Cooling heat exchanger

Abstract

Provided is a cooling heat exchanger having a novel structure capable of achieving stable cooling performance over a wider area of a cooling surface in contact with an object to be cooled.　A cooling heat exchanger 10 cools an object B to be cooled superimposed on a surface thereof by allowing a cooling heat medium to flow through an internally formed cooling flow path 38. The cooling flow path 38 comprises a supply flow path 40 to which the heat medium is supplied from the upstream side, and a discharge flow path 42 from which the heat medium is discharged from the downstream side. In the cooling flow path 38, a plurality of branch flow paths 44a to 44h connecting the supply flow path 40 and the discharge flow path 42 are provided in parallel, branching from a plurality of points in the length direction of the supply flow path 40. The plurality of branch flow paths 44a to 44h are partly provided with resistance adjustment parts 46a to 46h for adjusting the flow resistance of the heat medium, the flow resistance of the heat medium in the resistance adjustment parts 46 becoming smaller in the branch flow paths 44 that branch off further downstream of the supply flow path 40.

Description

cooling heat exchanger

[0001] The present invention relates to a cooling heat exchanger used to cool an object to be cooled, such as a battery pack, in an electrically powered vehicle such as an electric automobile.

[0002] In electrically powered vehicles such as electric vehicles and hybrid vehicles, the heat generated by the battery packs and electronic devices to be cooled is increasing due to miniaturization and high performance, making cooling performance increasingly important. Conventionally, as disclosed in International Publication No. 2019 / 008000 (Patent Document 1), for example, cooling heat exchangers have been used that have a structure in which cooling channels are formed between overlapping plates. In this cooling heat exchanger, one plate is overlapped with the cooling target, such as a battery pack, and the cooling target is cooled by the cooling of the one plate with a refrigerant flowing through the cooling channels.

[0003] International Publication No. 2019 / 008000

[0004] The cooling heat exchanger of Patent Document 1 has a cooling flow path in which a supply flow path located on the upstream side for supplying a heat medium and a discharge flow path located on the downstream side for discharging the heat medium are connected by a plurality of branch flow paths provided in parallel, and the branch flow paths have substantially the same shape and size.

[0005] However, in the structure of Patent Document 1, differences in flow rate due to pressure loss, etc., tend to occur between the branch flow path that branches off on the upstream side of the supply flow path and the branch flow path that branches off on the downstream side of the supply flow path, which tends to cause variations in cooling efficiency.

[0006] An object of the present invention is to provide a cooling heat exchanger having a novel structure that can achieve stable cooling performance over a wider range of the cooling surface that contacts the object to be cooled.

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0008] In a first aspect, a cooling heat exchanger cools a cooling object placed on its surface by allowing a heat medium for cooling to flow through a cooling flow path formed inside, the cooling flow path comprising a supply flow path through which the heat medium is supplied from the upstream side and a discharge flow path through which the heat medium is discharged from the downstream side, and the cooling flow path has a plurality of branch flow paths connecting the supply flow path and the discharge flow path, the branch flow paths being arranged in parallel at a plurality of locations along the length of the supply flow path, and the plurality of branch flow paths are each partially provided with a resistance adjustment section that adjusts the flow resistance of the heat medium, and the flow resistance of the heat medium in the resistance adjustment section is smaller for branch flow paths that branch further downstream from the supply flow path.

[0009] In a cooling heat exchanger constructed according to this aspect, the difference in the flow rate of the heat medium among the multiple branch flow paths is reduced, thereby suppressing variations in the cooling efficiency among the branch flow paths. Therefore, stable cooling performance can be achieved by the multiple branch flow paths over a wider cooling area. Furthermore, since the resistance adjustment units are partially provided in the branch flow paths, the branch flow paths outside the resistance adjustment units can be designed with a high degree of freedom.

[0010] In a second aspect, in the cooling heat exchanger described in the first aspect, at least one of the branch flow paths extends in a planar double spiral shape from the center toward the periphery, and both ends located on the periphery are connected to each of the supply flow path and the discharge flow path.

[0011] In the cooling heat exchanger constructed according to this aspect, the upstream section in which the low-temperature heat medium flows and the downstream section in which the high-temperature heat medium flows are alternately positioned adjacent to each other in the planar double-spiral branch flow passage, so that heat exchange occurs between the adjacent flow passages, reducing the temperature difference between the upstream and downstream sections of the branch flow passage. This suppresses changes in cooling efficiency along the length of the branch flow passage, and achieves stable cooling performance over a wide range.

[0012] Furthermore, since the branch flow path is spiral-shaped and curved or bent in the circumferential direction, the heat transfer medium flowing within the flow path is more easily stirred than in a straight branch flow path, and the temperature difference across the flow path cross section can be reduced.

[0013] In a third aspect, in the cooling heat exchanger described in the first or second aspect, the plurality of branch flow paths have the same flow path width dimensions in the portions outside the resistance adjustment section.

[0014] In the cooling heat exchanger constructed according to this aspect, by providing a partial orifice passage portion in the branch passage, it is possible to adjust the flow rates of the branch passages without making the passage width dimensions of the portions of the branch passages outside the orifice passage portion different from each other, thereby stabilizing the cooling performance. Therefore, in the portions of the branch passages outside the orifice passage portion, for example, the range of the cooling surface cooled by each branch passage and the cooling efficiency are made uniform, thereby further stabilizing the cooling performance.

[0015] In a fourth aspect, in the cooling heat exchanger described in the third aspect, the plurality of branch flow paths have the same flow path cross-sectional area in the portion outside the resistance adjustment section.

[0016] In a cooling heat exchanger constructed in accordance with this aspect, the flow path cross-sectional areas of the multiple branch flow paths outside the orifice flow path portions are made the same, thereby achieving uniform flow rates and flow speeds and further reducing variations in cooling performance between the branch flow paths.

[0017] In a fifth aspect, in the cooling heat exchanger described in any one of the first to fourth aspects, the flow path cross-sectional area of ​​the resistance adjustment section of the branch flow path that branches off further downstream from the supply flow path is made larger.

[0018] According to the cooling heat exchanger constructed in accordance with this aspect, the flow resistances at the orifice passage portions in the plurality of branch passages can be easily set by adjusting the flow passage cross-sectional area of ​​the orifice passage portion.

[0019] A sixth aspect is the cooling heat exchanger according to any one of the first to fifth aspects, wherein the resistance adjustment portion is provided at an end of the branch flow path.

[0020] In a cooling heat exchanger constructed according to this embodiment, since the orifice flow path portion is provided at the end of the branch flow path, the flow path cross-sectional area is secured without being reduced by the orifice flow path portion in the intermediate portion of the branch flow path where heat exchange takes place between the cooling object and the cooling surface that is superimposed thereon, and a decrease in cooling efficiency is prevented.

[0021] In a seventh aspect, in the cooling heat exchanger described in any one of the first to sixth aspects, a flow path member having a groove formed on its surface and a cooling surface component member that is placed on the object to be cooled are placed on top of each other, and the groove of the flow path member is covered by the cooling surface component member, so that the cooling flow path is formed between the overlapping surfaces of the flow path member and the cooling surface component member.

[0022] According to a cooling heat exchanger constructed in accordance with this embodiment, since the flow path forming member and the cooling surface forming member are stacked together, the cooling flow path can be easily formed between the overlapping surfaces of the flow path forming member and the cooling surface forming member by covering the opening of the groove formed in the flow path forming member with the cooling surface forming member.

[0023] In an eighth aspect, in the cooling heat exchanger according to the seventh aspect, the flow path member is made of synthetic resin, and the cooling surface constituent member is made of metal.

[0024] In a cooling heat exchanger constructed according to this aspect, the flow path forming member, in which the grooves that form the cooling flow path are formed, is made of synthetic resin, which makes it easier to form the grooves and improves the freedom and precision of their shape. Furthermore, the cooling surface forming member that forms the cooling surface that is overlaid on the cooling object is made of metal, which makes it easier to form it from a material with an excellent heat transfer coefficient, thereby improving the efficiency of heat exchange between the cooling object and the heat medium via the cooling surface forming member. Furthermore, the cooling surface forming member that comes into contact with the cooling object is made of metal, which makes it easier to ensure the durability of the contact surface with the cooling object. Furthermore, the flow path member is made of synthetic resin, which makes it easier to achieve a lighter weight than a metal member.

[0025] According to the present invention, in a cooling heat exchanger, it is possible to achieve more stable cooling performance on the cooling surface that comes into contact with an object to be cooled.

[0026] 1 is a perspective view showing a cooling heat exchanger according to a first embodiment of the present invention; 2 is a perspective exploded view of the cooling heat exchanger shown in FIG. 1; 3 is a plan view of the cooling heat exchanger shown in FIG. 1; 4 is a cross-sectional view of the cooling heat exchanger shown in FIG. 1, corresponding to the IV-IV cross section of FIG. 3; 5 is a cross-sectional view of the cooling heat exchanger shown in FIG. 1, corresponding to the V-V cross section of FIG. 3; 6 is a cross-sectional view of the cooling heat exchanger shown in FIG. 1, corresponding to the VI-VI cross section of FIG. 3

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0028] FIG. 1 shows a cooling heat exchanger 10 according to a first embodiment of the present invention. The cooling heat exchanger 10 cools a battery pack B (described below) as a cooling target placed on its surface by exchanging heat with a heat medium. As shown in FIG. 2, the cooling heat exchanger 10 has a laminated structure in which a resin plate 12 serving as a flow path member and a cooling plate 14 serving as a cooling surface component are stacked on top of each other. In the following description, the front-to-rear direction refers to the up-and-down direction in FIG. 3 (described below), the left-to-right direction refers to the left-to-right direction in FIG. 3, and the up-and-down direction refers to the left-to-right direction in FIG. 4 (described below), which is the direction in which the resin plate 12 and the cooling plate 14 are stacked.

[0029] As shown in Fig. 2, the resin plate 12 has a rectangular plate shape overall, and is longer in the front-to-rear direction than in the left-to-right direction. The resin plate 12 is made of synthetic resin, preferably a thermoplastic synthetic resin material. Suitable materials for the resin plate 12 include polyamide, polyester, fluororesin, and polyolefin. The resin plate 12 can also be made of fiber-reinforced synthetic resin reinforced with glass fiber, carbon fiber, or the like.

[0030] 3 to 6, the resin plate 12 has a groove 16 that opens to the top surface. The groove 16 includes vertical grooves 18a, 18b that extend linearly in the front-to-rear direction from both left and right ends, and a plurality of horizontal grooves 20 that interconnect the vertical grooves 18a, 18b. Note that in FIG. 3, which shows a top view of the cooling heat exchanger 10, the top surface of the resin plate 12 is shown as seen through the cooling plate 14.

[0031] The lateral groove 20 extends from the center toward the outer periphery in a planar double spiral shape. More specifically, the lateral groove 20 includes a first linear portion 22 extending linearly from the center in the left-right direction, first U-shaped folded portions 24 extending from the left and right ends of the first linear portion 22 toward either the front or rear and folding back 180°, second linear portions 26 extending linearly in the left-right direction from the first folded portion 24, substantially U-shaped second folded portions 28 extending from the left and right ends of the second linear portions 26 toward the other front or rear and folding back 180°, and third linear portions 30 extending linearly in the left-right direction from the second folded portions 28. The left and right ends of the third linear portions 30 connect the lateral groove 20 to the longitudinal groove 18.

[0032] In this embodiment, eight lateral grooves 20a-20h are arranged in parallel and spaced apart in the front-to-rear direction. The eight lateral grooves 20a-20h are substantially identical in shape and size. Lightening holes 32 are formed between adjacent lateral grooves 20, 20 in the front-to-rear direction in the resin plate 12 and on the front-to-rear outer sides of the lateral grooves 20a, 20h located at both front and rear ends, penetrating the resin plate 12 in the up-down direction. The shape and size of the lightening holes 32 are not particularly limited, but in this embodiment, they are substantially rectangular and longer in the left-to-right direction than in the front-to-rear direction. In this embodiment, the four front lateral grooves 20a-20d and the four rear lateral grooves 20e-20h are shaped inversely to each other front-to-rear.

[0033] In this embodiment, the resin plate 12 protrudes downward more than other portions at the portions where the grooves 16 are formed, ensuring the depth of the grooves 16. Therefore, the resin plate 12 has both left and right end portions, where the vertical grooves 18a and 18b are formed, protruding downward, and also has left and right intermediate portions, where the horizontal grooves 20 are formed, protruding downward.

[0034] The cooling plate 14 constitutes a cooling surface that is placed on the battery pack B (described later). In this embodiment, the cooling plate 14 has a substantially rectangular plate shape. The cooling plate 14 is made of metal. The cooling plate 14 is preferably made of a metal material with high thermal conductivity, such as aluminum, copper, stainless steel, or an alloy thereof.

[0035] 2, a supply port 34 and a discharge port 36 are provided at the front corners of the cooling plate 14. The supply port 34 has a generally cylindrical shape that protrudes upward, with a central hole that passes through the cooling plate 14 in the vertical direction. Similarly, the discharge port 36 has a generally cylindrical shape that protrudes upward, with a central hole that passes through the cooling plate 14 in the vertical direction. The supply port 34 and the discharge port 36 may be provided integrally with the cooling plate 14, or may be formed separately from the cooling plate 14 and fixed by means of welding, adhesive, or the like.

[0036] 2 and 4 to 6, the cooling plate 14 is placed on top of the resin plate 12. The resin plate 12 and the cooling plate 14 that are placed on top of each other are fixed to each other by means of bonding using an adhesive, friction stir welding, laser welding, or the like.

[0037] The recessed grooves 16 opening into the upper surface of the resin plate 12 are liquid-tightly covered by the cooling plate 14. The recessed grooves 16 with their openings covered by the cooling plate 14 form cooling channels 38. The cooling channels 38 are formed between the overlapping surfaces of the resin plate 12 and the cooling plate 14. Therefore, the cooling channels 38 are provided inside the cooling heat exchanger 10. A portion of the wall of the cooling channels 38 (the upper wall) is formed by the cooling plate 14. Because the cooling heat exchanger 10 has a laminated structure in which the resin plate 12 and the cooling plate 14 are overlapped in this way, the cooling channels 38 extending inside the cooling heat exchanger 10 can be easily formed.

[0038] The portion of the cooling flow path 38 formed by the right-side vertical groove 18a is a supply flow path 40. The portion of the cooling flow path 38 formed by the left-side vertical groove 18b is a discharge flow path 42. The supply flow path 40 extends linearly in the front-rear direction at the right end of the cooling heat exchanger 10 and is connected at its front end to the supply port 34. The discharge flow path 42 extends linearly in the front-rear direction at the left end of the cooling heat exchanger 10 and is connected at its front end to the discharge port 36.

[0039] The portion of the cooling flow path 38 formed by the lateral grooves 20a to 20h is designated as branch flow paths 44a to 44h. As can be seen from the description of the lateral grooves 20, the branch flow path 44 extends in a planar double spiral shape, with both ends located on the outer periphery connected to either the supply flow path 40 or the discharge flow path 42. The branch flow paths 44a to 44h branch off at multiple locations along the length of the supply flow path 40 and are arranged in parallel to one another. Furthermore, the multiple branch flow paths 44a to 44h merge with the discharge flow path 42 at multiple locations in the front-to-rear direction at the downstream end. Therefore, the supply flow path 40 and the discharge flow path 42 are connected to one another by the multiple branch flow paths 44a to 44h.

[0040] Among the branch flow paths 44a to 44h, the branch flow path 44a located at the front is connected most upstream to the supply flow path 40 and most downstream to the discharge flow path 42. On the other hand, the branch flow path 44h located most rearward among the branch flow paths 44a to 44h is connected most downstream to the supply flow path 40 and most upstream to the discharge flow path 42. In other words, the branch flow paths 44a to 44h located further forward are connected more upstream to the supply flow path 40 and more downstream to the discharge flow path 42.

[0041] The heat medium that flows in through the supply port 34 from an external flow path (not shown) flows from front to rear through the supply flow path 40, flows into the discharge flow path 42 through the branch flow paths 44a to 44h, and then flows from rear to front through the discharge flow path 42 to be discharged into the external flow path from the discharge port 36. The flow directions of the heat medium in the supply flow path 40 and the discharge flow path 42 are indicated by arrows in Fig. 3. The external flow path (not shown) is connected to a pump that causes the heat medium to flow, a refrigerator that cools the high-temperature heat medium to a low-temperature heat medium, and the like.

[0042] In this embodiment, the heat medium supplied through the supply port 34 provided at the front end, which is the upstream end of the supply flow path 40, flows from front to rear within the supply flow path 40, and the heat medium flowing from rear to front within the discharge flow path 42 is discharged to the outside through the discharge port 36 provided at the front end, which is the downstream end of the discharge flow path 42. In this way, since the supply port 34 and the discharge port 36 connected to the external flow path are both provided at the front end, it is easy to connect the external flow path and the path of the external flow path can be shortened.

[0043] 3 and 4, in the cooling heat exchanger 10 configured as described above, the battery packs B to be cooled are placed on the upper surface of the cooling plate 14. In this embodiment, one battery pack B is disposed on each of the portions of the cooling plate 14 that form the wall portions of the branch flow paths 44a to 44h, and the eight battery packs B, B, ..., B are arranged at intervals in the front-to-rear direction. As the heat medium flows through the cooling flow paths 38, heat exchange occurs via the cooling plate 14 between the low-temperature heat medium and the battery packs B, which become hot due to heat generation during use, thereby cooling the battery packs B.

[0044] The high-temperature heat medium, the temperature of which has increased due to heat exchange with the battery pack B, is cooled by a refrigerator (not shown) connected to the external flow path. The heat medium cooled by the refrigerator is then supplied from the supply port 34 to the cooling flow path 38. Note that the external flow path only needs to be provided with a mechanism for lowering the temperature of the high-temperature heat medium; for example, an air-cooling device such as a radiator or a liquid-cooling device can be provided instead of a refrigerator.

[0045] Because a low-temperature heat medium is supplied from the external flow path to the supply flow path 40 and a high-temperature heat medium is discharged from the discharge flow path 42 to the external flow path, the heat medium flowing through the branch flow path 44 tends to have a low temperature near the end connected to the supply flow path 40 and a high temperature near the end connected to the discharge flow path 42. Since the branch flow path 44 of this embodiment extends in a planar double spiral shape, portions through which a low-temperature heat medium flows and portions through which a high-temperature heat medium flows alternate in the radial direction. Therefore, heat exchange due to the temperature difference between adjacent portions through which a low-temperature heat medium flows and a high-temperature heat medium flows is likely to occur in the branch flow path 44, reducing the temperature difference between portions. As a result, the battery pack B overlapping the wall of the branch flow path 44 is cooled more evenly throughout.

[0046] The branch flow paths 44a to 44h are provided with orifice flow path portions 46a to 46h as resistance adjusting portions for adjusting the flow rate of the heat medium. The orifice flow path portion 46 is provided partially in the flow path length direction of the branch flow path 44. As shown in FIG. 3 , the orifice flow path portion 46 is provided at the end of the branch flow path 44 on the downstream side (discharge flow path 42 side).

[0047] The orifice passage portion 46 adjusts the flow resistance of the heat medium flowing therethrough, and in this embodiment, the flow resistance of the heat medium is adjusted by the flow path cross-sectional area. More specifically, the orifice passage portions 46a to 46g have smaller flow path cross-sectional areas than the other portions of the branch passage 44, and the flow resistance is set to be larger than the other portions of the branch passage 44. The orifice passage portion 46h has the same flow path cross-sectional area as the other portions of the branch passage 44, and the flow resistance of the heat medium is adjusted to be approximately the same as the other portions of the branch passage 44. The orifice passage portions 46a to 46g have smaller flow path widths and flow path depths than the other portions of the branch passage 44. The other portions of the branch passages 44a to 44h outside the orifice passage portions 46a to 46h have approximately the same flow path widths and flow path depths. Therefore, the other portions of the branch flow paths 44a to 44h other than the orifice flow path portions 46a to 46h have substantially the same flow path cross-sectional area.

[0048] The orifice passage sections 46a to 46h are set to have different flow resistances. That is, the flow resistance of the orifice passage section 46a is set to be greater than the flow resistance of the orifice passage section 46b. The flow resistance of the orifice passage section 46b is set to be greater than the flow resistance of the orifice passage section 46c. The flow resistance of the orifice passage section 46c is set to be greater than the flow resistance of the orifice passage section 46d. The flow resistance of the orifice passage section 46d is set to be greater than the flow resistance of the orifice passage section 46e. The flow resistance of the orifice passage section 46e is set to be greater than the flow resistance of the orifice passage section 46f. The flow resistance of the orifice passage section 46f is set to be greater than the flow resistance of the orifice passage section 46g. The flow resistance of the orifice passage section 46g is set to be greater than the flow resistance of the orifice passage section 46h. In this way, the flow resistance of the heat medium in the orifice passage sections 46a to 46h is smaller for the orifice passage section 46 provided in the branch passage 44 that branches off downstream of the supply passage 40.

[0049] In this embodiment, as shown in FIG. 5 , the orifice flow passage sections 46 provided in the branch flow passages 44 that branch off from the supply flow passage 40 have larger flow passage cross-sectional areas. In other words, the flow passage cross-sectional areas S(a) to S(h) of the orifice flow passage sections 46a to 46h are in the relationship S(a) < S(b) < S(c) < S(d) < S(e) < S(f) < S(g) < S(h). Furthermore, S(h) is set to be approximately the same as the flow passage cross-sectional area of ​​the branch flow passage 44 outside the orifice flow passage section 46. The flow resistance of the orifice flow passage sections 46a to 46h decreases as the flow passage cross-sectional area increases, assuming other conditions are the same. Therefore, by setting the flow passage cross-sectional areas of the orifice flow passage sections 46a to 46h as described above, the flow resistance decreases for the orifice flow passage sections 46 provided in the branch flow passages 44 that branch off from the supply flow passage 40 further downstream. The orifice flow passage sections 46a to 46h in this embodiment are composed of walls with an approximately semicircular cross-sectional shape, and the outer diameter dimensions in the cross section are approximately constant, while different flow passage cross-sectional areas are set depending on the thickness of the wall sections.

[0050] Although the lengths of the orifice passage sections 46a to 46h are substantially constant in this embodiment, they may be different from one another. For example, by shortening the lengths of the orifice passage sections 46a to 46h toward the orifice passage sections 46 in the branch passages 44 that branch off downstream of the supply passage 40, the flow resistance of the orifice passage sections 46 provided in the branch passages 44 that branch off further downstream of the supply passage 40 can be reduced by adjusting the lengths of the orifice passage sections 46. The frictional resistance acting between the wall surfaces of the orifice passage sections 46a to 46h and the heat medium is substantially the same because the wall sections of the orifice passage sections 46a to 46h are all formed by the resin plate 12 and the cooling plate 14.

[0051] The flow resistance of the orifice flow passage portions 46a to 46h is set taking into consideration differences in pressure loss resulting from differences in the branch positions of the branch flow passages 44a to 44h from the supply flow passage 40. In other words, the pressure loss increases the further downstream the branch flow passage 44 branches from the supply flow passage 40, resulting in a lower flow rate for the same flow resistance. Therefore, by setting the flow resistance of the orifice flow passage portion 46 to be smaller in the branch flow passage 44 that branches further downstream from the supply flow passage 40, the difference in flow rate among the branch flow passages 44a to 44h is reduced. The flow resistance of the orifice flow passage portions 46a to 46h is preferably adjusted so that the flow rates of the branch flow passages 44a to 44h are approximately constant.

[0052] In this way, by reducing the difference in flow rate among the branch flow paths 44a to 44h, differences in the performance of cooling the cooling plate 14 among the branch flow paths 44a to 44h are less likely to occur, and the cooling performance is stabilized over a wider range of the cooling plate 14. Therefore, each battery pack B that is placed on the wall-constituting portions of the branch flow paths 44a to 44h of the cooling plate 14 can be cooled stably.

[0053] By partially providing the orifice passage sections 46a to 46h in the branch passages 44, the flow cross-sectional area and therefore the flow width of the branch passages 44 are ensured in the portions outside the orifice passage sections 46. Therefore, the cooling area of ​​the branch passages 44 in the cooling plate 14 is efficiently ensured to obtain effective cooling performance, while the flow rate of the branch passages 44 can be adjusted by the orifice passage sections 46, stabilizing cooling performance over a wide range. In this embodiment, the orifice passage sections 46 are located away from the battery pack B in the vertical projection, so the orifice passage sections 46, which have small flow cross-sectional areas and narrow flow widths, are less likely to affect cooling performance. Furthermore, because the orifice passage sections 46 are located at the downstream ends of the branch passages 44, instability in the flow velocity distribution of the heat medium and flow turbulence caused by passing through the orifice passage sections 46 in the branch passages 44 are prevented. This makes it easier to control the flow of the heat medium throughout the entire branch passages 44, which is expected to stabilize cooling performance. In addition, in this embodiment, the flow path width dimensions of the branch flow paths 44a to 44h are approximately constant, and the flow path cross-sectional areas are approximately constant, making it easier to reduce variations in the cooling performance of the branch flow paths 44a to 44h.

[0054] The flow resistance of the orifice passage sections 46a to 46h is adjusted by the size of the flow path cross-sectional area. In particular, in this embodiment, the flow path lengths of the orifice passage sections 46a to 46h are substantially constant, and the orifice passage sections 46a to 46h are made of the same material, so the flow resistance of the orifice passage sections 46a to 46h is less likely to be affected by factors other than the flow path cross-sectional area. Therefore, the magnitude relationship of the flow resistance of the orifice passage sections 46a to 46h can be easily set by changing the flow path cross-sectional area of ​​the orifice passage sections 46a to 46h.

[0055] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific descriptions. For example, the shapes of the supply flow path and the discharge flow path are not limited to those that extend linearly. Furthermore, the supply flow path and the discharge flow path do not necessarily have to extend in the front-rear direction or parallel to each other.

[0056] The branch flow path preferably has a shape extending in a planar double spiral, but may also extend linearly, may have a spiral shape extending in a planar single spiral, or may extend in a curved or bent shape such as a wave or serpentine shape (including a linear zigzag). Furthermore, when a branch flow path extending in a planar spiral shape is employed, in the above embodiment, the cooling target is a rectangular battery pack, and therefore the planar shape of the entire branch flow path 44 is made rectangular as shown in Fig. 3 to improve cooling efficiency. However, the outer shape of the double spiral branch flow path in a planar view is not particularly limited, and may be, for example, a circular shape.

[0057] It is desirable that the branch flow paths have substantially the same shape and size as one another, but for example, at least one branch flow path may have a different shape and size from the other branch flow paths.

[0058] The number of branch flow paths is not particularly limited as long as it is plural, and is designed appropriately depending on the size, shape, etc. of the cooling heat exchanger. The arrangement of the plural branch flow paths is also not particularly limited.

[0059] The orifice passage portion 46 may be provided midway along the length of the branch passage 44, but is preferably provided at the end of the branch passage 44, which makes it possible to prevent the difference in the flow of the heat medium between the upstream and downstream sides of the orifice passage portion 46 and the change in flow velocity at the portion where the orifice passage portion 46 is formed from affecting the cooling performance. If the orifice passage portion 46 is provided at the upstream end of the branch passage 44, the heat medium in the branch passage 44 is agitated downstream of the orifice passage portion 46, and improvement in cooling efficiency can be expected.

[0060] The flow resistance of the resistance adjustment unit can be adjusted based on the flow path cross-sectional area, as with the orifice flow path unit 46 exemplified in the above embodiment. Alternatively, the flow resistance can be adjusted by providing the inner flow path surface of the resistance adjustment unit with irregularities (including embossed irregularities) or a low-friction coating layer. Furthermore, for example, the flow path cross-sectional area and the inner flow path irregularities of the resistance adjustment unit, which are different from those of the other parts of the branch flow paths, can be made substantially the same, while the flow path lengths can be made different, thereby making the flow resistance of the resistance adjustment unit different from each other. The flow resistance of the resistance adjustment unit can also be adjusted by combining multiple factors that affect the flow resistance, such as the flow path cross-sectional area and inner flow path irregularities of the resistance adjustment unit. It is desirable that the resistance adjustment unit, at least in the branch flow paths that branch off at the most upstream side of the supply flow path, increase the flow resistance using an orifice passage or the like to provide a predetermined flow resistance.

[0061] In the above embodiment, the resin plate 12 made of synthetic resin is used as the flow path member, but the flow path member may be made of metal, which makes it easier to reduce the thickness of the cooling heat exchanger. Furthermore, by using synthetic resin for both the flow path member and the cooling surface component, it is possible to further reduce the weight of the cooling heat exchanger. In this case, it is desirable to use, as the material for forming at least the cooling surface component, a thermally conductive synthetic resin, for example, a synthetic resin material mixed with a thermally conductive filler such as metal powder or powdered carbon, which has high thermal conductivity.

[0062] Furthermore, the cooling heat exchanger may have cooling surfaces that overlap with the object to be cooled on both sides, for example, by forming grooves on both sides of the flow path member and overlaying cooling plates on both sides of the flow path member. Alternatively, a single cooling heat exchanger may have multiple cooling surfaces extending in directions that intersect with each other. For example, by making the flow path member out of metal, at least one of the cooling surfaces that overlap with the object to be cooled may be formed by the flow path member.

[0063] In the above embodiment, the cooling heat exchanger 10 has a laminated structure in which the resin plate 12 and the cooling plate 14 are stacked, but the cooling heat exchanger is not limited to a laminated structure. For example, a cooling heat exchanger may have a structure in which pipes constituting the cooling flow path are arranged in a block-shaped or plate-shaped member so that the exposed portions of the pipes constitute the cooling surface.

[0064] The object to be cooled is not limited to the battery pack B exemplified in the above embodiment, but may be, for example, a control device that includes an electronic circuit or the like as a heat generating element.

[0065] REFERENCE SIGNS LIST 10 Cooling heat exchanger (first embodiment) 12 Resin plate (flow path member) 14 Cooling plate (cooling surface constituent member) 16 Groove 18 Vertical groove 18a Vertical groove 18b Vertical groove 20 Horizontal groove 20a Horizontal groove 20b Horizontal groove 20c Horizontal groove 20d Horizontal groove 20e Horizontal groove 20f Horizontal groove 20g Horizontal groove 20h Horizontal groove 22 First straight portion 24 First folded portion 26 Second straight portion 28 Second folded portion 30 Third straight portion 32 Lightening hole 34 Supply port 36 Discharge port 38 Cooling flow path 40 Supply flow path 42 Discharge flow path 44 Branch flow path 44a Branch flow path 44b Branch flow path 44c Branch flow path 44d Branch flow path 44e Branch flow path 44f Branch flow path 44g Branch flow path 44h Branch flow path 46 Orifice flow path section (resistance adjustment section) 46a Orifice flow path section (resistance adjustment section) 46b Orifice flow path section (resistance adjustment section) 46c Orifice flow path section (resistance adjustment section) 46d Orifice flow path section (resistance adjustment section) 46e Orifice flow path section (resistance adjustment section) 46f Orifice flow path section (resistance adjustment section) 46g Orifice flow path section (resistance adjustment section) 46h Orifice flow path section (resistance adjustment section) B Battery pack

Claims

1. A cooling heat exchanger that cools a cooling target superimposed on a surface by allowing a heat medium for cooling to flow through a cooling flow path formed inside, wherein the cooling flow path includes a supply flow path through which the heat medium is supplied from an upstream side and a discharge flow path through which the heat medium is discharged from a downstream side, and the cooling flow path is provided with a plurality of branch flow paths that connect the supply flow path and the discharge flow path and branch from the supply flow path at a plurality of locations in the flow path length direction of the supply flow path and are provided in parallel, and a resistance adjustment portion for adjusting the flow resistance of the heat medium is partially provided in each of the plurality of branch flow paths, and the flow resistance of the heat medium in the resistance adjustment portion is made smaller for the branch flow paths that branch on the more downstream side of the supply flow path.

2. The cooling heat exchanger according to claim 1, wherein at least one of the branch flow paths extends in a planar double spiral shape from the center toward the outer periphery, and both end portions located at the outer periphery are connected to one of the supply flow path and the discharge flow path.

3. The cooling heat exchanger according to claim 1 or 2, wherein the flow path width dimensions of the plurality of branch flow paths in the portion where the resistance adjustment portion is removed are the same as each other.

4. The cooling heat exchanger according to claim 3, wherein the flow path cross-sectional areas of the plurality of branch flow paths in the portion where the resistance adjustment portion is removed are the same as each other.

5. The cooling heat exchanger according to any one of claims 1 to 4, wherein the flow path cross-sectional area of the branch flow paths that branch on the more downstream side of the supply flow path is made larger for the resistance adjustment portion.

6. The cooling heat exchanger according to any one of claims 1 to 5, wherein the resistance adjustment portion is provided at an end portion of the branch flow path.

7. A flow path member having concave grooves formed on a surface and a cooling surface constituting member superimposed on the cooling target are superimposed on each other, and the concave grooves of the flow path member are covered by the cooling surface constituting member, and the cooling flow path is formed between the superimposed surfaces of the flow path member and the cooling surface constituting member. The cooling heat exchanger according to any one of claims 1 to 6.

8. The cooling heat exchanger according to claim 7, wherein the flow path member is made of synthetic resin and the cooling surface constituting member is made of metal.

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