Battery pack and vehicle mounting structure for battery pack

Abstract

To realize a battery pack that contributes to improving the accuracy of detecting water that has entered the battery pack.SOLUTION: A battery pack (1) according to an embodiment of the present disclosure includes a battery module (2) having a plurality of battery cells (8) stacked in a first direction, and a case (3) that houses the battery module (2), and the case (3) includes a lower case (17) that is arranged below the battery module (2), which is on one side of a second direction that is perpendicular to the first direction, and the lower case (17) includes a groove portion (17c) extending in the first direction and a storage portion (17d) that is arranged at at least one end of the groove portion (17c) in the first direction so as to be able to store water, and a water detection portion (7) is arranged in the storage portion (17d).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack and a vehicle mounting structure for the battery pack. [Background technology]

[0002] Battery packs such as lithium-ion batteries are configured to be able to detect water that has entered the battery pack. For example, the battery pack disclosed in Patent Document 1 is configured to be able to detect water that has entered the battery pack by arranging a water detection unit below the battery module. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-176081 Summary of the Invention [Problem to be solved by the invention]

[0004] The applicant has found the following problem: The battery pack of Patent Document 1 has a problem in that the water detection unit may not be able to detect water depending on the amount of water that has entered the battery pack, resulting in low water detection accuracy.

[0005] The present disclosure has been made in consideration of such problems, and provides a battery pack and a vehicle mounting structure for the battery pack that contribute to improving the accuracy of detecting water that has entered the battery pack. [Means for solving the problem]

[0006] A battery pack according to one embodiment of the present disclosure includes: a battery module including a plurality of battery cells stacked in a first direction; a case that houses the battery module; A battery pack comprising: when a second direction is perpendicular to the first direction and is a vertical direction of the battery pack, the case has a lower case that is disposed below the battery module, which is one side of the second direction; the lower case has a groove portion extending in the first direction and a first reservoir portion arranged at at least one end of the groove portion in the first direction so as to be able to store water; A water detector is disposed in the first reservoir.

[0007] In the battery pack described above, it is preferable that the groove portion includes a water guide portion that becomes lower toward the first reservoir portion.

[0008] In the above-described battery pack, it is preferable that the water guide portion is disposed in a portion of the lower case where condensation occurs due to cooling of the battery module by a cooling device.

[0009] The battery pack includes a low-voltage circuit, The water detection unit preferably has a second reservoir for storing water inside the water detection unit.

[0010] A vehicle mounting structure for a battery pack according to an aspect of the present disclosure is the vehicle mounting structure for the battery pack described above, the battery pack is mounted on the vehicle so that the first direction is the same as a front-to-rear direction of the vehicle; The first reservoirs are disposed at both ends of the groove in the first direction. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to realize a battery pack and a vehicle mounting structure for the battery pack that contribute to improving the accuracy of detecting water that has entered the battery pack. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a state in which a battery pack according to an embodiment is mounted on a vehicle; [Figure 2] 1 is a simplified exploded view showing a battery pack according to an embodiment of the present invention; [Figure 3] FIG. 2 is a partial YZ cross-sectional view of the battery pack according to the embodiment. [Figure 4] FIG. 2 is a partial XZ cross-sectional view of the battery pack according to the embodiment. [Figure 5] 4A and 4B are diagrams illustrating the shape of a lower case in the battery pack according to the embodiment. [Figure 6] 1A is a YZ cross-sectional view showing the water detection unit in the battery pack according to the embodiment, and FIG. 1B is an XZ cross-sectional view showing the water detection unit in the battery pack according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Specific embodiments to which the present disclosure is applied will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been simplified as appropriate. For clarity of explanation, the following description will be made using a three-dimensional (XYZ) coordinate system.

[0014] Fig. 1 is a diagram showing a state in which a battery pack according to this embodiment is mounted on a vehicle. In Fig. 1, the vehicle 100 is shown by a virtual line to simplify the drawing. The battery pack 1 is suitable as a battery pack to be mounted on the vehicle 100, for example, as shown in Fig. 1.

[0015] Here, the positive side of the X axis is the front side of the vehicle 100, and the negative side of the X axis is the rear side of the vehicle 100. The positive side of the Y axis is the left side of the vehicle 100, and the negative side of the Y axis is the right side of the vehicle 100. The positive side of the Z axis is the top side of the vehicle 100, and the negative side of the Z axis is the bottom side of the vehicle 100.

[0016] Fig. 2 is an exploded view showing a simplified battery pack of the present embodiment. Fig. 3 is a partial YZ cross-sectional view of the battery pack of the present embodiment. Fig. 4 is a partial XZ cross-sectional view of the battery pack of the present embodiment. As shown in Figs. 2 to 4, the battery pack 1 includes a battery module 2, a pack case 3, a control device 4, a cover 5, a cooling device 6, and a water detection unit 7.

[0017] 2 to 4, the battery module 2 includes a plurality of battery cells 8. Each battery cell 8 is formed, for example, by housing an electrode body inside a battery case 9. A first electrode terminal 10, either a positive electrode terminal or a negative electrode terminal, is provided at the end of the battery case 9 on the +Y axis side and on the +Z axis side, and a second electrode terminal 11, either a positive electrode terminal or a negative electrode terminal, is provided at the end of the battery case 9 on the -Y axis side and on the +Z axis side.

[0018] Such battery cells 8 are stacked in the X-axis direction (first direction) so that the positive electrode terminals and negative electrode terminals are alternately arranged in the X-axis direction on each of the Y-axis + side and Y-axis - side of the battery module 2.

[0019] 3, the first electrode terminals 10 of adjacent battery cells 8 on the + side of the Y axis of the battery module 2 are electrically connected by a first bus bar 12, and the second electrode terminals 11 of adjacent battery cells 8 on the - side of the Y axis of the battery module 2 are electrically connected by a second bus bar 13. In this way, the battery cells 8 that make up the battery module 2 are electrically connected in series.

[0020] 2 to 4, the pack case 3 houses the battery modules 2. The pack case 3 includes an upper case 16 and a lower case 17. The upper case 16 includes, for example, a housing portion 16a that protrudes toward the positive side of the Z axis and has an internal space capable of housing the battery modules 2, and a flange portion 16b that protrudes outward from the periphery of the housing portion 16a.

[0021] As shown in Figures 2 to 4, for example, the lower case 17 has a storage section 17a that is recessed toward the Z-axis negative side and has an internal space capable of storing the battery module 2, and a flange section 17b that protrudes outward from the periphery of the storage section 17a.

[0022] With the battery modules 2 arranged at a predetermined interval in the Y-axis direction housed inside the housing portion 16a of the upper case 16 and the housing portion 17a of the lower case 17, the flange portion 16b of the upper case 16 and the flange portion 17b of the lower case 17 are joined with an adhesive member.

[0023] Fig. 5 is a diagram illustrating the shape of the lower case in the battery pack of the present embodiment. As shown in Fig. 5, lower case 17 has groove 17c and storage portion 17d. Groove 17c is a recess formed on the surface of accommodation portion 17a of lower case 17 on the +Z-axis side, and extends in the X-axis direction.

[0024] In this case, the grooves 17c may be arranged so as to extend beyond the arrangement area of ​​the battery modules 2 on the positive and negative sides of the X axis in the X axis direction when viewed from the Z axis direction (second direction), as shown in Fig. 4. The grooves 17c may be arranged in the portions between the battery modules 2 adjacent to each other in the Y axis direction and in portions overlapping with the approximate centers of the battery modules 2 in the Y axis direction when viewed from the Z axis direction, as shown in Fig. 3.

[0025] Here, as shown in FIG. 3, the groove portion 17c may be arranged so as to overlap the first electrode terminal 10 of the battery cell 8 and the second electrode terminal 11 of the battery cell 8, which are arranged to face each other in the Y-axis direction, when viewed from the Z-axis direction.

[0026] In this case, the groove portion 17c may function as an escape portion for a restraint band to prevent interference with the restraint band that restrains the battery cells 8 of the battery module 2 in the X-axis direction when the battery module 2 is supported on the surface on the Z-axis + side of the storage portion 17a of the lower case 17, as shown in Figure 3, for example.

[0027] In addition, it is preferable that the groove portion 17c is positioned so as to overlap with a safety valve (not shown) provided at the end of the battery cell 8 on the negative side of the Z axis to discharge gas and ejected material from the battery cell 8 when viewed from the Z axis direction.

[0028] As shown in Fig. 4, reservoir 17d is a recess formed on the surface of housing 17a of lower case 17 on the +Z-axis side so as to be able to store water, and is disposed at the +X-axis side end and the -X-axis side end of groove 17c. In this case, reservoir 17d preferably extends in the Y-axis direction and connects the +X-axis side end and the -X-axis side end of groove 17c aligned in the Y-axis direction, as shown in Fig. 5.

[0029] Here, groove portion 17c may include water guide portion 17e so as to guide water to reservoir portion 17d, as shown by the imaginary line in Fig. 4. Water guide portion 17e may include, for example, a first inclined portion 17f that inclines toward the negative Z-axis side as it approaches the positive X-axis side, and a second inclined portion 17g that inclines toward the negative Z-axis side as it approaches the negative X-axis side, with the approximate center of groove portion 17c in the X-axis direction between them.

[0030] 2 and 4, the control device 4 includes, for example, an SBM (Satellite Battery Module) 18 and an ECU (Electronic Control Unit) 19. The SBM 18 and the ECU 19 form, for example, a 12V low-voltage circuit.

[0031] The SBM 18 monitors the voltage and other conditions of each battery module 2. For example, as shown in FIG. 4, the SBM 18 is disposed on the positive side of the X axis with respect to each battery module 2. The ECU 19 monitors the overall condition of the battery modules 2 based on the monitoring results of the SBM 18. For example, as shown in FIG. 2, the ECU 19 is supported on the surface of the upper case 16 of the pack case 3 on the positive side of the Z axis.

[0032] 1, the ECU 19 may be disposed on the negative side of the X-axis of the pack case 3. The cover 5 is fixed to the upper case 16 of the pack case 3 with the ECU 19 housed therein.

[0033] The cooling device 6 cools the battery modules 2. For example, as shown in Fig. 3, the cooling device 6 is a plate body having a circulation path for a cooling medium. The cooling device 6 is disposed, for example, between the grooves 17c aligned in the Y-axis direction, and cools the battery modules 2 via the lower case 17 of the pack case 3.

[0034] In this case, when the battery module 2 is cooled by the cooling device 6, condensation occurs around the side wall of the groove 17c adjacent to the cooling device 6, but the water guide portion 17e of the groove 17c is arranged in the area where the condensation occurs. Therefore, the condensation that occurs when the battery module 2 is cooled by the cooling device 6 can be efficiently guided to the reservoir 17d.

[0035] 6(a) is a YZ cross-sectional view showing the water detection unit in the battery pack of the present embodiment, and FIG. 6(b) is an XZ cross-sectional view showing the water detection unit in the battery pack of the present embodiment. The water detection unit 7 detects water that has entered the battery pack 1.

[0036] 4, the water detection unit 7 is disposed in the storage section 17d on the +X-axis side of the pack case 3, and in the storage section 17d on the -X-axis side of the pack case 3. The water detection unit 7 includes a first terminal 20, a second terminal 21, and a detection case 22, as shown in FIGS. 6(a) and 6(b), for example.

[0037] The first terminals 20 are made of a conductive material. The first terminals 20 of the water detector 7 on the positive X-axis side are electrically connected to, for example, an SBM 18 disposed on the positive X-axis side of the battery pack 1. On the other hand, the first terminals 20 of the water detector 7 on the negative X-axis side are electrically connected to, for example, an ECU 19 disposed on the negative X-axis side of the battery pack 1. In this way, the first terminals 20 are electrically connected to the SBM 18 or ECU 19 that are close to each first terminal 20, which simplifies the wiring arrangement.

[0038] The second terminal 21 is made of a conductive material. The second terminal 21 in the water detection unit 7 on the positive side of the X axis and the second terminal 21 in the water detection unit 7 on the negative side of the X axis are both electrically connected to, for example, a GND portion formed on the pack case 3.

[0039] As shown in Figures 6(a) and 6(b), the detection case 22 includes a storage section 23 and a cover 24. The storage section 23 is, for example, a cylindrical body with a closed bottom and an end on the negative Z-axis side that is closed, and extends in the Z-axis direction. A first opening 23b through which water can enter is formed in a side wall 23a on the positive Y-axis side of the storage section 23.

[0040] 6(a), first opening 23b is disposed at a distance from bottom 23c of reservoir 23 so that water can be stored in the negative Z-axis side of reservoir 23. Second opening 23e is formed in side wall 23d on the negative Y-axis side of reservoir 23, with which engaging claw 24a of cover 24 engages.

[0041] 6(a) and 6(b), the cover 24 is a cylindrical body with a closed bottom and an end on the +Z-axis side that is closed, and extends in the Z-axis direction. The outer shape of the cover 24 is slightly smaller than the inner shape of the storage portion 23 when viewed from the Z-axis direction so that the cover 24 can be fitted into the storage portion 23 from the +Z-axis side.

[0042] 6(a), a side wall portion 24b on the negative Y-axis side of the cover 24 is formed with an engagement claw 24a that protrudes from the side wall portion 24b toward the negative Y-axis side and engages with a second opening 23e of the storage portion 23. The engagement claw 24a may be provided with, for example, an inclined portion 24c that inclines toward the positive Y-axis side as it approaches the negative Z-axis side.

[0043] As shown in Figures 6(a) and 6(b), the first terminal 20 and the second terminal 21 are fixed to the ceiling portion 24d on the +Z-axis side of the cover 24 in a state where they hang down from the ceiling portion 24d. At this time, the first terminal 20 and the second terminal 21 are spaced apart in the Y-axis direction so as to prevent a short circuit when not immersed in water.

[0044] 6(a) and 6(b), cover 24 is fitted into reservoir 23 with first terminal 20 and second terminal 21 inserted inside reservoir 23, and engagement claws 24a of cover 24 are engaged with second opening 23e of reservoir 23, thereby fixing cover 24 to reservoir 23. Water detection unit 7 is arranged so that reservoir 23 of water detection unit 7 is placed on reservoir 17d of pack case 3.

[0045] 6(a) and 6(b), the negative end of first terminal 20 on the Z axis side and the negative end of second terminal 21 on the Z axis side are disposed near bottom 23c of storage portion 23. Side wall portion 24e on the positive Y axis side of cover 24 is disposed so as not to block first opening 23b of storage portion 23.

[0046] In this embodiment, the first terminal 20 is electrically connected to the SBM 18 or ECU 19, which are low-voltage circuits. Therefore, the distance between the first terminal 20 and the second terminal 21 can be narrower than when the first terminal 20 is electrically connected to the first bus bar 12 or the second bus bar 13 of the battery module 2, which are high-voltage circuits of 48 V. This allows the water detection unit 7 to be made smaller.

[0047] Such a battery pack 1 is fixed from below to the frame of a vehicle 100, for example, as shown in Fig. 1. At this time, the groove 17c of the pack case 3 extends in the X-axis direction, and the storage portion 17d of the pack case 3 is disposed at both ends of the groove 17c on the positive and negative sides of the X-axis.

[0048] Next, a description will be given of the flow of detecting water that has entered the battery pack 1 of this embodiment. For example, when the vehicle 100 decelerates and tilts forward, water that has entered the battery pack 1 passes through the groove 17c of the pack case 3 and is collected in the reservoir 17d on the positive side of the X axis.

[0049] This causes a short circuit between the first terminal 20 and the second terminal 21 of the water detection unit 7 arranged in the storage section 17d of the pack case 3, and when the SBM 18 detects the short circuit, the ECU 19 determines that water has entered the inside of the battery pack 1 and, for example, notifies the user of the vehicle 100 to stop using the vehicle 100.

[0050] On the other hand, for example, when the vehicle 100 accelerates and tilts backward, water that has entered the battery pack 1 is collected in the reservoir 17d arranged on the negative side of the X axis through the groove 17c of the pack case 3. This causes a short circuit between the first terminal 20 and the second terminal 21 of the water detection unit 7 arranged in the reservoir 17d of the pack case 3. When the ECU 19 detects this short circuit, the ECU 19 determines that water has entered the battery pack 1 and, for example, notifies the user of the vehicle 100 to stop using the vehicle 100.

[0051] In this case, the groove portion 17c and the storage portion 17d of the pack case 3 and the water detection portion 7 may be shaped and arranged so that water that has infiltrated into the battery pack 1 can be detected at a tilt angle that is smaller than the tilt angle of the vehicle 100 at which water that has infiltrated into the battery pack 1 comes into contact with the first electrode terminal 10 and the second electrode terminal 11 of the battery cell 8 that is located furthest on the +X-axis side when the vehicle 100 is tilted forward, or the first electrode terminal 10 and the second electrode terminal 11 of the battery cell 8 that is located furthest on the -X-axis side when the vehicle 100 is tilted backward.

[0052] In this way, the battery pack 1 of this embodiment is configured so that water that has entered the inside of the battery pack 1 can be collected in the storage section 17d through the groove section 17c formed in the pack case 3 and detected.

[0053] Therefore, compared to the battery pack of Patent Document 1, for example, the battery pack 1 of this embodiment can accurately detect water even if the amount of water that has infiltrated into the battery pack 1 is small. Moreover, even if the vehicle 100 tilts momentarily, the water can be retained in the reservoir 17d of the pack case 3, and the water can be detected by the water detector 7.

[0054] Furthermore, in the battery pack 1 of the present embodiment, when the groove 17c of the pack case 3 is provided with the water guide portion 17e, water that has entered the battery pack 1 can be effectively guided to the reservoir 17d of the pack case 3. Therefore, the battery pack 1 of the present embodiment can accurately detect water even when the amount of water that has entered the battery pack 1 is small.

[0055] At this time, if the water guide section 17e of the pack case 3 is arranged in the groove section 17c that is located near the portion of the lower case 17 where condensation occurs due to the cooling of the battery modules 2 by the cooling device 6, the condensation that occurs when the battery modules 2 are cooled by the cooling device 6 can be guided to the reservoir section 17d. Therefore, the battery pack 1 of this embodiment can detect not only water that has entered the battery pack 1, but also condensation that occurs when the battery modules 2 are cooled by the cooling device 6.

[0056] Furthermore, in the battery pack 1 of this embodiment, if the water detection unit 7 is equipped with a storage unit 23, even if the vehicle 100 tilts momentarily, the water can be retained in the storage unit 23 of the water detection unit 7, and the water can be detected by the water detection unit 7.

[0057] Furthermore, in the battery pack 1 of this embodiment, when viewed from the Z-axis direction, if the groove portion 17c of the pack case 3 is positioned in the portion between adjacent battery modules 2 in the Y-axis direction, the portion between the battery modules 2 can be effectively utilized, and the battery pack 1 can be made smaller.

[0058] In particular, in the battery pack 1 of this embodiment, when the first electrode terminal 10 and the second electrode terminal 11 of the battery cell 8 protrude laterally from the battery case 9, the area in which the first electrode terminal 10 and the second electrode terminal 11 of the battery cell 8 that face each other in the Y-axis direction are arranged can be effectively utilized.

[0059] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure.

[0060] For example, in the above embodiment, the first terminal 20 of the water detection unit 7 is electrically connected to the SBM 18 or the ECU 19, but it may also be electrically connected to the first bus bar 12, the second bus bar 13, or the like.

[0061] For example, in the above embodiment, the first electrode terminal 10 and the second electrode terminal 11 of the battery cell 8 protrude in different directions, but they may protrude in the same direction, and the arrangement of the first electrode terminal 10 and the second electrode terminal 11 is not limited.

[0062] For example, in the above embodiment, storage section 17d and water detection section 7 of pack case 3 are disposed on both the positive and negative X-axis sides, but they may be disposed on at least one side. Also, the direction in which groove section 17c of pack case 3 extends may be the same as the stacking direction of battery cells 8, and the locations of storage section 17d and water detection section 7 can be changed appropriately accordingly.

[0063] For example, the configuration of the water detector 7 in the above embodiment is merely an example, and it is sufficient that the water detector 7 includes at least the first terminal 20 and the second terminal 21. [Explanation of symbols]

[0064] 1 battery pack 2 Battery Module 3-pack case 4. Control device 5 Cover 6 Cooling device 7 Water detector 8 battery cells 9 Battery case 10 First electrode terminal 11 Second electrode terminal 12 First busbar 13 Second busbar 16 upper case, 16a housing portion, 16b flange portion 17 lower case, 17a accommodation portion, 17b flange portion, 17c groove portion, 17d storage portion, 17e water guide portion, 17f first inclined portion, 17g second inclined portion 20 First terminal 21 Second terminal 22 Detection Case 23 Storage section 23a Y-axis + side wall of the storage section 23b First opening of reservoir 23c Bottom of reservoir 23d Y-axis side wall of the storage section 23e Second opening of reservoir 24 Cover 24a Engagement claw 24b Y-axis - side wall of cover 24c Inclined portion of engaging claw 24d Cover ceiling 24e Y-axis + side wall of cover 100 vehicles

Claims

1. a battery module including a plurality of battery cells stacked in a first direction; a case that houses the battery module; A battery pack comprising: when a second direction is perpendicular to the first direction and is a vertical direction of the battery pack, the case has a lower case that is disposed below the battery module in one of the second directions, the lower case has a groove portion extending in the first direction and a first reservoir portion arranged at at least one end of the groove portion in the first direction so as to be able to retain water; The battery pack, wherein a water detection unit is disposed in the first storage unit.

2. The battery pack according to claim 1 , wherein the groove portion includes a water guide portion that becomes lower toward the first reservoir portion.

3. The battery pack according to claim 2 , wherein the water guide portion is disposed in a portion of the lower case where condensation occurs due to cooling of the battery module by a cooling device.

4. Equipped with low voltage circuitry, The battery pack according to claim 3 , wherein the water detection unit has a second reservoir for storing water therein.

5. The vehicle mounting structure for the battery pack according to any one of claims 1 to 4, the battery pack is mounted on the vehicle so that the first direction is the same as a front-to-rear direction of the vehicle; The first storage portion is disposed at both ends of the groove portion in the first direction.

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