JP3695811B2 - Pack battery - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a battery pack in which unit cells are housed in a parallel arrangement. Specifically, the upper and lower surfaces of a conductive polymer material having a PTC characteristic, that is, a characteristic that resistance increases as temperature rises, are sandwiched between a pair of metal plates. It is related with the improvement of the pack battery which electrically connected between unit cells in series via the overcurrent overheat protection element comprised by these.
[0002]
[Prior art]
As this type of conventional battery pack, for example, there is one disclosed in JP-A-3-127446. This battery pack further includes a lead plate spot-welded to the metal plate using an overcurrent overheat protection element in which the upper and lower surfaces of a conductive polymer material having PTC characteristics are sandwiched between a pair of metal plates. Spot welding is performed on the electrode terminals of the unit cells, and the unit cells are electrically connected in series. The spot welding between the metal plate and the lead plate is costly because it requires advanced technology because the thickness of the metal plate is as thin as about 65 μm. Therefore, this battery pack has a problem that the cost associated with the overcurrent overheat protection element is high. Further, since the spot welding strength between the metal plate and the lead plate is weak, there is a possibility that the welding may come off when vibration is applied to the battery pack or the battery pack is dropped. For this reason, a tape is wound around the welded portion to reinforce, but in this case, the cost is further increased.
[0003]
On the other hand, Japanese Utility Model Laid-Open No. 4-46359 proposes that an overcurrent overheat protection element, to which a lead plate is not welded, is incorporated in a unit cell in a state of being electrically connected by pressure welding. With this configuration, since there is no need to weld a lead plate to the overcurrent overheat protection element, the cost associated with one overcurrent overheat protection element is low, but a plurality of unit cells are electrically connected in series. When configuring a battery pack, each unit cell incorporates an overcurrent overheat protection element, so a plurality of overcurrent overheat protection elements are used in one pack battery, resulting in unnecessary component costs. There is a problem that it occurs. There is also a method of making a battery pack using two types of cells: a unit cell with a built-in overcurrent overheat protection element and a unit cell without a built-in overcurrent overheat protection element. Since there is a possibility that a unit battery can be produced, it is difficult to adopt this method, and if this method is adopted, the production management is very expensive.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and a battery pack in which the cells are electrically connected in series via the overcurrent overheat protection element while minimizing the cost associated with the overcurrent overheat protection element. Is a low-cost product.
[0005]
[Means for Solving the Problems]
[Invention of Claim 1]
A battery case comprising an insulating resin, comprising an upper lid, a cylindrical case, and a lower lid ;
Said plurality of elementary metal plate of the top surface with formed and a plurality of unit cells arranged in parallel to the cylindrical inner case, the upper and lower surfaces of the conductive polymer material having PTC characteristics is sandwiched by the pair of metal plates An overcurrent overheat protection element in contact with one unit cell of the battery ;
And a conductive connecting plate with a lower surface of the metal plate and an elastic contact with the elasticity of the protective device, there by battery pack connected in series with said plurality of cells via the over-current thermal protection element and the connecting plate hand,
The protective element is supported by a rib provided at the lower part of the cylindrical case, and a unit cell that is in contact with the metal plate on the upper surface of the protective element is sandwiched between the protective element and the inner surface of the upper lid . It is characterized by.
[0006]
The protection element is preferably supported by being fixed to a rib provided at a lower portion of the cylindrical case .
[0007]
Furthermore, it is desirable that a protrusion for pressing the connection plate in the direction of the protection element is formed on the inner surface of the lower lid .
[0008]
[Invention of claim 4]
A battery case comprising an upper lid, a cylindrical case, and a lower lid, made of an insulating resin, a plurality of unit cells arranged in parallel in the cylindrical case, and a conductive polymer material having PTC characteristics An overcurrent overheat protection element configured by sandwiching the lower surface between a pair of metal plates, elastic contact with the metal plate on the lower surface of the protection element, and one metal plate on the upper surface of the protection element among the plurality of unit cells A conductive connection plate having elasticity to be brought into elastic contact with the unit cell , the plurality of unit cells are connected in series via the overcurrent overheat protection element and the connection plate ,
A battery pack in which a protrusion for pressing the connection plate in the direction of the protection element is formed on the inner surface of the lower lid ,
The unit cell that is in contact with the metal plate on the upper surface of the protection element is sandwiched between the convex portion provided on the cylindrical case and the inner surface of the upper lid in the direction of contact with the metal plate on the upper surface. .
[0010]
[Action]
In the invention of claim 1, since the unit cell is sandwiched between the overcurrent overheat protection element supported by the rib provided at the lower part of the cylindrical case and the inner surface of the upper lid , the overcurrent overheat protection element and the unit cell The electrical connection between can be made by contact without spot welding. In addition, regarding the electrical connection between the other unit cell arranged in parallel with the unit cell and the protection element, an elastic conductive connection plate electrically connected to the other unit cell is brought into elastic contact with the protection element. Therefore, it is not necessary to spot weld the lead plate to the protective element. As described above, in the battery pack according to the present invention, since a high level of technology is required, the spot welding process between the protection element and the lead plate, which has been expensive, can be reduced, and at the same time, the number of spot welding points is reduced. The battery pack assembly workability is also improved. Furthermore, even when compared with a battery pack configured using a plurality of conventional unit cells having a built-in protective element, the battery pack of the present invention can use only one protective element, so that the number of protective elements used can be reduced. Since it is not necessary to incorporate a protective element in the unit cell, the unit cell itself can be easily assembled. Incidentally, the connection plate of the present invention has a more complicated structure than a simple lead plate, but it can be manufactured by pressing from a hoop-shaped metal plate. Compared to the cost reduced by the present invention, it is negligible.
[0011]
On the other hand, in the invention of claim 4, the unit cell is sandwiched between the convex part of the cylindrical case and the inner surface of the upper lid , and the overcurrent overheat protection element contacts the unit cell and the connection plate by the elastic force of the connection plate, respectively. Therefore, the electrical connection between the overcurrent overheat protection element and the unit cell and between the overcurrent overheat protection element and the connection plate can be made by contact without spot welding.
[0012]
According to a first aspect of the present invention, the protection element is supported by a rib provided at a lower portion of the cylindrical case. In the fourth aspect of the invention, the unit cell in contact with the protection element is projected from the cylindrical case. for parts and a configuration which is sandwiched between the inner surface of the upper lid, or shock is applied to the battery pack, even when such as dropping the battery pack, since the self-weight of the cell is supported by the ribs or protrusions This prevents the connection plate from being applied to the connection plate via the protective element, thereby preventing the elastic force of the connection plate from declining and improving the electrical connection by elastic contact between the connection plate and the protection element over a long period of time. It is possible to maintain.
[0013]
Furthermore, if a protrusion for pressing the connection plate in the direction of the protection element is provided on the inner surface of the lower lid, the electrical connection by elastic contact between the protection element and the connection plate can be further ensured.
[0014]
Further, in the invention of claim 1, when supported by the ribs by fixed by ultrasonic welding to the ribs forming the protective element in the cylindrical case, in the assembly process of the battery pack, in the cylindrical case when transported to the next step by inserting only protection element, tilting in the protection element the cylindrical case, it is not possible to stick out to the outside of the cylindrical case, with the assembly of the battery pack is improved, the assembly It is possible to prevent the protective element from moving in the cylindrical case later.
[0015]
【Example】
[Invention of Claim 1]
An embodiment of the battery pack according to the first aspect of the present invention will be described below with reference to FIGS.
[0016]
In these drawings, 1 is an upper lid, 2 is a cylindrical case, and 3 is a lower lid, both of which are formed of an insulating thermoplastic resin, and the upper and lower openings of the cylindrical case 2 are covered with the upper lid. The battery case is configured by being closed by 1 and the lower lid 3 respectively. A partition wall 11 is formed in the cylindrical case 2 so that the unit cells 4 and 5 made of cylindrical lithium batteries can be stored in parallel with each other in a state of being insulated from each other. The inside of the case 2 is divided into a left storage portion 12 and a right storage portion 13. 6 is an overcurrent overheat protection element constructed by sandwiching the upper and lower surfaces of a conductive polymer material having PTC characteristics between a pair of nickel plates, 7 is a connecting plate made of a stainless steel plate having elasticity and conductivity, and 8 is made of polypropylene. The insulating rings 9 and 10 are terminal fittings made of nickel plates that are electrically connected to the positive and negative terminals of the unit cells 4 and 5, respectively.
[0017]
The battery pack shown in FIGS. 1 to 4 is assembled as follows.
[0018]
First, the overcurrent / overheat protection element 6 is inserted into the right housing part 13 of the cylindrical case 2 from the upper opening and placed on the rib 19 formed at the lower part of the cylindrical case. Then, the unit cell 4 is inserted into the right storage unit 13 from the upper opening with the positive electrode terminal facing downward, and similarly, the unit cell 5 is inserted into the left storage unit 12 from the upper opening with the positive electrode terminal facing upward. . Next, terminal fittings 9 and 10 are spot welded to the negative electrode terminal of the unit cell 4 exposed at the upper opening of the cylindrical case 2 and the positive electrode terminal of the unit cell 5, respectively, and then the upper cover is opened to the upper opening of the cylindrical case 2. 1 is ultrasonically welded. At this time, the unit cell 4 is sandwiched and fixed between the protective element 6 supported by the rib 19 of the cylindrical case 2 and the inner surface of the upper lid 1, and the positive terminal of the unit cell 4 is the upper surface of the protective element 6. It will be in the state which contacted one nickel plate located in this. Further, the unit cell 5 is sandwiched and fixed between the rib 20 and the inner surface of the upper lid 1. On the other hand, the terminal fittings 9 and 10 are exposed to the outside of the battery case from the notches 14 and 14 of the upper lid 1 and the recesses 15 and 15 of the cylindrical case 2, and serve as external output terminals of the battery pack. Note that a positive electrode terminal is disposed at the center and an outer can that also serves as a negative electrode terminal is disposed at the end surface of the unit cell 5 where the positive electrode terminal is located, and the positive and negative terminals are short-circuited by the terminal fitting 10. In order to prevent this, an insulating ring 8 is attached to the positive electrode terminal side of the unit cell 5.
[0019]
Next, the through holes 16 and 16 provided in the connection plate 7 are fitted into the bosses 17 and 17 provided in the lower end portion of the partition wall 11 of the cylindrical battery case 2, and the bosses 17 and 17 are ultrasonically melted and connected. The plate 7 is fixed to the lower end of the partition wall 11. By fixing the connection plate 7, the elastic portion at one end of the connection plate 7 is brought into elastic contact with the other nickel plate located on the lower surface of the protection element 6, and electrical connection is performed. Since the unit cell 4 is sandwiched between the protective element 6 supported by the rib 19 of the cylindrical case 2 and the upper lid 1 as described above, the unit cell 4 may move below the rib 19. In addition, it is possible to prevent the elastic force of the connection plate 7 from declining due to the weight of the unit cell 4 being applied to the connection plate 7.
[0020]
On the other hand, the other end of the connection plate 7 is electrically connected by spot welding to the negative electrode terminal of the unit cell 5, whereby the unit cells 4 and 5 are connected in series via the protective element 6 and the connection plate 7. Finally, the lower lid 3 is fixed by ultrasonic welding to the lower opening of the cylindrical case 2, and the connection plate 7 is pressed in the direction of the protective element by the projection 18 formed on the inner surface of the lower lid 3. The battery pack is configured with further reliable electrical connection between the plate 7 and the nickel plate on the lower surface of the protective element 6.
[0021]
Next, another embodiment is shown and described in FIG. In FIG. 5, the same components as those in the embodiment shown in FIGS.
[0022]
In FIG. 5, the overcurrent overheat protection element 6 is fixed to the rib 19 by ultrasonic melting around the rib 19 of the cylindrical case 2, and the other portions are the embodiments shown in FIGS. Is the same. In this other embodiment, since the protection element 6 is fixed and supported by the rib 19, the protection element 6 tilts in the cylindrical case 2 or jumps out of the cylindrical case 2 in the assembly process of the battery pack. Without considering this, the cylindrical case 2 to which the protective element 6 is fixed can be transported to the next process.
[0023]
In the above embodiment, the connection plate 7 is fixed to the lower end of the partition wall 11 of the battery case and is electrically connected only by contact with the protective element 6. However, the connection plate 7 is fixed to the inner surface of the lower lid 3 to protect the protective element 6. 6 and the negative electrode terminal of the unit cell 5 can be electrically connected by contact.
[0024]
[Invention of claim 4]
An embodiment of the battery pack of the invention of claim 4 is shown in FIG. In FIG. 6, the same components as those in the embodiment shown in FIGS.
[0025]
The difference between the battery pack shown in FIG. 6 and the battery pack shown in FIGS. 1 to 4 described above is as follows.
[0026]
That is, in the battery pack of FIG. 6, a convex portion 21 is formed above the rib 19, and the unit cell 4 is sandwiched between the convex portion 21 provided on the cylindrical case 2 and the inner surface of the upper lid 1. Fixed.
[0027]
Further, the convex portion 21 is thicker than the protective element 6, and when the protective element 6 is in a position in contact with the upper surface of the rib 19, a slight gap is formed between the protective element 6 and the unit cell 4. It is. The electrical connection between the protection element 6 and the unit cell 4 is made by pushing up the protection element 6 upward by the elastic force of one end of the connection plate 7, and This is done by bringing the positive electrode terminal into contact.
[0028]
【The invention's effect】
In the battery pack of the present invention, the electrical connection between the overcurrent overheat protection element and the unit cell is made by contact, and the electrical connection between the protection element and the connection plate is also made by elastic contact, which has been conventionally performed. The spot welding process between the protective element and the lead plate can be reduced, and at the same time, the number of spot welds is reduced, so that the assembly workability of the battery pack is improved.
[0029]
In addition, even when vibration is applied to the battery pack or the battery pack is dropped, the unit cell's own weight is not applied to the connection plate via the protective element, and this reduces the elastic force of the connection plate. This can be prevented, and electrical connection by elastic contact between the connection plate and the protection element can be satisfactorily maintained over a long period of time.
[0030]
Accordingly, it is possible to provide a low-cost product of a battery pack in which the unit cells are electrically connected in series via the overcurrent overheat protection element.
[Brief description of the drawings]
1 is an exploded perspective view showing an overall configuration of a battery pack according to the present invention. FIG. 2 is a plan view after assembly of FIG. 1. FIG. 3 is a sectional view taken along line XX according to the invention of claim 1 of FIG. 4 is a bottom view of the battery pack of FIG. 2 with the bottom cover removed. FIG. 5 is a cross-sectional view taken along line XX of FIG. 2 according to claim 2. FIG. -X cross section [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ...... Upper cover 2 ... Cylindrical case 3 ... Lower cover 4, 5 ... Unit cell 6 ... Overcurrent overheat protection element 7 ... Connection plate 18 ... Projection 19 ... Rib 21 ... Projection

Claims (4)

A battery case comprising an insulating resin, comprising an upper lid, a cylindrical case, and a lower lid ;
Said plurality of elementary metal plate of the top surface with formed and a plurality of unit cells arranged in parallel to the cylindrical inner case, the upper and lower surfaces of the conductive polymer material having PTC characteristics is sandwiched by the pair of metal plates An overcurrent overheat protection element in contact with one unit cell of the battery ;
And a conductive connecting plate with a lower surface of the metal plate and an elastic contact with the elasticity of the protective device, there by battery pack connected in series with said plurality of cells via the over-current thermal protection element and the connecting plate hand,
The protective element is supported by a rib provided at the lower part of the cylindrical case, and a unit cell that is in contact with the metal plate on the upper surface of the protective element is sandwiched between the protective element and the inner surface of the upper lid . Pack battery characterized by. The battery pack according to claim 1, wherein the protection element is supported by being fixed to a rib provided at a lower portion of the cylindrical case . The battery pack according to claim 1, wherein a protrusion that presses the connection plate in the direction of the protection element is formed on an inner surface of the lower lid . A battery case comprising an upper lid, a cylindrical case, and a lower lid, made of an insulating resin, a plurality of unit cells arranged in parallel in the cylindrical case, and a conductive polymer material having PTC characteristics An overcurrent overheat protection element configured by sandwiching the lower surface between a pair of metal plates, elastic contact with the metal plate on the lower surface of the protection element, and one metal plate on the upper surface of the protection element among the plurality of unit cells A conductive connection plate having elasticity to be brought into elastic contact with the unit cell , the plurality of unit cells are connected in series via the overcurrent overheat protection element and the connection plate ,
A battery pack in which a protrusion for pressing the connection plate in the direction of the protection element is formed on the inner surface of the lower lid ,
The unit cell that is in contact with the metal plate on the upper surface of the protection element is sandwiched between the convex portion provided on the cylindrical case and the inner surface of the upper lid in the direction of contact with the metal plate on the upper surface. Pack battery.

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