Battery pack

Abstract

In one example, a battery pack includes a base plate, a front frame forming a front surface of the base plate, a rear frame forming a rear surface of the base plate, a pair of side frames having both ends connected to the front frame and the rear frame, and a plurality of battery cell assemblies mounted in an accommodation space formed by the front frame, the rear frame, and the pair of side frames, wherein each of the battery cell assemblies includes a battery cell unit including a plurality of cell stacks and a bus bar frame assembly mechanically and electrically connected to the plurality of cell stacks at both lateral ends from which leads of the cell stacks protrude, a first cell cross beam connected to the bus bar frame assembly in front of the battery cell unit, and a second cell cross beam connected to the bus bar frame assembly in the rear of the battery cell unit, and the plurality of battery cell assemblies are fixed to the base plate with the first cell cross beam and the second cell cross beam facing each other in the front-to-rear direction of adjacent battery cell assemblies overlapping each other.

Description

[Technical field]

[0001] The present invention relates to a battery pack, and more particularly to a battery pack that can improve the structural rigidity and space utilization rate of a pack case by using a cell cross beam corresponding to the overall width length of the battery pack, and can easily install battery cell assemblies in the pack, simplifying the assembly process while ensuring a firm fixing state.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0166606, filed December 2, 2022, and Korean Patent Application No. 10-2023-0036402, filed March 21, 2023, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference. [Background technology]

[0003] In order to improve the space utilization rate of a battery pack, a battery pack with a cell-to-pack structure has been proposed. The cell-to-pack structure has the advantage that it can improve the space utilization rate of a battery pack by directly assembling a plurality of battery cells into a battery pack without a structure for modularizing the battery pack.

[0004] In the cell-to-pack structure, since a separate module housing is omitted or simplified, it is important to ensure the rigidity of the battery pack. For example, a side frame may be coupled to a battery cell assembly (corresponding to a conventional battery module) in which multiple battery cells are assembled, and the side frame of the battery cell assembly housed in a pack case may be designed to function as a cross beam of the conventional battery pack.

[0005] However, when multiple battery cell assemblies are arranged in the width direction of the pack case in order to increase the capacity of the battery pack, the side frames of adjacent battery cell assemblies facing each other at the center of the battery pack in the width direction are not connected to each other, which causes a problem of weakening the structural rigidity of the battery pack.

[0006] To solve this problem, a structure can be designed in which a center beam is placed in the longitudinal center of the battery pack and the side frames that are not connected to each other are connected and fixed to the center beam. However, this structure in which the side frames and center beam are combined causes problems such as a complicated battery pack assembly process, an increase in the weight of the battery pack due to an increase in the number of parts, and a decrease in the energy density of the battery pack due to a decrease in space utilization rate as in the past. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a battery pack that can maintain good rigidity even with a simplified structure when configuring a battery pack with a cell-pack structure, and can simplify the process of mounting a plurality of battery cell assemblies in a pack case.

[0008] However, the technical problem that the present invention aims to solve is not limited to the above-mentioned problem, and other problems not mentioned can be clearly understood by a person skilled in the art from the description of the invention described below. [Means for solving the problem]

[0009] The present invention relates to a battery pack, and in one example, the battery pack includes a base plate, a front frame forming a front surface of the base plate, a rear frame forming a rear surface of the base plate, a pair of side frames having both ends connected to the front frame and the rear frame, and a plurality of battery cell assemblies mounted in an accommodation space formed by the front frame, the rear frame, and the pair of side frames, wherein each of the battery cell assemblies includes a battery cell unit including a plurality of cell stacks and a bus bar frame assembly mechanically and electrically connected to the plurality of cell stacks at both lateral ends from which leads of the cell stacks protrude, a first cell cross beam connected to the bus bar frame assembly in front of the battery cell unit, and a second cell cross beam connected to the bus bar frame assembly in the rear of the battery cell unit, and the plurality of battery cell assemblies are fixed to the base plate with the first cell cross beam and the second cell cross beam facing each other in the front-to-rear direction of adjacent battery cell assemblies overlapping each other vertically.

[0010] In one embodiment, the first cell cross beam and the second cell cross beam may have a length corresponding to the distance between the pair of side frames.

[0011] The first cell cross beam and the second cell cross beam may be coupled to bus bar frame assemblies provided in the plurality of battery cell units, respectively.

[0012] The first cell cross beam may have a protruding lower step, and the second cell cross beam may have a protruding upper step, and the first cell cross beam and the second cell cross beam may have a complementary shape in which the upper step engages with the lower step and overlaps with each other.

[0013] The plurality of battery cell assemblies may be secured to the base plate by bolts that pass through the stacked first and second cell cross beams and threadably connect to the base plate.

[0014] According to one embodiment of the present invention, the rear frame has a lower protrusion corresponding to the lower step of the first cell cross beam, and the battery cell assembly closest to the rear frame may be fixed to the base plate by having the upper step of the second cell cross beam overlap the lower protrusion vertically.

[0015] The battery cell assembly may further include a dummy cross beam having a shape corresponding to an upper step of the second cell cross beam, and the battery cell assembly closest to the front frame may be fixed to the base plate with the dummy cross beam vertically overlapping the lower step of the first cell cross beam.

[0016] Meanwhile, a battery pack according to an embodiment of the present invention includes a first step of preparing a pack case including a base plate, a front frame forming a front surface of the base plate, a rear frame forming a rear surface of the base plate, and a pair of side frames having both ends coupled to the front frame and the rear frame; a second step of preparing a battery cell assembly by preparing a first cell cross beam having a protruding lower step and a second cell cross beam having an upper step having a complementary shape that can be overlapped vertically with the lower step, and fixing a battery cell unit between the first cell cross beam and the second cell cross beam arranged in parallel; A battery cell assembly may be manufactured through a third step of fixing a battery cell assembly on the base plate with the cross beam and the second cell cross beam facing in the left-right direction of the pack case; a fourth step of preparing a new battery cell assembly through the second step, and fixing the new battery cell assembly on the base plate such that an upper step of the second cross beam of the new battery cell assembly is vertically overlapped with a lower step of the first cell cross beam of the battery cell assembly fixed on the base plate through the third step; and a fifth step of repeatedly performing the fourth step in a direction from the rear to the front of the pack case to fill all of the accommodation space of the pack case.

[0017] In the second step, the first cell cross beam and the second cell cross beam may have a length corresponding to a distance between the pair of side frames.

[0018] Then, in the second step, a plurality of battery cell units may be fixed between the first cell cross beam and the second cell cross beam arranged in parallel.

[0019] According to one embodiment, in the first step, the rear frame has a lower protrusion corresponding to the lower step of the first cell cross beam, and in the third step, the battery cell assembly that is first mounted in the pack case can be fixed to the base plate such that the upper step of the second cell cross beam overlaps the lower protrusion of the rear frame vertically.

[0020] In the fourth step, the new battery cell assembly may be secured to the base plate by bolts that pass through the stacked first and second cell cross beams and threadably connect to the base plate.

[0021] In the fifth step, a dummy cross beam having a shape corresponding to the upper step of the second cell cross beam is prepared, and the battery cell assembly to be finally mounted in the pack case may be fixed to the base plate such that the dummy cross beam vertically overlaps the lower step of the first cell cross beam. Effect of the Invention

[0022] In the battery pack of the present invention having the above-mentioned structure, the cell cross beams constituting the battery cell assemblies vertically overlap with the cell cross beams of other adjacent battery cell assemblies inside the pack case, so that the battery cell assemblies can be fixed to the base plate using even the weight of the other adjacent battery cell assemblies, and when the mounting of all the battery cell assemblies is completed, the fixed state is firmly maintained due to the overlap structure between the cell cross beams.

[0023] Furthermore, by fixing multiple battery cell units to a pair of cell cross beams, the number of assembly steps for the battery pack is reduced, improving productivity; and by making the length of the cell cross beam correspond to the overall width of the pack case, the rigidity of the pack case can be maintained well even without the need for a center beam, the number of parts is reduced, the battery pack can be made lighter, and space utilization rate is improved.

[0024] In addition, by utilizing a structure in which the cell cross beams of adjacent battery cell assemblies overlap, the battery cell assemblies can be fixed with bolts that penetrate the overlapping cell cross beams and screw into the base plate. Such bolt fixing can eliminate the need for a welding process for the cross beams, which improves the productivity of the battery pack by eliminating the need for a welding process, and improves space utilization by eliminating the interference problem caused by weld beads.

[0025] However, the technical effects that can be obtained by the present invention are not limited to the effects described above, and other effects not mentioned can be clearly understood by those of ordinary skill in the art from the description of the invention described below.

[0026] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. [Brief description of the drawings]

[0027] [Figure 1] 1 is a diagram showing a battery pack according to an embodiment of the present invention. [Diagram 2] 2 is a view showing a state in which a front battery cell assembly is separated from the battery pack of FIG. 1; [Diagram 3] FIG. 2 is a perspective view of a battery cell assembly. [Figure 4] 4 is a side view of the battery cell assembly of FIG. 3. [Diagram 5] 2 is a side view of the battery pack of FIG. 1 with a side frame removed. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing part “A” in FIG. 5. [Figure 7] 11 is a cross-sectional view showing a structure in which a battery cell assembly is fixed to a rear frame. FIG. [Figure 8] 11 is a cross-sectional view showing a structure in which the frontmost battery cell assembly is fixed to a base plate. FIG. [Figure 9] 13 is a diagram showing a state in which a battery cell assembly is initially mounted in a pack case. [Figure 10] 13 is a diagram showing the state in which a battery cell assembly is next mounted in the pack case. [Figure 11] 13 is a diagram showing a state in which a battery cell assembly is finally mounted in a pack case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be described in detail below.

[0029] However, this is not intended to limit the invention to any particular embodiment, but it should be understood to include all modifications, equivalents, or alternatives falling within the spirit and scope of the invention.

[0030] In the present invention, terms such as "comprise" and "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and may be understood as not precluding the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0031] In addition, in the present invention, when a layer, film, region, plate, or other portion is described as being "on" another portion, this includes not only the case where it is "directly on" the other portion, but also the case where there is another portion in between. Conversely, when a layer, film, region, plate, or other portion is described as being "under" the other portion, this includes not only the case where it is "directly under" the other portion, but also the case where there is another portion in between. In addition, in the present application, being "on" can include not only the case where it is located at the top, but also the case where it is located at the bottom.

[0032] The present invention relates to a battery pack, which in one example includes a base plate, a front frame forming a front surface of the base plate, a rear frame forming a rear surface of the base plate, a pair of side frames connected at both ends to the front frame and the rear frame, and a plurality of battery cell assemblies mounted in an accommodation space formed by the front frame, the rear frame, and the pair of side frames.

[0033] Here, each of the battery cell assemblies includes a battery cell unit including a plurality of cell stacks and a bus bar frame assembly that is mechanically and electrically connected to the plurality of cell stacks at both lateral ends from which the leads of the cell stacks protrude, a first cell cross beam that is connected to the bus bar frame assembly in front of the battery cell unit, and a second cell cross beam that is connected to the bus bar frame assembly in the rear of the battery cell unit.

[0034] The plurality of battery cell assemblies are fixed to the base plate in a state in which first cell cross beams and second cell cross beams facing each other in the front-rear direction of adjacent battery cell assemblies are stacked vertically.

[0035] For example, the plurality of battery cell assemblies may be secured to the base plate by bolts that pass through the stacked first and second cell cross beams and threadably connect to the base plate.

[0036] In the battery pack of the present invention having such a structure, the cell cross beams constituting the battery cell assemblies vertically overlap with the cell cross beams of other adjacent battery cell assemblies inside the pack case, so that the battery cell assemblies can be fixed to the base plate using even the weight of the other adjacent battery cell assemblies, and when the mounting of all the battery cell assemblies is completed, the fixed state is firmly maintained due to the overlapping structure between the cell cross beams.

[0037] In addition, by utilizing a structure in which the cell cross beams of adjacent battery cell assemblies overlap, the battery cell assemblies can be fixed with bolts that penetrate the overlapping cell cross beams and screw into the base plate. Such bolt fixing can eliminate the need for a welding process for the cross beams, which improves the productivity of the battery pack by eliminating the need for a welding process, and improves space utilization by eliminating the need for an interference problem caused by weld beads.

[0038] Hereinafter, a specific embodiment of the battery pack 10 according to the present invention will be described in detail with reference to the accompanying drawings. For reference, the directions of front / rear, up / down, left / right, and the like used in the following description to specify relative positions are intended to aid in understanding the invention, and unless otherwise specified, are based on the directions shown in the drawings.

[0039] (First embodiment) Fig. 1 is a view showing a battery pack 10 according to an embodiment of the present invention, Fig. 2 is a view showing a state in which a frontmost battery cell assembly 202 is separated from the battery pack 10 of Fig. 1, and Fig. 3 is a perspective view of the battery cell assembly 200. The battery pack 10 according to the present invention will be described in detail with reference to the accompanying drawings.

[0040] The battery pack 10 of the present invention includes a pack case 100 and a plurality of battery cell assemblies 200. The pack case 100 includes a base plate 110, a front frame 120 forming a front surface of the base plate 110, a rear frame 130 forming a rear surface of the base plate 110, and a pair of side frames 140 having both ends coupled to the front frame 120 and the rear frame 130. A storage space for mounting the plurality of battery cell assemblies 200 is formed by the frame surrounding the outer periphery of the base plate 110. For reference, in order to show the internal structure of the battery pack 10, a lead (lid) covering the upper surface of the pack case 100 to seal the storage space is omitted in the drawings.

[0041] In addition, the drawings show symbols of front, rear, left and right (FRLR), which are based on the directions shown in the drawings. The front, rear, left and right directions are based on the drawings for the convenience of explanation and to avoid confusion, and may not match the directions referred to for the battery pack 10 in the actual field. In the following description, the front, rear, left and right directions based on the drawings will be maintained.

[0042] According to the illustrated embodiment, the battery cell assembly 200 includes a battery cell unit 210 having a plurality of cell stacks 212 and a busbar frame assembly 214 that is mechanically and electrically coupled to the plurality of cell stacks 212 at both lateral ends from which the leads of the cell stacks 212 protrude.

[0043] In this specification, a secondary battery having a plurality of positive electrodes and negative electrodes with a separator laminated therebetween and a lead electrically connecting each electrode tab provided on the positive electrodes and negative electrodes is referred to as a cell stack 212. That is, the cell stack 212 refers to a completed secondary battery that can be repeatedly charged and discharged, and is not limited to a form such as a pouch-type battery or a square-type battery. The battery cell unit 210 corresponds to the concept of a module in which a plurality of such cell stacks 212 are assembled, and a bundle of cell stacks 212 is mechanically bound and electrically connected by bus bar frame assemblies 214 at both front and rear ends.

[0044] The battery cell assembly 200 includes a first cell cross beam 220 that is coupled to the bus bar frame assembly 214 in front of the battery cell unit 210, and a second cell cross beam 230 that is coupled to the bus bar frame assembly 214 in the rear of the battery cell unit 210. The first cell cross beam 220 and the second cell cross beam 230 are frames that maintain the structure of the battery cell assembly 200, and at the same time, when the battery cell assembly 200 is mounted in the pack case 100, they also function as cross beams that provide rigidity in the left-right direction of the pack case 100, i.e., in the overall width direction or lateral direction.

[0045] Here, the first cell cross beam 220 and the second cell cross beam 230 are referred to as cell cross beams to distinguish them from pack cross beams because they function as cross beams on the side of the pack case 100, but when considering the assembly process, they are first assembled in the form of the battery cell assembly 200 as a frame for fixing the battery cell units 210. The reason why the terms "first" and "second" are used to distinguish between the pair of cell cross beams 220, 230 is that there is a difference in shape depending on whether the first cell cross beam 220 or the second cell cross beam 230 is attached in the forward or rearward direction. This has been described above with reference to the drawings.

[0046] In the battery pack 10 of the present invention, a plurality of battery cell assemblies 200 are mounted on the base plate 110, and the first cell cross beams 220 and the second cell cross beams 230 of adjacent battery cell assemblies 200 facing each other in the front-rear direction are fixed to the base plate 110 in a vertically overlapping state. In other words, each battery cell assembly 200 has the same structure, and all the battery cell assemblies 200 are mounted in the pack case 100 with the first cell cross beams 220 and the second cell cross beams 230 facing in the left-right direction, so that the first cell cross beams 220 and the second cell cross beams 230 of adjacent battery cell assemblies 200 face each other closely.

[0047] Due to this repeated facing structure of the first cell cross beam 220 and the second cell cross beam 230, the first cell cross beam 220 and the second cell cross beam 230 of adjacent battery cell assemblies 200 can be vertically overlapped, and the vertically overlapping first cell cross beam 220 and second cell cross beam 230 can be fixed collectively to the base plate 110, thereby making it possible to simultaneously fix the facing front / rear edges of adjacent battery cell assemblies 200 to the base plate 110.

[0048] In one embodiment, the first cell cross beam 220 and the second cell cross beam 230 may have a length equivalent to the distance between a pair of side frames 140, i.e., the overall width of the pack case 100. As a result, even without the center beam configuration provided in conventional battery packs, the pack case 100 of the present invention can maintain good lateral rigidity by having a cross beam structure without any interruptions in the left-right direction.

[0049] The bus bar frame assemblies 214 provided on each of the plurality of battery cell units 210 may be coupled to the pair of first cell cross beams 220 and second cell cross beams 230. That is, the plurality of battery cell assemblies 200 may be fixed to the pair of first cell cross beams 220 and second cell cross beams 230 by bolts or the like. By fixing the plurality of battery cell assemblies 200 to the pair of first cell cross beams 220 and second cell cross beams 230 in this manner, the number of steps for mounting the battery cell assemblies 200 to the pack case 100 is reduced.

[0050] Taking the illustrated embodiment as an example, when a total of six battery cell assemblies 200 are mounted in the pack case 100, if one battery cell assembly 200 is fixed to the pair of cell cross beams 220, 230, a total of six mounting steps are required, but by fixing two battery cell assemblies 200 to the pair of cell cross beams 220, 230, the work can be completed with three mounting steps. Therefore, by fixing the multiple battery cell assemblies 200 to the first cell cross beam 220 and the second cell cross beam 230 with a length equivalent to the overall width of the pack case 100, not only the rigidity of the pack case 100 but also the productivity of the battery pack 10 can be improved.

[0051] FIG. 4 is a side view of the battery cell assembly 200 of FIG. 3. In the embodiment of the present invention, all the battery cell assemblies 200 have the same structure. Referring to FIG. 3 and FIG. 4, the first cell cross beam 220 has a protruding lower step 222, and the second cell cross beam 230 has a protruding upper step 232. The first cell cross beam 220 and the second cell cross beam 230 have a complementary shape in which the upper step 232 is engaged with the lower step 222 and overlaps with each other. That is, the upper step 232 of the second cell cross beam 230 is engaged with the lower step 222 of the first cell cross beam 220 to form an overlapping structure, and the overlapping first cell cross beam 220 and second cell cross beam 230 function as one pack cross beam.

[0052] 5 is a side view of the battery pack 10 of FIG. 1 with the side frame 140 removed, showing a connection structure between adjacent battery cell assemblies 200. With reference to the drawing, an overlapping structure can be seen in which the upper step 232 of the second cell cross beam 230 of the left battery cell assembly 200 is placed on the lower step 222 of the first cell cross beam 220 of the right battery cell assembly 200, and this overlapping structure is repeated at the front and rear edges of the battery cell assemblies 200.

[0053] 6 is an enlarged cross-sectional view of part "A" in FIG. 5. A plurality of battery cell assemblies 200 are fixed to the base plate 110 by bolts 240 that penetrate the first cell cross beam 220 and the second cell cross beam 230 that are stacked vertically and screwed to the base plate 110. In other words, the battery pack 10 of the present invention may utilize a structure in which the cell cross beams of adjacent battery cell assemblies 200 overlap each other, and may fix the battery cell assemblies 200 by bolts 240 that penetrate the overlapped cell cross beams and screwed to the base plate 110. Fixing the bolts 240 in this manner may omit a conventional welding process for the cross beams, which improves the productivity of the battery pack 10 by omitting the welding process, and improves space utilization by eliminating the interference problem of the battery cell assemblies 200 due to weld beads.

[0054] 5 and 6 show a coupling structure between adjacent battery cell assemblies 200, but there are no adjacent battery cell assemblies 200 in front of and behind the rearmost and frontmost battery cell assemblies 201, 202 of the battery pack 10, respectively. Therefore, a separate structure is required to complete the fixing of the rearmost and frontmost battery cell assemblies 201, 202 to the base plate 110.

[0055] 7 is a cross-sectional view showing a structure in which a battery cell assembly 200 is fixed to a rear frame 130. The rear frame 130 has a lower protrusion 132 corresponding to the lower step 222 of the first cell cross beam 220. As a result, the battery cell assembly 200 closest to the rear frame 130, i.e., the rearmost battery cell assembly 201, may be fixed to the base plate 110 with the upper step 232 of the second cell cross beam 230 vertically overlapping the lower protrusion 132 of the rear frame 130. The lower protrusion 132 of the rear frame 130 not only provides an efficient structure in which the rearmost battery cell assembly 201 is fixed to the base plate 110, but also contributes to increasing the rigidity of the pack case 100 as the cross-sectional area of ​​the lower protrusion 132 increases.

[0056] 8 is a cross-sectional view showing a structure in which the frontmost battery cell assembly 202 is fixed to the base plate 110. The pack case 100 requires a space for installing a venting device or arranging various mechanisms for electrical connection, and the pack case 100 according to an embodiment of the present invention has such a service space arranged on the front frame 120 side. Therefore, the frontmost battery cell assembly 202 is fixed to the base plate 110 using a dummy cross beam 250 having a shape corresponding to the upper step 232 of the second cell cross beam 230, instead of being fixed to the base plate 110 via the front frame 120 like the rearmost battery cell assembly 201. Referring to FIG. 8, the dummy cross beam 250 of the battery cell assembly 202 closest to the front frame 120 is overlapped upwardly with the lower step 222 of the first cell cross beam 220, and the bolts 240 passing through the dummy cross beam 250 and the first cell cross beam 220 are screwed to the base plate 110.

[0057] As described above, in the battery pack 10 of the present invention, the cell cross beams constituting the battery cell assemblies 200 vertically overlap with the cell cross beams of other adjacent battery cell assemblies 200 inside the pack case 100. As a result, the battery cell assemblies 200 can be fixed to the base plate 110 using even the weight of the other adjacent battery cell assemblies 200, and when the mounting of all the battery cell assemblies 200 is completed, the fixed state is firmly maintained due to the overlapping structure between the cell cross beams.

[0058] In addition, by utilizing a structure in which the cell cross beams of adjacent battery cell assemblies 200 overlap, the battery cell assemblies 200 are fixed with bolts 240 that penetrate the overlapping cell cross beams and screw into the base plate 110. Fixing the bolts 240 in this manner makes it possible to omit a welding process for the cross beams.

[0059] Second embodiment 9 to 11 are diagrams showing a series of manufacturing steps for the battery pack 10 according to one embodiment of the present invention. In the following description, details that overlap with the configuration of the battery pack 10 described above in the first embodiment will be omitted.

[0060] 9 is a view showing a state in which battery cell assemblies 200 are initially mounted in a pack case 100. A method for manufacturing a battery pack 10 according to the present invention includes a first step of preparing a pack case 100 including a base plate 110, a front frame 120 forming a front surface of the base plate 110, a rear frame 130 forming a rear surface of the base plate 110, and a pair of side frames 140 having both ends coupled to the front frame 120 and the rear frame 130.

[0061] Next, a second step is performed in which a first cell cross beam 220 having a protruding lower step 222 and a second cell cross beam 230 having a complementary upper step 232 that can overlap vertically with the lower step 222, and the battery cell unit 210 is fixed between the first cell cross beam 220 and the second cell cross beam 230 arranged in parallel to prepare the battery cell assembly 200.

[0062] In the second step, the first cell cross beam 220 and the second cell cross beam 230 can have a length equivalent to the distance between a pair of side frames 140, and further, multiple battery cell units 210 can be fixed between the first cell cross beam 220 and the second cell cross beam 230 arranged in parallel.

[0063] Here, the first step is a step of preparing the pack case 100, and the second step is a step of preparing the battery cell assembly 200, and these preparation steps may be performed in integrated or separate processes, and the order of their steps may vary.

[0064] The third step is a process of mounting the battery cell assembly 200 in the pack case 100, in which the battery cell assembly 200 is fixed onto the base plate 110 with the first cell cross beam 220 and the second cell cross beam 230 of the battery cell assembly 200 facing in the left-right direction of the pack case 100. At this time, the battery cell assembly 200 mounted first is the rearmost battery cell assembly 201 closest to the rear frame 130.

[0065] In order to improve the mounting efficiency of the rearmost battery cell assembly 201 and to increase the rigidity of the pack case 100, the rear frame 130 of the pack case 100 prepared in the first step may have a lower protrusion 132 corresponding to the lower step 222 of the first cell cross beam 220. Thus, in the third step, the battery cell assembly 200 that is first mounted in the pack case 100 may be fixed to the base plate 110 such that the upper step 232 of the second cell cross beam 230 vertically overlaps the lower protrusion 132 of the rear frame 130.

[0066] 10 is a view showing a state in which the next battery cell assembly 200 is mounted on the pack case 100. The fourth step is a step of fixing the new battery cell assembly 200 on the base plate 110 by seating the upper step 232 of the second cross beam of the new battery cell assembly 200 so that it overlaps vertically with the lower step 222 of the first cell cross beam 220 of the battery cell assembly 200 fixed on the base plate 110 through the third step.

[0067] When fixing the battery cell assembly 200 to the base plate 110 in this manner, as shown in Figures 6 and 7, not only the second cell cross beam 230 of the battery cell assembly 200 which is fixed to the base plate 110 together with the rear frame 130, but also the new battery cell assembly 200 can be fixed to the base plate 110 by bolts 240 which pass through the stacked first cell cross beam 220 and second cell cross beam 230 and screw-connect them to the base plate 110.

[0068] This fourth step is repeated in a fifth step in a direction from the rear to the front of the pack case 100 until the battery cell assemblies 200 fill the entire storage space of the pack case 100. In the illustrated embodiment, a total of three rows of battery cell assemblies 200 are mounted, so the mounting of the battery cell assemblies 200 in the fourth step is repeated once more, and the last battery cell assembly 200 to be mounted corresponds to the frontmost battery cell assembly 202.

[0069] 11 is a view showing a state in which the battery cell assembly 202 is finally mounted in the pack case 100. In the fifth step, a dummy cross beam 250 having a shape corresponding to the upper step 232 of the second cell cross beam 230 is prepared, and the battery cell assembly 202 last mounted in the pack case 100 is fixed to the base plate 110 such that the dummy cross beam 250 vertically overlaps the lower step 222 of the first cell cross beam 220. The structure of the corresponding battery pack 10 may be seen in FIG.

[0070] The present invention has been described in more detail above with reference to the drawings and embodiments, etc. However, the configurations described in the drawings or embodiments, etc. in this specification are merely one embodiment of the present invention and do not fully represent the technical ideas of the present invention, and therefore there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0071] 10: Battery pack 100: Pack case 110: Base plate 120: Front frame 130: Rear frame 132: Lower protrusion 140: Side frame 200: Battery cell assembly 201: Rearmost battery cell assembly 202: Frontmost battery cell assembly 210: Battery cell unit 212: Cell stack 214: Busbar frame assembly 220: First cell cross beam 222: Lower step 230: Second cell cross beam 232: Upper step 240: Bolt 250: Dummy cross beam

Claims

1. A base plate; a front frame forming a front surface of the base plate; a rear frame forming a rear surface of the base plate; a pair of side frames each having both ends connected to the front frame and the rear frame; a plurality of battery cell assemblies mounted in an accommodation space defined by the front frame, the rear frame, and the pair of side frames; Each of the battery cell assemblies comprises: a battery cell unit including a plurality of cell stacks and a bus bar frame assembly that is mechanically and electrically coupled to the plurality of cell stacks at both lateral ends from which the leads of the cell stacks protrude; a first cell cross beam coupled to the bus bar frame assembly in front of the battery cell unit; a second cell cross beam coupled to the bus bar frame assembly at a rear of the battery cell unit; the plurality of battery cell assemblies are fixed to the base plate in a state in which first cell cross beams and second cell cross beams facing each other in a front-rear direction of adjacent battery cell assemblies are vertically overlapped.

2. The first cell cross beam and the second cell cross beam are The battery pack according to claim 1 , having a length corresponding to a distance between the pair of side frames.

3. The first cell cross beam and the second cell cross beam are The battery pack according to claim 2 , wherein the battery pack is coupled to a bus bar frame assembly provided on each of the plurality of battery cell units.

4. the first cell cross beam has a protruding lower step; the second cell cross beam has a protruding upper step; The battery pack of claim 1 , wherein the first cell cross beam and the second cell cross beam have a complementary shape in which an upper step is engaged with the lower step and overlaps with each other.

5. The plurality of battery cell assemblies include The battery pack according to claim 4 , wherein the battery pack is fixed to the base plate by bolts that pass through the first cell cross beam and the second cell cross beam stacked one above the other and are screwed to the base plate.

6. the rear frame includes a lower protrusion corresponding to a lower step of the first cell cross beam, The battery pack according to claim 4 , wherein the battery cell assembly closest to the rear frame is fixed to the base plate with the upper step of the second cell cross beam vertically overlapping the lower protrusion.

7. The second cell cross beam further includes a dummy cross beam having a shape corresponding to an upper step of the second cell cross beam, The battery pack of claim 4 , wherein the battery cell assembly closest to the front frame is fixed to the base plate with the dummy cross beam vertically overlapping a lower step of the first cell cross beam.

8. a first step of preparing a pack case including a base plate, a front frame forming a front surface of the base plate, a rear frame forming a rear surface of the base plate, and a pair of side frames each having both ends connected to the front frame and the rear frame; a second step of preparing a battery cell assembly by preparing a first cell cross beam having a protruding lower step and a second cell cross beam having an upper step that is complementary to and overlaps the lower step, and by fixing a battery cell unit between the first cell cross beam and the second cell cross beam that are arranged in parallel; a third step of fixing the battery cell assembly on the base plate in a state in which a first cell cross beam and a second cell cross beam of the battery cell assembly are oriented in a left-right direction of the pack case; a fourth step of preparing a new battery cell assembly through the second step, and fixing the new battery cell assembly on the base plate by seating an upper step of a second cross beam of the new battery cell assembly so that the upper step of the second cross beam of the new battery cell assembly is vertically overlapped with a lower step of a first cell cross beam of the battery cell assembly fixed on the base plate through the third step; a fifth step of repeatedly performing the fourth step in a direction from the rear to the front of the pack case so as to fill all of the accommodation space of the pack case.

9. In the second step, The method for manufacturing a battery pack according to claim 8 , wherein the first cell cross beam and the second cell cross beam have a length corresponding to a distance between the pair of side frames.

10. In the second step, The method for manufacturing a battery pack according to claim 9 , further comprising fixing a plurality of battery cell units between the first cell cross beam and the second cell cross beam arranged in parallel.

11. In the first step, the rear frame includes a lower protrusion corresponding to a lower step of the first cell cross beam, In the third step, 9. The method for manufacturing a battery pack according to claim 8, wherein the battery cell assembly that is first mounted in the pack case is fixed to the base plate such that an upper step of the second cell cross beam vertically overlaps a lower protrusion of the rear frame.

12. In the fourth step, 9. The method of manufacturing a battery pack according to claim 8, wherein the new battery cell assembly is fixed to the base plate by a bolt that passes through the first cell cross beam and the second cell cross beam stacked one on top of the other and is screwed to the base plate.

13. In the fifth step, preparing a dummy cross beam having a shape corresponding to an upper step of the second cell cross beam; 12. The method of claim 11, wherein the battery cell assembly to be last mounted in the pack case is fixed to the base plate such that the dummy cross beam vertically overlaps a lower step of the first cell cross beam.

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