JP2014035971A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool a plurality of power storage cells configuring a power storage pack uniformly.SOLUTION: A power storage pack P is configured by juxtaposing a first power storage module M1 and a second power storage module M2, each laminating a plurality of power storage cells C in the lamination direction, in the width direction. Cooling medium supplied from a suction duct 38, provided along one external surface of the first power storage module M1 in the width direction, cools the power storage cells C of the first power storage module M1 and flows into an intermediate duct 42. The cooling medium mixed in the intermediate duct 42 and having a uniform temperature cools the power storage cells C of the second power storage module M2, before being discharged to an exhaust duct 39 provided along the other external surface of the second power storage module M2 in the width direction. Since both ends of the intermediate duct 42 in the lamination direction are closed with seal members 43, the cooling medium in the intermediate duct 42 is prevented from leaking to the outside, and cooling efficiency of the power storage cells C can be enhanced.

Description

  In the present invention, a first power storage module and a second power storage module in which a plurality of power storage cells are stacked in the stacking direction are juxtaposed in the width direction to form a power storage pack, and along one outer surface in the width direction of the first power storage module A cooling medium suction duct is provided, a cooling medium discharge duct is provided along the other outer surface in the width direction of the second power storage module, and the cooling medium supplied from the suction duct is supplied to the first and second power storage modules. The present invention relates to a power storage device that passes through a cooling medium passage formed between power storage cells and discharges it to the discharge duct.

  A plurality of power storage cells are stacked in the stacking direction with a power storage cell holder interposed therebetween to form a power storage module, a plurality of power storage modules are juxtaposed in a juxtaposition direction orthogonal to the stacking direction to form a power storage pack, and the upstream of the juxtaposition direction Japanese Patent Application Laid-Open No. 2004-228561 discloses a cooling medium that flows from a power storage module to a power storage module downstream in the juxtaposition direction to cool each power storage cell.

JP 2009-134937 A

  By the way, the above-mentioned conventional one passes through the plurality of juxtaposed power storage modules from the upstream one to the downstream one after another, so that the temperature of the cooling medium gradually increases toward the downstream, Compared to the upstream storage cell, the cooling efficiency of the downstream storage cell is lowered, and the temperature of each storage cell becomes non-uniform, which may adversely affect the durability.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to allow a plurality of power storage cells constituting a power storage pack to be uniformly cooled.

  In order to achieve the above object, according to the invention described in claim 1, a power storage pack is configured by juxtaposing a first power storage module and a second power storage module in which a plurality of power storage cells are stacked in the stacking direction in the width direction. A cooling medium suction duct is provided along one outer surface in the width direction of the first power storage module, and a cooling medium discharge duct is provided along the other outer surface in the width direction of the second power storage module. In the power storage device that discharges the cooling medium supplied from the cooling medium passage formed between the power storage cells of the first and second power storage modules to the discharge duct, between the first and second power storage modules, Forming an intermediate duct that communicates with the cooling medium passage of the first power storage module and the cooling medium passage of the second power storage module and extends in the stacking direction; Power storage device is proposed which is characterized in that it has closed the layer opposite ends.

  According to the invention described in claim 2, in addition to the configuration of claim 1, both ends in the stacking direction of the intermediate duct are arranged at both ends in the stacking direction of the first and second power storage modules, respectively. A power storage device is proposed, which is closed by a plate, and the upper and lower portions of the intermediate duct are closed by an upper restraining member and a lower restraining member connecting the end plates.

  According to the invention described in claim 3, in addition to the configuration of claim 2, the invention further comprises biasing means for biasing the first and second power storage modules toward the upper restraining member. A power storage device is proposed.

  According to the invention described in claim 4, in addition to the configuration of claim 3, it is provided with a sealing member having elasticity arranged between the first and second power storage modules and the lower restraining member. A power storage device featuring the above is proposed.

  According to the invention described in claim 5, in addition to the configuration of any one of claims 1 to 4, the upstream end of the cooling medium passage of the second power storage module opens into the intermediate duct. A power storage device is proposed in which the area is smaller than the area where the downstream end of the cooling medium passage of the first power storage module is open to the intermediate duct.

  According to the invention described in claim 6, in addition to the configuration of any one of claims 1 to 4, the cooling medium passage of the first electricity storage module and the cooling medium passage of the second electricity storage module. A power storage device characterized in that is shifted in the stacking direction is proposed.

  According to the invention described in claim 7, in addition to the configuration of any one of claims 1 to 6, a pair of the electricity storage packs are stacked in two upper and lower stages, and the electricity storage pack in the lower stage is The cooling medium is sucked from one end side in the stacking direction of the suction duct and discharged from the other end side in the stacking direction of the discharge duct, and the upper storage pack receives the cooling medium from the other end side in the stacking direction of the suction duct. A power storage device is proposed in which the cooling medium is discharged from one end side in the stacking direction of the discharge duct.

  According to the invention described in claim 8, in addition to the configuration of any one of claims 1 to 7, the intermediate duct is divided into two in the stacking direction at the dividing portion, and the cooling medium of the suction duct A power storage device is proposed in which the number of stacked storage cells downstream of the dividing unit is set larger than the number of stacked storage cells upstream of the dividing unit with respect to the flow direction. The

  The center plate 25 of the embodiment corresponds to the dividing portion of the present invention, the third upper restraining member 33 of the embodiment corresponds to the restraining member of the present invention, and the leaf spring 37 of the embodiment of the present invention. Corresponds to the biasing means.

  According to the configuration of claim 1, the power storage pack is configured by juxtaposing the first power storage module and the second power storage module in which the plurality of power storage cells are stacked in the stacking direction in the width direction. The cooling medium supplied from the suction duct provided along one outer surface in the width direction of the first power storage module cools the power storage cell of the first power storage module, flows into the intermediate duct, and mixes in the intermediate duct so that the temperature is uniform. The cooled cooling medium cools the power storage cell of the second power storage module, and then is discharged to a discharge duct provided along the other outer surface in the width direction of the second power storage module. In both the first and second power storage modules, the storage cell upstream of the suction duct is difficult to be cooled because the flow rate of the cooling air is small, and the storage cell downstream of the suction duct is easily cooled because the flow rate of the cooling air is large. However, the cooling medium that has passed through the first power storage module and has become non-uniform in temperature is mixed in the intermediate duct to equalize the temperature, and then supplied to the second power storage module to uniformly cool each power storage cell. Temperature difference can be minimized. In addition, since both ends of the intermediate duct in the stacking direction are closed, the cooling medium of the intermediate duct can be prevented from leaking to the outside, and the cooling efficiency of the storage cell can be increased.

  According to the second aspect of the present invention, both ends of the intermediate duct in the stacking direction are closed by the end plates disposed at both ends of the first and second power storage modules in the stacking direction, and the upper and lower portions of the intermediate duct are the end plates. Since it is obstruct | occluded by the upper restraint member and lower restraint member which connect between, the leakage of a cooling medium can be prevented, without requiring a special sealing member.

  According to the third aspect of the present invention, since the first and second power storage modules are provided with biasing means for biasing the first and second power storage modules toward the upper restraining member, the first and second power storage modules are brought into close contact with the upper restraining member. Further, it is possible to prevent leakage of the cooling medium without requiring a special seal member.

  According to the fourth aspect of the present invention, since the elastic sealing member disposed between the first and second power storage modules and the lower restraining member is provided, the first and second power storage modules are moved upward by the urging means. Even if it urges | biases toward a restraint member, it can prevent that a cooling medium leaks from between a 1st, 2nd electrical storage module and a lower restraint member.

  According to the configuration of claim 5, the area where the upstream end of the cooling medium passage of the second power storage module opens to the intermediate duct is larger than the area where the downstream end of the cooling medium passage of the first power storage module opens to the intermediate duct. Since it is small, the cooling medium that has flowed into the intermediate duct from the first power storage module side is less likely to flow out to the second power storage module side, thereby promoting the mixing of the cooling medium in the intermediate duct and enabling uniform cooling of the storage cells. be able to.

  According to the configuration of claim 6, since the cooling medium passage of the first power storage module and the cooling medium passage of the second power storage module are shifted in the stacking direction, the cooling medium flowing into the intermediate duct from the first power storage module side By making it difficult to flow out to the second power storage module side, mixing of the cooling medium in the intermediate duct can be promoted, and the power storage cells can be evenly cooled.

  According to the configuration of claim 7, the pair of power storage packs are stacked in two upper and lower stages, and the lower power storage pack sucks the cooling medium from one end side in the stacking direction of the suction duct and from the other end side in the stacking direction of the discharge duct. The cooling medium is discharged, and the upper storage pack sucks the cooling medium from the other end in the stacking direction of the suction duct and discharges the cooling medium from the one end in the stacking direction of the discharge duct. The difficult part and the easy-to-cool part downstream in the flow direction of the cooling medium are reversed in the upper storage pack and the lower storage pack, and heat exchange is performed with the high and low temperature parts of the upper and lower storage packs facing each other. Thus, it is possible to evenly cool the storage cells.

  According to the configuration of claim 8, the intermediate duct is divided into two in the stacking direction in the split section, and is divided more than the number of stacked storage cells upstream of the split section in the flow direction of the cooling medium in the suction duct. Since the number of stacked storage cells on the downstream side of the unit is set to be large, the number of storage cells arranged on the upstream side of the dividing unit with a small flow rate of the cooling medium is reduced, and the downstream side of the dividing unit with the large flow rate of the cooling medium By increasing the number of power storage cells arranged in the battery, it is possible to cool the power storage cells evenly.

The perspective view of a battery unit. (First embodiment) The perspective view of the principal part of a battery unit. (First embodiment) The exploded perspective view of a battery pack. (First embodiment) The exploded perspective view of an electrical storage cell group. (First embodiment) FIG. (First embodiment) FIG. 6 is a sectional view taken along line 6-6 of FIG. (First embodiment) FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. (First embodiment) FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 5. (First embodiment) FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 5. The schematic diagram explaining the flow path of a cooling medium. (First embodiment) The schematic diagram explaining the flow volume of a cooling medium. (First embodiment) The graph which shows the relationship between the total voltage of an electrical storage cell, and the depth of pitting by electric corrosion. (First embodiment) The figure which looked at the 2nd electrical storage module from the discharge duct side. (Second Embodiment) The perspective view of an electrical storage cell holder. (Second Embodiment) FIG. 15 is a cross-sectional view taken along a line 15A-15A and a line 15B-15B in FIG. (Second Embodiment) The figure corresponding to FIG. (Third embodiment)

First embodiment

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the present specification, the front-rear direction, the left-right direction (vehicle width direction), and the up-down direction are defined based on an occupant seated in the driver's seat (see FIG. 1).

  As shown in FIGS. 1 and 2, a power storage unit U that supplies power to a motor / generator of a hybrid vehicle includes a pair of power storage packs P and P that have substantially the same structure and are stacked one above the other. . The power storage unit U, the upper surface of which is covered with the flat cover 11, is mounted in the luggage compartment at the rear of the rear seat 12 including the seat cushion 12a and the seat back 12b. The suction passage 13 that extends forward from the front right side of the upper storage pack P includes a suction port 13a that opens into the vehicle compartment on the right side surface of the seat back 12b of the rear seat 12, and is a discharge that extends rearward from the rear left side of the storage pack P. A cooling fan 15 is provided at an intermediate portion of the passage 14, and a discharge port 14a is formed at the downstream end. Similarly, the suction passage 16 extending forward from the front left side of the lower storage pack P includes a suction port 16a that opens into the vehicle compartment on the left side surface of the seat back 12b of the rear seat 12, and rearward from the rear right side of the storage pack P. A cooling fan 18 is provided at an intermediate portion of the discharge passage 17 extending to the outlet, and a discharge port 17a is formed at the downstream end.

  Next, the structure of the electricity storage packs P and P will be described with reference to FIGS. Since the upper storage pack P and the lower storage pack P have substantially the same structure, the structure of the upper storage pack P will be mainly described.

  The power storage pack P includes a front first power storage module M1 and a rear second power storage module M2 made up of 25 power storage cells C ... stacked in the stacking direction. As is apparent from FIG. 4, the storage cell C constituting the first and second storage modules M1, M2 is made of, for example, a lithium ion battery formed in a rectangular parallelepiped shape, and the metal case 21 faces each other. A pair of main surfaces 21a, 21a, a pair of side surfaces 21b, 21b orthogonal to each other and opposed to the main surfaces 21a, 21a, and the main surfaces 21a, 21a and the side surfaces 21b, 21b orthogonal to each other. Are provided with a top surface 21c and a bottom surface 21d. Positive and negative electrodes 21e and 21e are provided on the top surface 21c.

  The pair of main surfaces 21a, 21a and the pair of side surfaces 21b, 21b of the metal case 21 made of aluminum alloy of each storage cell C are covered with an insulating sheet 22 made of synthetic resin, and the metal case 21 is insulated from other members. doing. However, the top surface 21c and the bottom surface 21d of each storage cell C are not covered with the insulating sheet 22, and the metal surface is exposed.

  In this specification, the direction connecting the top surface 21c and the bottom surface 21d perpendicular to the stacking direction of the storage cell C is defined as the vertical direction, and the pair of side surfaces 21b and 21b of the storage cell C orthogonal to the stacking direction is defined as The connecting direction is defined as the width direction (see FIG. 2).

  The first and second power storage modules M1 and M2 of the power storage pack P include a pair of end plates 23 and 23 and a pair of quarter plates 24 and 24, respectively, and the first and second power storage modules M1 and M2 are common 1 The center plate 25 is provided. In the first and second power storage modules M1 and M2, six power storage cells C are basically arranged between the end plates 23 and 23, the quarter plates 24 and 24, and the center plate 25. As is obvious from FIG. 11, in the upper storage pack P, seven storage cells C... Are arranged between the left end plate 23 and the left quarter plate 24, and in the lower storage pack P. Seven power storage cells C are arranged between the right end plate 23 and the right quarter plate 24.

  As is clear from FIG. 4, a synthetic resin storage cell holder 26, which is an insulator, is sandwiched between adjacent storage cells C, and the same storage cell holders 26 are connected to the end plates 23, 23 and the quarter. It is also sandwiched between the plates 24, 24 and the center plate 25 and the storage cells C. The storage cell holder 26 includes a corrugated plate portion 26a, four engaging portions 26b projecting in the stacking direction from the four corners of the plate portion 26a, and a plate shape projecting in one direction from the upper edge of the plate portion 26a. And a plate-like side surface contact portion 26d that protrudes from one side edge in the width direction of the plate portion 26a to one side in the stacking direction. The adjacent storage cell holders 26, 26 are positioned with each other by engaging the engaging portions 26 b..., And the engaging portions 26 b... Engage with the four corners of the storage cell C and contact the top surface. The storage cell C is positioned with respect to the storage cell holder 26 by the portion 26 c and the side contact portion 26 d contacting the top surface 21 c and the one side surface 21 b of the storage cell C. A plurality of cooling medium passages 27 (see FIG. 9) extending in the width direction are formed between the corrugated plate portion 26a and the main surfaces 21a, 21a of the storage cells C, C.

  As is clear from FIG. 9, the upper edge and the lower edge of the plate portion 26a of the storage cell holder 26 are bent in an S-shaped cross section, and the seal projections 26e at the tip thereof bite into the insulating sheet 22 of the storage cell C. The cooling medium made of cooling air is sealed so as not to leak from the upper and lower portions of the cooling medium passages 27.

  Inside the metal case 21 of the storage cell C, an electrode sheet 28 wound in a roll shape is housed in an impregnated state with an electrolytic solution. Further, an insulating member (not shown) is wound around the outer periphery of the electrode sheet 28. The intermediate portion 28a in the vertical direction of the electrode sheet 28 extends in the vertical direction along the inner surfaces of the pair of main surfaces 21a, 21a of the metal case 21, and the upper portion 28b and the lower portion 28c are U-shaped from the upper and lower ends of the intermediate portion 28a. Is curved. Since the electrode sheet 28 tends to return to a flat shape before being rolled into a roll shape by its own elasticity, the stacking direction width W1 of the upper part 28b and the lower part 28c is slightly larger than the stacking direction width W2 of the intermediate part 28a. As a result, the upper portion 28 b and the lower portion 28 c are pressed against the inner surfaces of the pair of main surfaces 21 a and 21 a of the metal case 21.

  The storage cells C... And the storage cell holders 26 configured as described above are stacked in the stacking direction in a state where a predetermined number is sandwiched between the pair of end plates 23, 23, the pair of quarter plates 24, 24 and the center plate 25. Thus, a power storage pack P is formed in which the first power storage module M1 and the second power storage module M2 are juxtaposed in the width direction. That is, as apparent from FIGS. 6 to 8, a pair of end plates 23, 23, a pair of quarter plates 24, 24 and a center plate 25 are placed on a lower restraining member 29 made of one flat metal plate material. The three first, second, and third upper restraining members 31, 32, 33 made of metal rods are fastened with bolts 30, and a pair of end plates 23, 23 and a pair of quarter plates 24, 24. And the 1st, 2nd electrical storage module M1, M2 is integrated by fastening with the volt | bolt 34 ... on the upper surface of the center plate 25, and the electrical storage pack P is comprised. The third upper restraining member 33 at the center in the width direction is wider than the first and second upper restraining members 31 and 32 at both ends in the width direction. The third upper restraining member 33 has a pair of end plates 23, a pair of quarter plates 24 and a center plate. By fastening so that it may straddle 25, the rigidity of the electricity storage pack P is increased.

  As is apparent from FIG. 11, the first and second power storage modules M1 and M2 of the power storage pack P are moved from the right side to the left side by the pair of end plates 23 and 23, the pair of quarter plates 24 and 24, and the center plate 25, respectively. The first storage cell group G1, the second storage cell group G2, the third storage cell group G3, and the fourth storage cell group G4 are divided. As described above, in the upper storage pack P, the first to third storage cells Each of the storage cell groups G1, G2, G3 includes six storage cells C ..., and only the fourth storage cell group G4 includes seven storage cells C .... On the other hand, in the lower storage pack P, the second to fourth storage cell groups G2, G3, G4 each have six storage cells C ..., and only the first storage cell group G1 has seven storage cells C ... It has.

  As apparent from FIG. 4, tray-like lower insulators 35 are fitted to the lower surface of the first power storage cell group G1 of the first and second power storage modules M1, M2, and the power storage cell C is mounted on the upper surface thereof. A tray-like upper insulator 36 having an opening exposing the electrodes 21e is fitted. The lower insulators 35 and the upper insulators 36 are made of a thin synthetic resin having insulating properties, and the metal case 21 of the storage cell C is formed by the lower restraint member 29 and the first to third upper restraint members 31 and 32. , 33 is prevented from liquid junction. The lower insulator 35 includes a bottom wall 35a and side walls 35b rising from the periphery thereof, and supports the bottom surfaces 21d of the six (or seven) storage cells C on the upper surface of the bottom wall 35a. Two protrusions 35c are provided so as to protrude from each storage cell C. A plurality of drain holes 35d are formed in the side wall 35b, and the height of the drain holes 35d is slightly lower than the bottom surface 21d of the storage cell C supported on the support convex portions 35c and 35c. The position is set (see FIG. 9). The same applies to the second storage cell group G2, the third storage cell group G3, and the fourth storage cell group G4.

  As is apparent from FIGS. 3 and 6, eight plate springs 37 made of a metal plate having elasticity are arranged on the upper surface of the lower restraining member 29. The leaf spring 37 provided for each of the six storage cells C... Or the seven storage cells C... Is provided with a linear attachment portion 37a and a plurality of comb-like protrusions protruding in the width direction from the attachment portion 37a. .., And each of the two arm portions 37b and 37b elastically abuts against the bottom surface 21d of the storage cell C via the lower insulator 35, thereby biasing the storage cell C upward. To do.

  As apparent from FIGS. 3 and 6, a suction duct 38 extending in the left-right direction is disposed on the front surface of the first power storage module M <b> 1 located on the front side of the power storage pack P, and the second power storage located on the rear side of the power storage pack P. A discharge duct 39 extending in the left-right direction is disposed on the rear surface of the module M2. The upper edges of the suction duct 38 and the discharge duct 39 are fastened to the first and second upper restraining members 31 and 32 by bolts 40... And the lower edges thereof are fastened to the lower restraining member 29 by bolts 41. The upper storage pack P has the suction passage 13 connected to the right end of the suction duct 38 and the discharge passage 14 connected to the left end of the discharge duct 39. The lower storage pack P has the suction passage connected to the left end of the suction duct 38. 16 is connected and the discharge passage 17 is connected to the right end of the discharge duct 39. The suction duct 38 and the discharge duct 39 are divided by the storage cell holders 26 sandwiched between the storage cells C of the first and second storage modules M1, M2, and so on (see FIGS. 9 and 10). Communicate with.

  As apparent from FIGS. 5 to 7, an intermediate duct 42 extending in the stacking direction is formed between the first and second power storage modules M <b> 1 and M <b> 2 of the power storage pack P. Both ends of the intermediate duct 42 in the stacking direction are sealed by the butted portions of the pair of end plates 23 and 23, respectively. That is, the projections 23a, 23a are formed so that the end plates 23, 23 of the first and second power storage modules M1, M2 face each other with a gap therebetween, and these projections 23a, 23a An elastic seal member 43 (see FIG. 5) is sandwiched and sealed in the formed labyrinth.

  The upper part of the intermediate duct 42 is sealed by the upper insulator 36 coming into contact with the lower surface of the third upper restraining member 33 (see FIG. 6). At this time, the storage cell is pushed up by the elastic force of the leaf spring 37. When the top surface 21c of C presses the upper insulator 36 against the lower surface of the third upper restraining member 33 via the upper engaging portion 26b of the storage cell holder 26, the sealing performance of that portion is enhanced. On the other hand, since the lower part of the intermediate duct 42 cannot be expected to have a sealing function due to the elastic force of the leaf spring 37 described above, the upper surface of the lower restraining member 29 and the lower insulators 35, 35 of the first and second power storage modules M 1, M 2. Sealing is performed by disposing an elastic seal member 44 between the opposing portions (see FIG. 6).

  In this way, the intermediate duct 42 is closed by being surrounded by the end plates 23, the upper and lower ends, the third upper restraining member 33 and the lower restraining member 29 at both ends in the stacking direction, and the cooling medium passage 27 only in the width direction. Are communicated with the suction duct 38 and the discharge duct 39 via. Further, since the first and second power storage modules M1 and M2 share one center plate 25, the intermediate duct 42 is divided into an upstream portion and a downstream portion by the center plate 25.

  Next, the operation of the first embodiment of the present invention having the above configuration will be described.

  As is apparent from FIG. 11, the storage cells C of the storage unit U generate heat as the hybrid vehicle travels, but the cooling sucked from the suction port 13a of the suction passage 13 by the cooling fan 15 of the upper storage pack P. The medium flows through the suction duct 38 from the right to the left, during which time the direction is changed to the rear, and flows through the cooling medium passage 27 (see FIG. 9) of the first power storage module M1 from the front to the rear to cool the storage cells C. After that, they merge at the intermediate duct 42. The cooling medium in the intermediate duct 42 flows from the front to the rear in the cooling medium passages 27 of the second power storage module M2 to cool the storage cells C, and then merges in the discharge duct 39, and flows through the discharge duct 39 from right to left. It is discharged from the discharge port 14a of the passage 14.

  On the other hand, the cooling medium sucked from the suction port 16a of the suction passage 16 by the cooling fan 18 of the lower power storage pack P flows from the left to the right through the suction duct 38, and changes its direction to the rear in the meantime, so that the first power storage module After cooling the storage cells C through the cooling medium passages 27 of M1 from the front to the rear. They merge at the intermediate duct 42. The cooling medium of the intermediate duct 42 flows through the cooling medium passages 27 of the second power storage module M2 from the front to the rear, cools the storage cells C, and then merges in the discharge duct 39, and flows through the discharge duct 39 from left to right and is discharged. The gas is discharged from the discharge port 17a of the passage 17.

  When the cooling medium flows through the cooling medium passages 27, if the cooling medium leaks from the upper and lower portions of the cooling medium passages 27, the cooling effect of the storage cells C is reduced. The insulating sheet 22 and the storage cell holders 26 can prevent leakage of the cooling medium. That is, when the storage cell C and the storage cell holder 26 are overlapped and fastened in the stacking direction, the upper and lower seal protrusions 26e of the storage cell holder 26 bite into the insulating sheet 22 covering the main surface 21a of the metal case 21 of the storage cell C. As a result, the portion is sealed and leakage of the cooling medium from the cooling medium passages 27 is prevented (see FIG. 9). Thus, the cooling medium passages 27 can be sealed without the need for a special sealing member, which can contribute to a reduction in the number of parts. In addition, since the sealing protrusions 26e of the storage cell holder 26 bite into the elastic insulating sheet 22, the distortion of the main surface 21a of the storage cell C can be absorbed by the elastic deformation of the insulating sheet 22 to ensure a sealing effect.

  Further, in order for the sealing projections 26e of the energy storage cell holder 26 to securely bite into the insulating sheet 22, the main surface 21a of the energy storage cell C needs to have sufficient rigidity, but as is apparent from FIG. An upper portion 28b and a lower portion 28c having high rigidity of the electrode sheet 28 are opposed to each other on the inner side of the main surface 21a of the metal case 21 in the vicinity of the C seal projections 26e, and the upper surface 28a and the lower portion 28 define the main surface 21a. By supporting from the inside so as not to be deformed, the rigidity of the main surface 21a can be increased. In particular, since the width W1 in the stacking direction of the upper part 28b and the lower part 28c of the electrode sheet 28 is slightly larger than the width W2 in the stacking direction of the intermediate part 28a, the upper part 28b and the lower part 28c are paired with the pair of metal cases 21. The rigidity can be further effectively increased by pressing against the inner surfaces of the main surfaces 21a and 21a.

  As is apparent from FIG. 11, in the upper storage pack P, the cooling medium flowing from the right to the left in the suction duct 38 tries to go straight by inertia, and after hitting the downstream end (left end) of the suction duct 38, Since there is a tendency to change the direction and flow into the cooling medium passages 27, the flow rate of the cooling medium flowing through the cooling medium passages 27 on the upstream side (first storage cell group G1 side) becomes small and the downstream side (the first storage cell group G1 side). The flow rate of the cooling medium flowing through the cooling medium passages 27 in the (4 storage cell group G4 side) increases. Thus, the number (seven) of the storage cells C... In the fourth storage cell group G4 on the downstream side where the flow rate of the cooling medium increases is set to the storage cells C of the other first to third storage cell groups G1 to G3. .. (6), the power storage cells C can be cooled as uniformly as possible to reduce the temperature difference, and the life of the storage cells C can be extended.

  In the lower storage pack P, since the cooling medium flows from the left to the right through the suction duct 38, the flow rate of the cooling medium flowing through the first storage cell group G1 on the downstream side is maximized, but the first storage cell group G1. By increasing the number (seven) of the storage cells C ... from the number (six) of the other storage cells C ... on the second to fourth storage cell groups G2-G4, each storage cell C ... The temperature difference can be reduced by cooling as uniformly as possible, and the life of the storage cells C can be extended.

  In the upper storage pack P, since the cooling medium flowing through the first storage cell group G1 of the first storage module M1 upstream of the suction duct 38 has a small flow rate, the first storage cell group G1 of the first storage module M1 The passing cooling medium becomes a relatively high temperature, and when the relatively high temperature cooling medium flows into the first storage cell group G1 of the second storage module M2 as it is, the storage cells C of the first storage cell group G1. The cooling efficiency will be reduced. On the other hand, since the cooling medium flowing through the fourth power storage cell group G4 of the first power storage module M1 on the downstream side of the suction duct 38 has a large flow rate, the cooling medium that has passed through the fourth power storage cell group G4 of the first power storage module M1 is compared. When the temperature becomes low and the relatively low-temperature cooling medium flows into the fourth storage cell group G4 of the second storage module M2 as it is, the cooling efficiency of the storage cells C of the fourth storage cell group G4 increases. There is a problem that the temperature difference between the storage cells C ... of the first storage cell group G1 of the second storage module M2 and the storage cells C ... of the fourth storage cell group G4 becomes significant.

  However, according to the present embodiment, since the intermediate duct 42 is provided between the first power storage module M1 and the second power storage module M2, the cooling medium having a temperature difference that has passed through the first power storage module M1 is the intermediate duct. 42, the temperature becomes uniform and the cooling medium having a uniform temperature is supplied to the first to fourth power storage cell groups G1 to G4 of the second power storage module M2 to minimize the temperature difference between the power storage cells C. Can be suppressed. In this embodiment, since the intermediate duct 42 is divided by the center plate 25, the effect of the intermediate duct 42 equalizing the temperature of the cooling medium is slightly reduced, but still a sufficient effect can be achieved. Can do. Therefore, if the intermediate duct 42 is not divided by a means such as forming an opening in the center plate 25, the temperature of the cooling medium can be made more uniform.

  Further, since the intermediate duct 42 is configured to be surrounded by the end plate 23, the lower restraining member 29, the third upper restraining member 33, and the side surface 21b of the storage cell C ... without providing any special duct member. This can contribute to a reduction in the number of parts. In addition, since both ends of the intermediate duct 42 in the stacking direction are sealed with a labyrinth composed of the projections 23a and 23a of the pair of end plates 23 and 23, and a seal member 43 (see FIG. 5) fitted to the labyrinth, it is simple. With the structure, leakage of the cooling medium from both ends of the intermediate duct 42 in the stacking direction can be reliably prevented.

  In addition, the top surface 21c of the storage cell C pushed up by the elastic force of the leaf spring 37 from the upper portion of the intermediate duct 42 causes the upper insulator 36 to be connected to the third upper restraining member 33 via the upper engaging portion 26b of the storage cell holder 26. The lower portion of the intermediate duct 42 is sealed between the upper surface of the lower restraining member 29 and the opposing portions of the lower insulators 35, 35 of the first and second power storage modules M1, M2. Since sealing is performed by disposing an elastic seal member 44 between them (see FIG. 6), the upper and lower portions of the intermediate duct 42 can be sealed with a simple structure to prevent leakage of the cooling medium.

  As is clear from FIG. 11, the upper storage pack P sucks the cooling medium from the right end side of the suction duct 38 and discharges the cooling medium from the left end side of the discharge duct 39. Part (first and second storage cell groups G1 and G2 side) becomes high temperature, and the left half (third and fourth storage cell group G3 and G4 side) where the flow rate of the cooling medium is large becomes low temperature. On the other hand, since the lower storage pack P sucks the cooling medium from the left end side of the suction duct 38 and discharges the cooling medium from the right end side of the discharge duct 39, the left half (third, fourth) with a small flow rate of the cooling medium. The storage cell group G3, G4 side) becomes hot, and the right half (the first and second storage cell groups G1, G2 side) where the flow rate of the cooling medium is large becomes low. Therefore, the low-temperature part and the high-temperature part of the lower storage pack P overlap the high-temperature part and the low-temperature part of the upper storage pack P, respectively. The temperature of the cells C can be made uniform.

  By the way, since the metal case 21 of the electricity storage cell C has a negative potential, if it contacts the lower restraint member 29 or the first, second, and third upper restraint members 31, 32, 33, a leakage occurs. Electric leakage is generated by disposing an insulating lower insulator 35 and upper insulator 36 between the metal case 21 of the cell C, the lower restraining member 29, and the first, second and third upper restraining members 31, 32, 33. Is prevented.

  Further, when the temperature of the storage cell C decreases, moisture in the air condenses on the surface of the metal case 21 and condensed water is generated. Although the main surfaces 21a, 21a and the side surfaces 21b, 21b of the storage cell C are covered with the insulating sheet 22, the generation of condensed water cannot be completely prevented, and the condensed water flows downward to form a metal lower portion. When it comes into contact with the restraining member 29, there is a possibility that electric leakage due to a liquid junction occurs. However, according to the present embodiment, the lower part of the six to seven storage cells C... Of the first to fourth storage cell groups G1 to G4 is covered with the tray-like lower insulator 35. Can be held in the lower insulator 35 and liquid junction with the lower restraining member 29 can be prevented.

  Further, when the metal case 21 made of an aluminum alloy of the plurality of storage cells C ... electrically connected in series is immersed in the condensed water accumulated in the lower insulator 35, the potential difference existing between the storage cells C ... There is a risk that the reaction will occur and the surface of the metal case 21 will be eroded and the electrolyte will leak from the metal case 21.

Al → Al ³⁺ + 3e ⁻
2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻
Al ³⁺ + 3OH ⁻ → Al (OH) ₃

  However, according to the present embodiment, the condensed water accumulated in the lower insulator 35 is discharged from the drain holes 35d (see FIGS. 4 and 9) formed in the side wall 35b, so that the lower part of the storage cells C is formed. Durability against electrolytic corrosion can be increased by preventing immersion in condensed water.

  The reason why the drainage holes 35d are provided in the side wall 35b of the lower insulator 35 but not in the bottom wall 35a is that the lower restraining member 29 is located on the lower surface of the bottom wall 35a and the drainage holes 35d. This is because there is a risk of liquid junction due to the condensed water.

  Even as described above, since it is difficult to completely prevent the lower part of the storage cells C ... from being immersed in the dew condensation water, there is a concern about the occurrence of electrolytic corrosion. However, in the present embodiment, as follows. Damage to electric corrosion can be minimized. Since 50 storage cells C of each storage pack P of the present embodiment are electrically connected in series, the potential difference between the metal cases 21 and 21 of the storage cells C and C at both ends thereof is large. If the liquid junction between the power storage cells C and C at both ends is generated by the dew condensation water, the damage of the electric corrosion becomes large. However, according to the present embodiment, 50 power storage cells C of each power storage pack P are divided into eight first to fourth power storage cell groups G1 to G4, and each group is an independent lower insulator 35. Is provided, the potential difference between the metal cases 21 and 21 of the storage cells C and C at both ends is suppressed to six or seven storage cells C. As a result, it is possible to increase the durability by minimizing the damage of the electric corrosion generated in the metal cases 21 of the storage cells C.

  The graph of FIG. 12 shows a case where the storage cell C having the metal case 21 made of aluminum and stainless steel is connected in series in a 3.5 wt% NaCl aqueous solution in an atmosphere of 50 ° C. for 7 days, The relationship between the total voltage of the power storage module, the metal case 21 and the depth of pitting corrosion due to electrolytic corrosion is shown. In any case, the depth of pitting corrosion increases as the total voltage increases, and the product is made of aluminum. It can be seen that the depth of pitting corrosion is greater than that of stainless steel.

  Therefore, the total voltage of the storage cell group and the thickness of the metal casing 21 of the storage cell C (particularly, the thickness of the bottom surface 21d, the main surface 21a, and the side surface 21b in the metal case 21 where the condensed water easily comes into contact), Based on the material of the metal casing 21 of the storage cell C, the preset assumed environmental temperature of the storage cell C, and the preset lifetime of the storage cell C, the maximum number of storage cells C constituting the storage cell group Can be set.

  As shown in Table 1, when a metal case 21 made of aluminum alloy having a thickness of 1 mm is adopted, when the total voltage is 23.35 V (when seven storage cells C... Are connected in series), the total voltage 167. Compared to the case of 5V (when 50 storage cells C ... are connected in series), the pitting corrosion penetrates the metal case 21 regardless of whether the ambient temperature (environment temperature) is 25 ° C or 50 ° C. It can be seen that the period until is extended more than 7 times. For example, when the metal case 21 is made of an aluminum alloy having a bottom surface 21d, a main surface 21a, and a side surface 21b having a thickness of 1 mm, the environmental temperature is 50 ° C., and the lifetime is 715 days, the storage cell C It can be seen that it is preferable to make the number of the maximum 7 or less.

Second embodiment

  Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.

  If the cooling medium flowing into the intermediate duct 42 from the cooling medium passage 27 of the first power storage module M1 immediately flows out into the cooling medium passage 27 of the second power storage module M2, mixing of the cooling medium in the intermediate duct 42 is performed. It becomes impossible to perform sufficiently, and the storage cells C of the second storage module M2 cannot be cooled uniformly.

  According to the present embodiment, the partition plate 26f is provided at a part of the portion where the storage cell holder 26 of the second storage module M2 faces the intermediate duct 42, and the cooling medium flowing into the intermediate duct 42 is separated from the partition plate 26f. To prevent the cooling medium from flowing out into the cooling medium passage 27 of the second power storage module M2, thereby increasing the time during which the cooling medium stays in the intermediate duct 42 and promoting the mixing. It becomes possible to make the temperature of the cooling medium flowing through the passages 27 more uniform. The number of the partition plates 26f in the present embodiment is three for each storage cell holder 26, and closes three of the six cooling medium passages 27 of each storage cell holder 26, but the partition plate 26f. The number of… is not limited to that.

Third embodiment

  Hereinafter, a third embodiment of the present invention will be described with reference to FIG.

  In the second embodiment, the partition plate 26f... Is provided in the energy storage cell holder 26, so that the intermediate duct 42 is the first with respect to the opening area in which the cooling medium passage 27 of the first energy storage module M1 opens in the intermediate duct 42. Although the opening area opened to the cooling medium passages 27 of the two power storage modules M2 is reduced, in the third embodiment, the power storage cells C of the first power storage modules M1 and the power storage cells C of the second power storage modules M2 are used. Are shifted in the stacking direction, and the cooling medium passage 27 of the first power storage module M1 and the cooling medium passage 27 of the second power storage module M2 are bent in a crank shape in the intermediate duct.

  Also in the third embodiment, the temperature of the cooling medium flowing through the cooling medium passages 27 of the second power storage module M2 is further increased by increasing the time during which the cooling medium stays in the intermediate duct 42 to promote mixing. It becomes possible to make uniform.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the storage cell C of the embodiment is not limited to a lithium ion battery, and may be another type of battery or capacitor.

  In the embodiment, the intermediate duct 42 is surrounded by the end plate 23, the lower restraining member 29, the third upper restraining member 33, and the side surface 21 b of the storage cell C. A special duct such as the above may be provided.

  In the embodiment, in the upper storage pack P, seven storage cells C are arranged between the left end plate 23 and the left quarter plate 24, and in the lower storage pack P, the right end plate 23 and Seven storage cells C... Are arranged between the right quarter plate 24, and similarly, the seven storage cells C are disposed between the left end plate 23 and the left quarter plate 24 in the upper and lower stages. .. May be arranged, or seven power storage cells C may be arranged between the right end plate 23 and the right quarter plate 24.

23 End plate 25 Center plate (divided part)
27 Cooling medium passage 29 Lower restraint member 33 Third upper restraint member (restraint member)
37 Leaf spring (biasing means)
38 Intake duct 39 Exhaust duct 42 Intermediate duct 44 Seal member C Power storage cell P Power storage pack M1 First power storage module M2 Second power storage module

Claims (8)

A first storage module (M) having a plurality of storage cells (C) stacked in the stacking direction is juxtaposed in the width direction to form a storage pack (P), and the first storage module ( A cooling medium suction duct (38) is provided along one outer surface in the width direction of M1), and a cooling medium discharge duct (39) is provided along the other outer surface in the width direction of the second power storage module (M2). The cooling medium supplied from the suction duct (38) is allowed to pass through the cooling medium passage (27) formed between the storage cells (C) of the first and second storage modules (M1, M2) and the discharge duct. In the power storage device discharged to (39),
The first and second power storage modules (M1, M2) communicate with the cooling medium passage (27) of the first power storage module (M1) and the cooling medium passage (27) of the second power storage module (M2). And forming an intermediate duct (42) extending in the stacking direction and closing both ends of the intermediate duct (42) in the stacking direction.   Both ends of the intermediate duct (42) in the stacking direction are closed by end plates (23) respectively disposed at both ends of the first and second power storage modules (M1, M2) in the stacking direction, and the intermediate duct (42) 2. The power storage device according to claim 1, wherein upper and lower portions are closed by an upper restraining member (33) and a lower restraining member (29) that connect the end plates (23).   The power storage device according to claim 2, further comprising biasing means (37) for biasing the first and second power storage modules (M1, M2) toward the upper restraining member (33).   The elastic sealing member (44) disposed between the first and second power storage modules (M1, M2) and the lower restraining member (29), according to claim 3, Power storage device.   The area where the upstream end of the cooling medium passage (27) of the second power storage module (M2) opens into the intermediate duct (42) is such that the downstream end of the cooling medium passage (27) of the first power storage module (M1) is open. 5. The power storage device according to claim 1, wherein the power storage device is smaller than an area opened in the intermediate duct (42).   The cooling medium passage (27) of the first power storage module (M1) and the cooling medium passage (27) of the second power storage module (M2) are shifted in the stacking direction. 5. The power storage device according to claim 1.   A pair of the power storage packs (P) are stacked in two upper and lower stages, and the lower power storage pack (P) sucks the cooling medium from one end side in the stacking direction of the suction duct (38) to form the discharge duct (39). The cooling medium is discharged from the other end side in the stacking direction, and the upper storage pack (P) sucks the cooling medium from the other end side in the stacking direction of the suction duct (38) and ends one end in the stacking direction of the discharge duct (39). The power storage device according to claim 1, wherein the cooling medium is discharged from the side.   The intermediate duct (42) is divided into two in the stacking direction in the split section (25), and the storage cell (upstream side of the split section (25) with respect to the flow direction of the cooling medium in the suction duct (38) ( The number of stacks of the storage cells (C) on the downstream side of the dividing unit (25) is set larger than the number of stacks of C), according to any one of claims 1 to 7, The power storage device described.

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