JP2005353536A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small battery pack excellent in heat dissipation and also high in stiffness and excellent in vibration resistance. <P>SOLUTION: The battery pack configured by adhering to laminate a plurality of flames with a plurality of flat unit cells held in planarity thereon in thickness directions of the flames has a cooling means to cool only specified flat unit cells disposed at positions at which the temperature of the cells become higher in temperature than those of other flat unit cells among the flat unit cells consisting of the battery pack. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an assembled battery with good heat dissipation efficiency.

  In recent years, in response to growing environmental problems, there is a movement to shift the power source of automobiles from an engine using fossil fuel to a motor using electric energy. At present, as an intermediate stage, hybrid vehicles are actively produced which are equipped with both an engine and a motor, and use a motor in a low speed region and an engine as a power source in other regions.

  A hybrid vehicle is required to be equipped with a battery that is small and light and can be charged and discharged with large electric power frequently and has excellent vibration resistance and heat dissipation. As an assembled battery excellent in heat dissipation capable of supplying large electric power, there is a battery as shown in Patent Document 1 below.

  The assembled battery disclosed in Patent Document 1 is arranged with a plurality of flat unit cells electrically connected in series, parallel, or series-parallel at predetermined intervals with a gap in the thickness direction of the unit cell. The plurality of arranged single cells are fixed by an exterior member. With such a structure, gaps are formed between the single cells, so that the heat dissipation characteristics of the single cells are improved and the cycle characteristics and rate characteristics of the assembled battery are improved.

Moreover, since the assembled battery disclosed in the cited document 1 uses a flat battery as a single battery, it is configured using a battery other than the flat battery (for example, a battery of a cylindrical shape, a rectangular shape, etc.). If the battery has the same energy capacity and a higher energy density than the conventional assembled battery, the battery is considerably downsized. For this reason, it can be said that the assembled battery comprised by the flat type cell is suitable as a battery for motor vehicles from the point of a small size and a high energy density compared with the conventional assembled battery.
JP 2000-195480 A

  However, since such a conventional assembled battery has to have a gap between the single cells in consideration of improvement in heat dissipation characteristics, it is difficult to further reduce the size and increase the energy density. In addition, due to the gap, it is difficult to ensure rigidity as an assembled battery, and there is a limit to improvement in vibration resistance.

  In order to solve the above problems, a configuration is conceivable in which flat batteries are stacked in close contact with each other in the thickness direction, and a heat sink is inserted for each arbitrary layer. However, in such a structure, indirect heat dissipation via the heat sink, naturally, uniform heat dissipation is not performed, and the three-dimensional temperature distribution of the assembled battery as a whole becomes considerably unbalanced. . In the case of a flat battery, excessive temperature distribution imbalance causes a reduction in battery life.

  The present invention has been made to solve the conventional problems as described above, and provides a battery pack that is compact and has excellent heat dissipation, high energy density, high rigidity, and excellent vibration resistance. With the goal.

  An assembled battery according to the present invention for achieving the above object is configured by laminating a plurality of frames each holding a plurality of flat unit cells in a plane in close contact with each other in the thickness direction of the frame. An assembled battery, wherein the assembled battery includes only a specific flat unit cell arranged at a position where the temperature is higher than other flat unit cells among the flat unit cells constituting the assembled battery. A cooling means for cooling is provided.

  Therefore, a specific flat battery in a position that is difficult to be cooled among the flat single cells constituting the assembled battery is efficiently cooled by the cooling means. For this reason, the cooling efficiency as the whole assembled battery improves, and the assembled battery with a large energy density which was small and excellent in heat dissipation can be provided.

  In addition, since the assembled battery according to the present invention is laminated in a state where the frames are in close contact with each other, the assembled battery including a flat unit cell has a solid structure, and is a highly rigid and excellent vibration resistant assembly. It becomes a battery.

  According to the assembled battery according to the present invention configured as described above, the cooling means for cooling only the specific flat cell disposed at a position where the temperature is higher than that of the other flat cell. Since it is provided, it is possible to efficiently cool a specific flat battery at a position that is difficult to be cooled, to make the temperature distribution as a whole battery uniform, and to form a battery pack with a high energy density. .

  Further, since the frames are stacked in close contact with each other, an assembled battery having a small size, high rigidity, and excellent vibration resistance can be configured.

  Hereinafter, the assembled battery according to the present invention will be described in detail according to the form of the cooling means, divided into [Embodiment 1] to [Embodiment 3].

  The structure of the assembled battery assumed in each embodiment is that four flat unit cells (hereinafter simply referred to as unit cells) are arranged in the width direction in one frame, and six frames are provided. An intermediate heat sink is stacked each time the stacks are stacked, and a total of 24 frames are stacked to form a battery unit. The battery units are pressed from both end surfaces in the stacking direction by heat sinks and are held together.

The assembled battery unit has 96 single cells, but all the single cells are connected in series by connecting means provided on a frame or a heat sink.
[Embodiment 1]
FIG. 1 is a perspective view showing an external appearance of an assembled battery according to the present invention, and FIG. 2 is an external view of a cooling device for cooling the assembled battery shown in FIG.

  As shown in FIG. 1, the assembled battery 100 according to the present invention includes a battery unit 200 in which a plurality of plate-shaped frames 210 are stacked in the thickness direction, sandwiched by heat sinks 300 and 340 from both ends in the stacking direction. It is pressed and held integrally.

  Each frame 210 has four holding portions (not shown) for arranging four unit cells in parallel. In the battery unit 200, 24 frames 210 are stacked, and three intermediate heat sinks 310, 320, and 330 are inserted every six stacking directions. Accordingly, in the battery unit 200, four unit cells arranged in parallel between the heat sinks are respectively stacked by 24 units, and a total of 96 unit cells are provided.

  Among the six frames 210 laminated between the heat sinks, a refrigerant inlet 230 for introducing air as a refrigerant into the battery unit 200 is provided on one side surface of the two frames 210 positioned in the middle. In addition, a refrigerant discharge port 250 for discharging air circulated in the battery unit 200 is formed on the other side surface. The refrigerant inlet 230 and the refrigerant outlet 250 are provided one by one on the opposite side surfaces of the frame 210. Since the battery unit 200 has 24 frames 210 laminated, the battery unit 200 has eight refrigerant inlets 230 and eight refrigerant outlets 250. The refrigerant introduction port 230 and the refrigerant discharge port 250 are formed at a place where there is a unit cell that has a higher temperature than other unit cells among the unit cells constituting the battery unit 200. In the battery unit 200, there is formed a refrigerant passage (not shown) for allowing air introduced from the refrigerant introduction port 230 to flow through the gap between the frame 210 and each unit cell and to be discharged from the refrigerant discharge port 250. .

  The heat sinks 300 and 340 are fixed by attaching six pressure units connecting the heat sinks with nuts 400A to 400F. The pressurizing unit has shafts fixed by nuts 400A to 400F attached to both ends of a tension coil spring. By attaching this between the heat sinks 300 and 340, all the single cells constituting the battery unit 200 are attached. On the other hand, an appropriate surface pressure is given in the stacking direction.

  The heat sinks 300 and 340 and the intermediate heat sinks 310, 320, and 330 are provided with a plurality of refrigerant circulation ports 300A, 340A, 310A, 320A, and 330A penetrating from one side surface to the other side surface.

  When the assembled battery 100 is mounted on a vehicle, it is cooled by a cooling device 500 as shown in FIG. 2 provided in the vehicle. FIG. 2 is an external view of a cooling device for cooling the assembled battery shown in FIG.

  The cooling device 500 includes an outer case 600 that houses the assembled battery 100, a refrigerant introduction duct 700 that introduces air into the outer case 600, and a refrigerant discharge duct 800 that discharges air introduced into the outer case 600.

  In the outer case 600, the refrigerant introduction port 230 and the refrigerant discharge port 250 of the battery pack 100 are on the leeward side, and the opening surfaces of the refrigerant introduction port 230 and the refrigerant discharge port 250 are parallel to the wind flow. Thus, the assembled battery 100 is arranged. Specifically, the assembled battery 100 is arranged so that the left side in FIG. 1 faces the refrigerant introduction duct 700 and the right side in FIG. 1 of the assembled battery 100 faces the refrigerant discharge duct 800 side. A single or a plurality of assembled batteries 100 are arranged in the outer case 600.

  An exhaust fan 850 is attached to the exterior case 600 side of the refrigerant discharge duct 800. The exhaust fan 850 includes a sensor that detects the temperature of air exhausted from the exterior case 600, and the rotational speed (exhaust amount) of the exhaust fan 850 is adjusted by a control device (not shown) according to the temperature detected by the sensor. Is done.

  Therefore, in the assembled battery 100 arranged in the exterior case 600, the air that has entered from the refrigerant introduction port 230 is discharged from the refrigerant discharge port 250 through the refrigerant passage in the assembled battery 100, so that the temperature is likely to rise. The specific cells that are in position, in other words, far from the heat sinks 300, 340 and the intermediate heat sinks 310, 320, 330, are difficult to cool and are directly cooled by air, and the heat sinks 300, 340 and intermediate Since air is flowing into the refrigerant circulation ports 300A, 340A, 310A, 320A, and 330A of the heat sinks 310, 320, and 330, the other single cells are indirectly cooled by these heat sinks.

  FIGS. 3 and 4 illustrate a normal frame configuration without a refrigerant inlet and a refrigerant outlet, and FIG. 5 illustrates a frame configuration with a refrigerant inlet, a refrigerant outlet, and a refrigerant passage. FIG.

  Of the six frames 210 (see FIG. 1) stacked between the heat sinks, the four frames 210 positioned on both ends in the stacking direction are rectangular outer frame 212 and outer frame as shown in FIG. It is comprised from three support | pillars 214A, 214B, and 214C spanned on two opposite sides of 212 in the shape of a ladder.

  The unit cells 220A, 220B, 220C, and 220D are lithium ion batteries in which the power generation element is covered with a laminate film, and have a trapezoidal shape in which a portion of the power generation element protrudes as shown in the figure. As shown in FIG. 4, each of the single cells 220 </ b> A, 220 </ b> B, 220 </ b> C, 220 </ b> D has a trapezoidal shape from below in a space formed between the outer frame 212 of the frame 210 and each support column 214 </ b> A, 214 </ b> B, 214 </ b> C. It is arranged so as to be inserted. Accordingly, the single cells 220A, 220B, 220C, and 220D are held in a plane by the outer frame 212 of the frame 210 and the individual support columns 214A, 214B, and 214C.

  Note that the thickness of the frame 210 is slightly larger than the thickness of the unit cell 214. This is because when the assembled battery 100 is formed, all the unit cells 214 are pressurized with a predetermined surface pressure, and all the frames 210 are compressed with some deformation.

  Of the six frames 210 laminated between the heat sinks, the two frames 210 located in the middle of the lamination direction are similar to the other frames 210, as shown in FIG. It is composed of three struts 214A, 214B, and 214C that are stretched over two opposite sides of the frame 212 in a ladder shape. As a notch for introducing air into the battery unit 200, one side surface of the outer frame 212 where the unit cell 220A located on the leeward side when the assembled battery 100 is formed is disposed. A refrigerant inlet 230 is formed, and a refrigerant outlet 250 as a notch for discharging the circulated air is formed on the other side surface. In the present embodiment, the refrigerant inlet 230 and the refrigerant outlet 250 are formed one by one, and the shape thereof is an inverted triangle, but the number and shape are not limited thereto. Each cell 220A, 220B, 220C, 220D has a trapezoidal shape from the bottom in the space formed between the outer frame 212 of the frame 210 and the columns 214A, 214B, 214C, like the other frames 210. It is arranged so as to be inserted. Therefore, the refrigerant passage is formed by the space of the outer frame 212 of the frame 210, the support column 214A, and the unit cell 220A. The air that has entered through the refrigerant inlet 230 flows into the refrigerant passage, directly contacts the surface of the unit cell 220A, and is discharged from the refrigerant outlet 250. Therefore, heat can be efficiently radiated from the peripheral portion 222A of the unit cell 220A. it can.

  As shown in FIG. 6, the frame 210 holding the single cells 220A, 220B, 220C, and 220D as described above is arranged in the middle in the stacking direction with the frame 210 in which the refrigerant inlet 230 and the refrigerant outlet 250 are formed. Laminate 6 sheets from the bottom so as to be positioned. When stacked, the cells and the frames are in direct contact with each other in the stacking direction, and a gap between the frame 210 and the cells 220 between the refrigerant inlet 230 and the refrigerant outlet 250 is provided in the frame 210 positioned in the middle. Thus, a refrigerant passage is formed.

  As shown in FIGS. 7 and 1, the laminate (single cell laminate) is laminated with the intermediate heat sinks 310, 320, 330 interposed therebetween, and the heat sinks 300 and 340 are sandwiched from both sides of the laminate. The assembled battery 100 is formed by being positioned and firmly fixed with the nuts 400A to 400F. When the cooling device 500 of FIG.

  FIG. 8 is a plan view of the frame 210 in which the refrigerant inlet 230 and the refrigerant outlet 250 are formed, and FIG. 9 is a side view of a portion of the frame 210 shown in FIG.

  Since the frames 210 are in close contact with each other in the stacking direction, air enters the refrigerant introduction port 230 shown in FIGS. 7 to 9 in the frame 210 in which the refrigerant introduction port 230 and the refrigerant discharge port 250 are formed. The entered air is discharged from the refrigerant outlet 250 through the refrigerant path formed by the gap between the unit cell 220A and the frame 210. Therefore, the unit cell 220A is directly cooled by the air flowing on the side surface and the surface of the peripheral portion 222A.

  Further, as shown in FIGS. 8 and 9, the refrigerant introduction port 230 is formed on the upstream side having a higher atmospheric pressure than the refrigerant discharge port 250, so that air flows from the refrigerant introduction port 230 toward the refrigerant discharge port 250. Will flow. Therefore, it becomes possible to cool the unit cell 220A existing at a position where the temperature is increased only by indirect cooling with the heat sink, and the three-dimensional temperature distribution of the assembled battery 100 as a whole can be made uniform. .

In the present embodiment, air is described as an example of the refrigerant. However, the present invention is not limited to this, and an inert gas such as nitrogen or a liquid such as oil can be used according to the required cooling capacity.
[Embodiment 2]
In the first embodiment, the refrigerant inlet, the refrigerant outlet, and the refrigerant passage are provided as the cooling means, and the unit cell is directly cooled with air. However, in the present embodiment, the first embodiment is described. In addition to the above structure, a cooling fin is attached to a specific unit cell, the cooling fin is projected from the outside of the frame, and the unit cell can be indirectly cooled by the cooling fin.

  FIG. 10 is a perspective view showing the cell stack in a state where the cooling fins are attached, and FIG. 11 is a side view of the cell stack shown in FIG.

  Of the six frames 210 laminated between the heat sinks, the four frames 210 positioned at both ends in the lamination direction have the same configuration as that shown in FIG. The two frames 210 positioned at the same position as those shown in FIG. As shown in FIGS. 10 and 11, the cooling fins 260 </ b> A are provided so as to protrude from the refrigerant introduction port 230, and the cooling fins 260 </ b> B are provided so as to protrude from the refrigerant discharge port 250.

  As shown in FIGS. 12 and 13, the cooling fins 260 </ b> A and 260 </ b> B are attached to the inclined portions 225 </ b> A and 225 </ b> B on both sides in the longitudinal direction of the unit cell 220 </ b> A so that one end protrudes from the refrigerant inlet 230 and the refrigerant outlet 250. It is done. The cooling fins 260A and 260B are attached after the unit cell 220A is attached to the frame 210. The attachment is preferably performed with an adhesive having good thermal conductivity. When the frames 210 are stacked as shown in FIG. 10, the cooling fins 260 </ b> A and 260 </ b> B are firmly fixed with their upper and lower ends sandwiched between the outer frames 212 of the frame 210.

  In order to allow the cooling fins 260A and 260B to be attached before the unit cell 220A is attached to the frame 210, the shape of the refrigerant inlet 230 and the refrigerant outlet 250 is changed from the inverted triangular shape of FIG. It is necessary to change to a square shape.

Thus, when the cooling fins 260A and 260B are attached to the unit cell 220A, the unit cell 220A is indirectly cooled by the air flowing along the longitudinal direction of the frame 210. Therefore, the cooling efficiency is improved in the configuration of the present embodiment than in the configuration of the first embodiment.
[Embodiment 3]
In the present embodiment, a cooling passage is formed in the cooling fin shown in the second embodiment so that the cooling fin itself can be cooled to improve the cooling efficiency of the unit cell.

  14 is a perspective view showing the unit cell stack in a state where the cooling fins having the refrigerant passages are attached, and FIG. 15 is a side view of the unit cell stack shown in FIG.

  Of the six frames 210 laminated between the heat sinks, the four frames 210 positioned on both ends in the lamination direction have the same configuration as that shown in FIG. The two frames 210 positioned at the same position as those shown in FIG. As shown in FIGS. 14 and 15, the cooling fin 265 </ b> A is provided so as to protrude from the refrigerant introduction port 230, and the cooling fin 265 </ b> B is provided so as to protrude from the refrigerant discharge port 250.

  As shown in FIG. 16, the cooling fins 265 </ b> A and 265 </ b> B are attached to the inclined portions 225 </ b> A and 225 </ b> B on both sides in the longitudinal direction of the unit cell 220 </ b> A so that one end protrudes from the refrigerant inlet 230 and the refrigerant outlet 250. The cooling fins 265A and 265B have a triangular cross-sectional shape as shown in FIG. 17, and refrigerant passages 270A and 270B for circulating air are formed therein. Of course, the shapes of the cooling fins 265A and 265B are not limited to the triangle as described above, and the shapes of the refrigerant passages 270A and 270B are not limited to the triangle as described above. The cooling fins 265A and 265B are attached after the unit cell 220A is attached to the frame 210. The attachment is preferably performed with an adhesive having good thermal conductivity. In the state where the frames 210 are stacked as shown in FIG. 14, the cooling fins 265 </ b> A and 265 </ b> B are firmly fixed with their upper and lower ends sandwiched between the outer frames 212 of the frame 210.

  As described above, when the cooling fins 265A and 265B are attached to the unit cell 220A, the unit cell 220A is indirectly cooled by the air flowing along the longitudinal direction of the frame 210 in the outer case 600 of the cooling device 500. It becomes like this. Further, the cooling fins 265A and 265B themselves are also cooled by the air flowing through them. Therefore, the cooling efficiency is improved in the configuration of the present embodiment than in the configuration of the second embodiment.

  The configuration from the first embodiment to the third embodiment has been described above. Next, a result of verifying how much the configuration of each embodiment has on cooling of the unit cell 220A will be described.

  FIG. 18 is a diagram visualizing the temperature distribution between the heat sinks in a conventional battery pack in which the frame 210 is not provided with a cooling means. As shown in the figure, in the case of the conventional assembled battery, it can be seen that the temperature is highest in the vicinity of the position B (portion indicated by black) located on the leeward side of the cooling air. FIG. 19 is a graph showing an average temperature distribution from the A position to the B position of the assembled battery shown in FIG.

  As shown in FIG. 19, the conventional battery pack has a temperature difference between the A position and the B position of about 20 ° C., and the temperature at the B position is as high as 50 ° C., as shown by the solid curve. However, the assembled battery having the structure shown in the first embodiment has a temperature at the B position lower by about 5 ° C. than the conventional assembled battery. Further, in the assembled battery having the structure shown in the second embodiment, the temperature at the B position is lower by about 9 ° C. than the conventional assembled battery. Furthermore, the battery at the position B is lower by about 12 ° C. in the assembled battery having the structure shown in the third embodiment than in the conventional assembled battery.

  As is apparent from this result, by applying the present invention, the three-dimensional temperature distribution of the assembled battery as a whole can be made uniform to some extent, and the assembled battery is formed at a position that is particularly difficult to cool. The battery life of the existing unit cell can be improved.

  An assembled battery with good heat dissipation efficiency can be provided by the action of the cooling means, and can be applied in the field of power batteries such as automobiles.

It is a perspective view which shows the external appearance of the assembled battery concerning this invention. It is an external view of the cooling device which cools the assembled battery shown in FIG. 6 is a diagram for explaining a configuration of a frame in Embodiment 1. FIG. 6 is a diagram for explaining a configuration of a frame in Embodiment 1. FIG. 6 is a diagram for explaining a configuration of a frame in Embodiment 1. FIG. 6 is a diagram for explaining a configuration of a frame in Embodiment 1. FIG. FIG. 3 is a schematic configuration diagram of a laminated body of frames in the first embodiment. 2 is a plan view of a frame in Embodiment 1. FIG. FIG. 9 is a front view of a part of the frame shown in FIG. 8. It is a perspective view which shows the single cell laminated body of the state in which the cooling fin in Embodiment 2 was attached. It is a side view of the cell stack shown in FIG. FIG. 10 is a diagram for explaining an attachment state of cooling fins in the second embodiment. It is a figure for demonstrating the attachment state of a cooling fin. It is a perspective view which shows the single cell laminated body of the state in which the cooling fin in Embodiment 3 was attached. FIG. 15 is a side view of the unit cell stack shown in FIG. 14. FIG. 10 is a diagram for explaining an attachment state of cooling fins in the second embodiment. FIG. 10 is a diagram showing a structure of a cooling fin in a second embodiment. It is the figure which visualized the temperature distribution between heat sinks in the conventional assembled battery. 19 is a graph showing an average temperature distribution from position A to position B of the assembled battery shown in FIG.

Explanation of symbols

100 battery packs,
200 battery unit,
210 frames,
212 outer frame,
214A to 214C struts,
220A-220D cell,
222A peripheral edge,
230 refrigerant inlet,
250 refrigerant outlet,
260A, 260B cooling fins,
265A, 265B cooling fins,
270A, 270B refrigerant passage,
300, 340 heat sink,
310, 320, 330 Intermediate heat sink,
400A-400F nut,
500 cooling device,
600 exterior case,
700 refrigerant introduction duct,
800 refrigerant discharge duct,
850 Exhaust fan.

Claims (8)

An assembled battery configured by laminating a plurality of flat cells that are held in a plane in close contact with each other in the thickness direction of the frame,
The assembled battery includes a cooling unit for cooling only a specific flat unit cell arranged at a position where the temperature is higher than other flat unit cells among the flat unit cells constituting the assembled battery. A battery pack characterized by that.   The cooling means includes a refrigerant inlet and a refrigerant outlet opened in the frame, a refrigerant passage for communicating the refrigerant inlet and the refrigerant outlet, and a refrigerant supplied to the refrigerant passage. The assembled battery according to claim 1.   The set according to claim 2, wherein the refrigerant enters the refrigerant passage from the refrigerant introduction port, directly contacts the surface of the specific flat unit cell, and is discharged from the refrigerant discharge port. battery.   2. The assembled battery according to claim 1, wherein the cooling unit is a cooling fin that is directly attached to the specific flat unit cell and protrudes to the outside of the frame.   The assembled battery according to claim 4, wherein the cooling fin is formed with a refrigerant passage through which a refrigerant flows.   In the assembled battery, heat sinks for cooling the flat unit cells are provided at both ends in the stacking direction of the frames, or interposed between the frames every time a certain number of the frames are stacked. The assembled battery according to claim 1, wherein:   The frame has an outer frame and a plurality of ladder-shaped support columns, each flat unit cell is held by the outer frame and the individual support columns, and the refrigerant inlet is on one side surface of the outer frame of the frame. By providing a cutout portion, the refrigerant discharge port is formed by providing a cutout portion on the other side surface of the frame, and the refrigerant passage is formed by a gap between the outer frame of the frame and the support column and the flat unit cell, respectively. The assembled battery according to claim 2, wherein:   The assembled battery according to claim 1, wherein the flat unit cell is a lithium ion battery covered with a laminate film.