JP2005071674A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack with a simple structure and provide the battery pack having high cooling efficiency. <P>SOLUTION: This battery pack has a plurality of unit cells and a plurality of bus bars to electrically connect each unit cell. (1) Each bus bar has a cooling fin which also works as a cooling member to each unit cell. In other words, by giving the bus bar, which is an essential constituent element, a function as the cooling member, the number of the constituent elements is reduced. Then, it has an advantage that a new cost for improving heat transfer is not required. (2) Each cooling fin is arranged along the flowing direction of a cooling medium, and each fin is arranged by shifting between adjoining each cooling member so that they do not completely overlap with the flowing direction of the cooling medium. That is to say, since the cooling fin is arranged along the flowing direction of the cooling medium, it does not obstruct the flow of the cooling medium. Then, by shifting the cooling fin between the adjoining cooling members, a turbulent flow is generated in the cooling medium and cooling capability can be demonstrated to the maximum extent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an assembled battery having a feature in cooling means, and more particularly to an assembled battery having a secondary battery that allows a large current to flow in a unit battery.

  In recent years, electric vehicles such as electric vehicles and hybrid vehicles have been actively developed. As a power source for driving this electric vehicle, there is an increasing demand for a secondary battery excellent in performance, reliability, and safety.

  In these electric vehicles, the driving power source is required to have a high power density. In order to obtain a high power density, an assembled battery in which a plurality of unit batteries are connected in series and / or in parallel is used as the driving power source.

  By the way, when an assembled battery is applied to an electric vehicle, a large current flows through the assembled battery and heat is generated in the power generation element. Due to this heat generation, the power generation element of each unit battery is overheated and damaged, and the battery performance is lowered. For this reason, the assembled battery needs to have a heat dissipation measure for the purpose of preventing the livestock heat of the battery against heat generated by a large current.

  As a conventional battery pack cooling means, there is disclosed a method of cooling a battery by restraining it in a state where a passage through which a refrigerant can pass is provided between each of a plurality of batteries constituting the battery pack, and passing the refrigerant between them. (Patent Document 1). Further, a means is disclosed in which a heat transfer plate is embedded in the battery case of each battery constituting the assembled battery, a part of the heat transfer plate is protruded, and the portion is cooled by an appropriate cooling means. (Patent Document 2).

  However, in the assembled battery described in Patent Document 1, it is necessary to provide a gap through which the refrigerant is passed in a state where the refrigerant passage is provided between the unit batteries, and the volume energy density of the assembled battery is reduced. And since the assembled battery of patent document 2 transfers heat through a battery case, there exists a possibility that cooling efficiency may not be enough.

Therefore, Patent Document 3 discloses an assembled battery in which a cooling member is joined to a terminal member included in a unit battery to improve cooling efficiency.
JP 2003-7355 A JP 2003-36819 A JP 2002-56904 A

  However, the assembled battery of Patent Document 3 has a problem that the structure is complicated and the cost increases. Further, further improvement in cooling efficiency is required from the viewpoint of performance improvement required for the assembled battery.

  Accordingly, in view of the above circumstances, the present invention has a first problem to be solved to provide an assembled battery with a simple configuration. In addition, providing a battery pack with high cooling efficiency is a second problem to be solved.

(1) An assembled battery of the present invention that solves the first problem includes an electrode body that is a power generation element, a plurality of unit batteries each having a terminal member that transmits and receives power to the electrode body, and the unit batteries. A plurality of bus bars for electrically connecting the terminal members;
Each bus bar has a cooling fin, and also serves as a cooling member for cooling each unit battery.

  That is, the constituent elements are reduced by providing a function as a cooling member to the bus bar which is an essential constituent element in configuring the assembled battery. In addition, since the bus bar is a member through which a large current flows, sufficient electrical connection is made with the terminal member and the heat transfer is considered to be good, so that a new cost is required to improve the heat transfer. There is no advantage.

(2) Moreover, the assembled battery of the present invention that solves the second problem includes an electrode body that is a power generation element, a plurality of unit batteries each having a terminal member that transmits and receives power to the electrode body, A plurality of bus bars that are electrically connected between the terminal members of the unit battery, and a plurality of cooling members that are connected to each of the unit batteries and have cooling fins that cool the unit battery by radiating heat to the refrigerant. An assembled battery comprising:
The cooling fins are arranged along the flow direction of the refrigerant, and are arranged so as to be shifted between the adjacent cooling members so as not to completely overlap the flow direction of the refrigerant.

  When cooling is performed by flowing a refrigerant to the cooling fins of the cooling member, the cooling fins are arranged along the flow direction of the refrigerant so as not to disturb the flow of the refrigerant. Further, by shifting the cooling fins between adjacent cooling members, a slight turbulent flow is generated in the refrigerant flow, so that the cooling capacity of the refrigerant can be maximized and the variation in the cooling capacity of each unit cell can be reduced.

  As described above, since the number of parts can be reduced, it is preferable that the bus bar also serves as the cooling member.

  Further, it is preferable that the cooling member has a cross-sectional shape in a direction perpendicular to the flow direction of the refrigerant having a repeating unit at a predetermined interval, and a deviation of the cooling fin between the adjacent cooling members is half of the predetermined interval. . Since the overlap between the continuously arranged cooling members is half of the predetermined interval, the overlap between the two in the refrigerant flow direction can be minimized, so that the cooling efficiency can be improved while minimizing the resistance to the refrigerant flow. It can be improved.

  (3) Further, in the above-described assembled battery, each of the cooling members is divided into one or more groups, and each of the groups is continuously arranged in the refrigerant flow direction. It is preferable to provide a refrigerant duct for adjusting the flow of the refrigerant every time. The refrigerant flow can be appropriately controlled by the refrigerant duct. Moreover, it is preferable that the said refrigerant | coolant duct has a partition plate arrange | positioned with a predetermined angle with respect to the flow direction of a refrigerant | coolant, and obstructing a part of refrigerant | coolant flow. Cooling efficiency can be improved by generating a turbulent flow in a part of the refrigerant flow by the partition plate.

  In the assembled battery of this embodiment, the terminal members of the unit battery are electrically joined by the bus bar. The unit battery has an electrode body that is a power generation element and a terminal member that transmits and receives power to the electrode body. Although it does not limit as a kind of unit battery, applying to a secondary battery is desirable, and applying to a nickel-hydrogen secondary battery and a lithium secondary battery with a high energy density especially is desirable. The assembled battery of this embodiment has a cooling member that cools the unit battery by flowing a refrigerant. A fluid such as air can be used as the refrigerant.

(First form)
The bus bar has cooling fins and also serves as a cooling member. As a result, the number of parts of the assembled battery can be reduced. In addition, since the electrical connection is sufficiently performed with the electrode body which is a heat generation source in the assembled battery, the thermal connection can be sufficiently ensured without employing any additional means / method.

  The shape (particularly the cross-sectional area) of the bus bar is determined by the magnitude of the current flowing between the unit cells. It is not essential that all bus bars have cooling fins, but most bus bars have cooling fins. Although the material which comprises a bus-bar is not limited, The material which is stable in the atmosphere by which an assembled battery is arrange | positioned, and the material excellent in electrical conductivity and heat conductivity is desirable. For example, copper, aluminum, stainless steel, copper alloy and the like. It is preferable from the viewpoint of improving the cooling performance that the cooling fins of the bus bar are integrally formed by press molding, extrusion molding, casting or the like, or integrally joined by brazing, welding, or the like.

  Furthermore, it is preferable to have a cooling fan or the like for flowing a coolant such as air through the cooling fin. Further, in order to appropriately control the refrigerant flow, it is preferable to cover the cooling fin with a refrigerant duct that guides and rectifies the refrigerant flow. The refrigerant duct preferably has a partition plate disposed at a predetermined angle in the refrigerant flow direction. The partition plate is, for example, a plate-like body disposed in a direction perpendicular to the refrigerant flow, and improves the cooling efficiency by disturbing the refrigerant flow.

(Second form)
The assembled battery of this embodiment has a cooling member having cooling fins and is connected to each unit battery. The cooling fins are disposed along the flow direction of the refrigerant. For example, the cooling fin is a plate-like body, and the plate-like body is directed along the direction in which the refrigerant flows, and is disposed at a predetermined interval. As a result, the cooling fins are arranged in parallel. Although the material which comprises a cooling member is not limited, the material which is stable in the atmosphere by which an assembled battery is arrange | positioned, and the material excellent in heat conductivity is desirable. For example, copper, aluminum, stainless steel, copper alloy and the like. The cooling fins of the cooling member are preferably formed integrally by press molding, extrusion molding, casting, or the like, or integrally joined by brazing, welding, or the like from the viewpoint of improving cooling performance.

  The cooling members are shifted so that the cross-sectional shapes with respect to the direction in which the refrigerant flows do not overlap as much as possible. The amount of shifting may be slight. For example, the cooling member (particularly the cooling fin portion) adopts a shape in which the cross-sectional shape in the direction perpendicular to the refrigerant flow direction has a repeating unit at a predetermined interval, and the cooling fin between the adjacent cooling members An effective cooling action can be exhibited by setting the deviation to half of the predetermined interval. That is, after the refrigerant has passed between the cooling fins, the refrigerant and the cooling fin can be brought into maximum contact with each other by repeating the collision with the next cooling fin, and the cooling action can be effectively exhibited.

  Further, the number of parts can be eliminated by having the bus bar also serve as a cooling member as in the first embodiment. Moreover, it is preferable to have a cooling fan or the like for flowing a coolant such as air through the cooling fin. Further, in order to appropriately control the refrigerant flow, it is preferable to cover the cooling fin with a refrigerant duct that guides and rectifies the refrigerant flow. The refrigerant duct preferably has a partition plate disposed at a predetermined angle in the refrigerant flow direction. The partition plate is, for example, a plate-like body disposed in a direction perpendicular to the refrigerant flow, and improves the cooling efficiency by disturbing the refrigerant flow.

[Example 1]
(Constitution)
The assembled battery of the present invention will be described below in detail with reference to the drawings. As shown in FIGS. 1-3, the assembled battery of this embodiment has the laminated bodies 1a and 1b which laminated | stacked the unit battery 1 in multiple numbers. The unit battery 1 is a prismatic battery, and is laminated in the thickness direction to form laminates 1a and 1b. The unit cell 1 has electrodes at both ends of the upper end surface. Corresponding electrodes between the unit cells 1 constituting the stacked bodies 1a and 1b are connected by bus bars 10a and 10b which also serve as cooling members, and finally, power is transferred from the total terminals 5 and 6.

  Each of the bus bars 10a and 10b is a member formed by bending a metal plate, and three peaks and three valleys are alternately formed at predetermined intervals. In other words, the cooling members (bus bars 10a and 10b) have a repeating unit with a predetermined interval (between peaks and peaks and between valleys and valleys) in the cross-sectional shape in the refrigerant flow direction. And each bus bar 10a and 10b connected to the unit battery 1 which comprises the laminated bodies 1a and 1b is a predetermined space | interval so that the peak part and trough part of bus bar 10a and 10b may overlap between the adjacent unit batteries 1. FIG. It is fixed by shifting by half. The bus bars 10a and 10b and the terminal member of the unit battery 1 are connected by ultrasonic welding.

  As shown in FIG. 4, the unit battery 1 is formed by sealing an electrode body 12 that is a power generation element and terminal members 14 and 15 with a resin case 11 made of a laminate film. The upper ends of the terminal members 14 and 15 are bent at a right angle. An electrolytic solution is injected into the resin case 11. The electrolyte is injected from the gas discharge member 13, and after the injection of the electrolyte, the gas discharge port of the gas discharge member 13 is closed with a laminate film. Each unit battery 1 has a gas discharge member 13 and is arranged in a straight line when the stacked bodies 1a and 1b are formed. Gas discharge pipes 3 a and 3 b for guiding the gas to the outside are attached to the gas discharge port of the gas discharge member 13.

  As shown in FIGS. 1 and 5, the laminated bodies 1a and 1b are fixed on the base 9 by end plates 92a and 92b and restraint bands 4a and 4b. The end plates 92a and 92b are screwed onto the base 9 so as to sandwich the stacked bodies 1a and 1b. The laminated bodies 1a and 1b are sandwiched between the end plates 92a and 92b via the protective plate 16 and the leaf spring 17 at both ends. The stacked bodies 1 a and 1 b are held in the stacking direction of the unit cells 1 by the protection plate 16 and the leaf spring 17.

  Restraint bands 4a and 4b hold the side surfaces of the laminated bodies 1a and 1b. Pins 8 are connected to both ends of the restraining bands 4a and 4b, and are fitted into fitting holes provided at both ends of the end plates 92a and 92b, respectively.

  A case 7 that houses the laminates 1 a and 1 b is fixed to the base 9. A space defined by the inner surface of the case 7 and the upper surfaces of the laminates 1a and 1b acts as a refrigerant duct that controls the flow of the refrigerant. That is, air as a refrigerant is guided to this space and efficiently flows between the cooling fins. Furthermore, the duct partition plates 71 and 72 provided in the case 7 form a duct through which refrigerant flows independently between the laminate 1a and the laminate 1b. The case 7 is provided with an inlet for air as a refrigerant. Further, a partition plate 18 is provided above the inner surface of the case 7 so as to reach the upper end of the cooling fin.

(Function and effect)
The assembled battery of this embodiment generates heat when used. Heat generation in the assembled battery is considered to be mainly in the electrode body 12 portion that is a power generation element. The heat generated in the electrode body 12 reaches the cooling fins of the bus bars 10a and 10b by heat conduction. Since the bus bars 10a and 10b are sufficiently connected to the terminal members 14 and 15 to withstand the output from the battery, the thermal resistance between them is a sufficiently small value.

  Air as a refrigerant flows into the cooling fin from the left side of FIG. The heat of the cooling fin is carried away by the inflowing air. Here, the cooling fins of the bus bars 10a and 10b are shifted to some extent between the adjacent unit cells 1, so that the inflowing refrigerant flows between the cooling fins while colliding with the cooling fins. As a result, the flow of the refrigerant becomes turbulent and can efficiently exhibit a cooling action.

  The gas discharge member 13 has a function of reducing the internal pressure of the unit cell 1 by discharging gas through the inside and outside of the unit cell 1 when the internal pressure of the unit cell 1 is increased for some reason. The gas discharged from the gas discharge port of the gas discharge member 13 is guided out of the case 7 through the gas discharge pipes 3a and 3b.

[Modification]
Instead of the unit battery 1 of the first embodiment, a unit battery 2 having a metal case 19 as shown in FIG. 6 is used. As shown in FIG. 8, the unit battery 2 has an electrode body 12 similar to that of the unit battery 1. As shown in FIGS. 7 and 8, the electrode body 12 has plate-like terminal members 22 and 24. These are housed in a metal case 19 as shown in FIG. An electrolyte solution inlet 20 and a gas discharge member 23 are formed in the upper lid 21 of the metal case 19.

  Bus bars 25a and 25b that also serve as cooling members are connected to the tip portions of the terminal members 22 and 24, respectively. The bus bars 20a and 20b have substantially the same cooling fins as the bus bars 10a and 10b. The arrangement of the cooling fins (shifting between adjacent unit cells 2) is almost the same (FIG. 9).

It is a disassembled perspective view of the assembled battery of an Example. It is the plane schematic of the laminated body of the assembled battery of an Example, and its periphery. It is the schematic of one unit battery which comprises the assembled battery of an Example. It is the schematic which shows the electrode body and terminal member which comprise the unit battery of an Example. It is a partial cross section figure of the assembled battery of an Example. It is the schematic of one unit battery which comprises the assembled battery of a modification. It is the schematic inside one unit battery which comprises the assembled battery of a modification. It is the schematic inside one unit battery which comprises the assembled battery of a modification. It is the schematic of one unit battery which comprises the assembled battery of a modification. It is the plane schematic diagram of the laminated body of the assembled battery of a modification, and its periphery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Unit battery 1a, 1b ... Laminated body 11 ... Resin case 12 ... Electrode body 13, 23 ... Gas exhaust member 14, 15, 22, 24 ... Terminal member, 16 ... Protection plate 17 ... Plate spring 19 ... Metal case DESCRIPTION OF SYMBOLS 20 ... Electrolyte injection port 21 ... Upper cover 10a, 10b, 25a, 25b ... Cooling member 3a, 3b ... Gas exhaust pipe 4a, 4b ... Restraint band 5, 6 ... Total terminal 7 ... Case 18 ... Partition plate 8 ... Pin 9 ... Base 92a, 92b ... End plate

Claims (6)

A plurality of unit cells each having an electrode body that is a power generation element and a terminal member that transmits and receives power to the electrode body; and a plurality of bus bars that electrically connect the terminal members of each unit battery. An assembled battery,
Each bus bar has a cooling fin and also serves as a cooling member for cooling each unit battery. A plurality of unit cells each having an electrode body that is a power generation element and a terminal member that transmits and receives power to the electrode body; a plurality of bus bars that electrically connect the terminal members of each unit battery; A plurality of cooling members having cooling fins that are connected to each of the unit cells and radiate heat to the refrigerant to cool the unit cells,
The assembled battery is characterized in that the cooling fins are arranged along the flow direction of the refrigerant, and are shifted between the adjacent cooling members so as not to completely overlap the flow direction of the refrigerant.   The assembled battery according to claim 2, wherein the bus bar also serves as the cooling member. The cooling member has a repeating unit at a predetermined interval in a cross-sectional shape in a direction perpendicular to the flow direction of the refrigerant,
The assembled battery according to claim 2 or 3, wherein a deviation of the cooling fin between the adjacent cooling members is half of the predetermined interval. Each of the cooling members is divided into one or more sets, and each of the cooling members is continuously arranged in the flow direction of the refrigerant.
Furthermore, the assembled battery in any one of Claims 1-4 provided with the refrigerant | coolant duct which arranges the flow of a refrigerant | coolant for every group of this cooling member.   The assembled battery according to claim 5, wherein the refrigerant duct includes a partition plate that is disposed at a predetermined angle with respect to a flow direction of the refrigerant and partially blocks the flow of the refrigerant.

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