CN218896753U

CN218896753U - Battery pack

Info

Publication number: CN218896753U
Application number: CN202223465351.9U
Authority: CN
Inventors: 后藤优一
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2022-12-23
Filing date: 2022-12-23
Publication date: 2023-04-21
Anticipated expiration: 2032-12-23

Abstract

The utility model provides a battery pack. The battery pack includes a plurality of battery modules each including a predetermined number of battery cells stacked in a vehicle width direction, and a box-shaped case accommodating the plurality of battery modules and having an upper side open, the case including a rectangular frame in plan view, a bottom plate provided at a bottom of the frame, the frame being constituted by a front frame and a rear frame that face each other in a vehicle length direction, and a pair of side frames that face each other in the vehicle width direction and connect the front frame and the rear frame, and outside brackets that extend outward in the vehicle width direction and have a plurality of times of meandering front end portions being provided outside the side frames; inside each side frame, an inside bracket is provided, which extends to a position above the upper end of the battery module, and the front end of which is bent a plurality of times. With the above configuration, the acceleration acting on the mounting device in the case during the running of the vehicle can be reduced, and the load transmitted to the battery module during the compression test can be reduced.

Description

Battery pack

Technical Field

The present utility model relates to a battery pack.

Background

In general, an electric vehicle (also referred to as BEV) is equipped with a battery pack configured by accommodating a plurality of battery modules each formed by stacking a predetermined number of battery cells in a vehicle width direction in a box-shaped case body having an open upper side. In general, such a case of a battery pack includes a rectangular frame in plan view and a bottom plate provided at the bottom of the frame. The frame body is composed of a front frame and a rear frame which are opposite to each other in the vehicle length direction, and a pair of side frames which are opposite to each other in the vehicle width direction and connect the front frame and the rear frame.

As such a battery pack, a large-sized BEV battery pack capable of improving production efficiency is widely used. In the case of using a large-sized BEV battery pack, since the case is large, even if the vehicle type and the power output are changed, the case does not need to be changed, and a different output can be achieved by changing the number of battery molds accommodated in the case.

However, in a low-output battery pack in which the number of battery modules on both sides in the vehicle width direction is reduced, the interval between the end plate and the side frame, which are fixed to the bottom plate with the plurality of battery modules interposed therebetween, is widened, and the bending strength of the battery pack is reduced. Therefore, in the large BEV battery pack with low output, since the bending strength is reduced, the interval between the upper portion of the end plate and the upper portion of the side frame during running of the electric vehicle is further increased (referred to as "opening mode"), and there is a possibility that the battery pack is deformed by bending. If the battery pack is deformed by bending, the battery pack resonates during running of the electric vehicle, and the mounted device housed in the battery pack is subjected to a large acceleration, which may cause malfunction of the mounted device.

In this regard, it is conceivable to increase the flexural strength of the battery pack by adding a lid (top plate) that covers a box-shaped case that is open at the top. However, the battery pack with the cover added only changes the natural value of the vibration, and the acceleration response level (the magnitude of the acceleration) cannot be reduced.

In addition, the battery packs are required to meet the requirements of the extrusion test. In general, the crush test is a special test for confirming safety of the battery pack when the battery pack is greatly deformed by applying an external force to the battery pack using a crusher. In the case where only the cover is added, in the compression test, there is a possibility that the crusher hits the side frames and transmits an external force to the battery module or the crusher presses the battery module, and in the worst case, a fire may be caused.

Disclosure of Invention

In view of the above, an object of the present utility model is to provide a battery pack capable of reducing the acceleration of a mounting device acting in a battery case during running of a vehicle and reducing the load transmitted to a battery module during a crush test.

As an aspect of the present utility model to solve the above-described problems, there is provided a battery pack including a plurality of battery modules each including a predetermined number of battery cells stacked in a vehicle width direction, and a box body having a box shape accommodating the plurality of battery modules and having an upper side open, the battery pack including: the case includes a rectangular frame in plan view, a bottom plate provided at a bottom of the frame, the frame including a front frame and a rear frame that face each other in a vehicle longitudinal direction, and a pair of side frames that face each other in the vehicle width direction and connect the front frame and the rear frame, and outer side brackets that extend outward in the vehicle width direction and have a front end portion that is bent a plurality of times are provided outside the side frames; inside each side frame, an inside bracket is provided, which extends to a position above the upper end of the battery module and the front end of which is bent a plurality of times.

The battery pack according to the present utility model has an advantage in that the front end portions of the outer bracket provided outside the side frame and the inner bracket provided inside the side frame are bent a plurality of times, and the number of times of bending of the front end portion of the outer bracket or the number of times of bending of the front end portion of the inner bracket are appropriately set, whereby the outer bracket or the inner bracket can be vibrated when the battery pack resonates to function as a mass damper. Specifically, since the number of turns of the distal end portion of the outer bracket or the inner bracket is correlated with the dynamic damping effect, the dynamic damping effect can be obtained by appropriately setting the number of turns, and the acceleration acting on the mounting device in the case of the battery during the running of the vehicle can be reduced.

Further, since the outer bracket provided outside the side frame extends outward in the vehicle width direction, when the crusher is pressed from the side in the crush test, the front end portion of the outer bracket is first touched instead of the side frame, and the load transmitted to the battery module can be reduced.

Further, since the inner bracket provided inside the side frame extends to a position above the upper end of the battery module, when the crusher is pressed down from above in the crush test, the front end of the inner bracket is first touched instead of the battery module, and the crusher can be prevented from being pressed against the battery module, whereby the occurrence of fire can be prevented.

In the battery pack according to the present utility model, it is preferable that one of the outer brackets is provided on the outer side of each of the side frames so as to occupy the entire length range in the vehicle longitudinal direction; one of the inner side brackets is provided on the inner side of each of the side frames so as to occupy the entire length range in the vehicle longitudinal direction.

With this structure, since the outer bracket and the inner bracket each occupy the entire length range of the side frame in the vehicle length direction, the contact area between the crusher pressed from the side and the outer bracket is large, and the load transmitted to the battery module can be effectively reduced; similarly, the contact area between the crusher and the inner bracket, which are pressed from above, is large, and the crusher can be reliably prevented from being pressed against the battery module.

In the above-described battery pack according to the present utility model, it is preferable that a plurality of the outer holders are provided on the outer side of each of the side frames at intervals in the vehicle longitudinal direction; a plurality of inner side brackets are provided on the inner side of each side frame at intervals in the vehicle longitudinal direction.

With this structure, since the plurality of outer brackets and the plurality of inner brackets are provided on the outer side and the inner side of the side frame at intervals in the vehicle length direction, respectively, the load transmitted to the battery module can be effectively reduced, the crusher can be reliably prevented from being pressed against the battery module, and the weight reduction of the battery pack can be facilitated.

Drawings

Fig. 1 is a schematic view showing a partial structure of a battery pack according to an embodiment of the present utility model.

Fig. 2 (a) is a schematic diagram for explaining the dynamic damping effect of the medial bracket.

Fig. 2 (b) is a graph for comparing the magnitudes of accelerations.

Fig. 3 is a schematic view showing the state of the battery pack in the compression test in stages.

Fig. 4 is a schematic view showing the state of the battery pack in the compression test in stages.

Fig. 5 is a schematic view showing the state of the battery pack in the compression test in stages.

Fig. 6 is a schematic view showing the state of the battery pack in the compression test in stages.

Fig. 7 is a schematic view showing the state of the battery pack in the compression test in stages.

Fig. 8 is a schematic view showing the state of the battery pack in the compression test in stages.

Fig. 9 (a) is a schematic diagram showing a mouth opening mode of a battery pack according to the related art.

Fig. 9 (b) is a graph showing acceleration acting on the battery pack shown in fig. 9 (a).

Fig. 10 is a schematic view showing a state of a related art battery pack in a compression test.

Fig. 11 is a schematic view showing a state of a related art battery pack in a compression test.

Detailed Description

Hereinafter, a battery pack according to an embodiment of the present utility model will be described with reference to the accompanying drawings. However, the present utility model is not limited to the following embodiments. The dimensional relationships (length, width, etc.) in the drawings do not reflect the actual dimensional relationships. The left-right direction in each figure coincides with the vehicle width direction.

Fig. 1 is a schematic view showing a partial structure of a battery pack according to the present embodiment, and shows an end portion of a battery pack 1 on one side in a vehicle width direction. In the present embodiment, the battery pack 1 is mounted on an electric vehicle (not shown).

As shown in fig. 1, the battery pack 1 includes a plurality of battery modules 5 each formed by stacking a predetermined number of battery cells 3 in the vehicle width direction, an end plate 7 that clamps and fixes the plurality of battery modules 5 to a bottom plate 15 in the vehicle width direction, and a box-shaped case 10 that houses (accommodates) the plurality of battery modules 5 and has an upper side open.

The case 10 includes a rectangular frame in plan view, a rectangular bottom plate 15 provided at the bottom of the frame, and a fastening member 17. The frame body is composed of a front frame (not shown) and a rear frame 11 that face each other in the vehicle longitudinal direction, and a pair of side frames 13 (only one of which is shown in fig. 1) that face each other in the vehicle width direction and connect the front frame and the rear frame 11. In addition, as shown in fig. 1, the side frames 13 are constructed to be far higher than the front and rear frames 11.

The case 10 of the battery pack 1 is supported by a cross member 20 extending in the vehicle width direction and is fixedly connected to a side member 21 extending in the vehicle length direction by a fastening member 17. Thereby, the battery pack 1 is mounted on the electric vehicle.

In the present embodiment, the battery pack 1 is a low-output battery pack in which the number of battery modules 5 on both sides in the vehicle width direction is reduced, and the case 10 used is the same as the case of the high-output battery pack in size in order to improve the production efficiency. Therefore, in the assembled battery 1, as shown in fig. 1, the distance between the end plate 7 and the side frame 13 in the vehicle width direction increases.

Here, in order to facilitate understanding of the present embodiment, a structure of a battery pack in the related art will be described first. Fig. 9 (a) is a schematic diagram for explaining the opening mode of the conventional assembled battery 101, and fig. 9 (b) is a graph showing acceleration G' acting on the conventional assembled battery 101 at each frequency during running of the electric vehicle, wherein the horizontal axis shows frequency (Hz) and the vertical axis shows acceleration (G).

The conventional battery pack 101 shown in fig. 9 (a) also uses a low-output battery pack in which the number of battery modules 105 is reduced while using a case 110 (see fig. 10 described below) having the same size as the case of the high-output battery pack. As in the battery pack 1 of the present embodiment, the distance between the end plate 107 and the side frame 113 in the vehicle width direction increases, so that the bending strength of the battery pack 101 decreases.

As described above, since the bending strength of the battery pack 101 of the related art is reduced, the interval C between the upper portion of the end plate 107 and the upper portion of the side frame 113 is further increased, that is, the battery pack 101 is subjected to bending deformation called "opening mode" as indicated by the arrow in fig. 9 (a) during running of the electric vehicle. When such bending deformation occurs, as shown in fig. 9 (b), the battery pack 101 resonates during running of the electric vehicle, and the mounting device (for example, a junction box or the like) in the case 110 of the battery pack 101 is subjected to a large acceleration G', which may cause the mounting device to malfunction. In contrast, even if a cover is added to cover the box-shaped case 110 with the upper side open, the intrinsic value can be changed only, and the magnitude of the acceleration G' cannot be reduced. Thus, simply adding a cover to the battery pack cannot solve the above-described problems.

Fig. 10 and 11 are schematic diagrams showing the state of a battery pack 101 of the related art in a compression test. In the case of the conventional battery pack 101 having only the cover added thereto, when the crush test is performed, the crusher 50 is pressed down from above as indicated by the open arrow in fig. 10 and then pressed against the battery module 105, and in the worst case, a fire may be caused. Further, as indicated by the open arrow in fig. 11, the crusher 50 is pressed from the side and then hits the side frame 113, and as indicated by the solid arrow in fig. 11, the load is transmitted to the battery module 105.

In contrast, in the present embodiment, as shown in fig. 1, an outer bracket 30 that extends outward in the vehicle width direction and has a front end 31 that is bent multiple times (two times) is provided on the outer side of the side frame 13; meanwhile, inside the side frames 13, there is provided an inside bracket 40 that extends to a position above the upper ends of the battery modules 5 and the front end portions 41 are bent a plurality of times (four times), that is, the position of the upper ends of the bent front end portions 41 is higher than the position of the upper ends of the battery modules 5.

More specifically, as shown in fig. 1, the outer bracket 30 extends outward in the vehicle width direction from the outer surface of the side frame 13, and the front end 31 thereof is bent upward and extended, and then is bent inward in the vehicle width direction and extended.

Meanwhile, as shown in fig. 1, the inner side bracket 40 extends inward in the vehicle width direction from the inner side surface of the side frame 13, and the front end portion 41 thereof is bent upward and extended to be bent and extended to the vehicle width direction outer 5 side, and then is bent downward and extended to be bent and extended to the vehicle width direction inner side,

finally, the device is bent upwards and extends. That is, in the present embodiment, the number of turns of the front end portion 41 of the inner holder 40 is set to be the number of times that the inner holder 40 can vibrate only when the battery pack 1 resonates without vibrating the battery pack 1 except when the battery pack 1 resonates.

In the present embodiment, the side frames 13 are pierced, and the outer bracket 30 and the inner bracket 40 are configured by only one member. However, the present utility model is not limited thereto, and the outer bracket 30 and the inner bracket 40 may be independent members. In this case, the outer bracket 30 may be attached to the outer surface of the side frame 13, and the inner bracket 40 may be attached to the inner surface of the side frame 13.

Fig. 2 (a) is a diagram for explaining the dynamic damping effect generated by the inner bracket 40. Fig. 2 (b) is a graph for comparing the magnitudes of accelerations, and shows acceleration G acting on the assembled battery 1 of the present embodiment and acceleration G' acting on the assembled battery 101 of the related art at each frequency during running of the electric vehicle, wherein the horizontal axis represents frequency (Hz) and the vertical axis represents acceleration (G).

In the battery pack 1 of the present embodiment, the inner holder 40 is configured as shown in fig. 2

(a) As shown, since the battery pack 1 vibrates when resonating, the effect of a mass damper (shock absorber) can be obtained. Specifically, since the number of 5 turns of the distal end portion 41 of the inner bracket 40 is correlated with the frequency of the dynamic damping effect, in the present embodiment, the distal end portion 41 is turned four times, so that the inner bracket 40 does not vibrate except when the battery pack 1 resonates, but vibrates only when the battery pack 1 resonates.

As described above, since the dynamic damping effect is obtained, as shown in fig. 2 (b), the acceleration acting on the battery pack 1 of the present embodiment during running of the electric vehicle is reduced as compared with the battery pack 101 of the related art 0. Specifically, as shown by the hatched arrows in fig. 2 (b), the peak value P2 of the acceleration G acting on the battery pack 1 of the present embodiment is significantly lower than the peak value P1 of the acceleration G' acting on the battery pack 101 of the related art.

Fig. 3 to 5 are schematic views showing the state of the battery pack 1 in the compression test in stages. As shown by the open arrow in fig. 3, when the crusher 50 approaches the battery pack 1 from above, in the battery pack 1 without the cover, as shown in fig. 4, the crusher 50 first hits the front end portion 41 (upper end of the front end portion 41) of the inner holder 40 extending to a position above the upper end of the battery module 5, instead of the upper end of the battery module 5. Thereafter, as shown in fig. 5, the crusher 50 is further lowered, and the front end 41 of the inner bracket 40 is further pressed downward, so that the front end 41 is deformed to be bent, but the crusher 50 does not touch the battery module 5.

As described above, in the assembled battery 1 of the present embodiment, the front end portion 41 of the inner holder 40 provided inside the side frame 13 is bent a plurality of times, and the upper end of the front end portion 41 is positioned higher than the upper end of the battery module 5. Therefore, in the crush test, when the crusher 50 is pressed down from above, the front end portion 41 of the inner holder 40 is first hit without hitting the battery module 5. Thus, the crusher 50 can be prevented from being pressed against the battery module 5 to cause a fire.

Fig. 6 to 8 are schematic views showing the state of the battery pack 1 in the compression test in stages. In the present embodiment, when the crusher 50 approaches the assembled battery 1 from the side as indicated by the open arrow in fig. 6, the crusher 50 first hits the front end 31 of the outer bracket 30 extending outward in the vehicle width direction from the outside of the side frame 13, as shown in fig. 7, instead of the side frame 13. Thereafter, as shown in fig. 8, the crusher 50 is further moved inward in the vehicle width direction, and the front end portion 31 of the pressed outer bracket 30 is deformed, so that the load transmitted to the battery module 5 via the side frame 13 is small.

As described above, in the assembled battery 1 of the present embodiment, the outer bracket 30 provided on the outer side of the side frame 13 extends outward in the vehicle width direction, and the front end portion 31 is bent a plurality of times. Therefore, in the crush test, when the crusher 50 is pressed from the side, the outer bracket 30 is first hit without hitting the side frame 13, and the load transmitted to the battery module 5 can be greatly reduced.

In the present embodiment, the number of turns of the front end portion 41 of the inner holder 40 is set to be the number of times the inner holder 40 is made to vibrate when the battery pack 1 resonates. However, the number of turns of the front end 31 of the outer holder 30 may be set to be the number of times the outer holder 30 is vibrated when the battery pack 1 resonates.

Further, one outer bracket 30 and one inner bracket 40 may be provided on the outer side and the inner side of each side frame 13, respectively, to occupy the entire length range in the vehicle longitudinal direction. With this structure, the contact area between the crusher 50 and the outer bracket 30 is large when the crusher is pressed from the side, so that the load transmitted to the battery module 5 can be effectively reduced; similarly, the contact area between the crusher 50 and the inner bracket 40 is large when the crusher 50 is pressed down from above, and the crusher 50 can be reliably prevented from being pressed against the battery module 5.

Further, a plurality of outer brackets 30 and a plurality of inner brackets 40 may be provided on the outer side and the inner side of each side frame 13 at intervals in the vehicle longitudinal direction. With this structure, the load transmitted to the battery module 5 can be reduced, and the crusher 50 can be prevented from pressing against the battery module 5, and the weight reduction of the battery pack 1 can be facilitated.

Claims

1. A battery pack comprising a plurality of battery modules each formed by stacking a predetermined number of battery cells in a vehicle width direction, and a box-shaped case body accommodating the plurality of battery modules and having an upper side open, characterized in that:

the box body is provided with a rectangular frame body in a top view and a bottom plate arranged at the bottom of the frame body,

the frame body is composed of a front frame and a rear frame which are opposite to each other in the vehicle length direction, and a pair of side frames which are opposite to each other in the vehicle width direction and connect the front frame and the rear frame,

an outer bracket extending outward in the vehicle width direction and having a front end portion bent a plurality of times is provided on an outer side of each of the side frames; inside each side frame, an inside bracket is provided, which extends to a position above the upper end of the battery module and the front end of which is bent a plurality of times.

2. The battery pack of claim 1, wherein:

one outer bracket occupying the whole length range of the side frames in the vehicle length direction is arranged on the outer side of each side frame;

one of the inner side brackets is provided on the inner side of each of the side frames so as to occupy the entire length range in the vehicle longitudinal direction.

3. The battery pack of claim 1, wherein:

a plurality of outer side brackets are provided on the outer side of each of the side frames at intervals in the vehicle length direction;

a plurality of inner side brackets are provided on the inner side of each side frame at intervals in the vehicle longitudinal direction.