Heat sink and power storage device

Abstract

To provide a heat sink and a power storage device that reduce the sudden temperature rise of a battery during charging and discharging.SOLUTION: A heat sink includes a cooling container body that is placed in contact with a heat generating body, the cooling container body includes an interior divided into a plurality of rectangular compartments, and each of the compartments containing a block made of a porous body made of a metal material impregnated with a phase change material (PCM) that absorbs heat using latent heat.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a heat sink and an electrical storage device. [Background technology]

[0002] Conventionally, a battery pack (battery module) consists of multiple cells (power cells) in an insulating resin case. The cells are connected in series and parallel with bus bars to obtain the desired voltage and current. A monitoring board is provided to monitor whether the cell group is in a normal state. In some cases, the monitoring board is housed in a resin case or the like, and the main circuit and communication cable wiring section are arranged on the monitoring board. The monitoring board is called, for example, a Cell Monitoring Unit (CMU). By connecting multiple battery packs in series and parallel, the battery system It is possible to obtain the desired power, voltage, and current as a battery or battery pack. Such battery systems are used, for example, in emergency battery systems for railway vehicles and in UPS (Uninterruptible Power Supplies). It is used for storage battery panels for electrical installations.

[0003] In the case of emergency running battery equipment or UPS battery panels, rapid charging and discharging is performed for several minutes (2 to 5 minutes). In such a battery system, rapid charging and discharging can cause sudden The temperature rises. And the battery system module is placed in a high-temperature environment. The internal deterioration of the battery cell accelerates. There is a need for a cooler (heat sink) that can reduce the temperature rise. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-18863 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem that the present invention aims to solve is the development of a heater that reduces the rapid temperature rise of a battery during charging and discharging. The object is to provide a sink and a storage device. [Means for solving the problem]

[0006] In order to solve the above problem, the heat sink according to this embodiment is provided in contact with a heat generating body. a cooling vessel body, and a metal material contained in the cooling vessel body and impregnated with a phase change material. and a block made of a porous material. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 10 is a perspective view of an electricity storage device in which a heat sink is provided on the bottom surface of a battery pack. [Figure 2] 2 is a cross-sectional view of the lower part of the electricity storage device taken along the dashed line in FIG. 1, viewed from the X direction. [Figure 3] FIG. 2 is a perspective view of a cooling container body according to the first embodiment. [Figure 4] FIG. 4 is a perspective view showing blocks accommodated in the compartments of FIG. 3. [Figure 5] FIG. 5 is a cross-sectional view of FIG. 4 as seen from the direction of arrow A. [Figure 6] FIG. 5 is a plan view of a portion of the section in FIG. 4 as seen from above. [Figure 7] FIG. 10 is a graph showing the relationship between porosity and temperature rise time. [Figure 8] 1 is a cross-sectional view of a heat sink having an inclusion as viewed from the direction of arrow A. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments for carrying out the invention will be described.

[0009] (First embodiment) The heat sink of the first embodiment will be described with reference to Figs. 1 to 5. Fig. 1 shows a battery pack 1 2 is a perspective view of the power storage device in which a heat sink 3 is provided on the bottom surface of the power storage device. 3 is a cross-sectional view of the lower part of the electricity storage device taken along the line and viewed from the X direction. FIG.

[0010] The power storage device of FIG. 1 includes a battery pack 1, a heat sink 3 provided on the bottom surface of the battery pack 1, and a heat sink 4. and a heat dissipation fin 5 provided on the underside of the tank 3.

[0011] The power storage device is mounted on a railway vehicle or the like and is used as a power source to drive an electric motor (not shown). Railway vehicles normally run on power supplied from overhead lines, but if a power outage occurs, the overhead lines may not function properly. When the power supply to the train is cut off, the electric storage device installed on the train can be used as an emergency power source. It is used to travel to the nearest station.

[0012] For this reason, the battery pack 1 installed in the railway vehicle cannot be used for a long time, but it can be used at the nearest It is used to supply power for a short period of time to travel to the station. Therefore, the battery pack 1 for railway vehicles discharges a large current in a short time, and therefore the temperature rises rapidly. In order to reduce this temperature rise, a device for rapidly cooling the heat generated by the battery pack 1 is required. A heat sink 3 is required.

[0013] The battery pack 1 includes a plurality of prismatic cells 2 so as to obtain a desired power. The cell 2 is also called a battery cell, a single cell, or a battery. For example, the cell 2 is a lithium ion battery. A non-aqueous electrolyte secondary battery, which is a flat or A roughly rectangular parallelepiped outer container and a power generating element (not shown) housed in the outer container together with a non-aqueous electrolyte. It is equipped with the basics.

[0014] The power generating element is, for example, a long thin plate serving as an anode and a long thin plate serving as a cathode, which are connected to a non-aqueous electrolysis The cell 2 is wound with the liquid and stored in the outer container of the cell 2. The thermal conductivity varies depending on the direction and in-plane direction, and the ease of heat dissipation varies depending on the direction and in-plane direction. The coil of cell 2 differs in the winding direction, stacking direction, and in-plane direction. Since the wound cell 2 is housed in the outer container, The amount of heat generated by the coil is different for each of the long side, short side, and bottom of the outer container. The battery pack 1 is designed to place the cell outer containers at high density in a limited space rather than focusing on cooling capacity. Since this is a priority, a heat sink 3 is provided on the bottom surface of the battery pack 1.

[0015] Next, the heat sink 3 will be described. As shown in FIG. The cooling container 3 includes a cooling container body 11 and a partition plate that divides the inside of the cooling container body 11 into multiple compartments. 13, a block 15 impregnated with a phase change material (PCM) housed in each compartment, and a cooling volume and a cooling container lid 17 that closes the top of the container body 11.

[0016] The cooling container body 11, the partition plate 13, and the lid 17 of the cooling container are made of metal materials. In this embodiment, aluminum, which has high thermal conductivity, is used as an example. Not limited.

[0017] Block 15 is made of a metal material impregnated with a phase change material (hereinafter simply referred to as PCM). In this embodiment, the metal porous body is made of aluminum. However, copper or the like may also be used, and the type of metal is not limited. The main body 11 is provided with a partition plate 13, which forms a plurality of rectangular compartments, each of which is provided with a block. Lock 15 is housed here.

[0018] A method for impregnating a metal porous block 15 with a phase change material (PCM) For example, this can be done as follows: A PCM such as polyethylene glycol is heated and melted. The fully melted PCM is poured into a container containing block 15. The block 15 is then immersed in the PCM. The block 15 is placed in a heating container together with the container. A heating element such as a heater is provided under the heating container to heat the liquid phase. By reducing the pressure in the heating vessel while maintaining the temperature so that the PCM does not become solid, Air bubbles escape through the tiny pores in Lock 15, allowing the PCM to penetrate into the pores and achieve impregnation.

[0019] The phase change material (PCM) in this embodiment absorbs thermal energy and changes temperature. The PCM is a material that changes phase from solid to liquid when the temperature rises. It changes from solid to liquid due to the absorption of water and the temperature rising. It is a material that absorbs a large amount of heat, which is the latent heat per unit volume, during the conversion process. The sudden heat generated in the battery 1 can be absorbed, thereby reducing the temperature rise of the battery 1.

[0020] As shown in FIG. 2, the cooling vessel body 11 is provided with heat dissipation fins 5 on its lower surface. The heat emitted from the battery pack is transferred to the cooling container body 11 of the heat sink 3 and the various components in the cooling container body 11. The temperature rise of the porous body is transmitted to the block 15 of the porous body. Therefore, heat is absorbed, but the PCM's heat absorption is large, so the temperature rise of the PCM is gradual. Then, as the temperature of the PCM rises, it liquefies, and then the heat released by the battery pack 1 causes As a result, the temperatures of the cooling vessel body 11 and the block 15 made of a porous metal body also rise. Since the container body 11 is made of metal, it has high thermal conductivity, and the temperature rise of the cooling container body 11 is caused by radiation. The heat is transferred to the heat fins 5, and then the heat is released into the outside air from the heat dissipation fins 5 by forced air cooling. do.

[0021] The heat dissipation fins 5 have a plurality of plate-shaped fins on the underside of the cooling container. The fins extend along the longitudinal direction. The fins are arranged at intervals in the lateral direction. The air blown by a fan (not shown) passes between the adjacent fins. It is cooled by flowing longitudinally.

[0022] Next, the configuration of cooling vessel body 11 will be described with reference to FIG.

[0023] The cooling container body 11 has a pair of side walls 21 extending in the short direction of the cooling container, and a cooling container body 1 The base plate 25 is formed in a rectangular shape with a bottom, and includes a pair of side walls 23 extending in the longitudinal direction of the base plate 1. The pair of side walls 21 extending in the lateral direction shown in FIG. Although the width is large, the width may be the same.

[0024] As shown in FIG. 3, a pair of side walls 21 extending in the short direction of the cooling container body 11 and a cooling container A pair of side walls 23 extending in the longitudinal direction of the main body 11 and a bottom plate 25 surrounded by the side walls 23 are provided with a plurality of fittings. The partition plates 13 are formed. The partition plates 13 are continuous in the longitudinal direction, and each of them has a predetermined Three partition plates 13A are provided at intervals, and the partition plates 13A are spaced apart from each other and between the partition plates 13A. A and a side wall 23 extending in the longitudinal direction are provided with a predetermined interval between them, and the partition plate 13A is perpendicular to the partition plate 13A. and a plurality of partition plates 13B formed in the direction of the partition plate 13A. The plate 13B may be formed integrally with the cooling vessel body 11 or may be formed at the bottom of the cooling vessel body 11. The partition plates 13A and 13B may be fixed to the plate 25. As shown, it is formed at a height that contacts the lid 17.

[0025] The partition plate 13A has a length extending from one side wall 21 to the other side wall 21 in the short side direction. The side wall 21 is in contact with the side wall 21 without any gaps.

[0026] As shown enlarged in FIG. 6, the partition plate 13B has a pair of side walls 23 extending in the longitudinal direction, A predetermined gap is provided between the partition plate 13A and the adjacent partition plate 13A. That is, adjacent sections in the longitudinal direction are separated by gaps. As will be described later, the PCM filled in each compartment is The fluid can flow through the section to the adjacent compartment.

[0027] At both ends in the longitudinal direction, a partition plate 13C is formed integrally with the side wall 21 extending in the lateral direction. By forming the partition plate 13C, the partition plate 13C and A gap (recess) 19 is formed between the pair of side walls 23 extending in the longitudinal direction and the partition plate 13A. The cooling vessel body 11 is provided with a partition plate 13A, a partition plate 13B, and a partition plate 13C. The interior of the cooling vessel body 11 is divided into a plurality of rectangular compartments by the above.

[0028] In addition, holes 27 are formed at the four corners of a pair of side walls 21 facing each other in the longitudinal direction of the cooling vessel body 11. The holes 27 are formed so that the bolts 2 are inserted when the heat sink 3 is fixed to the battery pack 1. 9 is the hole into which the bolt is inserted and fastened.

[0029] Next, referring to FIG. 4, it will be explained how the block 15 impregnated with the phase change material functions as a cooling vessel. The following explains how the main body 11 is housed.

[0030] As shown in FIG. 3, the cooling vessel body 11 is made of metal partition plates 13A and 13B. Each of the thus formed sections is divided into a plurality of sections. The blocks 15 are each housed in a container. As shown in FIG. 4, the blocks 15 are arranged in a total of 24 pieces, 4 pieces in the short direction and 6 pieces in the long direction. It is placed there.

[0031] Each block 15 is large enough to fit tightly against the partition plates 13A and 13B that form each section. As shown in FIG. 6, each block 15 may have a partition plate 13A and a It may be of a size that does not contact the partition plate 13B. It may be of a size that does not contact the partition plates 13A and 13B. When the formed blocks 15 are accommodated, each block 15 is placed in a predetermined position as shown in the figure. Each block 15 is accommodated along the positioning guide. The reason why the size is set so that it does not come into contact with the partition plates 13A and 13B is that the PCM is liquefied by heat. When the block 15 expands, the PCM bulges out from the tiny holes in the block 15 and comes out of the block 15. When the liquid enters the block 15, the partition plates 13A and 13B do not prevent the liquid from flowing out of the block 15. This is to ensure that

[0032] Furthermore, after the blocks 15 are accommodated in each compartment, the PCM is liquefied by applying heat and then poured into the cooling vessel body. After the liquefied PCM is filled into each compartment of the cooling vessel body 11, The cooling container body 11 and the lid 17 are closed to prevent the PCM from leaking. The joining method of 17 is, for example, joining with adhesive or using a flexible sealing material on the part that will be the glue. The cooling vessel body 11 and the lid 17 are fastened with bolts to crush the gasket. There are two methods for joining: using a double-sided tape or joining by taping.

[0033] The compartments of the cooling container body 11 are aligned because there is a gap between the partition plates 13A and 13B. The PCM flows into the adjacent compartment through the connecting part. It has a movable configuration.

[0034] Furthermore, by providing a gap 20 between the partition plates 13A and 13B, the liquid PCM When filling the cooling container body 11 with PCM, there is a variation in the amount and liquid level of the PCM filled in each compartment. It is difficult to do this.

[0035] Next, a cross-sectional view of FIG. 5, which is viewed from the direction of arrow A in FIG. 4, will be described. As shown, when PCM is cooled (below its melting point), it is in a solid state and its volume is In this state, the volume of the PCM in the cooling vessel body 11 is small, so P The top surface of the CM does not reach the lid 17, and a gap is formed between the PCM and the lid 17. As shown in FIG. 5(b), when the cooling container body 11 is heated by the battery pack 1 (when the battery pack 1 When the PCM absorbs heat from the material, its temperature rises and it changes into a liquid, expanding and increasing in volume. When the PCM changes from solid to liquid, its volume increases, and the liquid surface The height will rise. Therefore, it is necessary to take into consideration the change in the liquid level and fill it completely. As shown in FIG. 5(a), a small gap is formed between the top surface of the PCM and the lid 17. Fill as shown.

[0036] As shown in FIG. 6, when heat from the battery pack 1 is applied to the cooling container body 11, the PCM utilizes the latent heat. When the material absorbs heat and turns into a liquid, the impregnated PCM flows out of the porous material. When the discharge of battery pack 1 is completed and battery pack 1 cools down again, the warmed and liquefied PCM cools down. When the mixture is cooled and changes to a solid phase, it liquefies again because the PCM is filled in the compartment. The PCM returns to the hole in block 15.

[0037] In addition, a gap 20 is provided between the partition plates 13A and 13B, so that the assembled power When the PCM absorbs heat from Pond 1 and liquefies, it flows between the adjacent compartments. The temperature near the center of the cooling container body 11 is higher than the surrounding area, so the PCM liquefies quickly. The flow from the compartments near the center to the surrounding compartments. When the gap 20 is provided, the molten and liquefied PCM is released from the block 15. This allows the water to flow out into the gaps within the compartment.

[0038] In this embodiment, after a predetermined time has elapsed since the start of rapid discharging or rapid charging of the battery pack 1, The porosity at which the PCM impregnated in block 15 begins to undergo a phase change (from solid to liquid). It is formed.

[0039] Figure 7 shows the relationship between porosity and temperature rise time. The ratio of voids to the volume of the rock (the ratio of continuous voids in a porous body produced by compressing metal powder) The block 15 made of porous metal contains PCM. The more pores there are, the more PCM there is in the pores. Therefore, the PCM absorbs the latent heat, slowing down the temperature rise.

[0040] Curve (1) in Figure 7 shows the heating element (battery assembly 1) when the porosity is low and the amount of PCM impregnation is small. In this example, a block 15 impregnated with PCM was heated. In this case, the metal was more likely to stick than the PCM. Since the temperature is dominant, the high thermal conductivity of the metal becomes dominant, and the plateau temperature that represents the phase change time of the PCM is The curve (latent heat) time is short, and the temperature rise also tends to occur in a short period of time.

[0041] On the other hand, curve (2) shows that when the porosity is high and the amount of PCM impregnation is large, the heating element (battery assembly 1) In this example, the PCM impregnated block 15 is heated. Since the temperature rise time of block 15 is slower than that of curve (1), Even if heated, it takes time for the temperature to rise, and the time it takes for the phase change to begin is also delayed.

[0042] Since the porosity and the time to start the phase change are directly proportional, the porosity that corresponds to the time to start the phase change is The block 15 is manufactured at a different porosity by changing the porosity through an impregnation structure using a porous material. By adjusting the thermal conductivity, it is possible to speed up or slow down the phase change start time. By starting the start time within the discharge time, it is possible to reduce the rise in battery cell temperature.

[0043] Next, an example of a phase change material will be described.

[0044] Phase change materials are in a solid state at room temperature, for example, around 25°C, and can change from a solid to a Non-flammable materials with a melting point of 45℃ to 65℃ that causes a phase change to liquid are used. The changeable material has, for example, a thermal conductivity of about 0.2 [W / mK] to about 0.4 [W / mK]. In this embodiment, for example, polyethylene glycol (PEG) is used as the phase change material. More specifically, the phase change material is, for example, polyethylene glycol having a melting point of about 60°C. The phase change material is not limited to polyethylene glycol, and may be paraffin. A stencil or the like may also be used.

[0045] In the case of a block made of porous aluminum, the thermal conductivity depends on the porosity, but is approximately It is around 8 to 60 [W / mK].

[0046] The aluminum block 15 is impregnated with a phase change material that has low thermal conductivity but high heat capacity. By doing so, the equivalent thermal conductivity of the block 15 is almost maintained while the PCM melts (melts). ), shortening the time until the phase change.

[0047] Therefore, the heat sink 3 of this embodiment can be used in emergency battery devices for railways, UPS (Uninterruptible Power Supply) By using it in a battery panel for a power supply unit, it can reduce the sudden temperature rise of the battery during charging and discharging. can be done.

[0048] In addition, by arranging the heat sink 3 on the bottom side of the battery pack 1, which becomes hot, When 1 generates heat due to charging and discharging, the thermal resistance corresponding to the amount of heat dissipated through the bottom surface is low. The PCM absorbs heat using latent heat, temporarily reducing the sudden temperature rise of battery pack 1. It is possible.

[0049] (Second embodiment) Next, a second embodiment will be described with reference to FIG. 5. The same parts as those of the heat sink 3 of the first embodiment in FIG. 5 are denoted by the same reference numerals and will be explained below. The second embodiment differs from the first embodiment in that the cooling vessel body 11 The difference is that an interposition member 31 is provided between the inner bottom plate 25 and the block 15.

[0050] As shown in FIG. 8, the bottom plate (bottom surface) 25 of each compartment provided inside the cooling vessel body 11 is The rectangular inclusions 31 are provided on both end sides of each section. The block 15 is provided on the inclusion 31. When the block 15 is accommodated on the inclusion 31, In this case, a positioning guide (not shown) is provided to place each block 15 at a predetermined position. The block 15 is accommodated along the positioning guide.

[0051] By providing the inclusions 31 on the bottom plate 25 of the cooling vessel body 11, the PCM is poured into each compartment. When the block 15 is pressed, the PCM liquid flows around the block 15, including between the block 15 and the bottom plate 25. This not only makes it easier to keep the liquid level even, but also prevents the PCM from liquefying and breaking down. After swelling from block 15, the PCM forms in block 15 when the temperature of the PCM drops. This makes it easier for the particles to re-enter the holes that have been created.

[0052] In addition, when the PCM is liquefied by heat, it tends to bulge out below the block 15. In addition, the PCM around block 15 becomes more likely to flow.

[0053] Although several embodiments of the present invention have been described, these embodiments are presented by way of example only. These novel embodiments are not intended to limit the scope of the invention. It is possible to implement the invention in various other forms, and various modifications are possible without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention. It is included in the summary and in the scope of the invention described in the claims and their equivalents. . [Explanation of symbols]

[0054] 1. Battery pack 2...Cell 3...Heat sink 5...Heat dissipation fin 11...Cooling container body 13...Partition board 13A...Divider plate extending in the longitudinal direction 13B...Divider plate extending in the short direction 13C...Partition plate (protruding part) formed integrally with the end face 15...block 17...Cooling container lid 19...Gap (recess) 21...A pair of side walls extending in the short direction 23...A pair of side walls extending in the longitudinal direction 25...Bottom plate of cooling container (bottom surface) 27...Cooling vessel hole 29...Bolt 31...Inclusions

Claims

1. a cooling container body provided in contact with a heat generating body; A multi-layer cooling vessel is housed inside the cooling vessel body and is made of a metal material impregnated with a phase change material. a block made of a porous body; A heat sink equipped with

2. The cooling vessel body is internally divided into a plurality of rectangular compartments, and the block Each of the divided compartments is housed in its own compartment. The heat sink of claim 1 .

3. A gap is formed between the bottom surface of the compartment inside the cooling vessel body and the block. Inclusions are provided for this purpose. The heat sink of claim 2 .

4. A phase change material is filled around the block in the compartment of the cooling vessel body. The heat sink according to claim 2 or 3.

5. The compartments of the cooling vessel body are partially in communication with adjacent compartments, and the cooling vessel body is filled with The phase change material is configured to be able to flow into adjacent compartments through the communicating portions. The heat sink of claim 4.

6. The cooling container further includes a lid that closes the top of the cooling container body, and the cooling container body and the cooling container The lid of the main body is made of metal material. The heat sink of claim 1.

7. The block, after a predetermined time from the start of rapid discharge or rapid charge of the heating element, The block is impregnated with a phase change material, which is formed with porosity that initiates a phase change from solid to liquid. There are, The heat sink of claim 1 .

8. The heat sink is provided in contact with the surface of the heat generating element that becomes the hottest. The heat sink of claim 1 .

9. A battery pack; a cooling container body provided in contact with the battery pack; and a cooling device housed inside the cooling container body. a porous block made of a metal material impregnated with a phase change material; and A power storage device having the above structure.

10. The block, after a predetermined time from the start of rapid discharging or rapid charging of the battery pack, the block is impregnated with a phase change material and is formed with a porosity that initiates a phase change; The power storage device according to claim 9.

Images