Cooling heat exchanger

Abstract

Provided is a cooling heat exchanger of a novel structure that can be expected to further improve cooling performance. The cooling heat exchanger 10 has a cooling flow path 18, through which a cooling heat medium flows, formed therein, and cools an object to be cooled that is placed on a cooling surface 12 provided on the surface of the cooling heat exchanger 10, wherein the wall inner surface of the cooling flow path 18 is provided with protrusions 36 that protrude. An upstream-side surface 42 and a downstream-side surface 44 of a top part 40 of each of the protrusions 36 include a curved surface having an arc-shaped cross-section, and a radius of curvature R2 of the downstream-side curved surface 44 is smaller than a radius of curvature R1 of the upstream-side curved surface 42. A downstream-side surface 50, which is the surface on the downstream side of the top part 40 of the protrusion 36, has an inclination angle θ at a connection end 52 with the top part 40 within the range of 35-90°.

Description

Cooling heat exchanger

[0001] The present invention relates to a cooling heat exchanger used for cooling a cooling target such as a battery used in an electrified vehicle.

[0002] Conventionally, cooling heat exchangers used for cooling batteries, inverters, etc. are known. As disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-165939 (Patent Document 1), the cooling heat exchanger has a structure in which a refrigerant passage through which a cooling medium flows is formed in an internal region between the opposing surfaces of a pair of outer shell plates that are overlapped with each other. Then, the surface of the outer shell plate is cooled by heat exchange with the cooling medium flowing through the refrigerant passage, so that the cooling target overlapped on the surface is cooled.

[0003] Japanese Patent Application Laid-Open No. 2011-165939

[0004] By the way, in the cooling heat exchanger of Patent Document 1, the cooling medium flowing near the cooling target in the refrigerant passage is easily warmed by heat exchange with the cooling target, while the cooling medium flowing away from the cooling target is less likely to undergo heat exchange with the cooling target and is less likely to contribute to the cooling performance. Therefore, in Patent Document 1, projections (constriction portions) protruding into the refrigerant passage are formed, and the cooling medium is agitated by climbing over the projections.

[0005] However, as a result of the study by the present inventors, it has been found that even if projections such as those in Patent Document 1 are provided, the cooling performance may still be insufficient in some cases.

[0006] The problem to be solved by the present invention is to provide a cooling heat exchanger with a novel structure that can be expected to further improve the cooling performance. Another object of the present invention is to provide a method for manufacturing a novel metal plate for a flow path that can be expected to further improve the cooling performance.

[0007] The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is illustrative and can be combined with others as appropriate. Furthermore, the multiple components described in each embodiment can be recognized and adopted as independently as possible, and can be combined with any component described in another embodiment as appropriate. Thus, the present invention is not limited to the embodiments described below, and various other embodiments can be realized.

[0008] The first embodiment is a cooling heat exchanger in which a cooling medium is formed inside a cooling channel through which a cooling medium flows, and a cooling object is placed on a cooling surface provided on the surface, wherein a projection is provided on the inner surface of the wall of the cooling channel, the top of the projection has an upstream surface and a downstream surface, each including a curved surface with an arc-shaped cross-section, the radius of curvature of the curved surface on the downstream surface is smaller than the radius of curvature of the curved surface on the upstream surface, and the downstream side surface, which is the surface downstream of the top of the projection, has an inclination angle at the connection end with the top in the range of 35 to 90°.

[0009] In a cooling heat exchanger with a structure according to this embodiment, in the upstream portion of the protrusion where the radius of curvature of the top of the protrusion is large and the slope is gentle, a smooth flow of the heat transfer medium is formed along the surface of the protrusion and over the protrusion, thereby suppressing pressure loss due to overcoming the protrusion. Furthermore, in the downstream portion of the protrusion where the radius of curvature of the top of the protrusion is small and the slope angle of the downstream side of the protrusion is larger than that of the upstream side, the heat transfer medium tends to flow away from the surface of the protrusion. As a result, the stirring action caused by the flow of heat transfer medium separating from the surface of the protrusion is efficiently exerted downstream of the protrusion, improving cooling performance by averaging the temperature of the heat transfer medium.

[0010] The second embodiment is a cooling heat exchanger described in the first embodiment, wherein the bulge of the downstream side of the projection into the cooling channel is smaller than the bulge of the upstream side, which is the surface upstream of the top of the projection, into the cooling channel.

[0011] According to the cooling heat exchanger structured in this embodiment, the small bulge of the downstream side of the protrusion into the cooling channel makes it easier to secure space for turbulence to form downstream of the protrusion. In particular, in order for a vortex flow (swirl current) to be formed downstream of the protrusion with the channel length as the axis, it is desirable that the bulge of the downstream side of the protrusion into the cooling channel be small so that the protrusion does not obstruct the vortex flow of the heat transfer medium. Therefore, according to this embodiment, the generation of vortices downstream of the protrusion is promoted, and efficient stirring of the heat transfer medium by the vortex current can be expected.

[0012] A third embodiment is a cooling heat exchanger described in the first or second embodiment, wherein the average inclination angle of the downstream side surface of the projection is greater than the average inclination angle of the upstream side surface, which is the surface upstream of the top of the projection.

[0013] According to the cooling heat exchanger structured in this embodiment, the average inclination angle of the downstream side of the projection is greater than the average inclination angle of the upstream side. This allows for pressure loss to be reduced on the upstream side of the projection, where the inclination angle is smaller, while effectively obtaining a stirring effect due to flow turbulence on the downstream side of the projection.

[0014] The fourth embodiment is a cooling heat exchanger described in any one of the first to third embodiments, wherein the downstream side of the projection has a straight section with a constant inclination angle.

[0015] According to the cooling heat exchanger structured in this embodiment, a straight section with a constant inclination angle is provided on the downstream side. Compared to, for example, a case where the entire downstream side is a convex curved surface that bulges toward the cooling channel, it becomes easier to secure space downstream of the protrusion, and a stirring action due to turbulence in the flow of the heat transfer medium can be efficiently obtained downstream of the protrusion.

[0016] The fifth embodiment is a cooling heat exchanger described in any one of the first to fourth embodiments, wherein the radius of curvature of the curved surface downstream at the top of the projection is within the range of 20 to 60% of the radius of curvature of the curved surface upstream at the top.

[0017] In a cooling heat exchanger with a structure according to this embodiment, the radius of curvature on the downstream side of the projection's top is sufficiently smaller than the radius of curvature on the upstream side. This allows the downstream side with a larger inclination angle to be smoothly continuous with the top, thereby more advantageously achieving the stirring action of the heat transfer medium downstream of the projection. Furthermore, by not making the radius of curvature on the downstream side of the projection's top excessively smaller than the radius of curvature on the upstream side, the radius of curvature on the upstream side does not become too large, preventing the length of the projection in the direction of the cooling channel from becoming excessively long.

[0018] The sixth embodiment is a cooling heat exchanger described in any one of the first to fifth embodiments, wherein the protruding height of the projection is within the range of 10 to 90% of the flow path depth in the cooling channel.

[0019] According to the cooling heat exchanger structured in this embodiment, by setting the height of the protrusions sufficiently high relative to the depth of the cooling channel, the stirring action of the heat transfer medium by overcoming the protrusions is effectively exerted, thereby effectively improving the cooling performance. Furthermore, by preventing the height of the protrusions from becoming too high relative to the depth of the cooling channel, sufficient space for the heat transfer medium to flow is secured on the side of the protruding tip of the protrusion, thereby effectively generating a flow of heat transfer medium over the protrusions.

[0020] The seventh aspect is a method for manufacturing a metal plate for a flow channel, which constitutes the wall portion of a cooling channel through which a heat transfer medium for cooling flows and has a projection extending in the width direction of the cooling channel, employing the steps of: preparing a metal sheet having a thickness in the range of 0.7 to 1.3 mm; press-forming the metal sheet to form a projection base that protrudes toward the cooling channel side; and pressing at least one of the inclined portions on the upstream and downstream sides of the projection base from the flow channel side to form a top edge with a small radius of curvature, thereby forming the projection having a top edge with a protruding height in the range of 0.2 to 2.5 mm and a radius of curvature in the range of 0.4 to 1.2 mm.

[0021] The metal flow plates used in cooling heat exchangers are thin-walled from the standpoint of heat capacity and weight. However, when attempting to form protrusions with relatively high protrusion heights using top edges with small radii of curvature, conventional techniques have made it difficult to stably secure the wall thickness in the protrusion formation area. This has resulted in problems such as insufficient accuracy and reproducibility of the protrusion shape during manufacturing, and insufficient durability during use.

[0022] Therefore, according to the manufacturing method of the flow channel metal plate according to this embodiment, after forming a projection base by press-forming a metal sheet with a thickness in the range of 0.7 to 1.3 mm, the inclined portion of the projection base is pressed from the flow channel side, thereby enabling the stable and accurate formation of a top edge with a projection height in the range of 0.2 to 2.5 mm and a radius of curvature in the range of 0.4 to 1.2 mm, which was difficult to form with conventional single-step press-forming. Furthermore, instability in wall thickness, such as excessive thinning of the projection formation portion, is avoided, and sufficient durability of the flow channel metal plate can be ensured.

[0023] The eighth aspect is a method for manufacturing a flow channel metal plate as described in the seventh aspect, wherein the minimum thickness of the protrusion is 0.4 mm or more.

[0024] According to the manufacturing method of the flow channel metal plate according to this embodiment, the minimum thickness of the protrusion is ensured to be 0.4 mm or larger, thereby ensuring sufficient accuracy and stability of the shape of the protrusion.

[0025] According to the present invention, further improvements in cooling performance can be expected in a cooling heat exchanger.

[0026] Figure 1 shows an exploded perspective view of a cooling heat exchanger as a first embodiment of the present invention. Figure 1 shows an enlarged view of a part of the cooling heat exchanger. Figure 2 shows an enlarged cross-sectional view of a part of the cooling heat exchanger, corresponding to the III-III section in Figure 2. Figure 3 shows an enlarged cross-sectional view of a part of the cooling heat exchanger, corresponding to the IV-IV section in Figure 3.

[0027] Embodiments of the present invention will be described below with reference to the drawings.

[0028] Figure 1 shows a cooling heat exchanger 10 as a first embodiment of the present invention. The cooling heat exchanger 10 has a structure in which a flat upper plate 14 with a cooling surface 12 is superimposed on a concave lower plate 16, and a cooling channel 18 through which a cooling heat transfer medium flows is formed between the upper plate 14 and the lower plate 16. A cooling object, such as a battery (not shown), which is superimposed on the cooling surface 12, is cooled by heat exchange with the heat transfer medium via the upper plate 14. In the following description, the vertical direction refers to the vertical direction in Figure 3, the front-rear direction refers to the vertical direction in Figure 2, and the left-right direction refers to the left-right direction in Figure 2. In this embodiment, the length direction of the cooling channel 18, which will be described later, is the left-right direction, and the width direction of the channel is the front-rear direction.

[0029] The upper plate 14 is made of, for example, a metal such as iron or an aluminum alloy, or a heat-conducting synthetic resin mixed with a heat-conducting filler, and preferably has a higher thermal conductivity than the lower plate 16. The upper plate 14 is a thin, roughly rectangular flat plate that extends to a roughly constant thickness, and its upper surface is a flat cooling surface 12. The upper plate 14 is longer in the left-right direction, which is the length direction of the cooling channel 18, than in the front-back direction, which is the width direction of the cooling channel 18.

[0030] The lower plate 16 is made of a metal such as iron or aluminum alloy, or a synthetic resin, and has a generally rectangular plate shape. The lower plate 16 has an outer shape that corresponds to the upper plate 14 when viewed in the vertical direction. A rectangular frame-shaped outer peripheral wall portion 20 is provided at the outer peripheral end of the lower plate 16, projecting upward. The inner circumference of the outer peripheral wall portion 20 of the lower plate 16 is a rectangular recess that opens upward, and a supply hole 22 and a discharge hole 24 are formed at one diagonal portion of the recess, penetrating in the vertical direction. The supply hole 22 and the discharge hole 24 are each provided with cylindrical connecting portions that project from the lower surface of the lower plate 16.

[0031] Multiple partition walls 26 are provided on the inner circumference side of the outer peripheral wall 20 of the lower plate 16. The partition walls 26 protrude upward from the lower wall of the lower plate 16 and extend linearly in the left-right direction with a substantially constant cross-section. The left and right ends of the partition walls 26 do not reach the outer peripheral wall 20, but are located away from the left and right center. The number of partition walls 26 is not particularly limited, but in this embodiment there are four, and they are arranged at substantially equal intervals in the front-rear direction.

[0032] The upper plate 14 is then superimposed on the upper surface of the lower plate 16, and the upper plate 14 and the lower plate 16 are fixed to each other. The upper plate 14 is superimposed on the upper surfaces of the outer peripheral wall portion 20 and the plurality of partition wall portions 26 of the lower plate 16, and the overlapping surfaces of the upper plate 14 and the lower plate 16 are fixed together by means of brazing, bonding, welding, etc., and are sealed in a liquid-tight manner.

[0033] Between the upper plate 14 and the lower plate 16, a sealed region 28 is formed on the inner circumference side of the outer peripheral wall portion 20, in which a heat transfer medium is sealed. The sealed region 28 can be connected to an external pipeline (not shown) by a supply hole 22 and a discharge hole 24, so that the heat transfer medium is supplied through the supply hole 22 and discharged through the discharge hole 24.

[0034] Multiple cooling channels 18 are formed in the sealed region 28. The cooling channels 18 are formed between adjacent outer peripheral wall portions 20 and partition wall portions 26 in the front-rear direction, and between adjacent partition wall portions 26, 26 in the front-rear direction. In the cooling channel 18, the left side (left side in Figure 2), which is on the supply hole 22 side, is the upstream side, and the right side (right side in Figure 2), which is on the discharge hole 24 side, is the downstream side, so that the heat transfer medium flows from left to right. In this embodiment, five cooling channels 18a to 18e are arranged in the front-rear direction, and these five cooling channels 18a to 18e arranged in parallel constitute a parallel channel section 32. The walls of the cooling channels 18 are made up of an upper plate 14 and a lower plate 16.

[0035] Single-channel sections 34 are formed on both the left and right sides of the enclosed region 28, away from the parallel channel section 32 in the left-right direction. Each of the single-channel sections 34 is connected to one of the five cooling channels 18a to 18e. A supply hole 22 is formed in the upstream single-channel section 34a, and a discharge hole 24 is formed in the downstream single-channel section 34b. The heat transfer medium supplied from an external supply pipeline (not shown) through the supply hole 22 to the upstream single-channel section 34a is distributed and flows through the five cooling channels 18a to 18e, then merges in the downstream single-channel section 34b, and is discharged through the discharge hole 24 to an external discharge pipeline (not shown). This causes the heat transfer medium to circulate within the enclosed region 28, including the cooling channels 18. Devices that cool the heat transfer medium, such as radiators or refrigerators, are connected to the external supply pipeline. The heat transfer medium is supplied in a low-temperature state from an external supply pipeline to the cooling channel 18, where it is heated through heat exchange with the battery pack or other object to be cooled. After heating, it is discharged to an external discharge pipeline and cooled again by a heat sink or the like. In this way, it is desirable for the heat transfer medium to flow circulatingly through a closed circuit.

[0036] Multiple protrusions 36 are formed on the bottom wall of the cooling channel 18, which is composed of a lower plate 16. The protrusions 36 are integrally formed with the lower plate 16 and project upward from the lower plate 16 onto the inner surface of the wall of the cooling channel 18. As shown in Figure 3, the protrusions 36 in this embodiment have a cross-section that tapers towards the tip of the protrusion in the cross-section in the length direction of the cooling channel 18 and extend in the width direction of the cooling channel 18. The protrusions 36 are provided with a pair of inclined portions 38, 38 that extend outward on both sides in the width direction of the cooling channel while inclining toward the downstream side of the cooling channel 18, and are approximately V-shaped when viewed from above. In this embodiment, the dimension of the inclined portion 38 in the length direction of the flow path decreases as it moves from the center outward in the width direction of the flow path. As shown in Figures 3 and 4, the maximum protrusion height dimension of the protrusions 36 in the width direction of the flow path is approximately constant at each part. In this embodiment, multiple protrusions 36 are distributed throughout the entire parallel flow channel section 32, which is composed of five cooling channels 18a to 18e.

[0037] The projection 36 that protrudes upward from the lower plate 16 is separated downward from the upper plate 14 which is superimposed on the lower plate 16. The protrusion height H of the projection 36 is preferably in the range of 10 to 90% of the flow path depth D of the cooling flow path 18, and more preferably in the range of 20 to 80%.

[0038] Furthermore, the maximum width dimension of the projection 36 is preferably 50% or more of the flow path width dimension of the cooling flow path 18, and more preferably 70% or more. In this embodiment, the projection 36 is provided continuously over the entire flow path width direction in the cooling flow path 18, and its end in the flow path width direction is directly and continuously connected to the outer peripheral wall portion 20 or the partition wall portion 26.

[0039] As shown in Figure 3, the projection 36 has a curved surface with an arc-shaped cross-section on the top 40 of the projection 36, where different radii of curvature are set on the upstream and downstream sides. Specifically, the top 40 of the projection 36 has a large radius surface 42 on the upstream side, which is a curved surface with an arc-shaped cross-section having a large radius of curvature R1, and a small radius surface 44 on the downstream side, which is a curved surface with an arc-shaped cross-section having a small radius of curvature R2. The radius of curvature R2 of the small radius surface 44 should be smaller than the radius of curvature R1 of the large radius surface 42, but preferably it is in the range of 20 to 60% of the radius of curvature R1 of the large radius surface 42, and more preferably it is in the range of 25 to 50%. In this embodiment, the large radius surface 42 and the small radius surface 44 are directly connected so as to be continuous.

[0040] The base portion 46 that constitutes the lower part of the projection 36 has an upstream side surface 48 located on the upstream side of the cooling channel 18, which is a curved surface that is continuous with the same radius of curvature R1 as the large R surface 42 of the top portion 40 in a cross-section in the channel length direction corresponding to Figure 3, and a downstream side surface 50 located on the downstream side of the cooling channel 18, which is a plane that extends in the tangential direction at the downstream end of the small R surface 44 in a cross-section in the channel length direction. The downstream side surface 50 in this embodiment is a straight section that is linear in the cross-section shown in Figure 3, and the angle of inclination with respect to the channel length direction is approximately constant. As a result, the upstream side surface 48 bulges upstream, while the downstream side surface 50 does not bulge downstream, and the bulge of the downstream side surface 50 toward the cooling channel 18 (bulge toward the downstream side) is smaller than the bulge of the upstream side surface 48 toward the cooling channel 18 (bulge toward the upstream side). In this embodiment, the projection 36 has a top portion 40 above the connection point between the small radius surface 44 and the downstream side surface 50, and a base portion 46 below it. However, for example, the top portion 40 may be defined as being within a predetermined ratio of the projection height H of the projection 36 from the upper end (protruding tip) of the projection 36.

[0041] The upper end of the downstream side surface 50 is a connecting end 52 that is continuous with the downstream end of the small radius surface 44. In this embodiment, the projection 36 has a top portion 40 above the connecting end 52 and a base portion 46 below the connecting end 52. The surface of the top portion 40 (large radius surface 42, small radius surface 44) and the surface of the base portion 46 (upstream side surface 48, downstream side surface 50) are smoothly continuous without any corners or steps. In short, the projection 36 in this embodiment has a smoothly continuous surface without corners, steps, or localized irregularities. In particular, the downstream side surface 50 is a straight line extending tangentially at the downstream end (lower end) of the small radius surface 44 in the cross-section shown in Figure 3, and the small radius surface 44 and the downstream side surface 50 are smoothly continuous at the connecting end 52.

[0042] The inclination angle θ of the downstream side surface 50 of the connection end 52 with respect to the flow path length direction, in other words, the inclination angle θ of the tangent line at the downstream end of the small R surface 44, is within the range of 35 to 90°, more preferably within the range of 45 to 80°. In the present embodiment, the inclination angle at the connection end 52 of the downstream side surface 50 is 45°. The inclination angle θ is an angle with the elevation side being positive with respect to the direction line from the downstream side to the upstream side, or an angle with the depression side being positive with respect to the direction line from the upstream side to the downstream side of the flow path. In the present embodiment, the downstream side surface 50 is a flat surface, and since the inclination angle of the downstream side surface 50 is substantially constant over the entire portion including the connection end 52, in FIG. 3, for the sake of clarity, the inclination angle θ at the connection end 52 of the downstream side surface 50 is illustrated as the inclination angle at the lower end portion of the downstream side surface 50.

[0043] Further, the average inclination angle of the downstream side surface 50 is made larger than the average inclination angle of the upstream side surface 48. It is desirable that the average inclination angle of the downstream side surface 50 is 1.2 times or more the average inclination angle of the upstream side surface 48.

[0044] Note that the pair of inclined portions 38, 38 of the protrusion 36 extend in the flow path width direction while inclining toward the downstream side, and in the orthogonal cross section with respect to the extending direction of the inclined portion 38, which is the flow direction of the heat medium when crossing the protrusion 36, it is desirable that the shape is set to satisfy each of the above numerical ranges. However, the cross-sectional shape of the inclined portion 38 in the flow path length direction may be set to satisfy each of the above numerical ranges over the entire length of the extending direction of the inclined portion 38.

[0045] When the upper plate 14 is overlapped with the lower plate 16 having such a structure, the cooling heat exchanger 10 is formed. An external pipe line (not shown) is connected to the supply hole 22 and the discharge hole 24 provided in the lower plate 16 of the cooling heat exchanger 10, and the heat medium flows through the cooling flow path 18 formed between the upper plate 14 and the lower plate 16.

[0046] Furthermore, a battery pack (not shown), which is the object to be cooled, is placed on top of the cooling surface 12, which is the upper surface of the upper plate 14. Then, heat exchange occurs between the battery pack, which generates heat when operating, and the low-temperature heat transfer medium flowing through the cooling channel 18, via the upper plate 14, thereby cooling the battery pack. The arrangement of the battery pack on the cooling surface 12 is not particularly limited, but for example, multiple battery packs may be arranged in line along the length of the cooling channel 18, and all of these battery packs will be cooled by the heat transfer medium flowing through the cooling channel 18. In addition, the battery pack may be placed directly on top of the cooling surface 12, but it may also be placed indirectly via, for example, a flexible heat conductive gel or a heat conductive sheet, so that the gap with the cooling surface 12 is filled with a material with high thermal conductivity, and an improvement in heat exchange efficiency can be expected.

[0047] In conventional cooling heat exchangers, the heat transfer medium flowing through the cooling channel 18 gradually becomes hotter as it moves downstream due to heat transfer from the battery pack. Therefore, the temperature difference between the heat transfer medium and the battery pack becomes smaller downstream of the cooling channel 18 compared to the upstream side, reducing the cooling efficiency of the battery pack, or in other words, the cooling performance of the cooling heat exchanger. In particular, the heat transfer medium flowing in the upper part of the cooling channel 18, which is close to the cooling surface 12, is prone to temperature increases due to heat exchange with the battery pack. As a result, in conventional cooling heat exchangers, the cooling performance decreases as the temperature of the upper heat transfer medium rises, even if the lower heat transfer medium remains at a low temperature.

[0048] Therefore, in the heat exchanger 10 for cooling of the present embodiment, a protrusion 36 is provided on the bottom surface (lower wall surface) of the cooling flow path 18. When the heat medium flows over the protrusion 36 and through the cooling flow path 18, the heat medium flowing in the upper part and the heat medium flowing in the lower part of the cooling flow path 18 are mixed when overcoming the protrusion 36. Thereby, it is possible to prevent only the upper heat medium from becoming high temperature due to heat exchange with the battery pack, and by efficiently using the heat capacity of the heat medium flowing in the cooling flow path 18, excellent cooling performance can be realized. In particular, since it is also possible to suppress the temperature rise of the heat medium up to the downstream side of the cooling flow path 18, the battery pack arranged on the downstream side of the cooling flow path 18 can also be effectively cooled.

[0049] Further, on the downstream side of the protrusion 36, the heat medium that has overcome a pair of inclined portions 38, 38 flows inward in the flow path width direction of the cooling flow path 18 and merges, so that the formation of a vortex-like flow can also be expected. Thus, in the heat exchanger 10 for cooling, since the heat medium is also agitated by the formation of the vortex, the cooling performance is improved by averaging the temperature of the heat medium.

[0050] The heat exchanger 10 for cooling is configured such that the protrusion 36 has a cross-sectional shape as shown in FIG. 3, thereby improving the cooling performance while suppressing the pressure loss of the flowing heat medium.

[0051] That is, the surface of the upstream portion of the protrusion 36 is composed of the upstream side surface 48 of the base portion 46 with a large radius of curvature R1 set and the large R surface 42 of the top portion 40, and the inclination angle of the upstream side surface 48 and the large R surface 42 with respect to the flow path length direction is smaller than the surface of the downstream portion of the protrusion 36 described later. Thereby, when the heat medium flowing through the cooling flow path 18 overcomes the protrusion 36, the heat medium easily flows smoothly along the surface on the upstream side of the protrusion 36, and the pressure loss is reduced. As a result, high pump performance is not required to flow the heat medium, and a relatively inexpensive pump can be employed.

[0052] Furthermore, the surface of the downstream portion of the projection 36 is composed of a small radius R surface 44 of the top portion 40 with a small radius of curvature R2, and a flat downstream side surface 50 of the base portion 46. The inclination angle of the downstream side surface 50 with respect to the length of the flow path is larger than that of the surface of the upstream portion of the projection 36. As a result, a rapid change in the flow path cross-sectional area of ​​the cooling flow path 18 occurs in the downstream portion of the projection 36, causing the flow of the heat transfer medium to become turbulent and agitated. Consequently, the temperature of the heat transfer medium is averaged by agitation downstream of the projection 36, and an improvement in cooling performance can be expected. In particular, the heat transfer medium flowing in the downstream portion of the projection 36 easily separates from the surface of the projection 36 due to the large inclination angle of the surface in the downstream portion of the projection 36, forming a vortex flow downstream of the projection 36. A high agitation effect due to this vortex flow can also be expected, resulting in excellent cooling performance.

[0053] The inclination angle θ of the downstream side surface 50 of the projection 36 at the connection end 52 with the top 40 is within the range of 35 to 90°, and more preferably within the range of 40 to 80°. This makes it easier for the flow of the heat transfer medium flowing over the downstream side surface 50 to separate from the downstream side surface 50, and the formation of a vortex flow can be further promoted. Therefore, the temperature averaging by stirring the heat transfer medium is advantageously achieved, and the cooling performance is improved by, for example, demonstrating effective cooling performance further downstream.

[0054] In this embodiment, the upstream side surface 48 of the projection 36 is a convex curved surface that protrudes upstream, and the downstream side surface 50 of the projection 36 is a flat surface. As a result, the bulge of the downstream side surface 50 of the projection 36 toward the cooling channel 18 is smaller than the bulge of the upstream side surface 48 of the projection 36 toward the cooling channel 18. This makes it easier for a vortex flow of the heat transfer medium to form downstream of the projection 36 without being obstructed by contact with the projection 36, thereby more advantageously achieving improved cooling performance through stirring of the heat transfer medium.

[0055] Furthermore, for example, if multiple battery packs are arranged in a line along the length of the cooling channel 18, it may be important to effectively cool all of them. That is, if the performance of even one of these battery packs deteriorates, the overall performance of the battery may deteriorate significantly. In this case, for example, with conventional cooling heat exchangers, battery packs located downstream of the cooling channel 18 are prone to deterioration due to insufficient cooling, and the desired battery performance may not be achieved. In contrast, the cooling heat exchanger 10 of this embodiment is more efficient at maintaining cooling performance down to the downstream side of the cooling channel 18 compared to conventional cooling heat exchangers, thus preventing downstream battery packs from deteriorating due to heat and achieving stable battery performance.

[0056] By the way, the lower plate 16, which is a metal plate for flow channels equipped with projections 36, can be manufactured by, for example, the following manufacturing method. First, a metal base plate to be made into the lower plate 16 is prepared. This metal base plate is a rectangular flat plate and has a thickness in the range of 0.7 to 1.3 mm.

[0057] Next, the prepared metal sheet is press-formed to create the outer peripheral wall portion 20 and the partition wall portion 26, forming the sealed region 28 and five cooling channels 18a to 18e, as well as a projection base that protrudes into the cooling channel 18. In the cross-section in the direction of the length of the channel shown in Figure 3, the projection base has an arc shape in which the radius of curvature of the surface is R1 of the large R surface 42 throughout, and the radius of curvature of the surface is relatively large and substantially constant throughout, so that localized thinning is avoided and it is possible to form it in a stable shape. The projection base is provided in the part of the lower plate 16 where the projection 36 is formed, and in this embodiment, multiple projection bases are provided that are distributed throughout the cooling channel 18.

[0058] Next, the inclined portion on the downstream side of the projection base is pressed from the cooling channel 18 side to form a top edge on the downstream side, which has a smaller radius of curvature than the projection base. This top edge has a projection height of 0.2 to 2.5 mm from the bottom wall surface of the cooling channel 18, and a surface radius of curvature R2 of 0.4 to 1.2 mm. In addition, for both the formation of the projection base and the formation of the top edge, it is possible to form them by pressing the mold from one side of the lower plate 16, or by pressing the mold against both sides of the lower plate 16 and performing press processing.

[0059] As described above, a projection 36 can be formed on the bottom wall of the cooling channel 18 on the lower plate 16, with the upstream side being a large R surface 42 with a large radius of curvature formed from a part of the projection base, and the downstream side being a small R surface 44 with a small radius of curvature formed from the top edge. The thickness dimension of the lower plate 16 at the projection 36 is preferably 0.4 mm or more, and more preferably 0.6 mm or more.

[0060] This method for manufacturing the lower plate 16 makes it possible to stably form a projection 36 with a top edge (small R surface 44) having an extremely small radius of curvature, which could not be achieved with conventional press working, at a sufficient height. Furthermore, the thickness dimension of the lower plate 16 in the projection 36 formation portion can be set to 0.4 mm or more, ensuring sufficient durability (pressure resistance) of the lower plate 16 in the projection 36 formation portion. In particular, by forming the top edge with a small radius of curvature by press working mainly involving compressive deformation relative to the projection base, it becomes possible to stably form the top edge while avoiding localized thinning, etc.

[0061] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, the downstream side surface of the projection is not limited to a plane that widens at a constant angle of inclination, but rather the angle of inclination of the connection end with the top surface of the projection, in other words, the angle of inclination of the tangent at the connection end with the downstream side surface of the top surface, should be within the range of 35 to 90°. Therefore, the downstream side surface of the projection may be a curved surface with a continuously changing angle of inclination, a bent surface with a stepped change in angle of inclination, etc. The downstream side surface of the projection may have a shape that bulges towards the cooling channel on the downstream side, but it is preferable that it be a flat surface or a concave surface that does not bulge downstream. Furthermore, such a downstream side surface is preferably formed with a radius of curvature (an absolute value, including a plane with an infinite radius of curvature) that is larger than either the upstream surface (large radius surface) or the downstream surface (small radius surface) that constitute the top surface of the projection.

[0062] The upstream side surface of the projection is not limited to a curved surface with the same radius of curvature as the curved surface (large radius surface) on the upstream side of the apex; for example, it may be a curved surface with a different radius of curvature from the upstream portion of the apex surface, or it may be a flat surface or a bent surface.

[0063] The surface of the top of the projection does not necessarily have to consist solely of large-radius and small-radius surfaces, as long as it has a large-radius surface on the upstream side and a small-radius surface on the downstream side. Specifically, for example, a plane or curved surface connecting the large-radius surface on the upstream side and the small-radius surface on the downstream side may be provided. Preferably, the surface of the top of the projection has a large-radius curved surface (large-radius surface) in the portion including the upstream end connected to the upstream side surface, and a small-radius curved surface (small-radius surface) in the portion including the downstream end connected to the downstream side surface.

[0064] The large radius and small radius surfaces that constitute the surface at the top of the projection are not necessarily limited to a perfectly circular arc cross-section, and their radii of curvature may vary. That is, the surface at the top of the projection only needs to be a convex curved surface as a whole, without having a concave surface (a curved surface where the center of curvature is located above the projection) in the flow direction, and preferably a smoothly connected curved surface without any bends (points without common tangents) in the flow direction. The large radius and small radius surfaces can be, for example, curved surfaces with an elliptical (long circular arc) cross-section. In this case, the minimum radius of curvature of the large radius surface is made larger than the minimum radius of curvature of the small radius surface.

[0065] When multiple protrusions are provided, it is not necessary for all of them to be protrusions according to the present invention; it is sufficient if at least one of them is a protrusion according to the present invention.

[0066] The protrusions are not limited to a shape that extends in the width direction with a substantially constant maximum height dimension, as shown in the first embodiment, and the maximum height dimension may vary in the width direction. For example, at least one of a high protrusion and a low protrusion may be partially provided in the width direction. More specifically, a plurality of protrusions may be composed of a first protrusion in which the central part in the width direction is a high protrusion and both ends in the width direction are low protrusions, and a second protrusion in which the central part in the width direction is a low protrusion and both ends in the width direction are high protrusions, and these first and second protrusions may be provided alternately in the flow path length direction. The high protrusions and low protrusions may be provided so that their height changes in a stepped manner, but preferably they are provided so that their height changes gradually.

[0067] The protrusions are not limited to those with a V-shape when viewed from above. For example, V-shaped protrusions that narrow towards the upstream direction and inverted V-shaped protrusions that narrow towards the downstream direction may be provided alternately. Alternatively, W-shaped or other protrusions, such as multiple V-shaped protrusions arranged in the direction of the channel width, can also be used.

[0068] A metal plate for flow channels having a projection with a small radius of curvature (top edge) on the upstream side, or a metal plate for flow channels having projections with small radius of curvature (top edge) on both the upstream and downstream sides, can also be used as a lower plate for a cooling heat exchanger.

[0069] The present invention is suitably applied to a member (lower plate) that constitutes the wall portion on the side of the cooling channel that does not form a cooling surface in a cooling heat exchanger equipped with only one cooling surface, but it may also be applied to a member that constitutes a cooling surface, or to an inner fin that partitions a sealed area.

[0070] 10 Cooling heat exchanger (first embodiment) 12 Cooling surface 14 Upper plate 16 Lower plate (metal plate for flow path) 18 (18a to 18e) Cooling flow path 20 Outer peripheral wall 22 Supply hole 24 Discharge hole 26 Partition wall 28 Enclosed area 32 Parallel flow path section 34 (34a, 34b) Single flow path section 36 Projection 38 Inclined section 40 Top 42 Large radius surface (upstream curved surface on the top surface) 44 Small radius surface (downstream curved surface on the top surface, top side edge) 46 Base 48 Upstream side surface 50 Downstream side surface 52 Connection end H Projection height of projection D Flow path depth of cooling flow path R1 Radius of curvature of large radius surface R2 Radius of curvature of small radius surface θ Incline angle of downstream side surface

Claims

1. A cooling heat exchanger having a cooling channel formed inside through which a cooling heat transfer medium flows, for cooling an object to be cooled superimposed on a cooling surface provided on the surface, wherein a projection is provided on the inner surface of the wall of the cooling channel, the top of the projection has an upstream surface and a downstream surface, each including a curved surface with an arc-shaped cross-section, the radius of curvature of the downstream curved surface is smaller than the radius of curvature of the upstream curved surface, and the downstream side surface, which is the surface downstream of the top of the projection, has an inclination angle at the connection end with the top in the range of 35 to 90°.

2. The cooling heat exchanger according to claim 1, wherein the bulge of the downstream side surface of the projection toward the cooling channel is smaller than the bulge of the upstream side surface, which is the surface upstream of the top of the projection toward the cooling channel.

3. The cooling heat exchanger according to claim 1 or 2, wherein the average inclination angle of the downstream side surface of the projection is greater than the average inclination angle of the upstream side surface, which is the surface upstream of the top of the projection.

4. The cooling heat exchanger according to any one of claims 1 to 3, wherein the downstream side surface of the projection has a straight portion with a constant inclination angle.

5. The cooling heat exchanger according to any one of claims 1 to 4, wherein the radius of curvature of the curved surface on the downstream side at the top of the projection is within the range of 20 to 60% of the radius of curvature of the curved surface on the upstream side at the top.

6. The cooling heat exchanger according to any one of claims 1 to 5, wherein the protruding height of the projection is within the range of 10 to 90% of the flow path depth in the cooling channel.

7. A method for manufacturing a metal plate for a flow channel, comprising the steps of: preparing a metal sheet having a thickness in the range of 0.7 to 1.3 mm; press-forming the metal sheet to form a projection base that protrudes toward the cooling channel side; and pressing at least one of the inclined portions on the upstream and downstream sides of the projection base from the cooling channel side to form a top edge with a small radius of curvature, thereby forming the projection having a top edge with a protrusion height in the range of 0.2 to 2.5 mm and a radius of curvature in the range of 0.4 to 1.2 mm.

8. The method for manufacturing a flow channel metal plate according to claim 7, wherein the minimum thickness of the projection is 0.4 mm or more.

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