battery pack

Abstract

To provide a battery pack in which cooling efficiency of batteries can be improved furthermore.SOLUTION: A battery pack includes: a holding member holding a plurality of batteries; a stacked battery in which the plurality of batteries are stacked via the holding member in a stacking direction; and a ventilation flue adjacent to the stacked battery and extending in the stacking direction, the ventilation flue forming a flow passage of cooling air that cools the plurality of batteries. The ventilation flue has an intake port taking the cooling air into the ventilation flue. The holding member has ventilation holes that are open on a ventilation flue side and on a side opposite to the ventilation flue to ventilate the cooling air from the ventilation flue to the stacked battery. The ventilation holes include a bottom ventilation hole that is open toward a space formed between the bottom of the plurality of batteries and the bottom of the holding member.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] In recent years, there has been a demand for high-capacity, high-output secondary batteries as power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs), which use a motor to assist part of their drive. The secondary batteries are, for example, lithium-ion secondary batteries, and are used by connecting multiple secondary batteries in series to form a module, and then connecting multiple modules in series or in parallel to form a pack.

[0003] When a secondary battery is charged or discharged, it generates heat due to the electrical resistance of the constituent materials inside the secondary battery. The temperature rise caused by the self-heating accelerates the deterioration of the secondary battery and shortens its lifespan. Therefore, the secondary battery needs to be cooled appropriately. Therefore, as disclosed in Patent Documents 1 to 3, a battery pack generally employs a structure in which a flow path for a coolant such as air or water is provided inside the battery pack to cool the secondary battery. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Application No. 2010-153141 [Patent Document 2] Patent Application No. 2015-005362 [Patent Document 3] Patent Application No. 2019-131026 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is room for improvement in the coolant flow path structure, and there is a demand for further improvement in the cooling efficiency of the battery. [Means for solving the problem]

[0006] In one aspect of an embodiment of the present invention, a battery pack includes a holding member that holds a plurality of batteries; a stacked battery in which the plurality of batteries are stacked in a stacking direction via the holding member; a ventilation passage that extends adjacent to the stacked battery in the stacking direction and forms a flow path for cooling air that cools the plurality of batteries; and a housing that houses the stacked battery and the ventilation passage, wherein the ventilation passage has an intake port that takes in the cooling air into the ventilation passage and an exhaust port that discharges the cooling air after cooling the plurality of batteries, and the holding member has ventilation holes that open on the ventilation passage side and on the opposite side of the ventilation passage and allow the cooling air to ventilate from the ventilation passage to the stacked battery, and the ventilation holes include bottom ventilation holes that open toward a space formed between the bottom surfaces of the plurality of batteries and the bottom surface of the holding member. [Effects of the Invention]

[0007] According to the embodiment of the present invention, the cooling efficiency of the battery in the battery pack can be further improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a battery pack according to a first embodiment. [Figure 2] FIG. 2 is a plan view showing the battery modules and main ventilation passages of the battery pack of the first embodiment. [Figure 3] FIG. 2 is a perspective view showing a battery module and a main ventilation passage of the battery pack of the first embodiment. [Figure 4] 3 is a perspective view showing an example of the configuration of a battery holder that holds a battery inside the battery pack of the first embodiment. FIG. [Figure 5] 3 is a perspective view showing an example of the configuration of a battery holder that holds a battery inside the battery pack of the first embodiment. FIG. [Figure 6] FIG. 2 is a perspective view showing the connection of multiple battery holders according to the first embodiment. [Figure 7] FIG. 3 is a side view showing the connection of multiple battery holders according to the first embodiment. [Figure 8] FIG. 4 is a side view showing the ventilation holes formed by connecting the battery holders of the first embodiment. [Figure 9] 3 is a perspective view illustrating the definition of the cross section of the ventilation hole and the cross section of the main ventilation passage of the battery holder according to the first embodiment. FIG. [Figure 10] Cross section AA of Figure 9. [Figure 11] Cross section B-B of Figure 9. [Figure 12] FIG. 5 is a cross-sectional view of the battery holder taken along line BB of the first embodiment. [Figure 13] FIG. 10 is a comparison diagram of simulation results of temperature distribution in a battery module according to the prior art (without cross-sectional area ratio conditions) and embodiment 1 (with cross-sectional area ratio conditions). [Figure 14] FIG. 10 is a perspective view showing a battery module and a main ventilation passage of a battery pack according to a second embodiment. [Figure 15] FIG. 10 is a diagram for explaining the temperature distribution in a battery module with no specified cross-sectional area ratio for a battery pack configured similarly to that of the second embodiment. [Figure 16] FIG. 11 is a perspective view showing a battery module and a main ventilation passage of a battery pack according to a third embodiment. [Figure 17] FIG. 11 is a diagram for explaining the temperature distribution in a battery module with no specified cross-sectional area ratio for a battery pack configured similarly to that of the third embodiment. [Figure 18] FIG. 10 is a perspective view showing a battery module and a main ventilation passage of a battery pack according to a fourth embodiment. [Figure 19] FIG. 10 is a perspective view showing the battery modules and main ventilation duct of the battery pack of embodiment 4 (with the upper battery module and main ventilation duct removed). DETAILED DESCRIPTION OF THE INVENTION

[0009] Each embodiment of the present invention will be described with reference to the drawings. To facilitate understanding of each embodiment, the size and proportions of components may be exaggerated or simplified in the drawings. In the description of each embodiment, the same components are assigned the same reference numerals, and duplicate descriptions will be omitted. In each embodiment, multiple identical components will be described by adding a subscript to the same reference numeral when distinguishing between them, and will be described by the same reference numeral without the subscript when not distinguishing between them.

[0010] In the description of each embodiment, an XYZ Cartesian coordinate system with the X, Y, and Z axes as its positive coordinate axes is used. The arrows on the X, Y, and Z axes indicate the positive direction of the coordinate axis. The X axis is the coordinate axis in the width direction of the battery. The Y axis is the coordinate axis in the stacking direction of the batteries. The Z axis is the coordinate axis in the height direction of the battery. The plane formed by the X and Y axes is called the XY plane, the plane formed by the Y and Z axes is called the YZ plane, and the plane formed by the X and Z axes is called the XZ plane. However, the XYZ Cartesian coordinate system only represents relative positional relationships.

[0011] [Embodiment 1] (Outline of battery pack 1 of embodiment 1) FIG. 1 is a perspective view showing a battery pack 1 of Embodiment 1. FIG. 1 schematically shows the battery pack 1 in a state in which a battery module 3 and a main ventilation passage 4 are housed in a battery casing 2. FIG. 2 is a plan view showing the battery module 3 and the main ventilation passage 4 of the battery pack 1 of Embodiment 1. FIG. 3 is a perspective view showing the battery module 3 and the main ventilation passage 4 of the battery pack 1 of Embodiment 1. The battery pack 1 is mounted as a power supply source in various vehicles that use electric power as driving energy, such as electric vehicles and hybrid electric vehicles.

[0012] The battery pack 1 is an assembled battery comprising a hollow battery casing 2, two battery modules (stacked batteries) 3a and 3b, and a main ventilation passage 4. The material of the battery casing 2 may be any material that satisfies required specifications such as strength, durability, and workability. Furthermore, the number of battery modules 3 housed in the battery casing 2 is not limited to two.

[0013] The battery module (stacked battery) 3 is a stacked battery in which multiple batteries 31 are stacked in the Y-axis direction (stacking direction) via multiple battery holders 32 (described later with reference to Figures 4 to 6). The batteries 31 are wound secondary batteries, with a group of wound batteries housed in a metal battery can. Battery module 3a is placed on the negative side of the main ventilation passage 4 in the X-axis direction. Battery module 3b is placed on the positive side of the main ventilation passage 4 in the X-axis direction.

[0014] The main ventilation passage 4 is adjacent to the battery module 3. The main ventilation passage 4 extends along the Y-axis and constitutes a ventilation passage for cooling air that cools the batteries 31 inside the battery housing 2. The main ventilation passage 4 can be formed, for example, by attaching plate-shaped members to the battery modules 3a, 3b so as to block the gap between the battery modules 3a, 3b from both sides along the Z-axis when the battery modules 3a, 3b are aligned in the X-axis direction. The main ventilation passage 4 has an intake duct 41 on the negative side of the Y-axis. The intake duct 41 has an intake port 411 that opens on the negative side of the Y-axis.

[0015] The intake duct 41, the main ventilation passage 4, and the exhaust duct 21 constitute a ventilation passage that forms a flow path for cooling air that cools the battery 31. That is, the ventilation passage has an intake port 411 that takes in cooling air into the ventilation passage, and an exhaust port 421 that discharges the cooling air after cooling the battery 31.

[0016] As shown by arrow A (FIG. 1), cooling air, which is a refrigerant that cools the batteries 31, is taken into the main ventilation path 4 from the intake port 411 through the intake duct 41. Then, as shown by arrow B (FIG. 2), the cooling air branches into small branches through a group of ventilation holes 332 (FIG. 8) provided on the main ventilation path 4 side of the battery modules 3a, 3b, and flows from the main ventilation path 4 toward the battery modules 3a, 3b.

[0017] Furthermore, as shown by arrow C (FIG. 3), the cooling air flows in a direction away from the battery modules 3a, 3b through a group of ventilation holes 332 (FIG. 8) provided on the opposite side of the main ventilation passage 4 of the battery modules 3a, 3b. Finally, the cooling air collides with the inner wall of the battery housing 2 of the battery pack 1, changes course, and is discharged in the positive direction of the Z axis from the exhaust port 221 of the exhaust duct 21 provided on the positive side of the Z axis of the battery housing 2, as shown by arrow D (FIG. 1).

[0018] The battery pack 1 may be configured without the battery casing 2 and the exhaust port 211. In this case, the cooling air forms a flow path between the intake port 411 and the ventilation holes (first ventilation hole 322a, second ventilation hole 322b, third ventilation hole 326, fourth ventilation hole 328, fifth ventilation hole 330, etc.).

[0019] (Configuration example of battery holder 32) 4 and 5 are perspective views showing an example of the configuration of a battery holder 32 that holds batteries 31 inside the battery pack 1 of embodiment 1. FIG. 5 is a perspective view of the battery holder 32 shown in FIG. 4 as viewed from the direction of arrow E. The battery holder 32 may be made of any material as long as it meets the required specifications, such as strength, durability, and workability. The battery holder 32 is an individual holding member that holds the batteries 31.

[0020] 4 and 5, the battery holder 32 has a first bottom surface 321a and a second bottom surface 321b. The battery holder 32 also has a first ventilation hole 322a and a second ventilation hole 322b. The battery holder 32 also has a first support base 323a, a second support base 323b, a column 324, a first beam 325, a third ventilation hole 326, a second beam 327, a fourth ventilation hole 328, a third beam 329, a fifth ventilation hole 330, and a fourth beam 331.

[0021] The battery holder 32 has a structure that is symmetrical with respect to an imaginary plane that includes a first beam portion 325, a second beam portion 327, a third beam portion 329, and a fourth beam portion 331 and is parallel to the XZ plane.

[0022] The first bottom surface portion 321a is located on the most negative Z-axis side of the battery holder 32 and forms the bottom surface (surface on the negative Z-axis side) of the battery module 3 in which batteries 31 are stacked while held by the battery holder 32. When the battery holder 32 is connected to another battery holder 32 in the Y-axis direction, the first bottom surface portion 321a, together with the second bottom surface portion 321b of the other battery holder 32, forms the bottom surface of the battery module 3.

[0023] When the battery 31 is held by the battery holder 32, the first support base 323a contacts the bottom surface (the surface on the negative Z-axis side) of the battery 31 to support the battery 31. When the battery holder 32 is connected to another battery holder 32 in the Y-axis direction, the first support base 323a, together with the second support base 323b of the other battery holder 32, forms a support surface for the battery 31.

[0024] When viewed in the XY plane, the first support base 323a has a narrower width in the Y-axis direction than the first bottom surface portion 321a. When viewed in the XY plane, the second support base 323b has a narrower width in the Y-axis direction than the second bottom surface portion 321b, and the width is approximately the same as that of the first support base 323a. Therefore, when the battery 31 is supported by the first support base 323a and the second support base 323b, a non-contact region that does not come into contact with the first support base 323a and the second support base 323b is generated on the bottom surface of the battery 31. The non-contact region on the bottom surface of the battery 31 faces the first bottom surface portion 321a and the second bottom surface portion 321b and forms a flow path 322 ( FIG. 12 ) for cooling air that directly cools the bottom surface of the battery 31.

[0025] The pillars 324 extend vertically (in the positive direction of the Z axis) from both ends of the first bottom surface 321a and the second bottom surface 321b in the X axis direction. The first beam 325 extends between the two pillars 324, standing in the positive direction of the Z axis relative to the first support base 323a and the second support base 323b.

[0026] The third ventilation hole 326 is provided in the two pillars 324 midway between the position where the first beam 325 is connected and the position where the second beam 327 is connected.

[0027] The second beam portion 327 spans between the two pillar portions 324 at a position intermediate between the third ventilation hole 326 and the fourth ventilation hole 328 of each of the two pillar portions 324 .

[0028] The fourth ventilation hole 328 is provided in the two pillar portions 324 midway between the position where the second beam portion 327 is connected and the position where the third beam portion 329 is connected.

[0029] The third beam portion 329 spans between the two pillar portions 324 at a position intermediate the fourth ventilation hole 328 and the fifth ventilation hole 330 of each of the two pillar portions 324 .

[0030] The fifth ventilation hole 330 is provided in the two pillars 324 at a midpoint between the position where the third beam portion 329 is connected and the position where the fourth beam portion 331 is connected.

[0031] The fourth beam portion 331 spans between the two pillar portions 324 at a position above (in the positive direction of the Z axis) the fifth ventilation holes 330 of each of the two pillar portions 324 .

[0032] Fig. 6 is a perspective view showing the connection of multiple battery holders 32 according to embodiment 1. Fig. 7 is a side view showing the connection of multiple battery holders 32 according to embodiment 1. Fig. 8 is a side view showing the ventilation hole group 332 formed by connecting battery holders 32 according to embodiment 1. Figs. 6, 7, and 8 are illustrative examples and have been appropriately simplified in illustration.

[0033] As shown in Figure 6, multiple battery holders 32 are connected in the Y-axis direction, forming a holding space 32a between two adjacent battery holders 32, each holding one battery 31. The bottom of the holding space 32a that holds the battery 31 is formed by the first support base 323a of one of the two adjacent battery holders 32 facing the second support base 323b of the other. The holding space 32a is separated from adjacent holding spaces 32a by a first beam portion 325, a second beam portion 327, a third beam portion 329, and a fourth beam portion 331.

[0034] 6 and 7 , the battery holder 32 has a first beam 325, a second beam 327, a third beam 329, and a fourth beam 331 in an imaginary plane parallel to the XZ plane including the dashed line L1 parallel to the Z axis. Therefore, cooling air flows into and out of one holding space 32a via the third ventilation hole 326, the fourth ventilation hole 328, and the fifth ventilation hole 330 of two adjacent battery holders 32. In other words, one battery holder 32 allows cooling air to flow into and out of two adjacent holding spaces 32a via the third ventilation hole 326, the fourth ventilation hole 328, and the fifth ventilation hole 330.

[0035] When two battery holders 32 are connected, the first vent 322a of one battery holder 32 and the second vent 322b of the other battery holder 32 are in contact with each other in the opposite direction of the stacking direction of the batteries 31 when viewed in the YZ plane, as shown in Figure 7. At this time, the two battery holders 32 form bottom vents 322h. One bottom vent 322h is formed at each end of the X-axis direction of adjacent battery holders 32.

[0036] The bottom vents 322h are open toward the space formed between the bottom surface of the battery 31 and the first and second bottom surfaces 321a and 321b of the holding member (battery holder 32). Therefore, the bottom vents 322h at both ends in the X-axis direction of adjacent battery holders 32 are connected by the flow path 322 (FIG. 12).

[0037] Thus, the holding member 32S that holds the batteries 31 inside the battery pack 1 of the first embodiment is configured by connecting multiple individual holding members (battery holders 32) that respectively hold multiple batteries 31. In this configuration, for example, the first ventilation holes 322a and the second ventilation holes 322b that make up the bottom ventilation holes 322h can be formed as notches that face each other in the stacking direction of the batteries 31 (e.g., the positive direction of the Y axis) and the opposite direction of the stacking direction (e.g., the negative direction of the Y axis). In other words, the battery holder 32 has a recess on its end surface in the stacking direction (Y axis). The recess is a space formed between the first bottom surface portion 321a and the first support base 323a, extending across both ends of the battery holder 32 in the X axis direction, when the battery holder 32 is viewed cross-sectionally on the YZ plane. The bottom ventilation holes 322h are formed so that a recess formed in one battery holder 32 faces a recess formed in another battery holder 32 adjacent to the battery holder 32 in the stacking direction. This has the advantage that precision machining for forming the bottom vent holes 322h becomes easier.

[0038] However, the method for constructing the battery 31 holding member is not limited to the method of connecting battery holders 32 that respectively hold multiple batteries 31. The method for constructing the holding member is not limited as long as it is provided with the ventilation holes including the first ventilation hole 322a and the second ventilation hole 322b and the flow path 322 (FIG. 12).

[0039] FIG. 8 is a side view of the battery module 3b as viewed from the positive direction of the X axis.

[0040] As shown in FIG. 8, the battery module 3b has a bottom surface ventilation hole group 332L below and a main surface ventilation hole group 332U above the Z-axis height position of the support bases 323 (first support base 323a and second support base 323b). The bottom surface ventilation hole group 332L includes a plurality of bottom surface ventilation holes 322h. The main surface ventilation hole group 332U includes a plurality of third ventilation holes 326, a plurality of fourth ventilation holes 328, and a plurality of fifth ventilation holes 330. The bottom surface ventilation hole group 332L and the main surface ventilation hole group 332U are collectively referred to as ventilation hole group 332.

[0041] The bottom ventilation hole group 332L allows cooling air to flow in from the main ventilation path 4 side in the X-axis direction to directly cool the bottom surface of the battery 31 held by the holding space 32a, and discharge it from the opposite side of the main ventilation path 4.

[0042] The main surface ventilation hole group 332U allows cooling air to flow from the main ventilation path 4 side in the X-axis direction toward the spaces between the main surfaces of the stacked batteries 31 held by the holding spaces 32a, directly cooling the main surfaces of the batteries 31, and discharges it from the opposite side of the main ventilation path 4. The main surfaces of the batteries 31 are the surfaces of the batteries 31 that face each other when the batteries 31 are stacked.

[0043] The main surface ventilation hole group 332U of the battery holder 32 (third ventilation hole 326, fourth ventilation hole 328, fifth ventilation hole 330) is provided on the pillar portion 324, for example, at equal intervals.

[0044] The third vent hole 326 is mainly intended to provide a heat dissipation measure below the battery 31, to reinforce the fastening strength of the battery 31, and to adjust the size to satisfy the cross-sectional area ratio of formula (1) described below. That is, in the design stage, after the sizes of the bottom surface vent hole 322h (first vent hole 322a, second vent hole 322b), fourth vent hole 328, and fifth vent hole 330 are determined, the size of the third vent hole 326 is adjusted to satisfy the cross-sectional area ratio of formula (1).

[0045] The fourth vent hole 328 is mainly intended to prevent heat generation from the wound group inside the battery 31. The fourth vent hole 328 is provided so that the center of the vent hole is near the center of the winding of the battery 31.

[0046] The fifth ventilation hole 330 is mainly intended to prevent heat generation from the bus bars and battery terminals of the battery pack 1. The third ventilation hole 326 is provided at a higher position in the positive direction of the Z axis within the allowable range of the strength of the battery holder 32.

[0047] Although FIG. 8 shows the ventilation hole group 332 on the side surface of the battery module 3b on the positive X-axis side, similar ventilation hole groups 332 are provided on the side surface of the battery module 3b on the negative X-axis side (main ventilation passage 4 side) and on both sides of the battery module 3b on the X-axis.

[0048] Fig. 9 is a perspective view showing the definitions of cross section 3CS of the ventilation hole group 332 and cross section 4CS of the main-air-passage channel 4 in embodiment 1. Fig. 10 is a cross-sectional view taken along line AA in Fig. 9. Fig. 11 is a cross-sectional view taken along line BB in Fig. 9. Fig. 12 is a cross-sectional view of the battery holder 32 in embodiment 1 taken along line BB (Fig. 9), and is an enlarged view of cross section 3CS of the battery module 3b shown in Fig. 11. Figs. 9, 10, 11, and 12 are illustrative examples, and the illustrations have been appropriately simplified.

[0049] A cross section 4CS of the main-air-passage passage 4 taken along line AA (FIG. 9) parallel to the X-axis is defined as shown in FIG. 10. A cross section 3CS of the battery module 3b taken along line BB (FIG. 9) parallel to the Y-axis is defined as shown in FIG.

[0050] The opening area S2 of the battery module 3b is defined as the sum of the opening areas of the ventilation hole groups 332 (bottom surface ventilation hole group 332L and main surface ventilation hole group 332U) included in the cross section 3CS. This opening area is the cross-sectional area of ​​the space of the battery holder 32, obtained by subtracting the cross-sectional area blocked by the battery 31 from the opening areas of the third ventilation hole 326, the fourth ventilation hole 328, and the fifth ventilation hole 330 when viewed in the YZ plane. The cross section 3CS and opening area S2 of the battery module 3a are defined in the same way as those of the battery module 3b.

[0051] In this case, the cross-sectional area ratio relationship holds that the cross-sectional area S1 of the main ventilation passage 4 is larger than the sum (S2+S2) of the opening areas S2 of the battery modules 3a, 3b. That is, the condition of the following formula (1) holds. S1>2×S2 (1)

[0052] The dimensions of each hole in the main surface ventilation hole group 332U and the bottom surface ventilation hole group 332L are optimized and determined to meet the required specifications such as strength, durability, and processability in accordance with the specifications and materials of the battery module 3 including the battery 31 and battery holder 32, the main ventilation path 4, and the battery holder 32.

[0053] (Effects of the First Embodiment (Regarding Cross-Sectional Area Ratio)) Fig. 13 is a comparison diagram of simulation results of temperature distribution in a battery module of the prior art (no cross-sectional area ratio condition) and embodiment 1 (with cross-sectional area ratio specified). Fig. 13 shows a schematic representation of the temperature distribution in the battery module when the battery module and main ventilation duct are viewed in the XY plane, with three relatively high temperature levels: T1, T2, and T3. The simulation was performed under the same conditions for the prior art and embodiment 1. In Fig. 13, the air intake is on the negative Y-axis side of main ventilation duct 4x,4.

[0054] In the battery modules 3ax, 3bx and main ventilation duct 4x of the prior art, high temperature T1 was distributed near the air intake, and medium temperature T2 and low temperature T3 were distributed with increasing distance from the air intake, as shown in FIG. 13(a).

[0055] On the other hand, in the battery modules 3a, 3b and main ventilation duct 4x of embodiment 1, as shown in Fig. 13(b), high temperature T1 was hardly distributed, medium temperature T2 was distributed generally regardless of the distance from the air intake, and low temperature T3 was only slightly distributed near the main ventilation duct 4. The standard deviation of the temperature of each battery 31 in embodiment 1 was about one-third of that of the conventional technology shown in Fig. 13(a).

[0056] That is, in the battery module 3 of embodiment 1, by observing the cross-sectional area ratio of the above formula (1), the amount of cooling air distributed from the main ventilation passage 4 to the main surface ventilation hole group 332U and the bottom surface ventilation hole group 332L is generally uniform regardless of the distance from the air intake port. Since cooling air reaches each battery 31 evenly, the result is less variation in temperature among the batteries 31. Reducing the variation in temperature among the batteries 31 has the effect of suppressing battery degradation and extending battery life.

[0057] (Effects of the First Embodiment (Regarding the Bottom Ventilation Hole Group 332L)) In conventional technology, the main surface of the battery is directly cooled with cooling air, and the bottom surface of the battery is indirectly cooled by thermal conduction. As such, the surface of the battery that can be cooled is often limited due to constraints such as battery pack size, production cost, and safety. However, air-cooling systems that use cooling air have problems with cooling efficiency due to low thermal conductivity. In addition, if the battery pack is placed in a thermally unstable location, heat dissipation from the bottom surface of the battery cannot be expected, resulting in reduced cooling efficiency.

[0058] To address this issue, the battery pack 1 of embodiment 1 includes a bottom surface ventilation hole group 332L in addition to the main surface ventilation hole group 332U, allowing the bottom surface of the battery 31 to be directly cooled with cooling air in the same way as the main surface, achieving stable cooling efficiency. In particular, when heat dissipation by thermal conduction through the bottom surface of the battery pack cannot be expected, even a small amount of cooling air flowing toward the bottom surface of the battery pack can have a significant cooling effect. By ventilating cooling air over substantially the entire surface of the battery 31, a battery pack installed in a vehicle, for example, can be stably cooled without being significantly affected by the heat of other vehicle components.

[0059] Simulation results showed that, compared to the conventional technology, the first embodiment was able to suppress the temperature rise of the batteries 31 in the entire battery pack 1 by about 2 to 4% by providing the bottom surface ventilation hole group 332L in addition to the main surface ventilation hole group 332U.

[0060] Furthermore, compared to conventional techniques that cool the bottom surface of the battery by thermal conduction, in the first embodiment, it is possible to eliminate the need for a thermally conductive sheet, etc., and therefore the manufacturing cost and number of steps for the battery pack 1 can be reduced.

[0061] [Embodiment 2] Fig. 14 is a perspective view showing a battery module 3 and main ventilation channels 4a and 4b inside a battery pack 1B of embodiment 2. As shown in Fig. 14, the battery pack 1B employs a configuration in which two main ventilation channels 4a and 4b are arranged on both sides of one battery module 3 in the X-axis direction. Cooling air is taken into the main ventilation channel 4b from an intake port 411 of an intake duct 41 in the direction of arrow F (Fig. 14), passes through a flow path inside the battery module 3 similar to that of embodiment 1, and is discharged from an exhaust port 421 of an exhaust duct 42 of the main ventilation channel 4a in the direction of arrow G (Fig. 14).

[0062] 15 is a diagram for explaining the temperature distribution in a battery module with no specified cross-sectional area ratio for a battery pack configured similar to that of Embodiment 2. The simulation was performed under the same conditions as in Embodiment 1.

[0063] In the configuration of the battery pack 1B, if the cross-sectional area ratio of the above formula (1) is not observed, the temperature of the battery 31 in the region R1 near the intake duct 41 becomes relatively high, and the temperature of the battery 31 in the region R2 near the exhaust duct 42 becomes relatively low, as shown in Figure 15.

[0064] On the other hand, in the configuration of the battery pack 1B, by providing a bottom ventilation hole 322h and complying with the cross-sectional area ratio of the above formula (1), it becomes possible to cool the batteries 31 more efficiently, as with the battery pack 1 of embodiment 1, and the temperature variation of each battery 31 is reduced.

[0065] A battery pack having a configuration in which the two main ventilation passages 4a and 4b in the battery pack 1B are interchanged is also similar to the battery pack 1B.

[0066] [Embodiment 3] Fig. 16 is a perspective view showing a battery module 3 and main ventilation channels 4a and 4c inside a battery pack 1C of embodiment 3. As shown in Fig. 16, the battery pack 1C employs a configuration in which two main ventilation channels 4c and 4b are arranged on both sides of one battery module 3 in the X-axis direction. The main ventilation channel 4c is the same as the main ventilation channel 4a of embodiment 2, but with its Y-axis direction reversed. Cooling air is taken into the main ventilation channel 4a from an intake port 411 of an intake duct 41 in the direction of arrow H (Fig. 16), passes through a flow path inside the battery module 3 similar to that of embodiment 1, and is discharged from an exhaust port 421 of an exhaust duct 42 of the main ventilation channel 4c in the direction of arrow I (Fig. 16).

[0067] 17 is a diagram for explaining the temperature distribution in a battery module with no specified cross-sectional area ratio for a battery pack configured similarly to that of Embodiment 3. The simulation was performed under the same conditions as in Embodiment 1.

[0068] In the configuration of the battery pack 1C, when the cross-sectional area ratio of the above formula (1) was not observed, the temperature of the battery 31 in the region R3 near the intake duct 41 and the exhaust duct 42 became relatively low, as shown in Fig. 17. Also, the temperature of the battery 31 in the region R4, which is the farthest from the intake duct 41 and the exhaust duct 42 in the Y-axis direction, became relatively high.

[0069] On the other hand, in the configuration of the battery pack 1C, by providing a bottom ventilation hole 322h and complying with the cross-sectional area ratio of the above formula (1), it becomes possible to cool the batteries 31 more efficiently, as with the battery pack 1 of embodiment 1, and the temperature variation of each battery 31 is reduced.

[0070] [Embodiment 4] 18 and 19 are perspective views showing the battery module 3 and main ventilation passage 4 of a battery pack 1D of embodiment 4. The battery pack 1D employs a configuration in which the battery modules 3a, 3b and main ventilation passage 4 units of embodiment 1 are stacked in two layers in the Z-axis direction, resulting in four battery modules 3a, 3b and one main ventilation passage 4D. Note that the number of stacked units is not limited to two layers.

[0071] In the fourth embodiment, the main ventilation path 4 between the upper battery modules 3a, 3b in the Z-axis direction and the main ventilation path 4 between the lower battery modules 3a, 3b in the Z-axis direction form a single main ventilation path 4D. In Fig. 19, the upper battery modules 3a, 3b in the Z-axis direction and the main ventilation path 4 unit in the battery pack 1D are not shown.

[0072] The battery pack 1D has an intake duct 41D and an exhaust duct 42D. The multiple main ventilation channels 4 of the stacked units converge at an intake port 411D of the intake duct 41D and communicate with each other. Cooling air is taken in through the intake port 411D of the intake duct 41D, as indicated by arrow J in FIGS. 18 and 19. The cooling air then passes through the main ventilation channel 4 and the flow paths within the battery modules 3a and 3b similar to those in the first embodiment, and is exhausted from an exhaust port 421D of the exhaust duct 42D, as indicated by arrow K in FIGS. 18 and 19.

[0073] The battery pack 1D requires a large amount of cooling air due to the number of stacked battery modules 3a, 3b. However, by providing the bottom ventilation holes 322h and complying with the cross-sectional area ratio of formula (1) above, the batteries 31 can be cooled more efficiently, and the temperature variation among the batteries 31 can be reduced, similar to the battery pack 1 of embodiment 1.

[0074] The batteries to which the embodiments are applicable are not limited to secondary batteries such as lithium ion batteries, but may also be other secondary batteries such as nickel-metal hydride batteries and lead batteries, primary batteries, or other batteries.

[0075] The above description is merely an example, and the technology disclosed herein is not limited to the configurations of the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the technology disclosed herein, and are not necessarily limited to those including all of the described configurations. Furthermore, the functions and configurations of each embodiment can be added, deleted, or replaced with the functions and configurations of other embodiments or modifications as long as there is no contradiction. [Explanation of symbols]

[0076] 1,1B,1C,1D: Battery Pack; 2: Battery Housing; 3,3a,3b: Battery Mogul; 4,4a,4b,4c,4D: Main Ventilation Channel; 31: Battery; 32: Battery Holder; 32S: Holding Component; 322a: First Ventilation Hole; 322b: Second Ventilation Hole; 326: Third Ventilation Hole; 328: Fourth Ventilation Hole; 330: Fifth Ventilation Hole; 322h: Bottom Ventilation Hole; 322L: Bottom Ventilation Hole Group; 332U: Main Ventilation Hole Group; 411,411D: Intake Port; 221,421,421d: Exhaust Port

Claims

1. a holding member for holding a plurality of batteries; a stacked battery in which the plurality of batteries are stacked in a stacking direction via the holding member; a ventilation channel extending in the stacking direction adjacent to the battery stack and forming a flow path for cooling air that cools the plurality of batteries; a housing that houses the stacked battery and the ventilation passage, The ventilation channel is an intake port that takes the cooling air into the ventilation path; The holding member is a ventilation hole that is open on the ventilation passage side and on the opposite side of the ventilation passage and that allows the cooling air to flow from the ventilation passage to the stacked battery; The ventilation hole is a bottom vent hole that opens toward a space formed between bottom surfaces of the plurality of batteries and a bottom surface of the holding member; The housing includes: an exhaust port on the opposite side of the bottom surface of the plurality of batteries and the bottom surface of the holding member; The exhaust port is the cooling air is taken into the ventilation passage from the intake port, is passed from the ventilation passage through the ventilation holes including the bottom ventilation hole to the stacked battery, flows to the opposite side of the ventilation passage, cools the plurality of batteries, and then collides with an inner wall of the housing and changes course, and is then discharged; The cross-sectional area of ​​the ventilation passage is larger than the total opening area of ​​all the ventilation holes. A battery pack characterized by:

2. a holding member for holding a plurality of batteries; a stacked battery in which the plurality of batteries are stacked in a stacking direction via the holding member; a ventilation channel extending in the stacking direction adjacent to the battery stack and forming a flow path for cooling air that cools the plurality of batteries; The ventilation channel is an intake port that takes the cooling air into the ventilation path; The holding member is a ventilation hole that is open on the ventilation passage side and on the opposite side of the ventilation passage and that allows the cooling air to flow from the ventilation passage to the stacked battery; The ventilation hole is a bottom vent hole that opens toward a space formed between bottom surfaces of the plurality of batteries and a bottom surface of the holding member; The holding member is The battery pack is configured by connecting a plurality of individual holding members that respectively hold the plurality of batteries, the plurality of individual holding members have recesses on end surfaces in the stacking direction, the bottom surface ventilation hole is formed so as to face the recess formed in a first individual holding member among the plurality of individual holding members and the recess formed in a second individual holding member among the plurality of individual holding members adjacent to the first individual holding member in the stacking direction.

3. a housing that houses the stacked battery and the ventilation passage; The housing includes:

3. The battery pack according to claim 2, further comprising an exhaust port for discharging the cooling air after cooling the plurality of batteries.

4. The holding member is 3. The battery pack according to claim 1, wherein the battery pack is configured by connecting a plurality of individual holding members that respectively hold the plurality of batteries.

5. 3. The battery pack according to claim 1, wherein the ventilation passage is disposed between a first battery cell and a second battery cell of the battery cells.

6. a plurality of units are stacked, each unit having the ventilation passage disposed between a first stacked battery and a second stacked battery among the stacked batteries; 3. The battery pack according to claim 1, wherein the plurality of ventilation passages provided in the plurality of stacked units are gathered at the intake port and communicate with each other.

7. the battery stack is disposed between a first ventilation path and a second ventilation path of the ventilation paths; the first ventilation passage has the intake port, and the second ventilation passage has the exhaust port; the first ventilation passage and the second ventilation passage form a flow path for the cooling air that runs from the first ventilation passage through the stacked battery to the second ventilation passage; the ventilation holes of the first ventilation passage allow the cooling air to flow from the first ventilation passage to the stacked battery; 4. The battery pack according to claim 3, wherein the ventilation holes of the second ventilation passage allow the cooling air to flow from the battery stack to the first ventilation passage.

8. A battery pack as described in claim 2, characterized in that the cross-sectional area of ​​the ventilation passage is greater than the sum of the opening areas of all the ventilation holes.

9. The ventilation hole is 3. The battery pack according to claim 1, further comprising main surface vent holes that open toward spaces formed between the main surfaces of the plurality of stacked batteries.

10. The holding member is 10. The battery pack according to claim 9, wherein a plurality of the main surface vent holes are disposed at equal intervals in the height direction of the battery.

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