JP2014127262A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress a temperature variation between single cells in a battery pack provided with one air inflow opening and two air exhaust openings.SOLUTION: Provided is a battery pack having: a battery module having a plurality of single cells laminated together, and having formed therein a conduction path for air to be conducted between the single cells adjacent in a lamination direction; and a case for accommodating the battery module. Inside the case are formed an inflow path and a discharge path extending in the lamination direction. The air inflow opening in the inflow path is formed in only one end part of the inflow path, and the air exhaust opening in the discharge path is formed in only one end part of the discharge path, the aperture area of the air inflow opening being larger than the aperture area of the air exhaust opening.

Description

  The present invention relates to a technique for suppressing temperature variation between single cells arranged inside a battery pack.

  A hybrid vehicle, an electric vehicle, or the like is equipped with a power storage device that stores operating power supplied to a vehicle driving motor. As this type of power storage device, a battery pack having an assembled battery, a case for housing the assembled battery, and a conduction path for conducting cooling air inside and outside the case is known (see, for example, Patent Document 1).

  Further, Patent Document 2 is a battery module having a plurality of unit modules and a case for housing the plurality of unit modules, and includes a gap between an inner wall surface of the case and a molded body of the unit module, and the fluid supply Disclosed is a battery module having a flow path communicating with an opening and the fluid discharge port, and wherein a cross-sectional area of the flow path on the fluid supply port side is larger than a cross-sectional area of the flow path on the fluid discharge port side To do.

  As another configuration of the battery pack, a battery pack provided with one inflow port and two discharge ports can be considered.

JP 05-343105 A JP 2012-156057 A

  By the way, when examining the cooling structure of the battery pack, it is necessary to consider the temperature variation between the unit modules. When the temperature variation between the unit modules increases, the unit module having a higher temperature deteriorates earlier, and the life of the battery pack is shortened.

  As described above, various cooling structures are conceivable for the battery pack, and the behavior of the cooling air changes as the cooling structure changes. Therefore, in order to suppress temperature variation between unit modules, it is necessary to consider an appropriate configuration according to each cooling structure.

  Accordingly, a first object of the present invention is to suppress temperature variations between single cells in a battery pack provided with one inlet and two outlets. Moreover, this invention makes it the 2nd objective to suppress the pressure loss of the air which flows between cell cells.

  In order to achieve the first object, the battery pack according to the present invention includes (1) a plurality of unit cells stacked, and a conduction path for conducting air between the unit cells adjacent in the stacking direction. In the battery pack having the formed battery module and a case for accommodating the battery module, an inflow path for allowing air to flow into the conduction path extends in the stacking direction inside the case. And a discharge path for discharging the air flowing out from the conduction path to the outside of the case extends in the stacking direction inside the case, and the air inlet in the inflow path is It is formed only at one end of the inflow path, the air discharge port in the discharge path is formed only at both ends of the discharge path, and the opening area of the air inlet is It is larger than the opening area of the air outlet.

  (2) In the first configuration, the opening areas of the two air discharge ports can be set to be the same. According to the configuration of (2), the flow path design can be simplified.

(3) In the above configuration (1) or (2), when the opening area of the air inlet is A and the opening area of the air outlet is B, the following expression (1) is preferably satisfied.
31/29 ≦ A / B ≦ 34/26 (1)

  According to the configuration of (3), it is possible to achieve both suppression of temperature variation between single cells and suppression of pressure loss of air introduced as a heat exchange medium.

  According to the present invention, in a battery pack provided with one air inlet and two air outlets, it is possible to effectively suppress temperature variations between single cells.

It is a disassembled perspective view of a battery pack. It is the schematic sectional drawing which cut | disconnected the battery pack in the direction orthogonal to the lamination direction of a cell. It is the schematic sectional drawing which cut | disconnected the battery pack by the XZ plane. FIG. 4 is a diagram corresponding to FIG. 3 and a schematic cross-sectional view of a battery pack according to Reference Example 2. FIG. 4 is a diagram corresponding to FIG. 3 and a schematic cross-sectional view of a battery pack according to a second modification.

  A battery pack according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of the battery pack. FIG. 2 is a schematic cross-sectional view of the battery pack cut in a direction orthogonal to the stacking direction of the unit cells. FIG. 3 is a schematic cross-sectional view of the battery pack taken along the XZ plane. The X axis, the Y axis, and the Z axis are three orthogonal axes different from each other. In the following description, the X-axis direction is the + X-axis direction, the opposite direction to the X-axis direction is the -X-axis direction, the Y-axis direction is the + Y-axis direction, the opposite direction to the Y-axis direction is the -Y-axis direction, and the Z-axis direction is + Z The direction opposite to the axial direction and the Z-axis direction is defined as the −Z-axis direction. However, when there is no need to particularly distinguish the + X-axis direction and the −X-axis direction, these are collectively referred to as the X-axis direction. When there is no need to particularly distinguish the + Y axis direction and the −Y axis direction, these are collectively referred to as the Y axis direction. When there is no need to particularly distinguish the + Z-axis direction and the −Z-axis direction, these are collectively referred to as the Z-axis direction.

  1 to 3, the battery pack 1 includes a battery module 10, an upper case 20, a lower case 30, a device cover case 40, an intake duct 50, a first exhaust duct 60, a second exhaust duct 70, a blower. 80. The battery pack 1 can be used for a power storage device that stores electric power supplied to a vehicle driving motor. The battery module 10 includes a plurality of unit cells 11 stacked in the X-axis direction, an end plate 12 disposed at a position sandwiching the unit cells 11, and a restraining rod 13 that connects these end plates 12. The unit cell 11 may be a secondary battery such as a lithium ion battery or a nickel metal hydride battery, or a capacitor.

  At the end of the unit cell 11 in the + Z-axis direction, a liquid injection port 11 a for injecting the electrolyte into the unit cell 11 is formed. As shown in FIG. 2, a convex positive electrode portion 11 b (or a negative electrode portion 11 c) is formed at an end portion in the + Y axis direction of the unit cell 11, and an end portion in the −Y axis direction of the unit cell 11. Is formed with a convex negative electrode portion 11c (or positive electrode portion 11b).

  The positive electrode part 11b of one unit cell 11 adjacent to the X-axis direction and the negative electrode part 11c of the other unit cell 11 are connected in series by a bus bar (not shown). Thereby, the battery pack 1 with high energy output is obtained. However, the adjacent unit cells 11 may be connected in parallel. In this case, the storage capacity of the battery pack 1 is increased.

  A plurality of convex ribs are formed on the end surface of the unit cell 11 in the X-axis direction, and these ribs extend in the Z-axis direction. In the assembled state of the battery pack 1, when these ribs come into contact with the outer surface of the adjacent unit cell 11, a conduction path 14 (see FIG. 3) for conducting air is formed. Here, each cell 11 can be cooled or heated by flowing air through the conduction path 14. By cooling each unit cell 11, the deterioration of each unit cell 11 can be suppressed. By heating each unit cell 11, the input / output characteristics of each unit cell 11 in a cryogenic state can be improved. In addition, you may form the conduction | electrical_connection path 14 by interposing the spacer member with a rib between the adjacent unit cells 11. FIG.

  The restraining rod 13 is fastened and fixed to the pair of end plates 12. Thereby, a pair of end plate 12 is pulled in the direction which approaches mutually, and the several cell 11 can be restrained. As a result, it is possible to suppress the displacement of the unit cell 11 and to suppress the performance deterioration of the unit cell 11.

  Referring to FIG. 2, upper case 20 includes a top surface portion 21, an upper step shape portion 22, and an upper flange portion 23. The top surface portion 21 is provided at a position separated from the unit cell 11 in the + Z-axis direction. The upper step-shaped portion 22 is formed at both ends of the top surface portion 21 in the Y-axis direction, and the bent portion is in contact with the upper surface (end surface in the + Z-axis direction) of the unit cell 11 via a seal member. An air intake chamber (corresponding to an inflow path) 24 for introducing air into the conduction path 14 is formed by a space surrounded by the top surface part 21, the upper step shape part 22, and the upper surface of the unit cell 11.

  The lower case 30 includes a bottom surface portion 31, a lower step shape portion 32, and a lower flange 33. The bottom surface portion 31 is provided at a position separated from the unit cell 11 in the −Z axis direction. The lower stepped portions 32 are formed at both ends in the Y-axis direction of the bottom surface portion 31, and the bent portions are bolted to the lower surface (end surface in the −Z-axis direction) of the battery module 10. An exhaust chamber (corresponding to a discharge path) for discharging the air flowing out from the conduction path 14 to the outside of the lower case 30 by a space surrounded by the bottom surface part 31, the lower step shape part 32, and the lower surface of the unit cell 11. 34 is formed.

  Referring to FIG. 1 again, the device cover case 40 is attached to the end of the upper case 20 in the −X axis direction. The attachment method may be fastening means or welding means. A closing plate 40a (see FIG. 3) is provided between the upper case 20 and the end plate 12, and one end of the intake chamber 24 is closed by the closing plate 40a. Therefore, the air introduced into the intake chamber 24 is blocked by the blocking plate 40 a and flows into the respective conduction paths 14.

  The intake duct 50 is connected to the end of the intake chamber 24 in the + X axis direction. The opening area when the opening of the intake chamber 24 on the side of the intake duct 50 (the air inlet 24a shown in FIG. 3) is viewed from the −X axis direction is “the opening of the air inlet” according to the claims. It corresponds to “Area A”. The blower 80 is connected to a duct connection port 52 formed at the end of the intake duct 50 in the + X-axis direction. By operating the blower 80, air is sucked and the sucked air is taken into the intake chamber 24. The blower 80 has a built-in fan, and the fan may be a sirocco type, propeller type, or crossflow type fan.

  The first exhaust duct 60 is connected to the end of the exhaust chamber 34 in the −X axis direction. The opening area when the opening of the exhaust chamber 34 on the first exhaust duct 60 side (the first air exhaust port 34a shown in FIG. 3) is viewed from the + X-axis direction is described in the claims. This corresponds to the opening area B of the air discharge port. The second exhaust duct 70 is connected to the end of the exhaust chamber 34 in the + X axis direction. The opening area when the opening of the exhaust chamber 34 on the second exhaust duct 70 side (second air discharge port 34b shown in FIG. 3) is viewed from the −X-axis direction is described in the claims. This corresponds to “the opening area B of the air discharge port”. Thus, the battery pack 1 of this embodiment is provided with one air inlet and two air outlets. The opening areas of the first air outlet 34a and the second air outlet 34b are preferably the same. By making the opening areas of the first air discharge port 34a and the second air discharge port 34b the same, it is easy to design in consideration of suppression of temperature variation and suppression of pressure loss.

  FIG. 4 corresponds to FIG. 3 and is a cross-sectional view of the battery pack according to Reference Example 1. Elements having the same functions as those in the above embodiment are given the same reference numerals. The battery pack 100 according to the reference example 1 is different from the configuration of the first embodiment in that the first air discharge port 34a is closed. That is, the battery pack 100 has one air inlet and one air outlet, and the cooling path is formed in a so-called U shape. Here, when the opening area of the air inlet 24a of the present Reference Example 1 is A 'and the opening area of the air outlet 34b is B', the bias of the cooling air is suppressed and the pressure loss is reduced (that is, the air volume is secured). The aperture area ratio A ′ / B ′ capable of effectively realizing the above was 28/32.

  On the other hand, when the opening area of the air inlet 24a of the first embodiment is A, the opening area of the first air outlet 34a is B, and the opening area of the second air outlet 34b is B, the above reference example. 1 is set to the same opening area ratio, that is, the opening area ratio A / B is set to 28/32 (hereinafter, the battery pack configured with this opening area ratio is referred to as Reference Example 2), and the cooling air in the battery pack 1 is set. When the bias and pressure loss were measured, these measured values increased from the measured values of the reference example.

Table 1 below shows the flow rate variation of Reference Example 1 and Reference Example 2, where the vertical axis represents the flow rate variation and the horizontal axis represents the number of the conduction path 14.

  Referring to Table 1, in Reference Example 1, the maximum value on the negative side of the flow rate variation was only −7.2%, whereas in Reference Example 2, the maximum value on the negative side of the flow rate variation was −18. It expanded to 8%.

Table 2 shows the static pressure distribution data obtained by measuring the static pressure value for each conduction path 14, and shows the static pressure distribution of the one-sided exhaust configuration as in Reference Example 1 and the double-sided exhaust configuration as in Reference Example 2. Comparing.

Referring to Table 2, the configuration of the double-sided exhaust is less biased in the static pressure distribution in the exhaust chamber than the one-sided exhaust configuration, and the back side (the side with the larger flow path number, the −X-axis direction side) It turns out that a lot of air can be supplied.

  The inventors of the present invention diligently studied the above-described problem of both-side exhaust, and found that the bias of the cooling air can be reduced by setting the opening area ratio of A and B to A> B. Further, the present inventors have found that by setting the opening area ratio of A and B to 31/29 ≦ A / B ≦ 34/26, it is possible to achieve both suppression of uneven cooling air and suppression of pressure loss. .

The reason why the ratio of the opening area of A and B is limited to the predetermined range will be described in detail with reference to examples. Table 3 below shows simulation results by CFD (computational fluid dynamics) analysis. The horizontal axis is the opening area ratio of A and B, the left vertical axis is the air flow variation, and the right vertical axis is the pressure. It is a loss. Table 4 shows the evaluation results of the simulation. The air volume of the blower 80 was set to 80 m ³ / h. Note that the opening area of the air inlet 24 a can be adjusted by changing the height of the intake chamber 24 in the Z-axis direction. The opening areas of the first air discharge port 34a and the second air discharge port 34b can be adjusted by changing the height of the exhaust chamber 34 in the Z-axis direction.

Regarding air flow variation, 11% or more was evaluated as x, less than 11% to more than 10% was evaluated as ◯, and 10% or less was evaluated as ◎. Regarding the pressure loss, 68 Pa or less was evaluated as ◯, and over 68 Pa was evaluated as Δ. The first object of the present invention is to suppress variation in air volume. Therefore, if the evaluation of airflow variation is ◎ or ○ and the evaluation of pressure loss is ○, the overall evaluation is ◎, and if the evaluation of airflow variation is ◎ or ○ and the evaluation of pressure loss is △ In the case where the overall evaluation is “◯” and the evaluation of the air flow variation is “x”, the overall evaluation is “x” irrespective of the evaluation of the pressure loss.

  With reference to Table 3, by setting the opening area ratio of A and B to A> B, the air flow variation was suppressed to less than 11%, and the air flow variation was evaluated as “◯” or “◎”. By setting the opening area ratio of A and B to 31/29 ≦ A / B ≦ 34/26, the air flow variation is suppressed to 10% or less, the air flow variation is evaluated as ◎, and the pressure loss is 68 Pa or less. The pressure loss was evaluated as “good”.

  As described above, it was found that by setting the opening area ratio of A and B to A> B, the unevenness of the cooling air is alleviated and the temperature variation between the single cells 11 can be effectively suppressed. Further, it was found that by setting the area ratio of A and B to 31/29 ≦ A / B ≦ 34/26, it is possible to achieve both suppression of variation in cooling air and suppression of pressure loss.

(Modification 1)
In the above-described embodiment, the opening areas of the first air outlet 34a and the second air outlet 34b are the same, but the present invention is not limited to this, and these opening areas are different from each other. Also good. Even in this configuration, the variation of the cooling air can be suppressed by making the opening area of each of the first air discharge port 34a and the second air discharge port 34b smaller than the opening area of the air inflow port 24a. it can.

(Modification 2)
In the above embodiment, the intake chamber 24 is formed on the upper side and the exhaust chamber 34 is formed on the lower side. However, the present invention is not limited to this, and as shown in FIG. 34 may be formed on the upper side.

DESCRIPTION OF SYMBOLS 1 ... Battery pack 10 ... Battery module 11 ... Single cell 14 ... Conduction path 20 ... Upper case 24 ... Intake chamber 24a ... Air inlet 30 ... Lower case 34 ... Exhaust chamber 34a ... 1st air exhaust port 34b ... 2nd air Discharge port 60 ... first exhaust duct 60
70 ... Second exhaust duct 80 ... Blower

Claims (4)

A battery module in which a plurality of unit cells are stacked, and a conduction path for conducting air between the unit cells adjacent in the stacking direction is formed;
In a battery pack having a case for housing the battery module,
Inside the case, an inflow path for allowing air to flow into the conduction path is formed extending in the stacking direction,
Inside the case, a discharge path for discharging air flowing out from the conduction path to the outside of the case is formed extending in the stacking direction,
The air inlet in the inflow path is formed only at one end of the inflow path,
The air discharge port in the discharge path is formed only at both ends of the discharge path,
The battery pack, wherein an opening area of the air inlet is larger than an opening area of the air outlet.   The battery pack according to claim 1, wherein the two air discharge ports have the same opening area. The battery pack according to claim 1 or 2, wherein when the opening area of the air inlet is A and the opening area of the air outlet is B, the following expression (1) is satisfied.
31/29 ≦ A / B ≦ 34/26 (1) The battery pack according to any one of claims 1 to 3,
A vehicle travel motor that operates with electric power stored in the battery pack;
Vehicle with.

Images