Battery module and its assembly method

Abstract

A method for assembling a battery module according to the present invention includes a subframe providing step of providing a subframe having a plate shape; a cell block mounting step of mounting a cell block, having a plurality of battery cells coupled thereto, on an upper surface of the subframe; a pre-assembly step of pre-fixing a main frame having a cross-sectional shape with one side open and three sides closed to the subframe so that the cell block can be accommodated therein; and a welding step of welding a contact point between the main frame and the subframe; The battery module according to the present invention includes a subframe having a plate shape; a cell block, having a cross-sectional shape with one side open and three sides closed, configured to couple a plurality of battery cells together and mounted on an upper surface of the subframe; and a main frame, having a cross-sectional shape with one side open and three sides closed, coupled to the subframe so that the open side is closed by the subframe and housing the cell block therein; and the main frame and the subframe are joined and fixed by welding.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0067848, filed on June 2, 2022, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] The present invention relates to a battery module in which a cell block in which a plurality of battery cells are stacked (combined) is mounted inside a space where a sub - frame and a main frame are combined, and a method of assembling the same. More specifically, the present invention relates to a battery module and a method of assembling the same that can increase cooling efficiency, can more easily perform an assembly process and a welding process, and can prevent internal inflow of spatter generated during welding.

Background Art

[0003] Secondary batteries having a high energy density are mounted not only in portable devices but also in electric vehicles (EVs) or hybrid electric vehicles (HEVs) driven by an electric drive source.

[0004] Such secondary batteries are attracting attention as a new energy source for environmental protection and energy efficiency improvement not only because of the primary advantage of significantly reducing the use of fossil fuels but also because no by - products are generated by energy use, and active research and development are being carried out.

[0005] Currently widely used types of secondary batteries include lithium - ion batteries, lithium - polymer batteries, nickel - cadmium batteries, nickel - metal hydride batteries, nickel - zinc batteries, etc. And the operating voltage of such a unit battery cell, that is, a unit battery cell, is about 2.5V to 4.2V.

[0006] Therefore, if a higher output voltage is required, multiple individual battery cells are linked together to form a secondary battery module, and these modules are then assembled to form a battery pack.

[0007] In this case, the battery module is composed of either a collection of cylindrical rechargeable batteries or a collection of pouch-type rechargeable batteries.

[0008] In this configuration, the battery module, which is composed of pouch-type secondary batteries, is configured such that, as shown in Figure 1 which illustrates the cross-section of a conventional battery module, a predetermined number of battery cells manufactured as pouch-type secondary batteries are stacked to form a cell block 1, which is mounted within a frame 2 having a "U"-shaped cross-section. The frame 2 is open at the top and is provided so as to face the bottom and both sides of the cell block 1.

[0009] Then, a plate-shaped lid 3 was attached to the open upper side of the frame 2 to close the open upper side of the frame 2. The lid 3 was attached to the upper end of the frame 2 and joined by brazing.

[0010] At the same time, a cooling unit 4 was attached to the lower part of the bottom surface of frame 2, in which a refrigerant circulates to cool cell block 1 and frame 2.

[0011] On the other hand, conventional battery modules provided with the above-mentioned configuration have the problem of reduced productivity and quality because the dimensions of flatness and bending angle must be controlled when folding the frame into a "U" shape.

[0012] Furthermore, when installing cell block 1, pressure is applied to frame 2 to forcibly open (both side walls), and there was a possibility that deformation and / or cracks could occur in frame 2 during this process.

[0013] Furthermore, when swelling occurred in the battery cells constituting the cell block 1, there was a possibility of cracks occurring in the brazing (welding) area of ​​the frame 2 and lid 3. In order to improve the cooling performance of the cooling section 4, the thickness of the frame 2 had to be minimized in the area located between the cell block 1 and the cooling section 4, but due to the processing characteristics of the frame 2, which is bent in a "U" shape, there was a problem in that it was not possible to reduce the thickness in a specific area.

[0014] At the same time, welding was performed on the upper end of the frame 2, which posed a risk of spatter generated during welding flowing into the interior of the frame 2 and damaging the cell block 1. [Overview of the project] [Problems that the invention aims to solve]

[0015] Therefore, the main objective of the present invention is to provide a battery module and a method for assembling the same that can increase cooling efficiency so as to solve the problems of conventional battery modules (such as frame deformation and / or cracking, reduced cooling performance of the cooling section due to frame thickness, and spatter flowing into the interior due to its own weight during welding), and the assembly and welding processes can be performed more easily and reliably, thereby increasing production efficiency and reducing the defect rate. [Means for solving the problem]

[0016] A battery module assembly method according to the present invention for achieving the aforementioned objectives is characterized by comprising: a subframe provisioning step of providing a plate-shaped subframe as a battery module assembly method; a cell block attachment step of attaching a cell block (composed of stacking a plurality of pouch-type battery cells) onto the upper surface of the subframe; a temporary assembly step of temporarily fixing a main frame having a "U"-shaped cross-sectional shape with one side open and three sides closed to the subframe so that the cell block is housed inside; and a welding step of welding the points where the main frame and the subframe come into contact.

[0017] The main frame has fitting holes drilled at points facing both ends of the subframe, and the subframe has protrusions formed at both ends that can enter the fitting holes. When these protrusions enter the fitting holes, the main frame and subframe are temporarily fixed together by fitting.

[0018] The lower surface of the subframe has base portions that protrude downward on both sides, and when the protruding portions enter the fitting holes, the main frame comes into contact with the base portions.

[0019] When the fitting hole is fitted into the protruding portion, the base portion has a height sufficient to allow the end of the main frame to be separated from the ground.

[0020] The process further includes a jig pressurizing step, in which pressure is applied through a jig to ensure a tight fit between the main frame and subframe at the point where they are fitted together, wherein the jig pressurizing step is performed before (or simultaneously with) the start of the welding step, and while the welding is progressing, the jig applies pressure to the portion where the main frame and subframe are temporarily fixed to secure them.

[0021] The jig pressurization step may include a correction step that adjusts the direction in which pressure is applied to the jig in order to suppress the occurrence of steps and twists between the main frame and the subframe.

[0022] The jig is drilled with a through hole through which a welding laser can pass, and welding is performed at a point where the welding laser is irradiated and fitted through the through hole while the jig applies pressure to the main frame and the sub-frame.

[0023] Further including a cooling part joining step of joining a cooling part that exchanges heat with the sub-frame and cools it to the lower surface of the sub-frame.

[0024] At the same time, the present invention further provides a battery module that can be manufactured by the manufacturing method of the battery module as described above.

[0025] The battery module provided by the present invention includes a sub-frame having a plate shape; a cell block formed by combining a plurality of battery cells and resting on the upper surface of the sub-frame; and a main frame having a "U" - shaped cross-sectional shape with one side open and three sides closed, and being coupled to the sub-frame such that the open side is closed by the sub-frame and the cell block is accommodated inside. The main frame and the sub-frame are joined and fixed by welding.

[0026] The main frame is drilled with fitting holes at points facing both ends of the sub-frame. Protrusions that can enter the fitting holes are formed at both ends of the sub-frame, and the protrusions are inserted into the fitting holes.

[0027] On the lower surface of the sub-frame, pedestals protrude downward on both sides. The pedestals are formed to have a height such that when the protrusions enter the fitting holes, the end of the main frame can be separated from the ground.

[0028] Welding is performed at a point where the protrusion is inserted into the fitting hole and the main frame abuts against the pedestal.

[0029] The system further includes a cooling section coupled to the lower surface of the subframe for cooling the subframe. [Effects of the Invention]

[0030] The present invention, having the technical features described above, is a structure in which the cell block is fixed onto a plate-shaped subframe, and since there is no need to apply excessive pressure to the side walls of the mainframe, deformation and the occurrence of defects can be suppressed. As a result, the dimensions of the subframe and mainframe can be stabilized, and production efficiency can be further increased and optimized.

[0031] The main frame has interlocking holes, and the subframe has protrusions. Welding is performed with the protrusions temporarily fixed in the interlocking holes, which improves welding quality and enables uniform welding. The interlocking holes and protrusions provide a guide function when joining the main frame.

[0032] Furthermore, a base portion is formed on the subframe, increasing the area that can be welded and allowing the main frame to maintain a tight fit with the subframe. In addition, since the base portion can support the load instead of the cooling portion that is attached to the bottom surface of the subframe, it is possible to prevent the load from being applied to the cooling portion.

[0033] At the same time, reducing the thickness of the subframe can further increase the cooling performance of the cooling unit.

[0034] Furthermore, in this invention, since laser welding is performed through through holes formed in the jig, the problem of spatter generated during welding flowing into the interior can be eliminated. [Brief explanation of the drawing]

[0035] [Figure 1] This is a diagram showing a vertical cross-section of a conventional battery module. [Figure 2]This is an exploded perspective view showing the battery module according to the present invention in a disassembled state. [Figure 3] This is a perspective view of a battery module according to the present invention. [Figure 4] Figure 3 is a diagram showing the cross-sectional shape of section AA. [Figure 5] This diagram sequentially shows how the battery module is assembled according to the assembly method provided in the present invention. [Figure 6] Figure 5 is a magnified view of the area where welding is performed. [Modes for carrying out the invention]

[0036] The present invention will be described below in detail, based on the attached drawings, so that it can be easily implemented by a person with ordinary skill in the art to which the invention pertains. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0037] To clearly explain the present invention, irrelevant parts have been omitted, and the same or similar reference numerals are used throughout the specification for identical or similar components.

[0038] Furthermore, the terms and words used in this specification and the claims shall not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors themselves may define the concepts of terms as appropriate in order to best describe their invention.

[0039] The present invention relates to a battery module and a method for assembling the same, in which a cell block 10 is provided, in which a plurality of battery cells are bonded (stacked) together inside a space where a subframe 20 and a mainframe 30 are joined. The embodiments provided in the present invention will be described in more detail below with reference to the attached drawings.

[0040] First Example The present invention provides a battery module as a first embodiment.

[0041] Figure 2 is an exploded perspective view showing the battery module according to the present invention in a disassembled state, Figure 3 is a perspective view of the battery module according to the present invention, and Figure 4 is a diagram showing the cross-sectional shape of part AA in Figure 3.

[0042] Referring to the figure, the battery module provided in this embodiment includes a cell block 10 provided by stacking multiple battery cells, a plate-shaped subframe 20, and a main frame 30 joined to the subframe 20 by welding.

[0043] The cell block 10 is provided by stacking thin, rectangular battery cells, and therefore has an overall rectangular shape with a predetermined thickness. The cell block 10 is then fixed onto the upper surface of a plate-shaped subframe 20. The subframe 20 is provided in a rectangular shape with an area slightly larger than that of the cell block 10.

[0044] The main frame 30 has a "U" shaped cross-section with one side open and three sides closed, and is connected to the subframe 20 with the open side facing downward. That is, the main frame 30 is connected to the subframe 20 such that the open side is closed by the subframe 20. As a result, the main frame 30 has a flat upper surface 30b that is placed on the cell block 10 and side wall surfaces 30a that extend on both sides of the upper surface 30b and are bent downward, and the cell block 10 is housed in the internal space formed by the main frame 30 and the subframe 20.

[0045] Then, the main frame 30 and the subframe 20 are joined by welding at the point where they come into contact with each other.

[0046] On the other hand, in the present invention, the subframe 20 and the main frame 30 are fitted together in such a way that they are temporarily fixed to each other before welding is performed.

[0047] Specifically, at the lower ends of the side wall surfaces 30a of the main frame 30, a plurality of fitting holes 31 are drilled at intervals from each other, at points where they face both ends of the subframe 20. The fitting holes 31 may be circular or have other shapes, and are provided in a rectangular shape (as shown in Figure 2) so that they can be adjusted consistently in the vertical, horizontal, and front-to-back directions when welding is performed.

[0048] Furthermore, protrusions 21 are formed on both ends of the subframe 20 (along both sides along the longitudinal direction) at points where the fitting holes 31 are located when the mainframe 30 enters, allowing them to enter the fitting holes 31. As a result, the mainframe 30 and the subframe 20 can be temporarily fixed together by inserting the protrusions 21 into the fitting holes 31.

[0049] At the same time, base portions 22 protrude downward from the lower surface of the subframe 20, spaced apart from each other on both sides. The base portions 22 are formed to have a height such that when the protrusions 21 enter the fitting holes 31, the ends of the main frame 30 (more precisely, the ends of the side walls of the main frame) are lifted off the ground.

[0050] When the protruding portion 21 is inserted into the fitting hole 31, the side walls 30a of the main frame 30 may come into contact with the base portion 22, and welding may be performed at the point of contact.

[0051] At the same time, a cooling section 40 can be attached to the lower surface of the subframe 20 to exchange heat with the subframe 20 and cool the subframe 20 and the cell block 10.

[0052] Second Example The present invention provides a method for assembling a battery module as a second embodiment.

[0053] Figure 5 is a diagram showing the sequential assembly process of the battery module provided by the present invention, and Figure 6 is a magnified view of the welding process shown in Figure 5.

[0054] Referring to Figures 5 and 6, the assembly method for the battery module provided in this embodiment comprises a subframe provisioning stage, a cell block installation stage, a preliminary assembly stage, and a welding stage.

[0055] That is, Figure 5 As shown, in the subframe provisioning stage, a plate-shaped subframe 20 is provided, and in the cell block installation stage, the cell block 10 is installed on the upper surface of the subframe 20.

[0056] In this configuration, the cell block 10 is positioned in the center so as not to detach from the base portions 22 that protrude from both sides of the bottom surface of the subframe 20.

[0057] And then, Figure 5 As shown, with the cell block 10 securely attached to the subframe 20, a preliminary assembly stage is performed in which the main frame 30 is temporarily fixed to the subframe 20.

[0058] The main frame 30 enters with its side walls 30a, which are bent on both sides of the upper surface 30b, slightly open in an elastically deformed state, and when the force applied to the side walls 30a is released, as shown in Figure 5. <c>As shown, the side wall surface 30a is elastically restored, and the protruding portion 21 of the subframe 20 is fitted into the fitting hole 31 formed in the main frame 30, thereby providing temporary fixation.

[0059] With the subframe 20 and mainframe 30 temporarily fixed in place, the point where the mainframe 30 and subframe 20 come into contact is shown in Figure 5. <d>The welding process is carried out by welding as shown.

[0060] As described above, two base portions 22 protrude downward from the lower surface of the subframe 20 at a distance from each other, and when the protruding portion 21 enters the fitting hole 31, the side wall surface 30a of the main frame 30 comes into contact with the base portions 22.

[0061] In this case, when the fitting hole 31 is fitted into the protruding portion 21, the base portion 22 has a height such that the lower end of the side wall surface 30a of the main frame 30 is separated from the ground, as shown in Figure 4.

[0062] On the other hand, before the welding stage is performed (or simultaneously with the welding stage), a jig pressurization stage is performed in which pressure is applied via the jig 50 to ensure a tight fit between the main frame 30 and the subframe 20 at the point where they are fitted together, so as to eliminate any gaps.

[0063] The jig pressurization step is performed before or simultaneously with the start of the welding step, and the jig 50 applies pressure to the portion where the main frame 30 and subframe 20 are temporarily fixed to prevent shaking. The jig 50 continues to apply pressure and fix the frame in place as the welding progresses.

[0064] The jig pressurization step may include a correction step that adjusts the direction in which pressure is applied to the jig 50 in order to suppress the occurrence of steps and twists between the main frame 30 and the subframe 20.

[0065] In other words, as shown in Figure 6, depending on the position of the main frame 30, welding proceeds with the protruding portion 21 in contact with the upper side of the fitting hole 31. Condition) Welding proceeds with the protruding portion 21 in contact with the lower part of the fitting hole 31. <ii>You may apply pressure to achieve the desired state.

[0066] However, in the two cases as well ( state and <ii>In both states, it is preferable that pressure is applied laterally (left-right direction in the drawing) so that the lowest end of the side wall surface 30a is in close contact with the protruding portion 21. Therefore, the jig 50 is divided into two parts 50a and 50b that can behave independently, and a space can be formed between them (a through hole can be formed) so that the laser can pass through.

[0067] In other words, a through-hole 51 is drilled in the jig 50 as a space through which a welding laser can pass, so that welding is performed at the point where the side wall surface 30a of the main frame 30 and the base portion 22 of the subframe 20 come into contact. As the jig 50 applies pressure to the main frame 30 and the subframe 20, the welding laser is irradiated through the through-hole 51, allowing welding to be performed at the point where the parts are fitted together.

[0068] Then, a cooling section joining step may be performed, in which a cooling section 40 that cools the subframe 20 by exchanging heat with it may be joined to the lower surface of the subframe 20. At this time, the cooling section 40 may be mounted so as to be located between the two base sections 22.

[0069] The present invention, having the technical features described above, has a structure in which the cell block 10 is fixed onto a plate-shaped subframe 20, and since there is no need to apply excessive pressure to the side walls (30a) of the main frame 30, deformation and the occurrence of defects can be suppressed. As a result, the dimensions of the subframe 20 and the main frame 30 can be stabilized, and production efficiency can be increased.

[0070] The main frame 30 has fitting holes 31, and the subframe 20 has protrusions 21. Welding is performed with the protrusions 21 temporarily fixed in the fitting holes 31, which improves welding quality and enables uniform welding. The formation of the fitting holes 31 and protrusions 21 provides a guide function when joining the main frame 30.

[0071] Furthermore, a base portion 22 is formed on the subframe 20, increasing the weldable area and allowing the main frame 30 to maintain a close contact with the subframe 20. In addition, since the base portion 22 can support the load instead of the cooling portion 40 which is bonded to the bottom surface of the subframe 20, it is possible to prevent the load from being applied to the cooling portion 40.

[0072] At the same time, reducing the thickness of the subframe 20 can further increase the cooling performance of the cooling section 40.

[0073] Furthermore, in this invention, since laser welding is performed through a through-hole 51 formed in the jig 50, the problem of spatter generated during welding flowing into the internal space can be eliminated.

[0074] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible by persons with ordinary skill in the art to which the present invention pertains, within the equivalent scope of the technical concept of the present invention and the claims described below. [Explanation of symbols]

[0075] 10 cell block 20 subframes 21 Protrusion 22 Base 30 Mainframes 31 Insertion Hole 40 Cooling section< / ii> < / ii> < / d> < / c>

Claims

1. This is a method for assembling a battery module. A subframe provision step, which provides a subframe having a plate shape, A cell block installation step involves installing a cell block, in which multiple battery cells are coupled together, onto the upper surface of the subframe. A preliminary assembly step involves temporarily fixing a main frame, which has a cross-sectional shape with one side open and three sides closed, to a subframe so that the cell block is housed inside; The process includes a welding step of welding the points where the main frame and the subframe come into contact, The main frame has insertion holes drilled at points facing both ends of the subframe, and the subframe has protrusions formed at both ends that can enter the insertion holes. The aforementioned protruding portion enters the fitting hole, thereby temporarily fixing the main frame and subframe together through fitting. A method for assembling a battery module, wherein the lower surface of the subframe has base portions that protrude downward on both sides, and when the protrusions enter the fitting holes, the main frame comes into contact with the base portions.

2. The method for assembling a battery module according to claim 1, wherein when the fitting hole is fitted into the protruding portion, the base portion has a height such that the end of the main frame is lifted off the ground.

3. The process further includes a jig pressurization step in which pressure is applied via a jig to ensure a tight seal by eliminating any gaps at the point where the main frame and subframe are fitted together. The method for assembling a battery module according to claim 1, wherein the jig pressurizing step is performed before the welding step begins, and while welding is in progress, the jig applies pressure to the portion where the main frame and subframe are temporarily fixed to secure them.

4. The method for assembling a battery module according to claim 3, wherein the jig pressurizing step includes a correction step that adjusts the direction in which pressure is applied to the jig so as to suppress the occurrence of steps and twists between the main frame and the subframe.

5. The method for assembling a battery module according to claim 3, wherein the jig has through-holes through which a welding laser can pass, and welding is performed at the fitted points by irradiating the jig with a welding laser through the through-holes while the jig applies pressure to the main frame and subframe.

6. The method for assembling a battery module according to claim 1, further comprising a cooling section joining step of joining a cooling section to the lower surface of the subframe for cooling by heat exchange with the subframe.

7. It is a battery module, A subframe having a plate shape, A cell block is formed by combining multiple battery cells and is fixed to the upper surface of the subframe, A main frame having a cross-sectional shape with one side open and three sides closed, coupled to the subframe such that the open side is closed by the subframe, and containing the cell block inside, The main frame and subframe are joined and fixed together by welding. The main frame has fitting holes drilled at points facing both ends of the subframe, and the subframe has protrusions formed at both ends that can enter the fitting holes, and the protrusions are inserted into the fitting holes. A battery module having a base portion that protrudes downward on both sides of the lower surface of the subframe, and the base portion is tall enough to lift the end of the main frame off the ground when the protrusion enters the fitting hole.

8. The battery module according to claim 7, wherein a protruding portion is inserted into the aforementioned fitting hole and welding is performed at the point where the main frame contacts the base portion.

9. The battery module according to claim 7, further comprising a cooling section coupled to the lower surface of the subframe for cooling the subframe.

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