JP2021034302A - Method for manufacturing battery module - Google Patents

Abstract

To provide a method for manufacturing battery modules, capable of increasing the strength of a weld between a bus bar and a connecting plate.SOLUTION: In a method for manufacturing battery modules, a pressed portion 59 is pressed with a pressing jig 61, and, while a welding ridge 56 is pressed against a bus bar 18, a laser is irradiated toward the welding ridge 56 so that all of the welding ridge 56 melt and the bus bar 18 and the connection plate 50 are welded. In addition, in the method for manufacturing battery modules, the distance between facing surfaces after the bus bar 18 and the connection plate 50 have been welded is made shorter than the distance between facing surfaces before welding.SELECTED DRAWING: Figure 8

Description

The present invention relates to a method of manufacturing a battery module including a connection plate for electrically connecting a voltage measurement line and a bus bar.

Vehicles such as EVs (Electric Vehicles) and PHVs (Plug in Hybrid Vehicles) are equipped with a plurality of secondary batteries such as lithium-ion batteries that store the power supplied to the electric motor that serves as the prime mover. The plurality of secondary batteries arranged side by side constitute a battery module electrically connected via a bus bar connecting the positive electrode terminals or the negative electrode terminals of the secondary batteries adjacent to each other in the parallel arrangement direction. The bus bar is made of, for example, aluminum. Further, the plurality of secondary batteries are housed in the case of the battery pack in a state of being restrained by end plates from both end sides of the secondary batteries in the parallel arrangement direction. Further, the battery case of the secondary battery contains an electrode assembly which is a laminated body of a positive electrode and a negative electrode, and an electrolytic solution.

In addition, the battery module is equipped with a monitoring device. The monitoring device is an integrated circuit, measures the voltage between the terminals of each secondary battery, and monitors whether or not the voltage between the terminals of the secondary battery is abnormal. A plurality of voltage measuring lines are electrically connected to the monitoring device, and each voltage measuring line is electrically connected to the bus bar via, for example, a copper connecting plate. Each voltage measuring line and the first end of the metal plate are connected by soldering, and each bus bar and the second end of the connecting plate are connected by welding (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2018-18612

Laser welding is often used as a method of welding the bus bar and the connecting plate, but during laser welding, after the aluminum bus bar and the copper connecting plate are melted to form a molten pool, the welding is performed. The molten pool solidifies to form a weld. Since this weld is an intermetallic compound formed by mixing dissimilar metals, its strength is lower than that of the bus bar or connecting plate itself before melting, and the thicker the weld, the more brittle the weld. The strength is reduced.

An object of the present invention is to provide a method for manufacturing a battery module for increasing the strength of a welded portion between a bus bar and a connecting plate.

A method for manufacturing a battery module for solving the above problems is to have a plurality of secondary batteries having a positive electrode terminal and a negative electrode terminal and arranged side by side in the parallel direction, and the secondary battery adjacent to the secondary battery in the parallel direction. A metal bus bar that electrically connects the positive electrode terminals to each other or the negative electrode terminals to each other, a measuring unit that measures the voltage between the terminals of the plurality of secondary batteries, and the voltage between the terminals of the plurality of secondary batteries. A metal different from the bus bar, which is erected between the voltage measurement line and the bus bar in order to electrically connect the voltage measurement line and the bus bar to a plurality of voltage measurement lines for inputting to the measurement unit. A method for manufacturing a battery module having a connection plate made of the above-made material, wherein the connection plate has one surface in the thickness direction of the connection plate facing the voltage measurement line and the bus bar from the one surface. The connection plate is pressed so that the protrusions protruding toward the surface, the protrusions for welding located at the tip of the protrusions from one surface in the protrusion direction, and the protrusions for welding toward the bus bar. The pressed portion is provided with a pressing portion for pressing the pressed portion with a pressing jig, and the welding ridge portion is pressed against the bus bar so that all of the welding ridge portions are melted. The bus bar and the connection plate are welded by irradiating a laser toward the welding ridge portion, and the distance between the pressed portion facing the thickness direction and the facing surface of the bus bar is the distance between the facing surfaces. Then, the gist is that the distance between the facing surfaces after welding the bus bar and the connecting plate is shorter than the distance between the facing surfaces before welding.

According to this, by pressing the pressed portion with the pressing jig, the welding ridge portion can be pressed against the bus bar and brought into contact with the bus bar. Then, at the time of laser welding, the welding ridge portion and the bus bar are melted to form a molten pool of dissimilar metals. By irradiating the laser so that the welding ridges are melted over the entire area, the portion of the connecting plate that forms the welding ridges is pushed toward the molten pool as the welding jig presses. Then, the distance between the facing surfaces becomes shorter after welding than before welding, the welding area between the bus bar and the connecting plate expands, and a part of the molten pool faces the root side of the welding ridge. It is pushed out of the molten pool and the molten pool expands. As a result, the thickness of the welded portion formed by solidifying the molten pool can be reduced and the area of the welded portion can be increased as compared with the case where the connecting plate is not pressed against the molten pool, and the strength of the welded portion can be increased. Can be enhanced.

Further, regarding the method of manufacturing the battery module, the pressed portion may be pressed by the pressing jig until the pressed portion abuts on the bus bar.
According to this, the portion of the connecting plate forming the welding ridge portion can be pushed toward the molten pool.

Further, regarding the method of manufacturing the battery module, the pressed portion is located outside the protrusion along the one surface of the connection plate, and the pressing jig presses the outside of the protrusion along the one surface. You may.

According to this, the pressing jig does not interfere with the laser radiated toward the welding ridge portion, and the welding work can be easily performed.

According to the present invention, the strength of the welded portion between the bus bar and the connecting plate can be increased.

The perspective view which shows the battery module of embodiment. The plan view which shows the battery module of an embodiment. The perspective view which shows the connection plate and the bus bar. The side view which shows the partition member and the connection plate in a battery module. A cross-sectional view showing a welded portion between a bus bar and a connecting plate. A partial cross-sectional view showing a state in which a welding ridge portion is in contact with a bus bar. The plan view which shows the state which pressed the pressed part by a pressing jig. The figure of the state in which the welding ridge part is pressed against the bus bar and laser welding is performed. FIG. 5 is a cross-sectional view showing a state in which the bottom of the connecting plate of another example is in contact with the bus bar. FIG. 5 is a cross-sectional view showing a state in which the pressed portion is pressed by a pressing jig.

Hereinafter, an embodiment embodying a method for manufacturing a battery module will be described with reference to FIGS. 1 to 8.
As shown in FIG. 1 or 2, the battery module 10 includes a plurality of secondary batteries 11. The secondary battery 11 is a lithium ion secondary battery or a nickel hydrogen secondary battery. The secondary battery 11 includes a battery case 12. The battery case 12 of the secondary battery 11 has a flat square box shape. The plurality of secondary batteries 11 are arranged so that the thickness direction of the battery case 12 is aligned with the parallel direction Z of the secondary batteries 11. The battery module 10 is mounted as a power source for EVs and PHVs.

The battery case 12 contains an electrode assembly and an electrolytic solution (not shown). The electrode assembly includes a positive electrode and a negative electrode. The battery case 12 is composed of a bottomed box-shaped case body 13 for accommodating the electrode assembly and a lid portion 14 for closing the opening of the case body 13. The thickness direction of the battery case 12 is the lateral direction of the lid portion 14.

In each secondary battery 11, terminal connecting members 26 for positive and negative electrodes are arranged on the outer surface 14a of the lid 14 via a plate-shaped insulating member 25. Each terminal connecting member 26 has a plate shape. The terminal connecting member 26 of the positive electrode is electrically connected to the positive electrode of the electrode assembly via an extraction terminal (not shown), and the terminal connecting member 26 of the negative electrode is electrically connected to the negative electrode of the electrode assembly via an extraction terminal (not shown). It is connected to the. The positive electrode terminal 15 is electrically connected to the terminal connecting member 26 of the positive electrode, and the negative electrode terminal 16 is electrically connected to the terminal connecting member 26 of the negative electrode. The direction in which the positive electrode terminal 15 and the negative electrode terminal 16 are lined up along the outer surface 14a of the lid portion 14 is defined as the lateral direction Y of the secondary battery 11 and the battery module 10.

In the secondary battery 11, a part of the electrode assembly generates heat due to an internal short circuit between the positive electrode and the negative electrode, overcharging and discharging, and the exothermic reaction of the electrode assembly is repeated uncontrollably, so-called thermal runaway. May fall into. When the secondary battery 11 is in a state of thermal runaway, the temperature of the secondary battery 11 continues to rise spontaneously. Then, the electrolytic solution is decomposed, gas is generated in the battery case 12, and the internal pressure of the battery case 12 rises.

The lid portion 14 is provided with a pressure release valve 17 for breaking and releasing the internal pressure of the battery case 12 when the internal pressure of the battery case 12 rises to exceed a predetermined pressure. The "specified pressure" is set to a pressure at which the pressure release valve 17 breaks before the battery case 12 is damaged by the internal pressure of the battery case 12 when the internal pressure of the battery case 12 increases. Then, when the internal pressure of the battery case 12 rises and the pressure release valve 17 breaks, gas is ejected from the inside of the battery case 12. The pressure release valve 17 is arranged between the positive electrode terminal 15 and the negative electrode terminal 16 in the lateral direction Y of the secondary battery 11. Then, in the battery module 10, a plurality of pressure release valves 17 are arranged in a row in the parallel direction Z.

The plurality of secondary batteries 11 are arranged so that the positive electrode terminals 15 and the negative electrode terminals 16 are adjacent to each other in the parallel direction Z, with a pair of secondary batteries 11 adjacent to each other in the parallel direction Z as a set. The positive electrode terminals 15 and the negative electrode terminals 16 of the secondary batteries 11 adjacent to each other in the parallel direction Z are connected in parallel by a bus bar 18 made of a metal plate such as aluminum. Further, the set of secondary batteries 11 connected in parallel is connected to a terminal of a pole different from that of the other set of secondary batteries 11 by a bus bar 18, and the plurality of secondary batteries 11 are connected in series.

The plurality of secondary batteries 11 are sandwiched by two end plates 20 from both sides in the parallel direction Z. Each of the end plates 20 has a rectangular plate shape. The through bolts 21 passed through the four corners of one end plate 20 penetrate the four corners of the other end plate 20, respectively. A nut 22 is screwed into each through bolt 21 that penetrates the other end plate 20. By screwing the nut 22 into the through bolt 21, the plurality of secondary batteries 11 are restrained by the pair of end plates 20 from both sides in the parallel direction Z.

As shown in FIG. 2, the battery module 10 includes a measuring device 30. The measuring device 30 measures the information of the secondary battery 11 such as the voltage and temperature between the terminals of each of the secondary batteries 11. The measuring device 30 includes a substrate 31 arranged on the outer surface of the other end plate 20, a monitoring IC 32 mounted on the substrate 31, and a connector 33 provided on the substrate 31. The monitoring IC 32 is an integrated circuit for measuring the voltage and temperature between the terminals of each secondary battery 11 and monitoring whether or not an abnormality has occurred in the voltage and temperature between the terminals of the secondary battery 11. In the present embodiment, the monitoring IC 32 functions as a measuring unit for measuring the voltage between the terminals of the secondary battery 11.

The battery module 10 includes a flexible printed circuit board 34 connected to the monitoring IC 32 via the connector 33. The flexible printed circuit board 34 includes a plurality of voltage measuring lines 35 for inputting the voltage between the terminals of the plurality of secondary batteries 11 into the monitoring IC 32. The flexible printed circuit board 34 has a structure in which a plurality of voltage measuring lines 35 are held by a flexible resin. The flexible printed circuit board 34 has a voltage measurement pattern composed of a plurality of voltage measurement lines 35. The flexible printed circuit board 34 also has a structure in which a temperature measurement line (not shown) for inputting the temperature to the monitoring IC 32 is held in the flexible resin. The voltage measuring line 35 extends linearly in the parallel direction Z. The flexible printed circuit board 34 includes a land 36 connected to each voltage measurement line 35. The connector 33 is arranged on the other end plate 20 and connects the voltage measuring line 35 and the substrate 31.

As shown in FIG. 1, the battery module 10 includes a partition member 40 mounted on the lids 14 of the plurality of secondary batteries 11. The partition member 40 has a shape that rises from between the positive electrode terminals 15 and the negative electrode terminals 16 arranged on both sides of the lid portion 14 in the lateral direction Y. The partition members 40 are arranged at intervals in the lateral direction Y, and have a pair of partition walls 41 that rise from the lid portion 14 and a top plate 42 that connects the protruding ends of the pair of partition walls 41 from the lid portion 14. Has.

The partition member 40 covers all the pressure release valves 17 arranged in the parallel direction Z, and one partition wall 41 is placed on one end side in the lateral direction Y of all the secondary batteries 11 arranged in the parallel direction Z. The other partition wall 41 is mounted on the other end side in the lateral direction Y of all the secondary batteries 11 arranged in the parallel direction Z. Therefore, the partition member 40 is placed on the lid portions 14 over a plurality of lid portions 14 arranged in the parallel arrangement direction Z.

A smoke exhaust passage 45 is formed between the partition member 40 and the outer surface of the lid portion 14 of each secondary battery 11, and the pressure release valve 17 faces the smoke exhaust passage 45. The length of the smoke exhaust passage 45 extends in the parallel direction Z. Both ends of the smoke exhaust passage 45 in the parallel direction Z are open to the outside. Therefore, when the pressure release valve 17 breaks and gas is ejected from the inside of the battery case 12, the ejected gas flows into the smoke exhaust passage 45, flows through the smoke exhaust passage 45, and is discharged to the outside of the battery module 10.

A flexible printed circuit board 34 is placed on the outer surface of the top plate 42 of the partition member 40. The direction in which the partition member 40 and the flexible printed circuit board 34 overlap is the vertical direction. In the battery module 10, the land 36 on the flexible printed circuit board 34 mounted on the partition member 40 and the bus bar 18 to which each secondary battery 11 is connected are located at the same height. The land 36 is electrically connected to the voltage measuring line 35, and can be said to constitute the voltage measuring line 35. The land 36 of the flexible printed circuit board 34 and the bus bar 18 are electrically connected by a connecting plate 50. The battery module 10 has a connection plate 50 erected between the voltage measurement line 35 and the bus bar 18 in order to electrically connect the voltage measurement line 35 and the bus bar 18.

As shown in FIG. 3 or 6, the connecting plate 50 has a rectangular plate-shaped land connecting portion 51 and a bus bar connecting portion 52 wider than the land connecting portion 51. The connecting plate 50 is made of copper, which is an example of a metal different from the bus bar 18. The lateral direction of the land connecting portion 51 is defined as the width direction X2 of the connecting plate 50. The dimension of the bus bar connecting portion 52 in the width direction X2 is longer than the dimension of the land connecting portion 51 in the width direction X2. The bus bar connecting portion 52 has a shape that widens from both ends of the land connecting portion 51 in the width direction X2.

In the connecting plate 50, the land connecting portion 51 is joined to the land 36 by soldering, and the bus bar connecting portion 52 is joined to the bus bar 18 in a state where the first surface 50a as one surface in the thickness direction faces the land 36 and the bus bar 18. It is joined by laser welding. The bus bar 18 is provided with a joint surface 18a on a surface connected to the connection plate 50, and the joint surface 18a is an upper surface in the present embodiment.

The connecting plate 50 includes a second surface 50b on a surface opposite to the first surface 50a in the thickness direction. In the connection plate 50, of the directions along the first surface 50a and the second surface 50b, the direction in which the land connection portion 51 and the bus bar connection portion 52 are continuous is defined as the axial direction X1, and the direction orthogonal to the axial direction X1 is the width direction X2. And.

As shown in FIG. 6, the connecting plate 50 before laser welding to the bus bar 18 includes a welding protrusion 53 at the bus bar connecting portion 52. The welding protrusion 53 includes a protrusion 54 that protrudes from the first surface 50a of the connecting plate 50 in a rectangular tubular shape, and a welding protrusion located at the tip of the protrusion 54 from the first surface 50a in the protruding direction. A unit 56 is provided. When the welding protrusion 53 is viewed from the second surface 50b in a plan view, the protrusion 54 has a rectangular shape. The protrusion 54 is recessed in a rectangular tubular shape from the second surface 50b of the connecting plate 50 toward the first surface 50a, so that the protrusion 54 projects in a rectangular tubular shape from the first surface 50a. The protrusion 54 has a pair of first wall portions 54a facing the width direction X2 of the connecting plate 50 and a pair of second wall portions 54b facing the axial direction X1 of the connecting plate 50.

In the protrusion 54, the tip end side in the protruding direction from the first surface 50a is closed by the bottom portion 55. The bottom portion 55 includes an inner surface 55a facing the inside of the protrusion 54 and an outer surface 55b on the opposite side of the inner surface 55a in the thickness direction of the bottom portion 55. The bus bar connecting portion 52 includes a bent portion 57 at a portion where the protruding portion 54 and the bottom portion 55 intersect.

The bottom portion 55 has a shape in which the outer surface 55b is gradually sharpened toward the center of the bottom portion 55 in the width direction X2 and the inner surface 55a is gradually recessed. A welding ridge 56 is provided at a portion where the outer surface 55b of the bottom 55 is sharp. The welding ridge 56 is provided over the entire bottom 55 along the axial direction X1. In a cross-sectional view of the bottom portion 55 in the thickness direction and the width direction X2, the inner surface 55a and the outer surface 55b of the bottom portion 55 are inclined downward while being gently curved from the pair of first wall portions 54a toward the welding ridges 56. It is a shape to be welded. Then, the protrusion 54 projects from the first surface 50a toward the bus bar 18 in a state where the first surface 50a of the connection plate 50 faces the land 36 forming the voltage measurement line 35 and the bus bar 18. In the bus bar connecting portion 52, the tip of the welding ridge portion 56 protrudes from the tips of the first wall portion 54a and the second wall portion 54b in the protrusion 54, and protrudes from the bent portion 57. That is, the welding ridge 56 is located at the tip of the connecting plate 50 in the protruding direction of the ridge 54 from the first surface 50a.

In the battery module 10, the connecting plate 50 is soldered to the land 36 at both ends of the land connecting portion 51 along the axial direction X1 on the opposite side of the bus bar connecting portion 52.

As shown in FIG. 5, in the bus bar connecting portion 52 of the connecting plate 50, the welding ridge portion 56 and the bus bar 18 are connected by laser welding. The battery module 10 includes a welded portion 60 for joining the bus bar connecting portion 52 and the bus bar 18. The welded portion 60 is an intermetallic compound formed by mixing aluminum, which is the material of the bus bar 18, and dissimilar metals of copper, which is the material of the connecting plate 50. In the cross section near the welded portion 60 along the width direction X2, the welded portion 60 has a V shape along the welding ridge portion 56 before welding. The welded portion 60 has a thin layer shape extending from the tip of the welding ridge portion 56 toward each first wall portion 54a.

In the welded portion 60, the portion forming the welding ridge portion 56 before welding is welded in a state of being pushed into the thickness from the joint surface 18a of the bus bar 18. The entire outer surface 55b of the bottom portion 55 of the bus bar connecting portion 52 is in contact with the joint surface 18a of the bus bar 18, while the welded portion 60 is formed on a part of the joint surface 18a and the outer surface 55b. In the bus bar connecting portion 52, the entire outer surface 55b of the bottom portion 55 from the bent portion 57 of the welding protrusion 53 to the welding ridge portion 56 is in contact with the bus bar 18.

The connection plate 50 includes a pressed portion 59 in a portion of the bus bar connecting portion 52 outside the protrusion 54 along the first surface 50a and the second surface 50b. The pressed portion 59 is a portion outside the welding protrusion 53 in the width direction X2, and is provided at a portion sandwiching the welding protrusion 53 in the width direction X2. The pressed portion 59 presses the connecting plate 50 with the welding ridge portion 56 facing the bus bar 18.

In the battery module 10, the first surface 50a located at the pressed portion 59 and the joint surface 18a of the bus bar 18 face each other. The first surface 50a of the pressed portion 59 and the joint surface 18a of the bus bar 18 are facing surfaces facing each other in the thickness direction of the connecting plate 50. Then, the distance between the first surface 50a of the pressed portion 59 and the joint surface 18a of the bus bar 18 is defined as the distance H between the facing surfaces. The distance H between the facing surfaces after welding the bus bar 18 and the bus bar connecting portion 52 is shorter than the distance H between the facing surfaces before welding.

Next, a method of manufacturing the battery module 10 will be described.
In a state where a plurality of secondary batteries 11 are restrained in the parallel direction Z by a pair of end plates 20, through bolts 21 and nuts 22, the partition member 40 is placed so as to cover the lids 14 of all the secondary batteries 11. Place. Next, the positive electrode terminals 15 and the negative electrode terminals 16 are connected by the bus bar 18.

Next, the flexible printed circuit board 34 is placed on the top plate 42 of the partition member 40. Then, as shown in FIG. 7, the connection plate 50 is placed on each land 36 and the bus bar 18 of the flexible printed circuit board 34. At this time, the end portion of the land connecting portion 51 is placed on the land 36, and the welding ridge portion 56 of the welding protruding portion 53 of the bus bar connecting portion 52 is placed on the joint surface 18a of the bus bar 18. Then, the welding ridge 56 comes into line contact with the joint surface 18a of the bus bar 18.

Next, as shown in FIG. 8, the pressed portion 59 provided at a position sandwiching the welding protrusion 53 in the width direction X2 is pressed toward the bus bar 18 by the pressing jig 61. At this time, the first surface 50a located on the pressed portion 59 is pressed until it comes into contact with the joint surface 18a of the bus bar 18. Then, the entire welding ridge 56 of the welding protrusion 53 is pressed against the joint surface 18a. The portion of the bottom portion 55 that is outside the welding ridge portion 56 and inside the pair of first wall portions 54a in the width direction X2 warps away from the joint surface 18a. Therefore, of the bottom portion 55, the outer portion of the welding ridge portion 56 in the width direction X2 is slightly separated from the joint surface 18a of the bus bar 18, and the welding ridge portion 56 is separated from the joint surface 18a with this separation. Is further pressed against.

Then, in a state where the entire welding ridge 56 is in contact with the joint surface 18a of the bus bar 18, the welding ridge 56 is melted from the inner surface 55a side of the bottom 55 so that all of the welding ridge 56 is melted. The laser is irradiated toward 56. Then, while the welding ridge 56 melts, the periphery of the welding ridge 56 in the bus bar 18 also melts, forming a molten pool in which dissimilar metals of aluminum and copper are mixed. Then, the distance H between the facing surfaces becomes shorter than before welding, the welding area between the bus bar 18 and the bottom portion 55 increases, and a part of the molten pool is directed toward the root side of the welding ridge portion 56. It is pushed out of the molten pool by the welding ridge 56, and the molten pool expands.
As a result, the thickness of the welded portion 60 formed by solidifying the molten pool can be reduced as compared with the case where the connecting plate 50 is not pressed against the molten pool. Further, the distance H between the facing surfaces is shorter after welding than before welding. As a result, the land 36 of the flexible printed circuit board 34 and the bus bar 18 are electrically connected by the connecting plate 50, and the battery module 10 is completed.

According to the manufacturing method of the battery module 10, the following effects can be obtained.
(1) By pressing the welding ridge 56 against the bus bar 18, a part of the molten pool is pushed out toward the root side of the welding ridge 56, so that the welding ridge facing the molten pool The thickness of the welded portion 60 formed by solidifying the molten pool can be reduced as compared with the case where the 56 is not pressed. As a result, the thickness of the welded portion 60 formed by solidifying dissimilar metals can be reduced to increase the strength of the welded portion 60.

(2) The distance H between the facing surfaces after forming the welded portion 60 is made shorter than the distance H between the facing surfaces before welding. Therefore, when the bus bar 18 and the welding protrusion 53 are laser-welded, the portion forming the welding ridge 56 can be made to bite into the thickness of the bus bar 18. As a result, the welding area between the bus bar 18 and the bottom portion 55 can be widened, the thickness of the welded portion 60 can be reduced, and the area of the welded portion 60 can be widened to increase the strength of the welded portion 60.

(3) The welding ridge 56 is welded to the bus bar 18 with the entire welding ridge 56 extending in the axial direction X1 in contact with the bus bar 18. Therefore, the welded portion 60 can be formed over the entire welding ridge portion 56, and the welded area can be expanded in the axial direction X1 to increase the strength of the welded portion 60.

(4) The pressed portion 59 is pressed by the pressing jig 61 until the first surface 50a located on the pressed portion 59 abuts on the joint surface 18a of the bus bar 18. The welding ridge 56 is located at the tip of the bus bar connecting 52 in the protruding direction of the ridge 54 from the first surface 50a. Therefore, by pressing the pressed portion 59 until the first surface 50a of the pressed portion 59 comes into contact with the joint surface 18a of the bus bar 18, the portion of the connecting plate 50 forming the welding ridge portion 56 is formed. It can be pushed into the thickness of the bus bar 18 until it bites into it.

(5) The pressed portion 59 is located outside the protrusion 54 in the width direction X2 along the first surface 50a and the second surface 50b. The pressing jig 61 presses the pressed portion 59 located outside the protruding portion 54 in the width direction X2. Therefore, the pressing jig 61 does not cover the welding ridge portion 56, the pressing jig 61 does not interfere with laser welding, and the welding work can be easily performed.

(6) The pressed portion 59 is located on both sides of the protruding portion 54 in the width direction X2. Therefore, when the pressed portion 59 is pressed by the pressing jig 61, the protruding portion 54 can be pressed against the bus bar 18 from both sides in the width direction X2, and the bottom portion 55 is pressed against the bus bar 18 over the entire width direction X2. Can be done. As a result, the bottom portion 55 is not tilted in the width direction X2 and pressed against the bus bar 18.

(7) In the connecting plate 50, the dimension of the bus bar connecting portion 52 in the width direction X2 is longer than the dimension of the land connecting portion 51 in the width direction X2. Therefore, while forming the protrusion 54 and the welding protrusion 56 on the bus bar connecting portion 52, the pressed portion 59 can be secured outside the protrusion 54. Therefore, a pressed portion 59 for pressing the welding ridge portion 56 against the bus bar 18 can be secured.

This embodiment can be modified and implemented as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
○ As shown in FIG. 9, the bottom portion 55 of the connecting plate 50 may have a flat plate shape. With this configuration, in order to manufacture the battery module 10, the end of the land connection 51 is connected to the land 36.
The bottom portion 55 of the welding protrusion 53 of the bus bar connecting portion 52 is placed on the joint surface 18a of the bus bar 18. At this time, the outer surface 55b of the bottom portion 55 comes into contact with the joint surface 18a of the bus bar 18.

Next, as shown in FIG. 10, the pressed portion 59 provided at a position sandwiching the welding protrusion 53 in the width direction X2 is pressed toward the bus bar 18 by the pressing jig 61. At this time, the first surface 50a located on the pressed portion 59 is pressed until it comes into contact with the joint surface 18a of the bus bar 18. Then, the entire outer surface 55b of the bottom portion 55 is pressed against the joint surface 18a. Then, with the entire outer surface 55b of the bottom 55 in contact with the joint surface 18a of the bus bar 18, the bottom 55 is irradiated with a laser from the inner surface 55a side of the bottom 55. Then, while the bottom portion 55 is melted, the bus bar 18 is also melted, and a molten pool in which dissimilar metals of aluminum and copper are mixed is formed. Then, when the molten pool is solidified and the welded portion 60 is formed, the land 36 of the flexible printed circuit board 34 and the bus bar 18 are electrically connected by the connecting plate 50, and the battery module 10 is completed.

In this configuration, the pressed portion 59 is pressed by the pressing jig 61 so that the entire outer surface 55b of the bottom portion 55 comes into contact with the joint surface 18a of the bus bar 18. Therefore, it is possible to suppress the formation of a gap between the outer surface 55b of the bottom portion 55 and the joint surface 18a of the bus bar 18, and to prevent the welding defect from occurring in the welded portion 60.

The welding ridge 56 may be formed so as to extend in the width direction X2 of the connecting plate 50. That is, the welding ridge 56 may be formed so as to be orthogonal to the welding ridge 56 of the embodiment. In this case, the pressed portion 59 is a portion of the bus bar connecting portion 52 outside the welding protrusion 53 along the axial direction X1.

○ A plurality of welding ridges 56 may be provided on the bottom 55.
The protrusion 54 of the protrusion 53 for welding may have a cylindrical shape, an elliptical cylinder shape, or a polygonal cylinder shape other than a rectangular cylinder, and the bottom portion 55 may have a shape that matches the cylinder shape of the protrusion 54. Even in these cases, the welding ridge 56 extends linearly.

○ If the entire welding ridge 56 can be pressed against the joint surface 18a of the bus bar 18, when the pressed portion 59 is pressed by the pressing jig 61, the first surface 50a located on the pressed portion 59 becomes the bus bar 18 It is not necessary to contact the joint surface 18a of the above.

○ The protrusion 54 does not have to have the second wall portion 54b. That is, the second surface 50b of the connecting plate 50 and the bottom portion 55 may not be continuously connected, and a gap may be formed instead of the protruding portion 54.

○ The bent portion 57 may not be formed on the bus bar connecting portion 52. In this case, the bottom portion 55 is not formed on the bus bar connecting portion 52, the pair of first wall portions 54a are inclined downward toward the welding ridge portion 56, and the welding protrusion 53 (projection portion 54) is at the tip. It has a V shape with a welding protrusion 56.

Next, the technical idea that can be grasped from the above embodiment and another example will be added below.
(1) The connection plate has a land connection portion connected to a land connected to the voltage measurement line and a bus bar connection portion connected to the bus bar, and the bus bar connection portion is connected to the land connection portion. Is also wide.

(2) The welding ridge portion is formed so as to have a sharpened bottom portion that closes the tip end side of the ridge portion.

H ... Distance between facing surfaces, Z ... Side-by-side direction, 10 ... Battery module, 11 ... Secondary battery, 15 ... Positive terminal, 16 ... Negative terminal, 18 ... Bus bar, 32 ... Monitoring IC as measuring unit, 35 ... Voltage Measurement line, 50 ... connection plate, 50a ... first surface as one surface in the thickness direction, 54 ... protrusion, 56 ... welding protrusion, 59 ... pressed portion, 61 ... pressing jig.

Claims (3)

A plurality of secondary batteries having a positive electrode terminal and a negative electrode terminal and arranged side by side in the parallel direction,
A metal bus bar that electrically connects the positive electrode terminals or the negative electrode terminals of the secondary batteries adjacent to each other in the parallel direction.
A measuring unit that measures the voltage between the terminals of the plurality of secondary batteries,
A plurality of voltage measurement lines for inputting the voltage between the terminals of the plurality of secondary batteries to the measurement unit, and
A method for manufacturing a battery module having a metal connection plate erected between the voltage measurement line and the bus bar and different from the bus bar in order to electrically connect the voltage measurement line and the bus bar. ,
The connection plate includes a protrusion that projects from the one surface toward the bus bar with one surface of the connection plate in the thickness direction facing the voltage measurement line and the bus bar.
A welding ridge located at the tip of the protrusion from one surface in the protruding direction,
A pressed portion for pressing the connecting plate so that the welding ridge portion faces the bus bar is provided.
In a state where the pressed portion is pressed by a pressing jig and the welding ridge portion is pressed against the bus bar, a laser is directed toward the welding ridge portion so that all of the welding ridge portions are melted. Weld the bus bar and the connecting plate by irradiating
Assuming that the distance between the facing surfaces of the pressed portion and the bus bar facing each other in the thickness direction is the distance between the facing surfaces, the distance between the facing surfaces after welding the bus bar and the connecting plate is the distance before welding. A method of manufacturing a battery module that is shorter than the distance between facing surfaces. The method for manufacturing a battery module according to claim 1, wherein the pressed portion is pressed by the pressing jig until the pressed portion abuts on the bus bar. The first or second aspect of the present invention, wherein the pressed portion is located outside the protrusion along the one surface of the connection plate, and the pressing jig presses the outside of the protrusion along the one surface. Battery module manufacturing method.