JP2012150977A - Battery cooling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery cooling structure which can effectively cool batteries so as to make uniform the battery temperature of a battery pack even if a width of a cooling air passage is changed by expansion of the batteries constituting the battery pack.SOLUTION: A battery cooling structure is configured such that a battery pack 1, which is made up of flat-plate like batteries 2, 2 aligned at predetermined intervals in a laminated manner, is housed in a battery case 6, and that the batteries are cooled by cooling air supplied to flow through gaps between the batteries. A flow control plate 5 is arranged upstream or downstream of the battery pack 1 so as to block a passage of the cooling air. The flow control plate 5 is provided with slits 51, 51 each extending in a direction along the gap between the batteries. The cooling air is made to flow through the slits 51 from upstream to downstream of the flow control plate so that the slits 51 and the gaps between the batteries serve as a plurality of flow channels individually arranged in parallel. When viewed along a flow direction of the cooling air between the batteries, a width S of each slit is made equal to or smaller than a gap d between batteries (S≤d).

Description

The present invention relates to a battery cooling structure for cooling an assembled battery in which a plurality of batteries are combined. In particular, the present invention relates to an air-cooled battery cooling structure that cools an assembled battery in which flat batteries are arranged in a stacked state at a predetermined interval with cooling air.

In an electric vehicle, a hybrid vehicle, and the like, an assembled battery 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, cooling air is sent into the battery case to cool the assembled battery.

The battery used for 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 battery is configured as an assembled battery, the flat batteries are separated from each other by a predetermined distance so that the wide surfaces of the batteries face each other so that the cooling air can be efficiently cooled. In general, the batteries are arranged in a stacked state and cooled by sending cooling air to the gaps between the batteries.

In cooling these assembled batteries, it is necessary to equalize the temperature of a plurality of batteries constituting the assembled battery as much as possible and cool the battery efficiently. For this purpose, various assembled battery structures and batteries are required. Cooling structures have been proposed.
For example, Patent Document 1 discloses an assembled battery cooling structure in which cooling air distributed between flat batteries arranged at a predetermined interval is guided to uniformly cool a plurality of batteries. ing. Patent Document 2 discloses an assembled battery structure in which an insulating separator is sandwiched between batteries, a cooling air passage (cooling gap) is formed by the uneven shape of the insulating separator, and insulation between the batteries is ensured. It is disclosed.

JP 2008-254627 A JP 2010-153141 A

In battery packs used in electric vehicles and the like, battery outer cans tend to be made thinner in order to reduce the system weight and save space. Here, when the battery outer can is made thinner with a flat battery such as a lithium ion battery, the tendency of the wide surface of the battery to be swollen by internal pressure becomes prominent due to changes in the temperature of the battery and the generation of gas inside. Cheap.

In the case of an assembled battery structure that does not have a member that restrains the expansion of the battery between the flat battery and the battery, as in the assembled battery structure described in Patent Document 1 (shown in FIG. 12), the wide surface of the battery When the battery expands, the gaps between the batteries become smaller, making it difficult for air to flow through the gaps. The cooling of the batteries adjacent to the gaps deteriorates, and the uniform cooling of the batteries cannot be performed successfully. There is a risk of abnormal heating of the battery. In the battery cooling structure disclosed in Patent Document 1, the width of the gap between the batteries directly regulates the flow rate of the cooling air flowing between the batteries. The variation is likely to be remarkable. If the battery temperature varies, the battery having a high temperature tends to expand and deteriorate, and the battery life also varies, which is not preferable because the life of the assembled battery is shortened.

If it is an assembled battery structure of the type which sandwiches an uneven | corrugated plate-shaped insulation separator between batteries as described in patent document 2, the expansion | swelling of a battery is positively suppressed and the clearance gap between batteries is appropriate. However, such an assembled battery structure requires a large number of components to be manufactured and assembled with high accuracy, which increases manufacturing costs and eliminates gaps between the batteries. In order not to change the dimensions, the system needs to have a certain rigidity and strength, and there is a limit to its weight reduction.

That is, the object of the present invention is to effectively cool the batteries and maintain the battery temperature uniformity even if the batteries constituting the assembled batteries expand and the width of the cooling air passage between the batteries changes. The object is to provide a battery cooling structure that can contribute to uniform battery life.

As a result of intensive studies, the inventors of the present invention have provided a flow control plate having slits and through holes corresponding to the gaps between the batteries in the cooling air passage in the battery cooling structure using cooling air, and the slit (through hole). The cooling air passages constituted by the gaps between the battery and the battery are arranged in parallel independently of each other, and in each cooling air passage, the cooling air is squeezed by this slit to adjust the air volume, and the size of the slit It has been found that if the battery is made smaller than the gap between the batteries, the change in battery temperature can be suppressed even if the gap between the batteries changes due to the swelling of the batteries. And if this was applied, it discovered that an air volume change, disturbance of air volume distribution, and non-uniform | heterogenous battery temperature could be prevented or suppressed, and completed this invention.

In the present invention, a battery pack in which a plurality of flat batteries are arranged in a stacked manner with a predetermined gap is accommodated in the battery case, and the cooling air flowing through the battery case is placed between the batteries. It is a battery cooling structure that sends the battery to pass and cools the battery, and a flow control plate is disposed on the upstream side or the downstream side of the assembled battery so as to block the passage of the cooling air. Slits extending in the direction along the gaps between the batteries are provided so that cooling air flows from the upstream side to the downstream side of the flow control plate through the slits. The ventilation paths formed by the slits corresponding to each other and the gaps between the batteries are independent ventilation paths arranged in parallel with each other, along the cooling air flow direction in the gaps between the batteries. When I saw it, Width S of the slit, as compared to the width d of the gap between the battery, a battery cooling structure that is the S ≦ d.

In the present invention, the width S of the slit is preferably 17% ≦ S / d ≦ 70% compared to the width d of the gap between the batteries. Further, the width S of the slit is the width of the gap between the batteries. It is particularly preferable that 25% ≦ S / d ≦ 50% as compared with d. In the present invention, it is preferable that a spacer member capable of suppressing the width between the battery gaps to be 40% or less of the initial width of the gap is provided in the gap between the batteries.

The present invention also provides a battery case in which battery packs in which a plurality of flat batteries are arranged in a stacked manner with a predetermined gap therebetween are accommodated in the battery case, and cooling air flowing through the battery case is provided between the batteries. A battery cooling structure that cools the battery by sending it through a gap, and a flow control plate is arranged on the upstream side or downstream side of the assembled battery so as to block the passage of the cooling air. There are through holes corresponding to each of the gaps between the batteries, and cooling air flows from the upstream side to the downstream side of the flow control plate through the through holes, and between the corresponding through holes and the batteries. The ventilation paths formed by the gaps are independent ventilation paths arranged in parallel with each other, the opening area of the through holes is Ah, and the gap between the batteries is seen along the cooling air flow direction. When the cross-sectional area at the time is Ag, substantially A Is a ≦ Ag was a battery cooling structure. Here, the shape of the through hole is not limited to a shape like a slit, and can be various through holes such as a circle, an ellipse, a rectangle (square, rectangle), and a rhombus.

According to the present invention, the air passages that are independently arranged in parallel are configured by the slits and the inter-battery gaps provided in correspondence with each other. Since the slit width S is less than or equal to the width d between the battery gaps (ie, S ≦ d), a ventilation resistor that determines the flow rate and flow distribution of the cooling air in these independent ventilation paths is provided in each flow path. It can be adjusted independently by the slit formed. Therefore, the flow distribution to each flow path can be performed by adjusting the slit width in advance.
Since the slit width S in each flow path is smaller than the width d between the battery gaps (S ≦ d), even if the gap between the batteries changes due to the expansion of the battery, the ventilation resistance of the entire flow path The change that occurs is limited, and the change in the flow rate of the cooling air is suppressed. And the rise in battery temperature by the reduction | decrease between battery gaps is also suppressed. This temperature rise suppression effect is particularly remarkable under conditions where the battery expands to such an extent that the width between the battery gaps is 40% to 70% of the initial width.

Therefore, according to the present invention, even if the gap between the batteries changes due to the expansion of the battery or the like, the flow rate of each flow path, its distribution, and the battery temperature are substantially maintained to improve the battery cooling performance and the battery temperature. Contributes to uniformity and uniform battery life.

Further, if the width S of the slit and the width d of the gap between the batteries are 17% ≦ S / d ≦ 70%, the battery of the type sandwiching the insulating separator shown in Patent Document 2 Compared to the cooling structure, the ventilation resistance of the cooling air can be made equal or less, and the cooling efficiency of the battery cooling system can be improved. Further, in this range, surprisingly, when the battery expands and the gap between the batteries is narrowed, the temperature of the battery can be lowered even if the cooling conditions are the same. Accordingly, the temperature of the expanded battery becomes lower than the temperature of the non-expanded battery, and further expansion and deterioration of the expanded battery are suppressed, which can greatly contribute to uniform battery life.

Further, if the width S of the slit and the width d of the gap between the batteries are set to satisfy 25% ≦ S / d ≦ 50%, the battery of the type sandwiching the insulating separator shown in Patent Document 2 Compared with the cooling structure, the battery temperature can be made equal to or lower, and the cooling efficiency of the battery cooling system can be improved. Furthermore, in this range, it is possible to effectively suppress the change in the cooling air volume under severe conditions, particularly where the gap between the batteries is halved.

Further, if a spacer member capable of suppressing the width between the battery gaps from being narrowed to 40% or less of the initial width is provided in the gap between the batteries, the battery temperature in the battery cooling system to which the present invention is applied. Can be suppressed particularly effectively.

In the present invention, even when the slit extending in the direction between the battery gaps is replaced with a through hole having an opening area Ah, the cross-sectional area when the gap between the batteries is viewed along the cooling air flow direction is represented by Ag. If the through hole is set so as to substantially satisfy Ah ≦ Ag, the same effect can be exhibited.

It is sectional drawing which shows the battery cooling structure of embodiment of this invention. It is an exploded view which shows the structure of the assembled battery structure used for the battery cooling structure of embodiment of this invention, and a flow control board. It is a perspective view which shows the flow control board used for embodiment of this invention. It is a graph which shows the relationship of the flow volume change with respect to the clearance gap between batteries for every slit width. It is a graph which shows the relationship of the battery temperature change with respect to the clearance gap between batteries for every slit width. It is a graph which shows the minimum value of the battery temperature change at the time of the clearance gap between batteries changing with respect to a slit width. It is a graph which shows the cooling air flow rate change with respect to a slit width on the basis of a comparative example. It is a graph which shows the change of the battery temperature with respect to the change between battery gaps for every slit width on the basis of a comparative example. It is a graph which shows the minimum value of the battery temperature change at the time of the gap between batteries changing with respect to a slit width on the basis of the temperature change of a comparative example. It is sectional drawing which shows the flow control board vicinity in the battery cooling structure of 2nd Embodiment of this invention. It is a figure which shows the other example of a shape of the slit in this invention. It is a figure which shows the example of the conventional battery cooling structure. It is a figure which shows the example (comparative example 2) of the conventional battery cooling structure.

Hereinafter, an embodiment of a battery cooling structure of the present invention will be described with reference to the drawings, taking a battery cooling structure for cooling an assembled battery for a hybrid vehicle as an example. FIG. 1 is a cross-sectional view of a first embodiment of the battery cooling structure of the present invention. FIG. 2 is an exploded view showing the structure and configuration of the flow control plate and the assembled battery incorporated in the battery cooling structure of this embodiment.

The battery cooling structure of the embodiment of the present invention shown in FIG. 1 will be described. A plurality of flat batteries 2, 2 are arranged in a battery case 6 as an assembled battery structure 1 arranged in a stacked manner with a predetermined gap therebetween. The flat batteries 2 and 2 are arranged so as to extend in the depth direction in FIG. 1, and the batteries 2 and 2 have a predetermined interval (gap) between the inner surface of the battery case 6 and an adjacent battery. It is accommodated and supported inside the box-shaped battery case 6 by spacers and support members so that the cooling air flows through the gaps.

The battery case 6 is a hollow box-shaped member formed of metal or synthetic resin. The battery case 6 is provided with a cooling air inlet 61 and a cooling air outlet 62 to cool the internal space of the battery case 6. It becomes a wind passage. The battery case 6 is used for cooling the assembled battery by connecting the cooling air inlet 61 and the cooling air outlet 62 with peripheral members such as a duct and a blower fan to form a series of cooling air passages.

In this embodiment, a blower fan (not shown) is provided on the downstream side of the cooling air outlet 62, and a cooling air duct (not shown) connected to the upstream side of the cooling air inlet 61 on the upper left in the drawing. Then, the cooling air flows into the battery case 6, cools the battery while passing through the gaps between the batteries 2, 2 and the battery case 6, and is heated from the cooling air outlet 62 to the lower right side of the figure. Cooling air flows out.

The assembled battery structure 1 incorporated in the battery cooling structure of the present embodiment will be described. FIG. 2 shows an exploded view of the battery cooling structure of the present embodiment with the battery case omitted, and the assembled battery structure 1 includes a battery 2, a holder member 3, and an end plate 4 assembled together. It is configured. The flat batteries 2 and 2 constituting the assembled battery are arranged in a stacked state at a predetermined interval from each other. The batteries 2 and 2 are electrically connected in series or in parallel to form an assembled battery. In the present embodiment, the battery constituting the battery module is a lithium ion battery, and the battery 2 has a flat plate shape (flat rectangular parallelepiped shape). The batteries 2 and 2 are laminated so that the wide flat surfaces face each other, and terminals are provided on the side surfaces (surfaces adjacent to the wide flat surfaces) of the respective batteries.

In order for the batteries 2 and 2 to be positioned and held in a stacked state, a pair of holder members 3 and 3 are provided so as to face the side surfaces of the batteries 2 and 2. The holder member 3 is formed in a plate shape so as to cover the entire side surface portions at both ends of the batteries 2 and 2, and the holder members 3 and 3 are provided with holding portions 31 each having a shape for holding the both end portions 21 and 21 of the battery. , 31 are provided. In the present embodiment, the holding portion 31 is provided so as to protrude from the holder member main body in a shape that surrounds and fits the both end portions 21 of the battery. The holder member is provided with a through hole H through which a terminal portion of the battery, a fixing protrusion and the like pass. The battery terminals exposed to the outside through the through holes of the holder member are connected to each other to function as an assembled battery.

A pair of end plates 4, 4 are provided so as to face the wide surfaces of the batteries at both ends in the stacking direction of the assembled battery positioned in a stacked manner. A pair of holder members 3, 3 are attached to the end plates 4, 4 and are fixed by bolts, bands or the like, and serve to maintain the battery fixing structure. The end plates 4 and 4 can be omitted or simplified as long as the holder member is appropriately attached. The batteries 2 and 2 are assembled in the battery case 6 as the assembled battery structure 1 including a holder member and an end plate.

In the present embodiment, the holder members 3 and 3 and the end plates 4 and 4 constitute a square tube-shaped ventilation path and a part of the cooling air ventilation path. In this way, the holder member and the end plate can be used as the battery case 6 that defines the cooling air passage. Note that the cooling air ventilation path does not necessarily have to be configured by the holder members 3 and 3 and the end plates 4 and 4, and the ventilation path can also be configured solely by the battery case.

In the present invention, a flow control plate 5 is provided inside the battery case 6 so as to partition the internal space of the battery case into a cooling air inlet side and a cooling air outlet side, and to block the flow of the cooling air. Yes. In the present embodiment, the flow control plate 5 is sized so as to cover the upstream edge of the assembled battery, and is substantially the same as the edge of the assembled battery at a position upstream of the assembled battery. It is integrally attached to the battery case 6 so as to be parallel.

As shown in FIG. 1 and its perspective view in FIGS. 2 and 3, the flow control plate 5 is provided with a plurality of slits 51, 51 extending in the direction along the gap between the batteries. Yes. In the present embodiment, the slits 51 and 51 correspond to the gaps between the batteries, and the position where one slit 51 faces the gap between the batteries with respect to one gap (that is, the stacking direction of the batteries). In the middle position of adjacent batteries). Moreover, the slit 51 is provided in the shape of a long hole having a length extending over the entire length of the gap in the length direction of the gap between the batteries (the depth direction in FIG. 1).

The slits 51 and 51 are provided through the flow control plate 5 so as to communicate the upstream space and the downstream space of the flow control plate 5 with each other. Then, the cooling air whose flow is blocked by the flow control plate 5 flows from the upstream side to the downstream side through the slits 51 provided in the flow control plate.

Further, in this embodiment, the ridges 52, 52 are formed in the portion where the flow control plate 5 faces the upstream edge of the battery 2, and the tip of the ridge 52 contacts the upstream edge of the battery. Touch and seal. By adopting such a configuration, the cooling air passages constituted by the slits 51 provided corresponding to each other and the gaps between the batteries become a plurality of independent cooling air passages. These independent cooling air passages are arranged in parallel in the battery case 6. And by adjusting the width of each slit, the flow rate of the cooling air flowing through each inter-battery gap can be adjusted independently.

The width S of the slits 51 and 51 is set to be equal to or smaller than the width d of the gap between the batteries (that is, S ≦ d), and the cooling air flow between the batteries is throttled by the slits 51 and 51. The flow rate is adjusted. For example, in this embodiment, the width S of the slit 51 is 40% of the width d of the gap between the batteries as viewed along the flow direction of the cooling air flowing in the gap between the batteries (the vertical direction in FIG. 1). That is, S / d = 0.4).

As will be described later, in order to reduce the change in the cooling air flow rate and the change in the battery temperature with respect to the change in the gap between the batteries due to the expansion of the battery, etc., and to cool the battery effectively, the width S of the slit 51 is set. What is necessary is just to set it as 100% or less with respect to the width | variety d of the clearance gap between batteries, More preferably, it is good to set it as 70% or less, Most preferably, it is 50% or less. On the other hand, if the width S of the slit 51 is too small, the air blowing resistance of the cooling air increases, so the width S of the slit 51 may be 10% or more of the width d of the gap between the batteries, more preferably 17% or more. Especially preferably, it is good to make it 25% or more.

The manufacturing method of the battery case constituting the battery cooling structure can be performed by a known manufacturing method. For example, the battery case 6 is made of a synthetic resin (for example, polypropylene resin) with a case member divided into an open box and a lid. It can be formed by injection molding. The flow control plate 5 can also be formed by injection molding of a synthetic resin (for example, polypropylene resin), and may be integrally formed with the case member of the battery case 6 if possible. Of course, the flow control plate 5 may be formed separately from the case by injection molding of a metal plate or synthetic resin and attached at a predetermined position when the battery case is assembled.

The assembled battery structure 1 incorporated in the battery cooling structure can be configured by a known manufacturing method. For example, the holder member 3 and the end plate 4 can be manufactured, for example, by injection molding of a synthetic resin, and can be combined with each other via a fastening member such as a bolt or a clip to constitute the assembled battery structure. These members can be made of metal members according to requirements such as strength and thermal requirements.

It is preferable to provide a sealing material made of rubber, elastomer, foamed resin, or the like at a portion of the battery case, holder member, or end plate that requires sealing performance. Moreover, it is also a preferred embodiment that at least a part of these members is integrally formed with rubber or elastomer.

The completed battery structure 1 is arranged at a predetermined position in the battery case 6, the battery case lid is closed with the flow control plate 5 incorporated, and the battery case in which the assembled battery of the above embodiment is accommodated and the battery cooling The structure is completed.

The operation and effect of the battery cooling structure of the present invention will be described.

In the present invention, as in the first embodiment, the slits 51 provided in correspondence with each other and the gaps between the batteries constitute a series of ventilation paths, and each of the gaps between the batteries is provided by the ridges 52 and the like. Independent cooling air passages are arranged in parallel. Therefore, by adjusting the width and size of the slits provided in the respective ventilation paths, the flow rate of the cooling air flowing through the respective inter-battery gaps can be adjusted independently. Even if there is a difference in the amount of cooling air supplied to the gaps between the batteries due to restrictions on the configuration and shape of the battery case 6, it is possible to distribute the cooling air between the batteries by adopting such a configuration. The variation can be reduced, which is effective for making the battery temperature uniform.

Furthermore, in the assembled battery structure of the present invention, the width S of the slit provided in the flow control plate is in a range of S ≦ d compared to the width d of the gap between the batteries. Even if the battery constituting the battery expands and the width of the cooling air passage (gap between the batteries) changes, the influence on the ventilation resistance of each cooling air passage is reduced. Therefore, according to the present invention, it is possible to suppress a change in the flow rate of the cooling air, effectively cool the battery while suppressing the influence of the battery expansion, and make the battery temperature of the assembled battery uniform.

In the conventional battery cooling structure shown in Patent Document 1 shown in FIG. 12 (refer to FIG. 3 in Patent Document 1 as FIG. 12), the resistance of the cooling air flowing through the gap between the batteries is It was mainly determined by the width of the gap between the batteries, and the flow rate was small when the width was narrow, and the flow rate was large when the width was large.

On the other hand, according to the battery cooling structure of the present invention, since the slit width of the flow control plate provided on the upstream or downstream side of the assembled battery is set to be equal to or less than the gap between the batteries, the airflow resistance generated in the cooling air flow is generated. The contribution of the slit in the factor is large. That is, in the present invention, it becomes possible to adjust the cooling air volume by restricting the flow by the slit. On the other hand, the effect of the change in the size of the gap between the batteries on the cooling airflow is relatively small. According to the present invention, even if the gap between the batteries changes somewhat, the change in the cooling airflow is suppressed. Will come to be.

The inventor calculated the ventilation resistance, the flow rate, and the battery surface temperature of the independent flow path portion constituted by the slit and the gap between the batteries by a thermal fluid simulation study on the above effect.
As an independent channel model, a flow channel having a width S on the upstream side and a downstream channel having a width d corresponding to the gap between the batteries is assumed, and the flow is assumed assuming a two-dimensional flow. A numerical fluid analysis is performed to determine a flow rate of cooling air at a given pressure difference between the uppermost stream and the downstream side of the path, and a heat conduction analysis is performed to give a predetermined cooling air temperature and a heat generation amount of the battery. The battery surface temperature was determined in combination with fluid analysis. Then, the change in the flow rate and the change in the battery surface temperature when the gap d between the batteries became smaller due to the expansion of the battery were obtained.

As an example corresponding to the first embodiment, the width S of the slit provided in the flow control plate is variously changed in comparison with the width between the battery gaps (initial width), and the above calculation is performed. went. In the following description of the simulation results, the width of the gap between the batteries is described as d0 as the initial width before the battery expands, and as the width when the battery expands and narrows as d.
In a series of studies, regarding the width S of the slit 51, the gap (initial width) d0 between the batteries is fixed, and the value of the slit width S based on the reference dimension d0 of the initial gap between the batteries, that is, S / d0. The thermal fluid simulation calculation was performed for the case where the values were 17%, 34%, 52%, 69%, 86%, and 100%.

In the series of simulations, typical specifications of the system that performed the calculation are as follows. The initial gap between the batteries was 3 mm, and the length of the battery along the cooling air flow direction was 110 mm. And the thickness of the flow control board provided with the slit was 2 mm. In the flow analysis, the pressure difference in the section from the upstream side of the flow control plate provided upstream of the battery to the most downstream part between the battery gaps was calculated as 55 Pa, and the steady solution of the flow field and the heat conduction field was obtained. .

Further, as Comparative Example 1, an example in which there is no flow control plate or slit upstream of the battery gap (corresponding to the prior art of Patent Document 1) was calculated. In Comparative Example 1, the calculation result graph indicates “no slit”.

The calculation results are shown in FIGS.
FIG. 4 shows the result of calculating the change in the flow rate of the cooling air when the gap between the batteries is reduced by changing the slit width. On the horizontal axis, the change in the inter-battery gap (battery channel width) is shown as d / d0, where d0 is the initial width between the battery gaps (battery gap before the battery expands). On the vertical axis, the change in the flow rate Q flowing through the cooling air passage is shown as Q / Q0, where Q0 is the initial flow rate before the battery expands.

According to FIG. 4, when the battery expands and the gap between the batteries becomes narrow (d / d0 becomes smaller), the cooling air flow rate tends to become smaller than the initial flow rate (Q / Q0 becomes smaller). In particular, in Comparative Example 1 (without slits), the flow rate decreases so as to be approximately proportional to the decrease in the inter-battery gap, whereas in each example of the present invention, the inter-battery gap decreases. It can be seen that the change in flow rate during the process is suppressed. In particular, when the slit width is set to S / d0 ≦ 70%, the effect of suppressing the flow rate change becomes remarkable, and when S / d0 ≦ 50%, the gap between the batteries is reduced to 80%. The change in flow rate can be reduced to 1/3 or less as compared with Comparative Example 1, and the effect becomes more remarkable. Moreover, it turns out that the flow volume change inhibitory effect can be maintained to the area | region where the gap between batteries became narrower by providing a narrower slit. For example, by setting S / d0 ≦ 34%, the flow rate change when the inter-battery gap is reduced to 40% can be reduced to 2/3 or less compared to Comparative Example 1, and S / d0 ≦ 17% Thus, the flow rate change when the inter-battery gap is reduced to 40% can be reduced to 1/3 or less as compared with Comparative Example 1.

FIG. 5 shows the result of calculation of the change in battery surface temperature when the gap between the batteries is reduced by changing the slit width. The change in the battery surface temperature is graphed by calculating the temperature difference (T) between the average value of the temperature of the entire surface of the battery and the incoming cooling air. The vertical axis of the graph indicates the battery surface temperature change (T−T0) / T0, where T0 is the difference between the battery surface temperature in the initial state before the battery expands and the cooling air temperature flowing in. A positive value of the battery surface temperature change (T−T0) / T0 indicates that the battery surface temperature has increased due to a decrease in the width of the battery gap, and conversely, (T−T0) / T0. A negative value indicates that the battery surface temperature has decreased due to a decrease in the width of the battery gap. In FIG. 5, the calculation example lines with S / d0 of 86% and 100% almost overlap each other, and the calculation example lines with S / d0 of 52% and 70% also almost overlap each other.

According to FIG. 5, according to the embodiment of the present invention, surprisingly, until the inter-battery gap is reduced to 60%, rather, the battery surface temperature is lowered when the inter-battery gap is reduced ( That is, it can be seen that (T−T0) / T0 becomes negative. On the other hand, in Comparative Example 1 (without slits), such an effect is very weak, and it can be seen that the battery surface temperature increases when the inter-battery gap is reduced to about 60%.

In the examples of the present invention, the effect of lowering the battery surface temperature when the inter-battery gap is reduced is presumed to be based on the following mechanism. In the embodiment of the present invention, the flow rate Q is maintained even when the inter-battery gap d decreases. Here, when the inter-battery gap d decreases, the cross-sectional area of the flow path between the batteries decreases, so if the flow rate Q is maintained, the flow rate of the cooling air increases, and the efficiency of heat exchange between the battery surface and the cooling air Is increased. Due to the effect of improving the heat exchange efficiency, in the embodiment of the present invention, even when the inter-battery gap d decreases, until the decrease in the flow rate Q becomes significant (d / d0 ≧ 60%), It is estimated that the battery surface temperature is lowered.

FIG. 6 shows how the effect of lowering the battery surface temperature due to the decrease between the battery gaps shown in FIG. 5 changes depending on the slit width. In FIG. 6, the horizontal axis indicates S / d0 in which the slit width is normalized by the gap between the batteries (initial value), and the vertical axis indicates the minimum value of the battery surface temperature change (T−T0) / T0 in the graph of FIG. Is plotted.

In Comparative Example 1 (without slits), the minimum value of the battery surface temperature change was −0.5%, and almost no effect was observed. On the other hand, in the example of the present invention, the minimum value of the battery surface temperature change was − From 1% to -5%, it can be seen that the battery expands and the temperature of the battery facing the gap with reduced width is rather lowered. In particular, if the slit width is set so that S / d0 is 10% to 70%, the minimum value of battery surface temperature change can be -2 to -5%, and the battery cooling effect is effective. Can get to.

The remarkable battery cooling effect that occurs in the above-described embodiment of the present invention, in which the battery surface temperature decreases rather when the inter-battery gap is reduced, is very useful for extending the life of the assembled battery. According to the conventional battery cooling system, when the battery expands, the flow of the cooling air does not flow well between the battery gaps narrowed by the expansion, the temperature of the battery facing the gap rises, the deterioration of the battery, There was a tendency for further expansion of the battery, and it was easy for the battery to expand and deteriorate at an accelerated rate. Therefore, it is difficult to make the battery deterioration and the battery life uniform, and there is a tendency that the life of the entire assembled battery is shortened due to the expansion and deterioration of some batteries.

However, according to the present invention, when the gap between the batteries is reduced due to the expansion of the battery, the surface temperature of the battery facing the gap is lowered, and the deterioration and further expansion of the battery are suppressed as compared with other batteries. It becomes like this. Therefore, the lifetime of each battery is made uniform, and the lifetime of the entire assembled battery is also increased. In addition, since the battery temperature rise is accelerated when the inter-battery gap is reduced, the robustness of the battery cooling system is also improved.

In the embodiment of the present invention, when the slit width S is small, the airflow resistance tends to increase and the air volume tends to decrease. FIG. 7 shows changes in the cooling air flow rate when the slit width (S / d0) is changed. The cooling air flow rate on the vertical axis is normalized by the cooling air flow rate Q_HOLDER in Comparative Example 2 described later, and is indicated as Q / Q_HOLDER. Here, the comparative example 2 is an example in which the same calculation was performed for a battery cooling structure in which an insulating separator as shown in Patent Document 2 is sandwiched between batteries. In Comparative Example 2, as shown in the outline of the calculation model in FIG. 13, a plate having a thickness d0 / 3 imitating the separators 8 and 8 is formed at the center between the battery gaps of the width d0 between the batteries 2 and 2. The calculation is performed as a battery cooling structure in which a cooling air passage is provided and there is no slit or flow control plate as in the present invention.

As shown in FIG. 7, in the present invention, the larger the slit width, the lower the airflow resistance of the battery cooling system, and more cooling air for a predetermined pressure difference (55 Pa in the above calculation example). It can flow. Further, according to the embodiment of the present invention, as long as the slit width S is set to satisfy S / d0 ≧ 17%, more cooling air can be obtained as compared with Comparative Example 2 having the same specifications. The battery cooling system can be reduced by reducing the load of the battery cooling system.

In FIG. 8, the change of the battery surface temperature when the gap between the batteries decreases is shown for each slit width on the basis of the battery surface temperature of Comparative Example 2. The vertical axis represents T / T_HOLDER in which the battery surface temperature is normalized by the battery surface temperature T_HOLDER of Comparative Example 2.

Further, FIG. 9 shows how the battery surface temperature changes as compared with Comparative Example 2 depending on the slit width. In FIG. 9, the vertical axis indicates T / T_HOLDER in which the battery surface temperature is normalized by the battery surface temperature T_HOLDER of Comparative Example 2 as in FIG. 8, and the horizontal axis indicates the slit width by S / d0.

According to FIG. 9, in the example of the present invention, the battery surface temperature can be lowered as compared with Comparative Example 2 in the region where S / d0 ≧ 25% (that is, T / T_HOLDER ≦ 100%). Even when compared with a battery cooling structure of the type in which the effect is obtained and the insulating separator shown in Patent Document 2 is sandwiched between batteries, there is an advantage that the battery surface temperature can be lowered.

As described above, if the slit width is less than or equal to the width between the corresponding battery gaps, the flow of cooling air can be changed even if the gap between the batteries changes while flowing a practical cooling air volume as a battery cooling system. Therefore, the battery can be effectively cooled, the uniformity of the battery temperature of the assembled battery can be maintained, and as a result, the battery life can be made uniform.

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, an example of changing the slit provided in the flow control plate will be described. The slits provided corresponding to the gaps between the batteries do not necessarily have to be provided in a one-to-one correspondence as in the above embodiment, and two or more slits are provided for each gap between the batteries. It is also possible to implement the present invention by providing a slit.

For example, FIG. 10 shows a cross section of the batteries 2 and 2 and the flow control plate 7 in the battery cooling structure of the second embodiment of the present invention. In the present embodiment, the flow control plate 7 is configured so that two slits 71 and 72 correspond to one gap between batteries. The two slits 71 and 72 are provided at positions that are substantially symmetrical with respect to the center plane between the battery gaps, and the first slit 71 is the upstream edge of the battery on the left side of the gap between the batteries in the figure. The second slit 72 is provided with a width S2 at a position facing the upstream edge of the battery on the right side of the gap of the battery in the figure. Yes. As in the first embodiment, these slits are configured such that independent flow paths are constituted by two slits corresponding to each other and one inter-battery gap. The width between the two slits and the gap between the batteries is the ratio of the total slit width (S1 + S2) to the width d between the gaps in the range of the slit width and the gap between the batteries in the first embodiment. Thus (that is, S1 + S2 ≦ d), the widths S1 and S2 of the respective slits are determined.

In this way, even if the number and shape of the slits change, the slit width and the opening area are summed up according to the correspondence with the gap between the batteries so that the slit width is equal to or less than the width between the battery gaps. Thus, the present invention can be implemented, and the same effect as that of the first embodiment can be obtained.

And according to this embodiment, a cooling wind flow is further improved in the inside of each independent flow path comprised by the slits 71 and 72 and the clearance gap between batteries. That is, the cooling air introduced from the first slit 71 flows along the left battery surface with respect to the gap, and the cooling air introduced from the second slit 72 along the right battery surface with respect to the gap. It begins to flow. In this way, new cooling air can be reliably guided to the surface of each battery. Therefore, according to this embodiment, the efficiency of battery cooling can be further improved. In addition, the slit widths S1 and S2 can be independently adjusted to adjust the degree of cooling of the left and right batteries to the gap to some extent, which is also effective in making the battery temperature uniform.

Further, in the above two embodiments, the case where the slit is one continuous long hole has been described, but other types of slits can be used. For example, a plurality of elongated holes 81, 81 are arranged side by side in the long axis direction to form a slit (see FIG. 11A), or a plurality of rectangular holes 82, 82 are arranged side by side to form a slit (FIG. 11). (See (b)), or a plurality of small holes 83, 83 dispersed in an elongated region (for example, in a mesh shape) to form slits (see FIG. 11 (c)). In short, in the present invention, the flow control plate can be used as a slit by providing a through-hole or a breathable portion over the elongated region in the direction along the gap between the batteries.

In the description of the above-described embodiment, the embodiment of the invention in which the slit extending in the direction along the gap between the batteries is provided in the flow control plate has been described. However, the slit provided in the flow control plate is used as a through hole in a form other than the slit. It is also possible to implement the present invention in a more expanded form with modification. The effects exhibited by the present invention are generated in the slits and through holes of the flow control plate by the size of the ventilation resistance generated in the gap between the batteries and the size of the ventilation resistance generated in the slits and through holes of the flow control plate. This is due to the increased contribution of ventilation resistance. Therefore, the present invention can also be implemented by providing a through hole in the flow control plate so that the slit and the ventilation resistance are equivalent.

Furthermore, the inventor examined the flow of cooling air passing through the flow control plate. It was found that the ventilation resistance of the cooling air flow passing through the through hole provided in the flow control plate is governed by the cross-sectional area Ah of the through hole. Then, it was found that the ventilation resistance is generally inversely proportional to the square of the cross-sectional area Ah of the through hole.

Furthermore, the inventor measured the ventilation resistance of the cooling air flow passing through the through hole of the flow control plate by changing the shape of the through hole. That is, a flow control plate is provided to block the cooling air in the cooling air passage of the test apparatus, and a through hole whose shape (especially the aspect ratio of the through hole) is changed is provided in the flow control plate, so that a constant amount of cooling air is supplied. The pressure resistance was measured by measuring the pressure difference between the upstream side and the downstream side of the flow control plate. In the test, the opening area of the through hole was 200 square mm, and the air volume was 22 L / min.

Table 1 shows the shape of the aperture hole in which the test was performed and the measurement results of the ventilation resistance. The ventilation resistance is shown by being standardized by the ventilation resistance when the through hole is formed in the shape of the through hole A (100 mm × 2 mm long and narrow through hole shape).

According to the measurement results, it was found that even if the aspect ratio of the through hole changes greatly, the ventilation resistance does not change greatly if the cross-sectional area of the through hole is the same. That is, even if the aspect ratio of the through hole is changed greatly, the change given to the ventilation resistance is only 20% or less, and it can be seen that the cross-sectional area of the through hole is more dominant in the ventilation resistance than the shape of the through hole. That is, if the cross-sectional area is the same, the ventilation resistance is substantially equal for the elongated slit and the general-shaped (for example, circular) through hole.

Therefore, even if the slit of the flow control plate described in the first embodiment is replaced with a through hole having the same cross-sectional area as that of the slit, it can be understood that the same effect as that of the first embodiment is exhibited. . The shape of the through hole is not limited to an elongated shape such as a slit, and can be various shapes such as a circle, an ellipse, a rectangle (square, rectangle), and a rhombus.

Therefore, according to the present invention, a battery pack in which a plurality of flat batteries are arranged in a stacked manner with a predetermined gap is accommodated in the battery case, and the cooling air flowing through the battery case is exchanged between the batteries. In a battery cooling structure that cools a battery by passing it through a gap, a flow control plate is disposed on the upstream side or downstream side of the assembled battery so as to block a cooling air passage, and the flow control plate includes a battery. Through holes are provided corresponding to each of the gaps, and cooling air flows from the upstream side to the downstream side of the flow control plate through the through holes, and the gaps between the corresponding through holes and the batteries The formed air passages are independent air passages arranged in parallel with each other, the opening area of the through holes is Ah, and the gap between the batteries is viewed along the cooling air flow direction. Assuming that the cross-sectional area is Ag, Be in the form of battery cooling structure such that h ≦ Ag is feasible, the same effect as the first embodiment are exhibited

Here, the cross-sectional area Ag of the gap between the batteries is a cross-sectional area of the gap when the gap is viewed along the cooling air flow direction. More specifically, the width between the battery gaps is d, Is a cross-sectional area obtained by Ag = d * W where W is the width in the paper surface depth direction (W).

The through hole provided in the flow control plate can have an arbitrary shape. If the through hole is set so that Ah ≦ Ag substantially, the ventilation resistance of the through hole portion is less than the overall ventilation resistance. It can be seen that the same effects as those of the first embodiment in which the flow control plate is provided with the slit can be exhibited.

When a plurality of through holes correspond to the gaps between the batteries, the areas of the respective through holes are added so that the added opening area is smaller than the cross-sectional area between the battery gaps. You can do it. For example, if there are three through holes corresponding to a gap between one battery and the opening areas of the respective through holes are A1, A2, and A3, the opening area Ah of the three through holes is represented by Ah = (A1 + A2 + A3). ) And the specific dimension of the through hole may be determined so that this is smaller than the cross-sectional area Ag between the battery gaps, that is, (A1 + A2 + A3) ≦ Ag.

Note that the size of the opening area Ah of the through holes provided corresponding to each other and the cross-sectional area Ag between the battery gaps is the airflow resistance generated in the through holes from the viewpoint of the size of the airflow resistance generated in each part. So that Ah ≦ Ag. As shown in Table 1, when the aspect ratio of the through hole approaches 1: 1, the ventilation resistance tends to increase by about 10 to 20%, and the ventilation resistance of the through hole is 2 of the opening area of the through hole. Since it is inversely proportional to the power, for example, if the opening area Ah of a circular or square through hole is about 1.1 times the inter-battery gap Ag, it is included in the range of substantially Ah ≦ Ag.

In the first embodiment, the slit width is S and the gap between the batteries is d, and it has been shown that a more specific effect can be obtained when the S / d value falls within a specific numerical range. Moreover, it can be expanded when a through hole having a general shape is provided. Therefore, in this embodiment in which the opening area of the through hole is Ah and the cross-sectional area between the battery gaps is Ag, S / d in the first embodiment can be replaced with Ah / Ag. When the value falls within a specific numerical range, the specific effect as shown in the first embodiment can be obtained similarly.

That is, if 17% ≦ Ah / Ag ≦ 70%, the airflow resistance of the cooling air can be made equal to or less than that of the battery cooling structure of the type sandwiching the insulating separator shown in Patent Document 2. It is possible to increase the cooling efficiency of the battery cooling system. In this range, when the battery expands and the gap between the batteries becomes narrow, the temperature of the battery can be lowered even if the cooling conditions are the same. Accordingly, the temperature of the expanded battery becomes lower than the temperature of the non-expanded battery, and further expansion and deterioration of the expanded battery are suppressed, which can greatly contribute to uniform battery life.

Furthermore, if 25% ≦ Ah / Ag ≦ 50%, the battery temperature can be made equal or lower than that of the battery cooling structure of the type shown in Patent Document 2 that sandwiches the insulating separator. The cooling efficiency of the battery cooling system can be increased. Furthermore, in this range, it is possible to effectively suppress the change in the cooling air volume under severe conditions, particularly where the gap between the batteries is halved.

In addition, the specific configuration when the cooling air passages formed by the slits / through holes and the gaps between the batteries are arranged in parallel independently of each other is replaced with the ridges 52 shown in the first embodiment. Other configurations can also be employed. For example, instead of the ridges 52, the flat plate portion of the flow control plate may be brought into direct contact with the battery edge, or a partition member that is a separate member may be provided between the flow control plate and the battery edge. Moreover, it is preferable to provide a sealing member made of rubber, elastomer, foamed resin, or the like as necessary at the contact portion of these members.

Moreover, it is also a preferable embodiment in the practice of the present invention to suppress excessive expansion of the battery by appropriately interposing a spacer between the batteries arranged in a stack with a predetermined gap. As seen in FIGS. 4 and 5, etc., when the gap between the batteries becomes too small (for example, d / d0 <40%), the cooling air flow rate is reduced and the battery is reduced in the embodiment of the present invention. Since the surface temperature rises significantly, when implementing the present invention, an additional means for limiting expansion displacement such as a spacer sandwiched between the batteries is additionally provided to prevent the gap between the batteries from becoming excessively small. It is preferable to do so. Examples of the spacer member as the battery expansion suppressing member include a rod-like member, a comb-like member, and a plate-like member. The spacer member may be a ring-shaped member (such as a rubber band) wound around the battery. These spacer members are preferably arranged along the cooling air flow direction so as not to disturb the cooling air flow. The material of the spacer member may be a relatively hard material such as metal or synthetic resin, but may be a relatively soft material such as elastomer or rubber.

If such a spacer member is used in combination with the structure of the flow control plate or slit of the present invention, the gap between the batteries can be reliably suppressed / prevented, so the effect of the present invention can be more reliably achieved. It can be demonstrated.

In addition, the position where the flow control plate is provided may be on either the upstream side or the downstream side of the assembled battery. However, if the flow control plate is located on the upstream side of the assembled battery, the cooling air that blows out from the slit is more flat. It is preferable that the flow control plate is provided on the upstream side of the assembled battery because it is easy to improve the cooling efficiency of the battery by being applied to the surface of the battery.

In 1st Embodiment, although the holder member 3 and the end plate 4 which comprise the assembled battery structure 1 were comprised by plate-shaped member, and embodiment was used as a square tube-shaped ventilation path, it comprised in this way. In such a case, these members can be used as a part of the battery case. When having a battery case that can constitute a cooling air passage by itself, the holder member and the end plate do not necessarily have to be plate-shaped, and the rod-shaped member and block are within the range in which the structure of the assembled battery can be appropriately maintained. You may comprise by a shape member, a band member, etc. Moreover, these members can also be divided | segmented suitably and comprised.

Further, in the description of the above embodiment, the form in which the assembled battery is accommodated in the hollow box-shaped battery case 1 has been described, but the embodiment of the battery case is limited to a hollow box-shaped one that is molded exclusively for the case. The battery case may be configured by combining a plurality of members such as a panel member and a block member. For example, an assembled battery is arranged on a floor panel of a vehicle body, a heat insulating panel or an electrode panel is provided so as to surround the assembled battery, and a battery case having a cooling air passage between the floor panel, the heat insulating panel, and the electrode panel is provided. It can also be configured. As described above, the battery case according to the present invention includes a battery case constituted by using / combining a member arranged around the assembled battery, in addition to the battery case constituted by a dedicated component member.

Examples of the battery constituting the assembled battery include a primary battery, a secondary battery (such as a lithium ion battery, a nickel hydride battery, and a nickel cadmium battery), a double electric capacitor, and the like. In the above embodiment, the battery has been described as having a flat plate shape, but the surface does not have to be completely flat, and is a battery having uneven strips for improving cooling performance and improving the rigidity of the battery outer can. There may be.

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 used for cooling assembled batteries used in a wide range of applications.

INDUSTRIAL APPLICABILITY The present invention can be used as a battery cooling structure for large-capacity assembled batteries used in electric vehicles, hybrid vehicles, power generators, and the like, and can effectively cool flat batteries constituting the assembled batteries. In addition, the industrial utility value is high, such as high robustness against battery expansion.

DESCRIPTION OF SYMBOLS 1 Battery assembly 2 Battery 3 Holder member 31 Holding part 4 End plate 5 Flow control plate 51 Slit 52 Projection 6 Battery case 7 Flow control plates 71, 72 Slit 8 Separator

Claims (5)

A battery pack in which a plurality of flat batteries are arranged in a stack with a predetermined gap is housed in the battery case, and the cooling air flowing through the battery case passes through the gap between the batteries. A battery cooling structure for sending and cooling the battery,
On the upstream side or downstream side of the assembled battery, a flow control plate is arranged so as to block the passage of the cooling air, and the flow control plate is provided with a slit extending in the direction along the gap between the batteries, The cooling air is allowed to flow from the upstream side to the downstream side of the flow control plate through the slit,
A slit is provided corresponding to each of the gaps between the batteries, and the ventilation paths formed by the slits corresponding to each other and the gaps between the batteries are independent and arranged in parallel with each other,
A battery cooling structure in which the width S of the slit is S ≦ d compared to the width d of the gap between the batteries when viewed along the cooling air flow direction in the gap between the batteries. 2. The battery cooling structure according to claim 1, wherein a width S of the slit is 17% ≦ S / d ≦ 70% compared to a width d of a gap between the batteries. The battery cooling structure according to claim 2, wherein the slit width S is 25% ≦ S / d ≦ 50% compared to the width d of the gap between the batteries. The spacer member which can suppress that the width | variety between the said battery gaps narrows to 40% or less of the initial width of a gap | interval was provided in the clearance gap between batteries. Battery cooling structure. A battery pack in which a plurality of flat batteries are arranged in a stack with a predetermined gap is housed in the battery case, and the cooling air flowing through the battery case passes through the gap between the batteries. A battery cooling structure for sending and cooling the battery,
On the upstream side or downstream side of the assembled battery, a flow control plate is arranged so as to block the cooling air passage, and the flow control plate is provided with through holes corresponding to each of the gaps between the batteries. The cooling air is allowed to flow from the upstream side to the downstream side of the flow control plate through the hole,
The ventilation path formed by the through hole and the gap between the batteries corresponding to each other is made to be a ventilation path arranged independently and in parallel with each other,
A battery cooling structure in which Ah is an opening area of the through hole, and Ag is a cross-sectional area when the gap between the batteries is viewed along the cooling air flow direction.

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