JP7736882B2 - Heat exchanger and method for manufacturing the same - Google Patents

Description

This disclosure relates to a heat exchanger and a method for manufacturing a heat exchanger.

Patent Document 1 discloses a heat exchanger for cooling a battery mounted on an electric vehicle by exchanging heat with the battery. This heat exchanger includes two plate-shaped members joined by laser beam welding and a flow path formed between the two plate-shaped members and through which a heat exchange medium passes. The flow path is defined by multiple joints where the two plate-shaped members are joined, and multiple joints aligned in an orthogonal direction perpendicular to the flow direction of the heat exchange medium. Patent Document 1 discloses a configuration in which multiple joints are arranged on a neutral axis extending in the orthogonal direction in a cross section of the heat exchanger taken along the orthogonal direction. Patent Document 1 also discloses a configuration in which multiple joints are arranged away from the neutral axis on a cooling surface of a plate-shaped member facing the battery that comes into contact with the battery and extends in a plane parallel to the neutral axis of the heat exchanger.

Special Publication No. 2020-510534

However, when multiple joints are positioned on the neutral axis of the heat exchanger, the heat exchanger does not come into contact with the battery at the locations where the multiple joints are located, which tends to reduce the cooling surface of the heat exchanger that comes into contact with the battery. This poses the problem of a tendency for the heat exchanger's cooling performance for the battery to decrease.

Furthermore, when multiple joints are positioned away from the neutral axis on the planar cooling surface of the heat exchanger, the thermal distortion of the heat exchanger caused by contraction stress when the multiple joints cool is likely to cause deformation of the cooling surface, making it difficult for the cooling surface to come into contact with the battery. This poses the problem of a deterioration in the cooling performance of the heat exchanger for the battery.

One aspect of the present disclosure aims to improve the cooling performance of a heat exchanger for a battery.

One aspect of the present disclosure relates to a heat exchanger that exchanges heat with a battery mounted on an electric vehicle, and includes a first plate member, a second plate member, and a joint. The first plate member is a plate-shaped member configured to face the battery. The second plate member is a plate-shaped member arranged to face the first plate member on the side opposite the battery, and forms a flow path through which a heat exchange medium passes between the first plate member and the second plate member. The joint is a portion where the first plate member and the second plate member are joined by welding. The joint also has multiple weld lines extending in a first direction and aligned in a second direction perpendicular to the first direction to define the flow path. The multiple weld lines are respectively positioned on the first plate member side and the second plate member side with respect to a neutral axis extending in the second direction in a cross section of the heat exchanger perpendicular to the first direction. Of the multiple weld lines, at least one weld line located closer to the first plate member than the neutral axis is defined as a first weld line, and at least one weld line located closer to the second plate member than the neutral axis is defined as a second weld line. The sum of the shortest distances from the neutral axis to each of the at least one first weld line is approximately the same as the sum of the shortest distances from the neutral axis to each of the at least one second weld line.

With this configuration, deformation of the heat exchanger caused by contraction stress when the first weld line cools is more likely to be offset by deformation of the heat exchanger caused by contraction stress when the second weld line cools. This reduces the effects of thermal distortion on heat exchangers with joints formed by welding. In other words, deformation of the first plate member is reduced, making it easier for the first plate member to come into contact with the battery. This improves the cooling performance of the heat exchanger for the battery.

In one aspect of the present disclosure, the number of the at least one first weld line and the number of the at least one second weld line may be the same. The shortest distance from the neutral axis to each of the at least one first weld line and the shortest distance from the neutral axis to each of the at least one second weld line may be the same.

With this configuration, deformation of the heat exchanger caused by the first weld line is more likely to be offset by deformation of the heat exchanger caused by the second weld line. This reduces the effects of thermal distortion on the heat exchanger, which has a joint formed by welding. This improves the cooling performance of the heat exchanger for the battery.

In one aspect of the present disclosure, the multiple weld lines may be arranged symmetrically with respect to a center line in a cross section of the heat exchanger perpendicular to the first direction. The center line may be a line that passes through the center of the second direction in the cross section of the heat exchanger perpendicular to the first direction and is perpendicular to the neutral axis.

This configuration makes it possible to suppress the effects of thermal distortion of the heat exchanger at each location on both sides of the center line.

In one aspect of the present disclosure, the first direction may be a longitudinal direction of the heat exchanger.
Since the weld lines extending in the longitudinal direction of the heat exchanger contribute more to the thermal distortion of the heat exchanger than the weld lines extending in the lateral direction of the heat exchanger, the above-described configuration makes it easier to suppress the effects of the thermal distortion of the heat exchanger.

In one aspect of the present disclosure, the first plate member may have a contact portion. The contact portion is a portion that comes into contact with the battery, is substantially parallel to the neutral axis, and extends in a substantially planar shape in the first and second directions. At least one first weld line may be disposed in the contact portion.

With this configuration, the portion of the contact portion where the flow path is provided and the portion where the first weld line is provided come into contact with the battery, thereby increasing the area of the surface of the contact portion that comes into contact with the battery and exchanges heat with the battery. This further improves the cooling performance of the heat exchanger for the battery.

In one aspect of the present disclosure, the multiple weld lines may be formed by heat input to the joint. The sum of the values obtained by multiplying the shortest distance from the neutral axis to each of the at least one first weld line by the amount of heat input when each of the at least one first weld line was formed may be approximately the same as the sum of the values obtained by multiplying the shortest distance from the neutral axis to each of the at least one second weld line by the amount of heat input when each of the at least one second weld line was formed.

With this configuration, the evaluation of the impact of thermal distortion on the heat exchanger takes into account not only the shortest distance from the neutral axis to each weld line, but also the amount of heat input when each weld line was formed. This means that even if, for example, the amount of heat input when each weld line was formed differs, resulting in different contraction stresses when each weld line cools, the deformation caused by the first weld line is more likely to be offset by the deformation caused by the second weld line. This reduces the impact of thermal distortion even in heat exchangers with joints that received heat under different conditions during welding. This improves the cooling performance of the heat exchanger for the battery.

In one aspect of the present disclosure, a method for manufacturing a heat exchanger may include overlapping a second plate member on a first plate member so that the first plate member and the second plate member abut at a joint, and forming multiple weld lines by inputting heat into the joint to join the first plate member and the second plate member. The sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one first weld line by the amount of heat input when each of the at least one first weld line is formed may be approximately the same as the sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one second weld line by the amount of heat input when each of the at least one second weld line is formed.

With this configuration, the evaluation of the impact of thermal distortion on the heat exchanger takes into account not only the shortest distance from the neutral axis to each weld line, but also the amount of heat input when each weld line was formed. This means that even if, for example, the amount of heat input when each weld line was formed differs, resulting in different contraction stresses when each weld line cools, the deformation caused by the first weld line is more likely to be offset by the deformation caused by the second weld line. This reduces the impact of thermal distortion even in heat exchangers with joints that received heat under different conditions during welding. This improves the cooling performance of the heat exchanger for the battery.

FIG. 2 is a schematic perspective view showing a heat exchanger. FIG. 2 is a side view schematically showing the arrangement of the heat exchanger relative to the battery. FIG. 2 is an end view taken along the line III-III in FIG. FIG. 2 is a schematic plan view showing a heat exchanger. FIG. 10 is a schematic perspective view showing a heat exchanger of a first modified example. FIG. 10 is a side view schematically showing the arrangement of a heat exchanger of a first modified example relative to a battery. FIG. 10 is a schematic plan view showing a heat exchanger of a first modified example. FIG. 10 is an end view in a cross section perpendicular to the longitudinal direction, schematically illustrating the configuration of one side of the center line of a heat exchanger of a second modified example. FIG. 11 is an end view in a cross section perpendicular to the longitudinal direction, schematically illustrating the configuration of one side of a heat exchanger of a third modified example with respect to a center line. FIG. 2 is a diagram schematically illustrating a state in which a heat exchange device is arranged in correspondence with a battery pack. FIG. 1 is a diagram schematically illustrating a heat exchange device in which a plurality of heat exchangers are connected together to form an integrated unit. FIG. 10 is a diagram schematically illustrating the shape of a flow path of a heat exchanger according to a fourth modified example. FIG. 13 is a diagram schematically illustrating the shape of a flow path of a heat exchanger according to a fifth modified example. FIG. 2 is a flow chart showing a method for manufacturing a heat exchanger.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
[1. Configuration]
The heat exchanger 100 shown in Fig. 1 exchanges heat with a battery mounted on an electric vehicle to cool or heat the battery. An electric vehicle is a vehicle that runs using all or part of the electrical energy stored in a battery as its power source. Electric vehicles include electric vehicles, plug-in hybrid vehicles, hybrid vehicles, and fuel cell vehicles. The heat exchanger 100 is configured so that a heat exchange medium such as coolant flows inside. The heat exchanger 100 has an inlet 101 through which the heat exchange medium flows into the heat exchanger 100 and an outlet 102 through which the heat exchange medium is discharged from the heat exchanger 100.

In this embodiment, the inlet 101 and outlet 102 are provided on the first plate member 1, which will be described later. Specifically, the inlet 101 is located at the first end S1 of the heat exchanger 100 in the short side direction S, and at the first end L1 of the heat exchanger 100 in the long side direction L. The outlet 102 is located at the first end S1 of the heat exchanger 100 in the short side direction S, and at the second end L2 of the heat exchanger 100 in the long side direction L. The positions at which the inlet and outlet are located in the heat exchanger can vary depending on the shape of the flow path through which the heat exchange medium flows.

As shown in FIG. 2, the heat exchanger 100 faces the contact surface 201 of the battery 200, and is positioned so that the battery 200 is located between the inlet 101 and the outlet 102. A thermally conductive material 300 is disposed between the heat exchanger 100 and the battery 200. Note that a thermally conductive material does not necessarily have to be disposed between the heat exchanger and the battery. The frame 400 is disposed around the side of the battery 200 that extends perpendicular to the contact surface 201, and the heat exchanger 100 is positioned inside the frame 400. The surface of the heat exchanger 100 opposite the surface facing the battery 200 is covered by a lower case 500. Note that for convenience, part of the frame 400 is not shown in FIG. 2.

The heat exchanger 100 may have a longitudinal direction L corresponding to the front-to-rear direction of the electric vehicle and a transverse direction S corresponding to the left-to-right direction of the electric vehicle, or alternatively, a longitudinal direction L corresponding to the left-to-right direction of the electric vehicle and a transverse direction S corresponding to the front-to-rear direction of the electric vehicle.

As shown in FIG. 3 , in this embodiment, the heat exchanger 100 includes a first plate member 1 , a second plate member 2 , eight joints 3 , and six flow paths 4 .
<First plate member 1>
The first plate member 1 is a substantially rectangular plate member that faces the contact surface 201 of the battery 200. The first plate member 1 is made of a metal with high thermal conductivity, such as aluminum. The first plate member 1 may also be made of a metal with high corrosion resistance, such as stainless steel. The first plate member 1 has two contact portions 11 and three non-contact portions 12.

The contact portion 11 is a portion of the first plate member 1 that comes into indirect or direct contact with the battery 200, and is generally parallel to the neutral axis N extending in the short direction S in a cross section (hereinafter simply referred to as the cross section) perpendicular to the longitudinal direction L of the heat exchanger 100, and extends in a generally planar manner in both the longitudinal direction L and the short direction S. The neutral axis is the line where the cross section intersects with a neutral plane, which is a plane where neither compressive nor tensile strain occurs in an object. At the neutral axis, even if a bending moment acts on the object, the tensile force and compressive force balance, and no stress is generated in the cross section. The two contact portions 11 are located on the same plane and arranged side by side in the short direction S.

The non-contact portions 12 extend in the longitudinal direction L of the heat exchanger 100. The three non-contact portions 12 are located on the same plane and are arranged side by side in the short-side direction S. Of the three non-contact portions 12, one non-contact portion 12 is located at the first end S1 in the short-side direction S, one non-contact portion 12 is located at the second end S2 in the short-side direction S, and one non-contact portion 12 is located between the two contact portions 11. The two contact portions 11 protrude toward the side where the battery 200 is located (e.g., upward) relative to the three non-contact portions 12. In other words, a step is formed between each non-contact portion 12 and each contact portion 11. In this embodiment, the first plate member 1 has multiple through holes 13 in the non-contact portion 12 located between the two contact portions 11. The multiple through holes 13 are arranged at intervals from each other in the longitudinal direction L. The first plate member does not necessarily have to have multiple through holes in the non-contact portion located between the two contact portions.

<Second plate member>
The second plate member 2 is a substantially rectangular plate member and is arranged to face the first plate member 1 and the battery 200 on the opposite side. For example, if the contact surface 201 of the battery 200 mounted on the electric vehicle extends in a substantially horizontal direction, the second plate member 2 is arranged below or above the first plate member 1. Furthermore, if the contact surface 201 of the battery 200 mounted on the electric vehicle extends in a substantially vertical direction, the second plate member 2 is arranged to the left, right, front, or rear of the first plate member 1. Like the first plate member 1, the second plate member 2 is made of a metal with high thermal conductivity, such as aluminum. The second plate member may also be made of a metal with high corrosion resistance, such as stainless steel. The second plate member 2 has five flat portions 21 and four protruding portions 22.

The flat plate portions 21 are portions that do not abut the contact portions 11 of the first plate member 1, and extend generally parallel to the neutral axis N and in a generally planar manner in the longitudinal direction L and the lateral direction S. The five flat plate portions 21 are located on the same plane and aligned in the lateral direction S. Of the five flat plate portions 21, one flat plate portion 21 located at the first end S1 in the lateral direction S, one flat plate portion 21 located at the second end S2 in the lateral direction S, and one flat plate portion 21 located at the center of the second plate member 2 abut against the respective non-contact portions 12 of the first plate member 1 that face each flat plate portion 21. In this embodiment, the second plate member 2 has multiple through holes 23 in the flat plate portion 21 located at the center in the lateral direction S. The multiple through holes 23 are aligned at intervals from each other in the longitudinal direction L. Each through hole 23 of the second plate member 2 overlaps with each through hole 13 of the first plate member 1. The second plate member does not necessarily have to have multiple through holes in the flat plate portion located in the center in the short-side direction S.

The convex portions 22 are portions that come into contact with the contact portions 11 of the first plate member 1 and extend in the longitudinal direction L of the heat exchanger 100. The four convex portions 22 are arranged side by side in the lateral direction S, and are each located between two adjacent flat plate portions 21. The four convex portions 22 protrude toward the first plate member 1 relative to the five flat plate portions 21. In other words, a step is formed between each convex portion 22 and each flat plate portion 21.

<Joint part>
The eight joints 3 are portions where the first plate member 1 and the second plate member 2 are joined by welding, and extend in the longitudinal direction L of the heat exchanger 100. For example, laser welding, arc welding, or the like is used for welding.

Each joint 3 is provided at a location where each contact portion 11 of the first plate member 1 abuts against each convex portion 22 of the second plate member 2, and at a location where each non-contact portion 12 of the first plate member 1 abuts against each flat portion 21 of the second plate member 2. The two contact portions 11 of the first plate member 1 and the five flat portions 21 of the second plate member 2 do not abut against each other but face each other with a gap between them. This forms six flow paths 4 between the first plate member 1 and the second plate member 2, through which the heat exchange medium passes.

As shown in Figures 3 and 4, each joint 3 has a weld line. In this embodiment, the heat exchanger 100 has eight weld lines 31a to 31h. The eight weld lines 31a to 31h are each parallel to the above-mentioned neutral plane along the neutral axis N, extend straight in the longitudinal direction L, and are aligned in the short direction S, dividing the space between the first plate member 1 and the second plate member 2 into the above-mentioned six flow paths 4. With respect to the neutral axis N, some of the eight weld lines 31a to 31h are positioned on the first plate member 1 side, and the rest are positioned on the second plate member 2 side. In the following description, of the eight weld lines 31a to 31h, the weld lines located closer to the first plate member 1 than the neutral axis N will also be referred to as first weld lines 31b, 31c, 31f, and 31g, and the weld lines located closer to the second plate member 2 than the neutral axis N will also be referred to as second weld lines 31a, 31d, 31e, and 31h.

The eight weld lines 31a to 31h are arranged symmetrically with respect to the center line A in the cross section of the heat exchanger 100. The center line A is a line that passes through the center of the cross section of the heat exchanger 100 in the short direction S and is perpendicular to the neutral axis N.

Specifically, first weld lines 31b and 31c are located at the contact portion 11 on the first end S1 side of the first plate member 1, and first weld lines 31f and 31g are located at the contact portion 11 on the second end S2 side of the first plate member 1. Second weld line 31a is located at the non-contact portion 12 located at the first end S1 of the first plate member 1, and second weld line 31h is located at the non-contact portion 12 located at the second end S2 of the first plate member 1. Second weld line 31d is located at the non-contact portion 12 located at the center of the first plate member 1 in the short direction S, closer to the first end S1 than the through holes 13 and 23, and second weld line 31e is located at the non-contact portion 12 closer to the second end S2 than the through holes 13 and 23.

The sum of the shortest distances LA1, LA2, LA3, and LA4 from the neutral axis N to each of the first welding lines 31b, 31c, 31f, and 31g is approximately the same as the sum of the shortest distances LB1, LB2, LB3, and LB4 from the neutral axis N to each of the second welding lines 31a, 31d, 31e, and 31h. In this embodiment, the number of first welding lines 31b, 31c, 31f, and 31g and the number of second welding lines 31a, 31d, 31e, and 31h are all four, and the shortest distances LA1, LA2, LA3, and LA4 and the shortest distances LB1, LB2, LB3, and LB4 are all the same, for example, 1.0 mm. That is, when the first welding lines 31b, 31c, 31f, 31g and the second welding lines 31a, 31d, 31e, 31h are equally spaced with respect to the neutral axis N as in this embodiment, the following relationship holds: (number of first welding lines × shortest distance from the neutral axis N to the first welding lines) = (number of second welding lines × shortest distance from the neutral axis N to the second welding lines).

The longitudinal direction L ends of each weld line 31a-31h are also connected by a weld line extending in the short direction S, so that six flow paths 4 are formed through which the heat exchange medium flows from the inlet 101 to the outlet 102 along the arrows shown in Figure 4.

<Heat exchanger manufacturing method>
Next, a method for manufacturing the heat exchanger 100 will be described with reference to Fig. 14. The method for manufacturing the heat exchanger 100 includes a pressing step S10, an arrangement step S20, and a joining step S30.

(Pressing process)
First, a flat blank is pressed to form the first plate member 1 and the second plate member 2 each having a predetermined shape. Specifically, the first plate member 1 is press-formed to form two contact portions 11 and three non-contact portions 12. The second plate member 2 is press-formed to form five flat portions 21 and four protrusions 22.

(Placement process)
Next, the second plate member 2 is placed on top of the first plate member 1 so that the first plate member 1 and the second plate member 2 abut at each joint 3 (see FIG. 3). Specifically, the first plate member 1 and the second plate member 2 are placed on top of each other so that, at each joint 3, the two contact portions 11 abut against the four protrusions 22 and the three non-contact portions 12 abut against the three flat portions 21 facing them.

(Joining process)
Next, eight weld lines 31a to 31h are formed by heat input to each joint 3, joining the first plate member 1 and the second plate member 2. Specifically, for example, a laser beam is irradiated onto each joint 3 along the longitudinal direction L. As a result, the eight weld lines 31a to 31h are formed such that the first weld lines 31b, 31c, 31f, and 31g and the second weld lines 31a, 31d, 31e, and 31h are positioned on both sides of the neutral axis N as described above (see FIG. 3). This completes the heat exchanger 100.

Each weld line 31a-31h is formed by heat input from a laser beam or the like to each joint 3, causing melting into the first plate member 1 and the second plate member 2. In this embodiment, heat input to each joint 3 in the joining process S30 is carried out under fixed conditions. That is, the amount of heat input when forming each weld line 31a-31h is approximately the same. The amount of heat input is calculated by (welding output ÷ welding speed × weld length).

[2. Effects]
According to the embodiment described above in detail, the following effects can be obtained.
(2a) In this embodiment, the first weld lines 31b, 31c, 31f, 31g and the second weld lines 31a, 31d, 31e, 31h are equally spaced relative to the neutral axis N. This makes it easier for deformation of the heat exchanger 100 caused by contraction stress when the first weld lines 31b, 31c, 31f, 31g cool to be offset by deformation of the heat exchanger 100 caused by contraction stress when the second weld lines 31a, 31d, 31e, 31h cool. This reduces the effects of thermal distortion on the heat exchanger 100, which has eight joints 3. That is, deformation of the first plate member 1 is reduced, making it easier for the two contact portions 11 of the first plate member 1 to indirectly or directly contact the battery 200. In other words, the surfaces of each contact portion 11 that face the battery 200 and exchange heat with the battery 200 to remain flat. This improves the cooling performance of the heat exchanger 100 for the battery 200. Furthermore, since deformation of the first plate member 1 is suppressed, the ease of assembling the heat exchanger 100 to the battery 200 also improves.

(2b) In this embodiment, the first weld lines 31b, 31c are located at the contact portion 11 on the first end S1 side of the first plate member 1, and the first weld lines 31f, 31g are located at the contact portion 11 on the second end S2 side of the first plate member 1. As a result, the portion of each contact portion 11 where each flow path 4 is provided and the portion where each first weld line 31b, 31c, 31f, 31g is provided are in indirect or direct contact with the battery 200. This makes it possible to ensure a large area for the surface of each contact portion 11 that is in indirect or direct contact with the battery 200 and that exchanges heat with the battery 200. This further improves the cooling performance of the heat exchanger 100 for the battery 200.

(2c) In this embodiment, the eight weld lines 31a to 31h are arranged symmetrically with respect to the center line A in the cross section of the heat exchanger 100. This makes it possible to suppress the effects of thermal distortion of the heat exchanger 100 in each region on both sides of the center line A.

(2d) In this embodiment, the eight weld lines 31a to 31h extend in the longitudinal direction L of the heat exchanger 100. Weld lines extending in the longitudinal direction L of the heat exchanger 100 contribute more to thermal distortion of the heat exchanger 100 than weld lines extending in the lateral direction S of the heat exchanger 100. Therefore, the configuration of the heat exchanger 100 in this embodiment makes it easier to suppress the effects of thermal distortion of the heat exchanger 100.

In this embodiment, the longitudinal direction L corresponds to an example of the first direction, and the transverse direction S corresponds to an example of the second direction.

3. Other Embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take on various forms.

(3a) In the above embodiment, the inlet 101 and outlet 102 for the heat exchange medium were located on the first plate member 1, but the location of the inlet and outlet is not limited to this. For example, as shown in Figures 5 to 7, the inlet 101a and outlet 102a of the heat exchanger 100a of the first modified example may be located at a position extending from the first end S1 of the first plate member 1a in the short direction S.

In this case, as shown in FIG. 6 , the heat exchanger 100a faces the contact surface 201 of the battery 200 and is positioned so that the battery 200 does not overlap the inlet 101a and outlet 102a in the short direction S. A thermally conductive material 300 may or may not be positioned between the heat exchanger 100a and the battery 200. The frame 400 is provided so as to surround the side of the battery 200, and the inlet 101a and outlet 102a are located outside the frame 400. For convenience, part of the frame 400 is not shown in FIG. 6 . The heat exchanger 100a of the first modified example can also serve as a lower case. Therefore, unlike the heat exchanger 100 of the above embodiment, the surface of the heat exchanger 100a opposite the surface facing the battery 200 does not need to be covered by the lower case.

(3b) In the above embodiment, a heat exchanger 100 was illustrated in which six flow paths 4 were formed by eight joints 3 having first weld lines 31b, 31c, 31f, 31g and second weld lines 31a, 31d, 31e, 31h that were equally spaced relative to the neutral axis N. However, the configuration of the heat exchanger is not limited to this, and the number of flow paths, i.e., the number of weld lines, is not limited.

For example, the heat exchanger 100b of the second modified example shown in Figure 8 may be configured such that eight flow paths 4b are formed by ten joints 3b. Specifically, the first plate member 1b may have two contact portions 11b and three non-contact portions 12b, and the second plate member 2b may have seven flat portions 21b and six protrusions 22b. For convenience, Figure 8 only illustrates the configuration of the half portion of the heat exchanger 100b on the first end S1 side (hereinafter referred to as the first portion) centered on the center line A, but the heat exchanger 100b has a structure that is axisymmetrical with respect to the center line A in the cross section of the heat exchanger 100b.

In the first portion of the heat exchanger 100b, each joint 3b has a weld line. The first portion of the heat exchanger 100b has five weld lines 32a to 32e. The first weld lines 32b, 32c, and 32d are located in the contact portion 11b on the first end S1 side of the first plate member 1b. The second weld line 32a is located in the non-contact portion 12b on the first end S1 of the first plate member 1b, and the second weld line 32e is located on the first end S1 side of the through holes 13 and 23 in the non-contact portion 12b located in the center of the first plate member 1b in the short direction S.

As a result, the portions of the contact portion 11b where each flow path 4b is provided and the portions of the first weld lines 32b, 32c, and 32d are provided are in indirect or direct contact with the battery 200. This ensures a large surface area for heat exchange with the battery 200 on the surface of the contact portion 11b that is in indirect or direct contact with the battery 200.

Furthermore, in the first part of heat exchanger 100b, there are three first welding lines 32b, 32c, and 32d, and two second welding lines 32a and 32e. The amount of thermal distortion caused by the joints of the heat exchanger varies depending on the distance between the neutral axis and the welding lines at the joints. Therefore, in a configuration such as heat exchanger 100b, where the number of first welding lines 32b, 32c, and 32d is different from the number of second welding lines 32a and 32e, the shortest distance from the neutral axis N to the first welding lines and the shortest distance from the neutral axis N to the second welding lines are set to different values. In the configuration of heat exchanger 100b, the shortest distances LC1, LC2, and LC3 from the neutral axis N to each of the first weld lines 32b, 32c, and 32d are, for example, 0.8 mm, and the shortest distances LD1 and LD2 from the neutral axis N to each of the second weld lines 32a and 32e are, for example, 1.2 mm. As a result, the sum of the shortest distances LC1, LC2, and LC3 from the neutral axis N to each of the first weld lines 32b, 32c, and 32d is approximately the same as the sum of the shortest distances LD1 and LD2 from the neutral axis N to each of the second weld lines 32a and 32e.

As a result, deformation of the heat exchanger 100b caused by contraction stress when the first weld lines 32b, 32c, and 32d cool is more likely to be offset by deformation of the heat exchanger 100b caused by contraction stress when the second weld lines 32a and 32e cool. This reduces the effects of thermal distortion on the heat exchanger 100b. In other words, deformation of the first plate member 1b is reduced, making it easier for the two contact portions 11b of the first plate member 1b to come into indirect or direct contact with the battery 200. This improves the cooling performance of the heat exchanger 100b for the battery 200.

Furthermore, for example, the heat exchanger 100c of the third modified example shown in Figure 9 may be configured such that 10 flow paths 4c are formed by 12 joints 3c. Specifically, the first plate member 1c may have two contact portions 11c and three non-contact portions 12c, and the second plate member 2c may have nine flat portions 21c and eight convex portions 22c. For convenience, Figure 9 only illustrates the configuration of the half portion (hereinafter referred to as the second portion) of the heat exchanger 100c on the first end S1 side, centered on the center line A. However, the heat exchanger 100c has a structure that is axisymmetrical with respect to the center line A in the cross section of the heat exchanger 100c.

In the second portion of the heat exchanger 100c, each joint 3c has a weld line. The second portion of the heat exchanger 100c has six weld lines 33a to 33f. The first weld lines 33b, 33c, 33d, and 33e are located in the contact portion 11c on the first end S1 side of the first plate member 1c. The second weld line 33a is located in the non-contact portion 12c on the first end S1 of the first plate member 1c, and the second weld line 33f is located on the first end S1 side of the through holes 13 and 23 in the non-contact portion 12c located in the center of the first plate member 1c in the short direction S.

As a result, the portions of the contact portion 11c where each flow path 4c is provided and the portions of the first weld lines 33b, 33c, 33d, and 33e are provided are in indirect or direct contact with the battery 200. This ensures a large surface area for heat exchange with the battery 200 on the surface of the contact portion 11c that is in indirect or direct contact with the battery 200.

Furthermore, in the second portion of heat exchanger 100c, the number of first weld lines 33b, 33c, 33d, and 33e is four, and the number of second weld lines 33a and 33f is two. Like heat exchanger 100b, heat exchanger 100c differs in the number of first weld lines 33b, 33c, 33d, and 33e from the number of second weld lines 33a and 33f. Therefore, in the configuration of heat exchanger 100c, the shortest distances LE1, LE2, LE3, and LE4 from the neutral axis N to each of the first weld lines 33b, 33c, 33d, and 33e are set to, for example, 0.7 mm, and the shortest distances LF1 and LF2 from the neutral axis N to each of the second weld lines 33a and 33f are set to, for example, 1.4 mm. As a result, the sum of the shortest distances LE1, LE2, LE3, and LE4 from the neutral axis N to each of the first welding lines 33b, 33c, 33d, and 33e is approximately the same as the sum of the shortest distances LF1 and LF2 from the neutral axis N to each of the second welding lines 33a and 33f.

As a result, deformation of the heat exchanger 100c caused by contraction stress when the first weld lines 33b, 33c, 33d, and 33e cool is more likely to be offset by deformation of the heat exchanger 100c caused by contraction stress when the second weld lines 33a and 33f cool. This reduces the effects of thermal distortion on the heat exchanger 100c. In other words, deformation of the first plate member 1c is reduced, making it easier for the two contact portions 11c of the first plate member 1c to come into indirect or direct contact with the battery 200. This improves the cooling performance of the heat exchanger 100c for the battery 200.

(3c) In the above embodiment and the first to third modified examples, a configuration was illustrated in which the shortest distance from the neutral axis N to each first welding line was constant, and the shortest distance from the neutral axis N to each second welding line was constant. However, for example, as long as the sum of the shortest distances from the neutral axis N to each first welding line is approximately the same as the sum of the shortest distances from the neutral axis N to each second welding line, the values of each shortest distance do not need to be constant.

(3d) In the above embodiment and the first to third modified examples, the multiple weld lines are arranged symmetrically with respect to the center line A in the cross section of the heat exchanger. However, for example, if the sum of the shortest distances from the neutral axis N to each of the first weld lines is approximately the same as the sum of the shortest distances from the neutral axis N to each of the second weld lines, the weld lines do not need to be arranged symmetrically with respect to the center line A.

(3e) In the above embodiment and the first to third modified examples, the first and second weld lines extend in the longitudinal direction L of the heat exchanger 100b to form six flow paths 4. However, for example, the first and second weld lines may extend in the lateral direction S of the heat exchanger to form multiple flow paths through which the heat exchange medium flows.

(3f) In the above embodiment and the first to third modified examples, the first weld line is located at the contact portion 11 of the first plate member 1, but the first weld line does not have to be located at the contact portion.

(3g) In the above embodiment, a heat exchanger 100 sized to correspond to the battery 200 is illustrated. However, as shown in FIG. 11 , multiple heat exchangers 100 may be connected in a row in the short-side direction S to correspond to the battery pack 220 shown in FIG. 10 , which is arranged within an annular frame 600 and is configured by combining multiple batteries 200. The heat exchange device 110, which is formed by connecting multiple heat exchangers 100, is arranged to face the battery pack 220. In the example shown in FIG. 11 , the longitudinal direction L of the heat exchanger 100 corresponds to the left-right direction of the electric vehicle, and the short-side direction S of the heat exchanger 100 corresponds to the front-rear direction of the electric vehicle. Note that the longitudinal direction L of the heat exchanger 100 may correspond to the front-rear direction of the electric vehicle, and the short-side direction S of the heat exchanger 100 may correspond to the left-right direction of the electric vehicle.

(3h) In the above embodiment, the shape of the flow path 4 along which the heat exchange medium flows from the inlet 101 to the outlet 102 along the arrows shown in FIG. 4 was exemplified, but the shape of the flow path is not limited to this. For example, as shown in FIG. 12, the heat exchanger 100d of the fourth modified example may have a flow path 4d shaped as shown by the arrows, in which the heat exchange medium flows from the inlet 101d to the outlet 102d. Furthermore, as shown in FIG. 13, the heat exchanger 100e of the fifth modified example may have a flow path 4e shaped as shown by the arrows, in which the heat exchange medium flows from the inlet 101e to the outlet 102e.

(3i) In the above embodiment, heat input to each joint 3 in the joining process S30 was performed under constant conditions. That is, in the above embodiment, the amount of heat input when forming each weld line 31a-31h was approximately the same. However, for example, in the joining process S30, heat input to each joint may be performed under different conditions. That is, the amount of heat input when forming each weld line may be different.

Here, if the amount of heat input changes, the contraction stress when the weld line cools changes. Therefore, for example, the impact of thermal distortion on the heat exchanger may be evaluated by taking into account the heat input when each weld line was formed, in addition to the shortest distance from the neutral axis N to each weld line. For example, in a heat exchanger having multiple weld lines, when the heat input is taken into account, the sum of the values obtained by multiplying the shortest distance from the neutral axis N to each first weld line by the heat input when each first weld line was formed may be approximately the same as the sum of the values obtained by multiplying the shortest distance from the neutral axis N to each second weld line by the heat input when each second weld line was formed.

Specifically, taking the example of the heat exchanger 100 having eight weld lines 31a-31h as in the above embodiment, ((shortest distance LA1 x heat input QA1) + (shortest distance LA2 x heat input QA2) + (shortest distance LA3 x heat input QA3) + (shortest distance LA4 x heat input QA4)) = ((shortest distance LB1 x heat input QB1) + (shortest distance LB2 x heat input QB2) + (shortest distance LB3 x heat input QB3) + (shortest distance LB4 x heat input QB4)). Each of the heat inputs QA1-QA4 is the heat input when each of the first weld lines 31b, 31c, 31f, and 31g is formed. Furthermore, each of the heat inputs QB1-QB4 is the heat input when each of the second weld lines 31a, 31d, 31e, and 31h is formed.

As a result, even if the shrinkage stresses of the weld lines differ due to differences in the amount of heat input, the deformation of the heat exchanger caused by the shrinkage stresses of the first weld lines as they cool is more likely to be offset by the deformation of the heat exchanger caused by the shrinkage stresses of the second weld lines as they cool. Therefore, the effects of thermal distortion can be suppressed even in heat exchangers with joints that have heat input under different conditions during welding, taking into account the shape, thickness, size, etc. of the heat exchanger. In other words, taking the amount of heat input into account can more easily broaden the design options for heat exchangers that improve cooling performance. Note that even if heat input to the joints is performed under consistent conditions in the joining process S30 and the amount of heat input during the formation of each weld line is approximately the same, the heat input during the formation of each weld line may be taken into account in addition to the shortest distance from the neutral axis to each weld line when evaluating the effects of thermal distortion on the heat exchanger.

(3j) The functions of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

[4. Technical Ideas Disclosed in the Present Specification]
[Item 1]
A heat exchanger that exchanges heat with a battery mounted on an electric vehicle,
a first plate member that is a plate-shaped member configured to face the battery;
a second plate member that is a plate-shaped member and is arranged to face the first plate member on the side opposite to the battery, and forms a flow path through which a heat exchange medium passes between the first plate member and the second plate member;
a joint portion where the first plate member and the second plate member are joined by welding;
Equipped with
the joint portion has a plurality of weld lines extending in a first direction and arranged in a second direction perpendicular to the first direction to define the flow path,
the plurality of weld lines are respectively arranged on the first plate member side and the second plate member side with respect to a neutral axis extending in the second direction in a cross section of the heat exchanger perpendicular to the first direction,
Among the plurality of weld lines, a weld line located closer to the first plate member than the neutral axis is defined as at least one first weld line, and a weld line located closer to the second plate member than the neutral axis is defined as at least one second weld line,
a sum of the shortest distances from the neutral axis to each of the at least one first weld line is approximately equal to a sum of the shortest distances from the neutral axis to each of the at least one second weld line.

[Item 2]
Item 1, a heat exchanger according to item 1,
the number of the at least one first weld line and the number of the at least one second weld line are the same;
a shortest distance from the neutral axis to each of the at least one first weld line and a shortest distance from the neutral axis to each of the at least one second weld line are the same.

[Item 3]
Item 1 or Item 2, a heat exchanger according to
the plurality of weld lines are arranged symmetrically with respect to a center line in the cross section,
A heat exchanger, wherein the center line is a line that passes through the center of the cross section in the second direction and is perpendicular to the neutral axis.

[Item 4]
The heat exchanger according to any one of items 1 to 3,
A heat exchanger, wherein the first direction is a longitudinal direction of the heat exchanger.

[Item 5]
Item 4: The heat exchanger according to any one of items 1 to 4,
the first plate member has a contact portion that is a portion that comes into contact with the battery, the contact portion being substantially parallel to the neutral axis and extending in a substantially planar shape in the first direction and the second direction;
The at least one first weld line is disposed at the contact portion.

[Item 6]
Item 6. The heat exchanger according to any one of items 1 to 5,
the plurality of weld lines are formed by heat input to the joint,
a heat exchanger, wherein a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one first weld lines by the heat input amount when each of the at least one first weld lines is formed is approximately equal to a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one second weld lines by the heat input amount when each of the at least one second weld lines is formed.

[Item 7]
A method for manufacturing a heat exchanger according to any one of items 1 to 5,
placing the second plate member on the first plate member so that the first plate member and the second plate member abut at the joint portion;
forming the plurality of weld lines by applying heat to the joint portion to join the first plate member and the second plate member;
Equipped with
a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one first weld lines by the heat input amount when each of the at least one first weld lines is formed is approximately equal to a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one second weld lines by the heat input amount when each of the at least one second weld lines is formed.

1, 1a to 1c...first plate member, 2,2b,2c...second plate member, 3,3b,3c...joint section, 4,4b to 4e...channel, 11,11b, 11c...contact section, 12,12b, 12c...non-contact section, 13,23...through hole , 21, 21b, 21c... flat plate portion, 22, 22b, 22c... convex portion, 31b, 31c, 31f, 31g, 32b to 32d, 33b to 33e... first welding line, 31a, 31d, 31e, 31h, 32a, 32e , 33a, 33f...second weld line, 100, 100a-100e...heat exchanger, 101, 101a, 101d, 101e...inlet, 102, 102a, 102d, 102e...outlet, 110...heat exchange device, 200...battery, 201...contact surface, 220...battery pack, 300...thermal conductive material, 400, 600...frame, 500...lower case, A...center line, L1, S1...first end, L2, S2...second end, N...neutral axis.

Claims (7)

A heat exchanger that exchanges heat with a battery mounted on an electric vehicle,
a first plate member that is a plate-shaped member configured to face the battery;
a second plate member that is a plate-shaped member and is arranged to face the first plate member on the side opposite to the battery, and forms a flow path through which a heat exchange medium passes between the first plate member and the second plate member;
a joint portion where the first plate member and the second plate member are joined by welding;
Equipped with
the joint portion has a plurality of weld lines extending in a first direction and arranged in a second direction perpendicular to the first direction to define the flow path,
the plurality of weld lines are respectively arranged on the first plate member side and the second plate member side with respect to a neutral axis extending in the second direction in a cross section of the heat exchanger perpendicular to the first direction,
Among the plurality of weld lines, a weld line located closer to the first plate member than the neutral axis is defined as at least one first weld line, and a weld line located closer to the second plate member than the neutral axis is defined as at least one second weld line,
a sum of the shortest distances from the neutral axis to each of the at least one first weld line is approximately equal to a sum of the shortest distances from the neutral axis to each of the at least one second weld line. 2. The heat exchanger of claim 1,
the number of the at least one first weld line and the number of the at least one second weld line are the same;
a shortest distance from the neutral axis to each of the at least one first weld line and a shortest distance from the neutral axis to each of the at least one second weld line are the same. The heat exchanger according to claim 1 or 2,
the plurality of weld lines are arranged symmetrically with respect to a center line in the cross section,
A heat exchanger, wherein the center line is a line that passes through the center of the cross section in the second direction and is perpendicular to the neutral axis. The heat exchanger according to claim 1 or 2,
A heat exchanger, wherein the first direction is a longitudinal direction of the heat exchanger. The heat exchanger according to claim 1 or 2,
the first plate member has a contact portion that is a portion that comes into contact with the battery, the contact portion being substantially parallel to the neutral axis and extending in a substantially planar shape in the first direction and the second direction;
The at least one first weld line is disposed at the contact portion. The heat exchanger according to claim 1 or 2,
the plurality of weld lines are formed by heat input to the joint,
a heat exchanger, wherein a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one first weld lines by the heat input amount when each of the at least one first weld lines is formed is approximately equal to a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one second weld lines by the heat input amount when each of the at least one second weld lines is formed. A method for manufacturing the heat exchanger according to claim 1,
placing the second plate member on the first plate member so that the first plate member and the second plate member abut at the joint portion;
forming the plurality of weld lines by applying heat to the joint portion to join the first plate member and the second plate member;
Equipped with
a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one first weld lines by the heat input amount when each of the at least one first weld lines is formed is approximately equal to a sum of values obtained by multiplying the shortest distance from the neutral axis to each of the at least one second weld lines by the heat input amount when each of the at least one second weld lines is formed.