JP5875920B2 - Assembled battery - Google Patents

Description

The present invention relates to an assembled battery in which a plurality of single cells are combined. In particular, the present invention relates to an assembled battery in which flat unit cells are arranged in a stacked state at a predetermined interval and are cooled by cooling air.

In an electric vehicle, a hybrid vehicle, and the like, an assembled battery (battery module) in which secondary batteries are assembled as a power source is used. In the process of charging or discharging, if the battery overheats or the temperature difference between the batteries increases, the performance of the battery may deteriorate or the battery may be damaged. Usually, these assembled batteries are stored in the battery case. Then, the assembled battery is cooled by sending cooling air into the battery case.

The unit cell used in the assembled battery includes a substantially flat battery such as a lithium ion battery, and such a battery is sometimes called a square battery because of its shape.
When a flat unit cell is configured as an assembled battery, the flat unit cells are spaced apart from each other by a predetermined distance so that the wide surfaces of the cells face each other so that cooling by cooling air can be performed efficiently. Generally, batteries are arranged in a stacked state, and cooling air is sent to the gaps between the batteries to cool the batteries.

In order to cool these assembled batteries, it is necessary to make the temperature of the plurality of single cells constituting the assembled battery uniform as much as possible, and to cool the battery efficiently. For this reason, various assembled batteries have been proposed. Has been done.
For example, in Patent Document 1, a separator is sandwiched between batteries, a cooling air passage (cooling gap) is formed by the corrugated uneven shape of the separator, the battery is cooled by cooling air, and the separator An assembled battery provided with a temperature sensor is disclosed.

JP 2010-287550 A

In such a battery cooling structure, it is required to increase the cooling efficiency so that the temperature of the battery can be kept low while reducing the amount of cooling air. Furthermore, it is required to make the temperatures of a plurality of unit cells constituting the assembled battery uniform. This is because if a unit cell having a high temperature exists, the unit cell deteriorates and the life of the entire assembled battery is shortened.

The inventors have studied an assembled battery in which a corrugated spacer member (a separator in Patent Document 1) as disclosed in the above patent document is sandwiched between single cells. And in the assembled battery of such a structure, it discovered that cooling efficiency was easy to become low especially in the downstream part of a cooling wind flow.

That is, an object of the present invention is to provide an assembled battery that can increase the cooling efficiency of the battery.

The inventor has examined the cause of the cooling efficiency on the downstream side. As a result, in the assembled battery having a structure in which the corrugated plate-like spacer member as disclosed in Patent Document 1 is sandwiched between the single cells, the cooling air passage becomes a narrow prismatic space, so that the inside of the cooling air passage It was discovered that the cooling air flows in an orderly laminar flow, and only the cooling air heated mainly on the upstream battery surface is supplied to the battery surface downstream of the cooling air flow.

Then, the inventors further studied, and when the bar member is provided at the center of the cooling air passage in the battery stacking direction so as to cross the cooling air passage, the cooling air is stirred and the downstream side of the rod member is cooled. As a result, the present invention has been completed.

The present invention is an assembled battery configured by stacking and arranging substantially flat unit cells, and a spacer member is sandwiched between adjacent unit cells, and the unit cell is stacked as the spacer member. A partition part extending in the direction and a connecting part extending in parallel with the surface of the unit cell, and between adjacent unit cells, the partition part of the spacer member, the connection unit, and the unit cell surface The cooling air passage is formed, and a bar member is provided between the adjacent partition portions so as to cross the cooling air passage, and the bar member is at the center of the cooling air passage in the battery stacking direction. The width d of the rod member in the battery stacking direction is provided such that H / 10 ≦ d ≦ H / 3 with respect to the width H of the cooling air passage in the battery stacking direction. (1st invention).

In the present invention, it is preferable that a plurality of rod members are provided in the cooling air passage so as to be separated in the cooling air flow direction (second invention). Furthermore, in the present invention, it is preferable that the rod member is provided substantially parallel to the cooling air flow direction of the cooling air passage and substantially parallel to the battery surface (third invention).

Further, in the present invention, the cross-sectional shape of the bar member is provided at a corner portion provided at a position offset from the cross-sectional center to the unit cell surface side, and at a position offset from the cross-sectional center to the spacer member connecting portion side. It is preferable that the shape has a corner portion (fourth invention).

According to the assembled battery of the present invention (first invention), the cooling performance of the battery surface on the downstream side of the cooling air flow is improved, and the effect that the cooling efficiency of the battery is enhanced is obtained.

Furthermore, in the case of the second to fourth inventions, the battery cooling efficiency can be more effectively increased.

It is a perspective view which shows the assembled battery of 1st Embodiment of this invention. It is an exploded view which shows the structure of the assembled battery of 1st Embodiment. It is a perspective view which shows the state by which the cell and the spacer member were laminated | stacked. It is the front view and sectional drawing which show the spacer member used for the assembled battery of 1st Embodiment. It is a schematic diagram which shows the flow in a cooling air path. It is a simulation result of the cooling air flow in 1st Embodiment. It is the front view and sectional drawing which show other embodiment of a spacer member. It is sectional drawing which shows other embodiment of a spacer member. It is a figure which shows the other example of a bar member provided in a spacer member.

Hereinafter, an embodiment of an assembled battery of the present invention will be described with reference to the drawings, taking an assembled battery for a hybrid vehicle as an example. FIG. 1 is a perspective view of a first embodiment of a battery pack of the present invention. FIG. 2 is an exploded view showing the component configuration of the assembled battery of this embodiment. In these drawings, the detailed configuration of the battery such as a terminal, a gas exhaust valve, and a bus bar provided in the unit cell is not shown. The white arrow in FIG. 2 indicates the direction in which the component is to be arranged. In addition, this invention is not limited to the separate embodiment shown below, The form can also be changed and implemented.

In the assembled battery structure (hereinafter also referred to as an assembled battery or a battery module) 1, the flat unit cells 2 and 2 constituting the assembled battery are spaced apart from each other by a predetermined distance so that the wide surfaces of the unit cells face each other. They are arranged in a stacked state with a gap therebetween. The unit cells 2 and 2 are electrically connected in series or in parallel to form an assembled battery. In the present embodiment, the unit cell constituting the battery module is a lithium ion battery, and the unit cell 2 has a flat plate shape (flat rectangular parallelepiped shape). Terminals are provided on the side surfaces (surfaces adjacent to a wide flat surface) of each battery.

Although illustration is omitted, on the upstream side and downstream side of the assembled battery 1, a blower fan and other ventilation path members (such as a duct) are provided to constitute a battery cooling system as a whole. Then, the single cells 2 and 2 arranged in a stacked manner are cooled by cooling air supplied to the side surfaces of the respective cells.

Spacer members 5 and 5 are sandwiched between the unit cells 2 and 2 adjacent to each other. A predetermined interval is maintained between the single cells 2 and 2 by the spacer member. The spacer member 5 and the single cell 2 form a cooling air passage, and the single cell is cooled by the cooling air sent to the cooling air passage.

The assembled battery is provided with a holding member so that the laminated structure of the unit cells 2 and 2 and the spacer members 5 and 5 is maintained. In the present embodiment, as the holding member, a pair of end plates 4 and 4 are provided so as to face the wide surfaces of the unit cells at both ends in the stacking direction of the assembled battery. Bolts (not shown) that clamp the assembled battery in the stacking direction are provided between the end plates 4 and 4 to maintain the battery stack structure. The holding member is not limited to the end plate and the bolt, and other structural members may be used, or other structural members may be used in combination.

The spacer member 5 sandwiched between the unit cells 2 and 2 arranged in a stacked manner will be described. FIG. 3 is a perspective view showing a state in which the unit cells 2 and 2 and the spacer members 5 and 5 are stacked in this embodiment, and FIG. 4 shows a front view and a cross-sectional view of the spacer member 5. In FIG. 4, only the part clamped between single cells is shown. The spacer member 5 is a plate-like member formed of a synthetic resin or the like, and is a member that maintains a gap between the single cells 2 and 2 and ensures insulation between the batteries as necessary. The spacer member 5 has partition parts 51 and 51 extending in the direction in which the unit cells are stacked, and connection parts 52 and 52 extending in parallel with the unit cell surface.

The partition portion 51 maintains the gap size between the adjacent cells, and partitions the cooling air passage between the batteries. In FIG. 3, the flow of the cooling air flowing into the cooling air passage between the batteries is indicated by white arrows. In this embodiment, the partition part 51 is an elongate plate-shaped part provided along the flow direction of the cooling air which flows between single cells, and is provided along with mutually parallel. Therefore, in this embodiment, the cooling air passage is also an elongated passage arranged in parallel to each other.

The connecting part 52 is a part in which adjacent partition parts 51 and 51 are connected and integrated with each other. The connecting portion is formed in a planar shape (plate shape) parallel to the battery surface. In this embodiment, the connection parts 52 and 52 are formed so that it may contact | adhere to one of the cell surface which adjoins mutually and opposes. And the adjacent partition parts 51 and 51 and the connection part 52 form the bowl-shaped part of a substantially U-shaped cross section. Moreover, in this embodiment, the connection parts 52 and 52 which mutually adjoin each other are arrange | positioned alternately so that it may become the other side in a battery lamination direction. That is, the spacer member 5 is configured such that a substantially corrugated portion is formed by the partition portions 51 and 51 and the connecting portions 52 and 52.

A cooling air passage is formed between the adjacent single cells 2 and 2 by the partition portions 51 and 51 of the spacer member 5, the connecting portion 52, and the single cell surface. That is, the aforementioned bowl-shaped portion of the substantially U-shaped cross section is covered with the battery surface to form a prismatic cooling air passage.

The spacer member in the present invention is further provided with rod members 53 and 53. The rod members 53 and 53 are provided between the partition portions 51 and 51 that are adjacent to each other and face each other so as to cross the cooling air passage. Further, the bar member 53 is provided at the center of the cooling air passage in the battery stacking direction. In the present embodiment, five rod members 53 are provided in each cooling air passage so as to be separated from each other in the cooling air flow direction.

The position in the battery stacking direction in which the rod member 53 is disposed in the cooling air passage does not have to be strictly the center, and the cross-sectional center C of the rod member has a width in which the width of the cooling air passage in the battery stacking direction is H. It may be arranged in the region of H / 4 to 3H / 4 in the direction, more preferably in the region of H / 3 to 2H / 3 in the width direction.

The material which comprises the bar member 53 is not specifically limited, The same material as the spacer member main body containing a partition part and a connection part may be sufficient. Alternatively, the bar member 53 may be made of a material different from that of the spacer member main body, such as a metal wire. The rod member 53 may be integrally formed with the partition portion and the connecting portion, or the rod member may be attached after the spacer member body including the partition portion and the connecting portion is formed.

Preferably, as in the present embodiment, the rod member 53 is provided so as to be substantially orthogonal to the cooling air flow direction of the cooling air passage and substantially parallel to the battery surface.
Further, the thickness of the rod member, that is, the width d of the rod member in the battery stacking direction is provided so that H / 20 ≦ d ≦ H / 2 with respect to the width H of the cooling air passage in the battery stacking direction. It is particularly preferable to provide such that H / 10 ≦ d ≦ H / 3. Typically, the width H of the cooling air passage in the battery stacking direction is about 2 to 8 mm, and the width d of the rod member in the battery stacking direction is about 0.3 to 3 mm.

FIG. 9A shows a cross-sectional shape of the bar member 53 in the present embodiment. In the present embodiment, the bar member 53 has a substantially D-shaped cross section, and the cooling air upstream side is round and the cooling air downstream side is linear. The cross-sectional shape of the rod member 53 includes, as in the present embodiment, a corner portion 531 provided at a position offset from the cross-sectional center C to the surface side of the unit cell 2 on the downstream side of the cooling air flow, The cooling air passage preferably has a corner portion 532 provided at a position offset to the spacer member connecting portion 52 side. And it is preferable that these corner | angular parts 531 and 532 are provided in the symmetrical position about the cooling air flow direction as an axis | shaft so that it may make a pair.

As described above, the spacer member 5 according to the present invention is a member having the partition portion 51, the connecting portion 52, and the rod member 53, but may include other portions as appropriate. As other parts, for example, a positioning part for positioning the relative position with the unit cell, an interval defining part for defining an interval between adjacent spacer members, a bolt inserted through the entire assembled battery, and the like can be passed. Examples of the portion formed in this manner, a portion to which a temperature sensor for measuring the temperature of the battery or the cooling air, and the like are attached.

The assembled battery can be configured by a known manufacturing method. For example, the end plate 4 and the spacer members 5 and 5 can be manufactured, for example, by injection molding of synthetic resin (especially thermoplastic resin), and these members and the unit cells 2 and 2 are assembled together by fastening members such as bolts. By combining these, the above assembled battery structure can be configured. These members can be made of metal members according to requirements such as strength and thermal requirements. Moreover, when there exists a part which needs sealing performance and elasticity in these members, it is preferable to comprise the site | part by elastic materials, such as rubber | gum and an elastomer.

The manufacturing method of the spacer member 5 is not particularly limited. For example, the spacer member 5 can be integrally formed including the rod member 53 by resin injection molding if a slide mold is used.

The operation and effect of the assembled battery of the present invention will be described.
In the assembled battery of the present invention, the cooling performance of each unit cell can be enhanced. In particular, in each unit cell, the cooling performance in the downstream portion of the cooling air can be enhanced.

With reference to FIG. 5, the operation of the assembled battery of the present invention will be described. FIG. 5 shows a cross section of the assembled battery in a plane including the cell stacking direction and the cooling air flow direction, that is, a cross section of the cooling air passage viewed along the rod member. FIG. 5A shows the cooling air flow when the bar member is provided as in the present invention, and FIG. 5B shows the cooling air flow when there is no bar member as in the prior art. In addition, in FIG. 5, the mode of the cooling air flow of the part in which one rod member was provided is shown typically.

As shown in FIG. 5B, when there is no bar member, the cooling air flows in a laminar flow parallel to the surface of the unit cell in each cooling air passage. At this time, for example, the lower surface of the cell A in the figure is mainly cooled by the cooling air flowing through the cooling air passage 1, and the lower surface of the cell B in the figure is mainly cooled by the cooling air passage 2. Cooled by. However, only the cooling air warmed by cooling the upstream portion of the battery is supplied to the battery surface on the downstream side (right side in the figure) of the cooling air flow. Therefore, the cooling efficiency of the battery surface in the downstream portion of the cooling air flow is deteriorated (and the battery surface temperature on the downstream side is slightly increased).

FIG. 5 (a) shows the flow of cooling air when a bar member as in the present invention is provided. In the portion upstream of the bar member, the cooling air flow is basically the same as when there is no bar member. In the region downstream of the rod member 53, the cooling air flow has a velocity component in the battery stacking direction, and the cooling air is stirred in the battery stacking direction. In this flow, a so-called Karman vortex (vortex line) is generated on the downstream side of the bar member 53 provided so as to cross the passage at the center of the cooling air passage, and the vortex is alternately generated, grown, and separated. It is a flow that occurs by going.

In the region on the downstream side (right side in the figure) from the rod member, this flow causes the cooling air to be agitated in the battery stacking direction, so that the cooling air that has not yet been heated is sent to the downstream battery surface. become. The change in the flow field can improve the cooling performance on the downstream side of the battery and improve the cooling efficiency of the battery. Moreover, since the cooling efficiency of the downstream area | region of a cooling wind flow can be improved, the difference of the battery surface temperature in each single cell also becomes small.

In FIG. 6, the simulation result of the flow of the cooling air path which provided the rod member in this invention is shown. The dark part is the part where the flow velocity and vorticity are large. From the state of the flow velocity distribution and the vorticity distribution, it can be confirmed that Karman vortex is generated in the downstream region of the rod member and the cooling air is stirred in the battery stacking direction (vertical direction in the figure). In the flow simulation, the bar member was a bar member having a triangular cross section as shown in FIG.

Along with the flow simulation, a thermal fluid simulation was performed in which a predetermined amount of heat generation was set for the battery and cooling air at a predetermined temperature was supplied.
In the example with the bar member and the comparative example without the bar member, the required air volume for making the battery average temperature the same target temperature was compared. In the example with the bar member, the flow rate of the cooling air was 45%. I found that I could do it less. In addition, the pressure loss around the assembled battery at that time increases only slightly despite the addition of rod members, and the amount of cooling air required is less when viewed from the pressure loss of the entire cooling system. It was found that it can be made smaller.

Further, as in the first embodiment, if a plurality of (for example, five) rod members are provided in the cooling air passage so as to be separated from each other in the cooling air flow direction, the stirring effect of the cooling air becomes larger and more effective. The cooling efficiency can be increased. The influence (stirring effect) of the Karman vortex generated by the bar member becomes weaker when it is separated from the bar member (for example, when the width of the cooling air passage in the battery stacking direction is H and is about 5H to 20H or more). Therefore, when the cooling air passage is long, it is preferable to arrange a plurality of rod members in the cooling air passage. And when arranging two or more bar members, it is especially preferable to arrange so that bar members may be about 5H-20H apart. If it does in this way, cooling efficiency can be raised effectively, suppressing the increase in ventilation resistance by a rod member to the minimum.

Further, it is preferable that the rod member is substantially orthogonal to the cooling air flow direction of the cooling air passage and is provided substantially parallel to the battery surface. In this way, the generation of Karman vortices can be ensured and strong. The cooling efficiency of the battery can be increased more effectively.

Further, as in the first embodiment, the cross-sectional shape of the bar member is provided on the downstream side of the cooling air flow, at the corner 531 provided at a position offset from the cross-sectional center C to the unit cell surface side, and the spacer from the cross-sectional center. If it has a shape (for example, D shape) having a corner portion 532 provided at a position offset to the member connecting portion side, the generation of Karman vortex can be made surely and strong, and the battery cooling efficiency is more effective. Can be increased.

The present invention is not limited to the above embodiment, and can be implemented with various modifications. Although other embodiments of the present invention will be described below, in the following description, portions different from the above embodiment will be mainly described, and the description of the same portions will be simplified or omitted.

First, the example of a change of the spacer member main-body part of a spacer member is demonstrated. The spacer member used in the assembled battery of the present invention is as shown in the spacer member 6 shown in FIG. 7 or FIG. The spacer member 7 may be used. Both the spacer member 6 and the spacer member 7 are the same as the spacer member 5 in the first embodiment in that the partition member (61, 71), the connecting portion (62, 72), and the rod member (63, 73) are provided. The connection relationship between the partition parts (61, 71) and the connecting parts (62, 72) is changed. In FIG. 8 showing the spacer member 7, only a cross-sectional view seen along the cooling air flow direction is shown.

In the spacer member 6 shown in FIG. 7, the connecting portions 62 and 62 are connected to one side of the partition portions 61 and 61 so that the whole becomes a single flat plate shape. And the partition parts 61 and 61 are provided in the shape of a rib from the connection part 62. FIG. Even in such a spacer member 6, since the rod member 63 is provided in the cooling air passage, the effect of increasing the cooling efficiency can be obtained as in the first embodiment.

In the spacer member 7 shown in FIG. 8, the connecting portions 72, 72 are connected and integrated with the central portion of the partition portions 71, 71 in the battery stacking direction so that the whole becomes one flat plate shape. And the partition parts 71 and 71 are provided in the shape of a rib so that it may protrude on both surfaces of the connection part 72. As shown in FIG. Even if it is such a spacer member 7, the effect which raises cooling efficiency is acquired similarly to 1st Embodiment by providing the rod member 73 in the cooling air path. In other words, the connecting portion of the spacer member in the present invention is not limited to that closely contacting the battery surface.

FIG. 9 shows a modification of the cross-sectional shape of the bar member. Each figure shows a cross section along the cooling air passage, and the cooling air flows from the left to the right in the figure. As the bar member, a bar member 53 having a substantially D-shaped cross section as shown in FIG. 9A (first embodiment), a bar member 54 having a circular cross section as shown in FIG. 9B, and FIG. 9C. , (F), bar members 55 and 58 having a triangular cross section, bar member 56 having a rectangular cross section as shown in FIG. 9 (d), bar member 57 having a deformed cross section as shown in FIG. 9 (e), and others Various cross-section bar members such as an oval cross-section and an oval cross-section can be used.

From the viewpoint of generating the Karman vortex reliably and strongly and increasing the cooling efficiency more effectively, the cross-sectional shape of the rod member is cooled as shown in FIGS. 9 (a), (c), (d), and (e). On the downstream side of the wind flow, corner portions 531, 551, 561, and 571 provided at positions offset from the cross-sectional center C to the cell surface side (one side of the opposing cooling wind passage wall surface), and spacer members from the cross-sectional center It is preferable to have a shape having corner portions 532, 552, 562, and 572 provided at positions offset to the connecting portion side (the other side of the opposing cooling wind passage wall surface). Then, like the bar member 55 shown in FIG. 9C and the bar member 57 shown in FIG. 9E, these corners 551, 552, 571, and 572 are made to have acute angles. Is particularly preferred.

The corner provided in the rod member is not limited to that provided on the downstream side of the cooling air flow. For example, as shown in FIG. 9 (f), the cross-sectional shape of the rod member 58 is offset from the cross-sectional center C to the cell surface side (one side of the opposing cooling air passage wall surface) on the upstream side of the cooling air flow. And a corner portion 582 provided at a position offset from the center of the cross section to the spacer member connecting portion side (the other side of the opposing cooling air passage wall surface). In this case, Karman vortices are generated reliably and strongly, and the cooling efficiency is more effectively increased.

As described in the first embodiment, the angle at which the rod member is placed in the cooling air passage is substantially orthogonal to the cooling air flow and is preferably provided substantially parallel to the battery surface. It may be done. If it is provided so as to be inclined with respect to both the cooling air flow and the battery surface, the velocity component in the battery stacking direction can be given to the cooling air flow. This can contribute to improvement of cooling efficiency.

Other members may be integrated in the assembled battery. For example, on the upstream side or downstream side of the assembled battery, a flow control plate for adjusting the flow (distribution) of cooling air (in the gap between the batteries) A plate provided with a slit so as to correspond), a gas vent collective pipe, or the like may be integrated.

Examples of the type of flat battery constituting the assembled battery include primary batteries, secondary batteries (lithium ion batteries, nickel metal hydride batteries, nickel cadmium batteries, etc.), double electric capacitors, and the like. Examples of the battery are modularized. In the above-described embodiment, the battery has been described as having a flat plate shape, but the battery may have a flat plate shape with some bends. Further, the surface of the flat battery does not need to be flat, and may be a battery having uneven strips for improving the cooling performance and improving the rigidity of the battery outer can.

The purpose and application for which the assembled battery is used are not limited to those for automobiles. For example, a secondary battery is used for the purpose of leveling generated power in a wind power generator or a solar battery power generator. The present invention can be utilized for assembled batteries used in a wide range of applications.

INDUSTRIAL APPLICABILITY The present invention can be used for large-capacity assembled batteries used in electric vehicles, hybrid vehicles, power generators, and the like, and can efficiently cool flat battery cells constituting the assembled batteries. The utility value of is high.

DESCRIPTION OF SYMBOLS 1 assembled battery 2 cell 4 end plate 5 spacer member 51 partition part 52 connection part 53 rod member 531 532 corner part

Claims (4)

An assembled battery constructed by laminating and arranging substantially flat unit cells,
A spacer member is sandwiched between adjacent unit cells,
The spacer member has a partition portion that extends in the direction in which the cells are stacked, and a connecting portion that extends in parallel with the surface of the unit cells.
Between adjacent unit cells, a cooling air passage is formed by the partition part and the connecting part of the spacer member, and the unit cell surface,
Between the partition portions adjacent to each other, a bar member is provided so as to cross the cooling air passage,
The bar member is provided at the center of the cooling air passage in the battery stacking direction ,
An assembled battery, wherein a width d of the rod member in the battery stacking direction is set to satisfy H / 10 ≦ d ≦ H / 3 with respect to a width H of the cooling air passage in the battery stacking direction . The assembled battery according to claim 1, wherein a plurality of rod members are provided in the cooling air passage so as to be separated in a cooling air flow direction. 3. The assembled battery according to claim 1, wherein the rod member is substantially orthogonal to the cooling air flow direction of the cooling air passage and is provided substantially parallel to the battery surface. The cross-sectional shape of the rod member is a shape having a corner provided at a position offset from the cross-sectional center to the unit cell surface side and a corner provided at a position offset from the cross-sectional center to the spacer member connecting part side. The assembled battery according to any one of claims 1 to 3.