JP2016177924A - Heat radiation mechanism in power storage device using secondary battery cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the temperature difference between battery cells generating heat in a power storage device using many battery cells when the battery cells are charged/discharged.SOLUTION: Cylindrical battery cell groups charged and discharged by a power storage device are arranged in rows to be adjacent to one another in a housing so that the axial directions of the battery cells 9 are parallel to one another. The housing is provided with an upstream-side passage and a downstream-side passage through which refrigerant is made to flow in a direction intersecting to the axial direction of the battery cell groups. A discharge member which contacts the battery cell groups along the peripheral surface shape of the battery cell groups and covers the battery cell groups at the downstream side is provided. A surface opposite to the surface on which the discharge member contacts the battery cell groups is a flat surface, a passage through which refrigerant flows is formed between the flat surface and the inner surface of the housing, and the passage is configured to be narrower toward the downstream side of the housing.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a heat dissipation mechanism that reduces a temperature difference between battery cells that generate heat during charging and discharging of battery cells in a power storage device using a large number of secondary battery cells.

  Interest in energy management is increasing against the background of consideration for the global environment and the problem of power supply in the event of an earthquake. A power storage device is indispensable for this energy management. This power storage device is used for peak shift of surplus power, stabilization of power supply, emergency power supply for server devices, and the like, and is expected to have a wide range of uses and roles in energy management.

In this power storage device, a large number of secondary battery cells (hereinafter referred to as “battery cells”) are connected in series and parallel, and charging and discharging are performed as necessary. However, the battery cells generate heat by this charging and discharging. become. Since battery cells show deterioration in characteristics such as shortening of the life or inability to charge and discharge at high temperatures, there is a need for measures that can stably exhibit battery characteristics.
As one of such measures, a battery cell cooling mechanism as shown in the following patent document has been proposed. In this cooling mechanism, battery cell groups are arranged in multiple stages at predetermined intervals, and a turbulent flow promoting body including a dummy battery unit is provided at the most upstream position of the casing through which air flows along the arrangement direction. Thus, it has been proposed to disturb the flow of air introduced into the housing.

JP 11-329518 A

  However, in the conventional cooling mechanism, it is necessary to arrange battery cells and the like at a predetermined interval and to provide a turbulent flow promoting body including a dummy battery unit at the most upstream position. It was not possible to arrange with high density.

  Accordingly, the present invention solves the conventional problems as described above, and provides a heat dissipation mechanism that can arrange battery cells in a housing at a high density and reduce the temperature difference of heat generation associated with charging and discharging of the battery cells. It is to provide.

  The present invention that solves the above-described problems includes a group of cylindrical battery cells that are charged and discharged by a power storage device, arranged adjacent to each other in a casing so that the axial directions of the battery cells are parallel to each other. Is provided with a passage through which the refrigerant flows in a direction perpendicular to the axial direction of the battery cell group, and is in contact with the circumferential surface of the battery cell group located at least downstream of the passage of the refrigerant along the circumferential shape. And a heat dissipating member covering the peripheral surface of these battery cell groups, a surface opposite to the surface contacting the battery cell group of the heat dissipating member is a flat surface, and between the flat surface and the inner surface of the housing The heat dissipation mechanism in the battery cell power storage device is characterized in that the passage through which the refrigerant flows is defined, and the passage becomes narrower toward the downstream side of the housing.

  According to the heat dissipation mechanism of the present invention, even when a large number of battery cells are densely arranged, by suppressing the temperature rise of at least some of the battery cell groups during charging and discharging. The temperature difference between battery cells can be reduced, and the occurrence of individual differences in charge / discharge characteristics between battery cells can be reduced.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

It is a perspective view which shows the thermal radiation mechanism in 1st Embodiment of this invention. It is a sectional side view which shows the thermal radiation mechanism in 1st Embodiment of this invention. It is a side view which shows the shape of the heat radiating member in 1st Embodiment of this invention. It is a figure which shows the battery cell arrangement | sequence used in order to demonstrate evaluation of the thermal radiation mechanism in 1st Embodiment of this invention. It is a perspective view which shows the thermal radiation mechanism in 2nd Embodiment of this invention. It is a sectional side view which shows the thermal radiation mechanism in 2nd Embodiment of this invention.

== First Embodiment ==
Hereinafter, with reference to FIGS. 1-2, an example of the thermal radiation mechanism in the electrical storage apparatus using the battery cell which concerns on this embodiment is shown.

  FIG. 1 is a perspective view of the heat dissipation mechanism 1 in the power storage device according to the first embodiment of the present invention when viewed from above with the top plate removed, and FIG. 2 is a side of the heat dissipation mechanism in the power storage device. It is sectional drawing. In the drawings, the X axis, the Y axis, and the Z axis indicate directions in order to clarify the positional relationship of each member in each drawing. The X axis is the left and right direction, and the Y axis is the front and rear. The direction and Z axis are defined as the vertical direction.

  The heat dissipation mechanism 1 according to the present embodiment includes a rectangular housing 2, and the housing 2 includes a bottom plate 2a, side plates 2b, 2c, and a top plate 2d (see FIG. 2). A refrigerant inlet 3 such as air is provided on the plate, a refrigerant outlet 4 is provided on the right side plate of the housing (see FIG. 2), and an exhaust fan 5 is attached to the outlet. When the exhaust fan 5 is driven, a refrigerant such as air enters the casing through the inlet 3, flows through the inside thereof, and is exhausted from the outlet 4. The charging / discharging control device 6 is accommodated in the left side of the housing, and a battery housing space 7 is provided in the housing portion on the right side thereof. The battery storage space 7 is defined by a partition plate 8 that extends in the left-right direction and is parallel to the front-rear direction. One partition plate 8 is arranged on each of the front end side and the rear end side, and two partition plates in the front-rear direction at positions where two battery storage spaces 7 are adjacently defined in the front-rear direction. 8 is arranged. That is, a total of six battery storage spaces 7 are defined by the 12 partition plates 8. The width of each battery storage space 7 in the front-rear direction is equal to the length of the battery cell 9 in the axial direction. In each battery storage space 7, a group of battery cells 9 arranged in a straight line with the cylindrical side surfaces in close contact in the left-right direction with the axial direction of the battery cells 9 as the front-rear direction is arranged in two upper and lower stages. The lower battery cell group is held in the battery storage space 7 at a predetermined interval from the bottom plate 2 a of the housing 1. As this holding mechanism, for example, a hook part (not shown) having a width of about several millimeters in the upper and lower sides is provided in the upper part of the front and rear of each partition plate 8 slightly (approximately 1 to 1.5 cm) from its lower end. What is necessary is just to make it support over both ends of the battery cell 9 of a lower stage with this collar part which opposes.

  The refrigerant inlet 2 and outlet 3 are formed on the left and right side walls on the extension of each battery storage space 7 partitioned by the front and rear partition plates 8. In addition, Preferably, a housing | casing and a partition plate are formed with a galvanized steel plate.

  The battery cell 9 according to this embodiment is constituted by, for example, a cylindrical nickel-hydrogen secondary battery. In a nickel-metal hydride secondary battery, a strip-shaped positive electrode plate, a separator, and a negative electrode plate are spirally wound in a cylindrical outer can and accommodated together with an electrolytic solution. And the positive electrode terminal and the negative electrode terminal are attached to the both ends of the longitudinal direction of an armored can, and it is comprised. And as for many secondary battery cells 9 accommodated in the housing | casing, each positive electrode terminal and negative electrode terminal are connected to an electric circuit (not shown), and charging / discharging is controlled by the charging / discharging control apparatus 6. FIG. The charge / discharge control device 6 has a charge / discharge control circuit that opens and closes electric circuits connected to a large number of battery cells, and discharges the battery cells 9 to supply electric power to an electric power load connected to the electric circuits. This is a well-known control device that receives a supply of power from a power source connected to the electric circuit and charges a large number of battery cells.

  And in the state which attached the top plate 2d to the housing | casing 1 of said structure as shown in FIG. 2, between the upper surface of the battery cell group arrange | positioned at two steps up and down, and the top plate of the housing | casing 1, As shown in FIG. 2, gaps S <b> 1 and S <b> 2 are formed between the lower surface of the battery cell group and the bottom plate 2 a of the housing 1.

  In the state where a large number of battery cells 9 are arranged in the battery storage space 7 in the casing as described above, the exhaust fan 5 is driven and a refrigerant such as air flows from the inlet 3 side of the casing 1 toward the outlet 4. The refrigerant flows in a direction perpendicular to the axial direction of each battery cell, and the upstream battery cell is sufficiently cooled by cold air, but the downstream battery cell is cooled by exhaust heat from the upstream side. Since it is warmed, the cooling capacity is reduced, and a large temperature difference is likely to occur between the upstream battery cell and the downstream battery cell, thereby causing variations in the life between the battery cells.

  In addition, a gap between adjacent battery cells, particularly a gap formed by adjacent curved curved surfaces increases the surface area where the battery cells come into contact with the cold air, while the large number of battery cells are sealed in the casing. It is considered that the structure disposed in the above causes turbulent flow and stagnation, which inhibits the flow of cold air and causes the heat dissipation effect to deteriorate.

  Therefore, in the present invention, the heat dissipating member 10 is provided in close contact with and covers the surface of the battery cell group housed in the battery housing space 7, and at the same time, the installation position of the heat dissipating member 10 and the turbulence and stagnation of the cold air are prevented. Adopted a mechanism.

  In the first embodiment of the present invention, as shown in FIGS. 1 and 2, the heat radiating member 10 is attached so as to cover the upper and lower surfaces of the downstream half battery cell group 9 housed in the battery housing space. As shown in FIG. 3, the cross-sectional shape of the heat dissipating member attached to the upper surface of the battery cell is such that the arcuate curved surface 10a is continuous so that its bottom portion is in close contact with the upper surface shape of the cylindrical battery cells arranged in series. The upper part 10b is formed and the upper part 10b becomes a smooth surface while the thickness increases toward the right. In addition, the heat radiating member 10 attached to the lower surface of the lower battery cell group accommodated in the battery accommodating space 7 is symmetrical to that shown in FIG. 3 in the vertical direction.

  FIG. 2 shows the heat dissipation mechanism of the first embodiment of the present invention in which the battery cell is arranged in the battery storage space 7 in the casing as described above and the heat dissipation member 10 is mounted and then the top plate 2d of the casing is mounted. As shown in the figure, gaps S1 and S2 that are vertically symmetrical are formed between the smooth surface 10b of the upper and lower heat radiating members and the top plate 1d and the bottom plate 1a of the casing, respectively. The width becomes narrower as going to the right outlet 4.

  According to the heat dissipation mechanism 1 of the first embodiment of the present invention, when the exhaust fan 5 provided at the right end of the housing is driven, air refrigerant enters the housing through the housing inlet 3 and is disposed in the battery housing space 7. A flow path is formed through the upper and lower gap passages S1 and S2 formed between the upper and lower portions of the battery cell group thus formed and the upper bottom plate of the casing to the outlet 4 at the right end of the casing. . At this time, the heat generated inside the battery cell group on the downstream side of the flow path is released into the flow path due to the high conductivity of the heat radiating member 10. Further, since the upper and lower flow paths S1 and S2 of the refrigerant formed between the upper and lower heat radiating members 10 and the top plate 2d and the bottom plate 2a of the casing are gradually narrowed toward the outlet 4 of the casing. The heat dissipation effect of the heat dissipation member 10 can be increased by increasing the flow velocity toward the outlet.

  As the heat radiating member 10 of a battery cell group, it is comprised with material with high heat conductivity, such as copper and aluminum, for example. And when giving priority to heat dissipation, it is desirable to use copper, which is a material with very high thermal conductivity, and when giving priority to weight reduction, it is desirable to use aluminum, which is a material with a small specific gravity.

(Evaluation)
In order to evaluate the heat dissipation effect of the heat dissipation structure according to the present embodiment, when a large number of battery cells 9 are arranged in the housing 2 and the heat dissipation member is not used (hereinafter referred to as “conventional example”), As a battery cell in the case of using a simple flat heat dissipation member (hereinafter referred to as “comparative example”) and in the case of using the heat dissipation member 10 according to the first embodiment of the present invention (hereinafter referred to as “example”) The surface temperature change was examined. Specifically, as shown in FIG. 2 and FIG. 4, 18 battery cells 9 are closely arranged in parallel in the left-right direction in the housing 2, and the upper battery cell is arranged as shown in FIG. Among them, the battery cell located on the most upstream side is referred to as battery 1, and the batteries separated by 5, 11 and 17 downstream are designated as battery 2, battery 3 and battery 4, respectively. The surface temperature of the batteries 1 to 4 was measured when a steady state was reached after starting.

  The heat dissipating members were arranged on the upper and lower surfaces of nine battery cells on the downstream side (right side) as in the first example. Each part of the heat dissipation mechanism used for this measurement is designed with the following dimensions. Specifically, the casing is made of a galvanized steel sheet having a length of 460 mm in the X direction, a length of 445 mm in the Y direction, a length of 53.5 mm in the Z direction, and a thickness of 3 mm. It is composed of a nickel-metal hydride battery with an axial length of 69 mm and a diameter of 17.8 mm. The heat dissipating member is 1 mm thick on the upstream side (b portion shown in FIG. 3) and 2.6 mm thick on the downstream side (a portion). The outlet fan was a 20 mm square intake fan (1000 rpm).

  Table 1 shows the surface temperatures of the batteries 1 to 4 measured at an environmental temperature of 50 ° C.

表１から、放熱部材を配設しない従来例の場合、冷媒としての空気が流通する方向の最上流側に配設された電池セル１と最下流側に配設され電池セル４との間で１１．２℃もの温度差が生じ、上流側と下流側の電池セルの充放電特性に大きな個体差が生じている。また、本実施形態に係る放熱部材を用いた場合は、従来例および比較例の場合に比して、上流側と下流側との電池セルの温度差がより平滑化されることが理解できる。これは、本実施形態の場合には、放熱部材の放熱効果に加えて、冷媒としての空気が電池セル表面と筐体の天板および底板との間の空隙Ｓ１，Ｓ２において乱流や滞留することがなくなるとともに、下流側に向かうほど流速が増して放熱効果が向上するためと考えられる。尚、本実施形態に係る放熱部材が上流側と下流側との温度差を平滑化できる度合は、平板状の放熱部材に比して０．５℃程度であるが、充放電は繰り返し長時間に亘って行われるため、この程度の温度差であっても十分な効果は期待できる。

From Table 1, in the case of the conventional example in which no heat radiating member is disposed, between the battery cell 1 disposed on the most upstream side in the direction in which the air as the refrigerant flows and the battery cell 4 disposed on the most downstream side. A temperature difference of 11.2 ° C. occurs, and a large individual difference occurs in the charge / discharge characteristics of the upstream and downstream battery cells. Moreover, when the heat radiating member which concerns on this embodiment is used, it can understand that the temperature difference of the battery cell of an upstream and a downstream is smoothed compared with the case of a prior art example and a comparative example. In the case of this embodiment, in addition to the heat dissipation effect of the heat dissipation member, air as a refrigerant turbulently or stays in the gaps S1 and S2 between the battery cell surface and the top and bottom plates of the housing. This is probably because the flow rate increases toward the downstream side and the heat dissipation effect is improved. The degree to which the heat radiating member according to the present embodiment can smooth the temperature difference between the upstream side and the downstream side is about 0.5 ° C. as compared with the flat plate-like heat radiating member. Therefore, a sufficient effect can be expected even with such a temperature difference.

  As described above, according to the heat dissipation mechanism according to the present embodiment, the heat dissipation effect on the downstream side of the refrigerant passage such as air can be enhanced, and the temperature difference between the upstream side and the downstream side of the battery cell can be reduced. Therefore, it is possible to prevent a relatively large individual difference from occurring in the charge / discharge characteristics of the battery cell.

=== Second Embodiment ===
FIG. 5 is a perspective view when the top plate of the heat dissipation mechanism according to the second embodiment of the present invention is removed and the internal structure is viewed from above, and FIG. 6 is a cross-sectional view showing the internal structure of the heat dissipation mechanism according to the second embodiment. It is.

The second embodiment is different from the first embodiment in that a heat radiating member is disposed so as to cover the entire upper and lower surfaces of the battery cell. Since other configurations are the same as those in the first embodiment, the same members as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
As shown in FIGS. 5 and 6, the heat radiating member 10a according to the second embodiment is arranged from the upstream end of the passage through which the refrigerant flows through the upper and lower surfaces of all battery cell groups arranged in the battery storage space in the housing. It is provided so as to cover the downstream end. The wall thickness gradually increases from the upstream end toward the downstream end. Accordingly, the gap between the passages S1 and S2 through which the refrigerant flows gradually becomes narrower from the upstream end toward the downstream end.

(Evaluation)
In order to evaluate the heat dissipation effect of the heat dissipation member according to the second embodiment, the temperature change of the surface of the battery cell was measured in the same manner as in the first example. In addition, the sample compared with 2nd Example was set as the structure which has arrange | positioned the flat heat radiating member of uniform thickness to the upper and lower surfaces of all the battery cell groups as a comparative example which does not use a heat radiating member, and a comparative example. .

表２から、本実施形態に係る放熱部材を配設した場合、放熱部材を設けない場合（従来例）や、平板状の放熱部材を配設した場合に（比較例）比して、電池セルの表面の温度差がより平滑化されることが理解できる。

From Table 2, when the heat radiating member according to the present embodiment is provided, the battery cell is compared with the case where the heat radiating member is not provided (conventional example) or the case where the plate-shaped heat radiating member is provided (comparative example). It can be understood that the temperature difference of the surface of the surface is smoothed.

  As described above, according to the heat dissipation mechanism according to the present embodiment, the heat dissipation effect on the downstream side can be enhanced and the temperature difference between the upstream side and the downstream side of the battery cell can be reduced, as in the first embodiment. Further, it can be said that the second embodiment is superior in reducing the temperature difference.

=== Other Embodiments ===
In the above embodiment, the heat dissipating member is provided for the battery cell group located downstream from the center of the passage through which the refrigerant such as air flows (first embodiment), and provided for all the battery cell groups. However, the present invention is not limited to this, and the heat dissipating member may be disposed only on the downstream side away from the center of the battery cell group, or the heat dissipating member. Even if it is extended from the downstream side of the battery cell group to a position where it partially enters the upstream side beyond the center, the temperature difference of the battery cell group can be reduced.

  In each of the above embodiments, air is used as the refrigerant. However, other gas may be used, and a blower fan may be used instead of the suction fan as means for circulating the refrigerant in the housing.

DESCRIPTION OF SYMBOLS 1 ... Discharge mechanism 2 ... Housing 3 ... Inlet 4 ... Outlet 5 ... Exhaust fan 6 ... Charge / discharge control device 9 ... Battery cell 10 ... Radiation member 10a ... Radiation member curved surface 10b ... Radiation member flat surface

Claims (5)

A group of cylindrical battery cells charged and discharged by the power storage device are arranged in a row adjacent to each other so that the axial directions of the respective battery cells are parallel,
The housing is provided with a passage through which the refrigerant flows in a direction orthogonal to the axial direction of the battery cell group,
Providing a heat dissipating member that contacts the peripheral surface of the battery cell group located at least downstream of the passage of the refrigerant along the peripheral surface shape and covers the peripheral surface of the battery cell group;
The surface of the heat radiating member opposite to the surface in contact with the battery cell group is a flat surface, and the passage through which the refrigerant flows is defined between the flat surface and the inner surface of the housing.
A heat dissipation mechanism in a battery cell power storage device, wherein the passage is narrower toward a downstream side of the housing.   2. The heat dissipation in the battery cell power storage device according to claim 1, wherein the thickness of the heat radiating member is gradually increased from the upstream side to the downstream side of the passage of the refrigerant. mechanism.   3. The battery cell power storage device according to claim 1, wherein the heat dissipating member is provided in contact with a peripheral surface of the battery cell located on the downstream side of the middle of the battery cell group. Heat dissipation mechanism.   3. The heat dissipation mechanism in the battery cell power storage device according to claim 1, wherein the heat dissipation member is provided in contact with a peripheral surface of all the battery cells of the battery cell group.   The battery cell groups are closely arranged in two rows in the casing in a direction orthogonal to the axial direction of the battery cells, and the heat dissipation is performed on a side circumferential surface facing the inner surface of the casing of the battery cell groups in each row. The member is provided, The heat dissipation mechanism in the electrical storage apparatus of the battery cell which concerns on any one of Claims 1-4 characterized by the above-mentioned.

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