently suppress the increase in the pressure loss were judged to be acceptable.

In addition, based on the evaluation results of manufacturability, cooling performance and pressure loss, a comprehensive judgment was made as follows. When the manufacturability is "A (manufacturable)", the cooling performance is "A (pass)", and the pressure loss is "A + (excellent)", it is judged that the product has excellent performance and sufficient manufacturability. , The symbol "A +" is described in the "Comprehensive judgment" column. If the manufacturability is "A", the cooling performance is "A", and the pressure loss is "A (pass)", it is judged that the product has good performance and sufficient manufacturability, and the "Comprehensive judgment" column is used. The symbol "A" is described in. If one or more of the manufacturability, cooling performance and pressure loss is "B (unmanufacturable or rejected)", it is judged that the performance or manufacturability is inferior, and the symbol "Comprehensive judgment" is displayed. B ”is described.

Further, FIG. 3 shows a graph summarizing the relationship between the “comprehensive judgment” in Table 1 and the slit width S and the slit spacing L in each test piece. The vertical axis of FIG. 3 is the slit width S [mm], and the horizontal axis is the slit spacing L [mm]. Further, the symbol “⊚” in the graph indicates a test piece whose overall judgment was “A +”. Similarly, the symbol "○" indicates a test body having a comprehensive judgment of "A", and the symbol "x" indicates a test body having a comprehensive judgment of "B".

Further, in FIG. 3, straight lines L1 to L6 represented by the following formula are indicated by broken lines. The straight lines L1 and L2 are equations corresponding to the boundary of the above equation (1). Further, the straight lines L3 to L6 are equations corresponding to the boundaries of the above equations (2) to (5), respectively.
L1: S = 0.5
L2: S = 5.0
L3: L = 1.0
L4: S = 0.625L + 0.125
L5: S = -0.88571L + 7.5
L6: S = -0.015L ² + 0.5253L-1.5511

As shown in Tables 1 and 3, test specimens A8 to A11, A15 to A18, A21 to A22, and A25 in which the slit width S and the slit spacing L satisfy the above formulas (1) to (4). ~ A26 was excellent in manufacturability and cooling performance, and could sufficiently suppress an increase in pressure loss. Further, among these test bodies, the test bodies A10 to A11 and A17 to A18 in which the slit width S and the slit spacing L satisfy the above formula (5) have a pressure loss as compared with the test bodies other than these. Was able to be further reduced.

On the other hand, for the test bodies A1 to A6 in which the slit width S is to be less than 0.5 mm, and the test bodies A7 and A13 in which the slit spacing L is to be less than 1.0 mm, slits having the target dimensions are provided. Could not be formed. Therefore, it was not possible to produce corrugated fins.
The test bodies A14, A20, A24 that do not satisfy the above formula (3) and the test body A28 having a slit width S of more than 5.0 mm are difficult to use in a heat exchanger because the pressure loss is excessively increased.
The test bodies A12, A19, A23 and A27 that did not satisfy the above formula (4) had insufficient improvement in cooling performance.

(Example 2)
This example is an example of a corrugated fin 102 in which the distance L1 of some slits 21 is different from the distance L2 of other slits 21. As shown in FIG. 4, the corrugated fin 102 of this example has an upstream portion 11 arranged at one end in the fin longitudinal direction and a downstream portion 12 arranged at the other end in the fin longitudinal direction and connected to the upstream portion 11. doing. The distance L1 [mm] between the adjacent slits in the upstream portion 11 is wider than the distance L2 [mm] between the adjacent slits in the downstream portion 12.

Others are the same as in Example 1. In addition, among the symbols used in FIG. 4, the same symbols as those used in the above-mentioned Examples represent the same components and the like as those in the above-mentioned Examples unless otherwise specified.

In this example, as shown in Table 2, corrugated fins (test bodies B1 to B3) in which the slit width S [mm] and the slit intervals L1 and L2 [mm] are changed are actually produced to evaluate the manufacturability. Was done. In addition, the cooling performance and pressure loss of these test specimens were evaluated by the same method as in Example 1. The results of these evaluations are as shown in Table 2.

As shown in Table 2, in the test bodies B1 to B3 of this example, all the slits satisfy the relationship of the above formulas (1) to (4). Therefore, the test bodies B1 to B3 showed excellent manufacturability and cooling performance. Further, since at least a part of the slits in these test specimens satisfies the relationship of the above formula (5), the effect of suppressing the increase in pressure loss was high.

(Example 3)
This example is an example of the corrugated fin 103 in which the shape of the connecting portion 303 is changed. As shown in FIG. 5, the corrugated fin 103 of this example is connected with a curved portion 31 connected to an end portion 22 in the fin height direction of each flat plate portion 2 and a top surface portion 32 connecting the curved portions 31 to each other. It has a unit 303. The top surface portion 32 has a flat surface 321 on the outer side in the fin height direction. That is, in the connecting portion 303 of this example, the top surface portion 32 has a flat arc shape in the cross section in the longitudinal direction of the fin. Others are the same as in Example 1. Even when the top surface portion 32 of the connecting portion 303 is formed flat as in this example, the same effect as in the first embodiment can be obtained.

1, 102, 103 Corrugated fin 2 Flat plate 21 Slit 3, 303 Connection S Slit width L, L1, L2 Spacing between adjacent slits

Claims (6)

A corrugated fin made of an aluminum plate, in which a flat plate portion erected in the fin height direction and a connecting portion connected to an end portion in the fin height direction of the flat plate portion are alternately connected.
The fin height of the corrugated fin is 5 to 10 mm.
The corrugated fin has a plurality of slits provided over the entire flat plate portion and one of the connecting portions of the pair of connecting portions connected to the flat plate portion.
The slit has a rectangular shape when viewed from the fin width direction.
The thickness of the aluminum plate is 0.4 to 1.0 mm.
The width of the upper Symbol slit and S [mm], in the above flat plate portion, the distance between the adjacent said slit is taken as L [mm], satisfies the following relationship formula (1) to (4), corrugated fin.
0.5 <S <5.0 ... (1)
L> 1.0 ・ ・ ・ (2)
S ≦ 0.625L + 0.125 ・ ・ ・ (3)
S ≦ -0.88571L + 7.5 ・ ・ ・ (4) The first aspect of the present invention, wherein the relationship between the width S [mm] of the slits and the distance L [mm] of the adjacent slits in at least a part of the slits further satisfies the relationship of the following formula (5). Corrugated fins.
S ≦ −0.015L ² + 0.5253L −1.5511 ・ ・ ・ (5) The corrugated fin according to claim 1 or 2, wherein the plurality of slits are arranged at equal intervals. It has an upstream portion arranged at one end in the fin longitudinal direction and a downstream portion arranged at the other end in the fin longitudinal direction and connected to the upstream portion, and the distance between adjacent slits in the upstream portion is the downstream portion. The corrugated fin according to claim 1 or 2, which is wider than a portion. The corrugated fin according to any one of claims 1 to 5, which is a corrugated fin used for heat exchange with a liquid cooling medium and has a plate thickness of 0.6 to 1.0 mm. The corrugated fin according to any one of claims 1 to 5 ,
A heat exchanger having a jacket that houses the corrugated fins.

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