JP2005317281A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack useful for miniaturization by the installation method of a circuit board on which a connector for being connected to outside appliances is mounted. <P>SOLUTION: The battery pack 1 is formed by mounting the end part of a connector 4 whose outside connecting part is exposed to the outside of a case on the end part of a circuit board 7 housed in the case together with a unit cell 3, a recessed part 6 is formed on the inner surface of the case facing the end part of the circuit board 7 in the vicinity of the connector 4, and the end of the circuit board 7 is fit to the recessed part 6. The recessed part 6 is formed by passing through the case, and the outer surface of the case containing the recessed part 6 is covered with a covering material 5. The connector 4 is mounted on the circuit board 7 with a connector pin 4a, the circuit board 7 has a shape formed by swelling out part of the end part of the circuit board to the outside along the the connector mounting surface, and the swelled out part is inserted into the recessed part 6 of the case as the circuit board end part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery pack in which a circuit board is housed in a case together with a unit cell, and a connector for connecting to an external device is mounted on the circuit board.

  This type of battery pack is widely used as a power source for portable external devices and PCs. Electronic components forming a control circuit for controlling charging / discharging of the battery are mounted on the circuit board, and are built in the case of the battery pack together with the secondary battery. In recent years, in response to the reduction in thickness and size of external devices, the battery pack has also been desired to be reduced in thickness and size, and the circuit board that effectively uses the constrained space in the battery pack is provided. Various methods have been studied (for example, Patent Document 1).

  By the way, the pack battery is configured to be detachable from the main body of the external device, and the outer shape is determined appropriately corresponding to the form of the external device. Therefore, the connector for connecting the pack battery to the external device is also a pack battery. Installed in various locations. Among them, there is a method of mounting the connector on the circuit board by inserting a mounting pin provided at the connector end portion through the insertion hole of the circuit board and soldering. This method is often used because the connector can be arranged in a limited space in the battery pack with a simple and sufficient bonding strength. This method will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a connector mounting portion on the circuit board and a proximity portion between the case and the circuit board.

Depending on the specifications of the external device, the connector 4 is disposed at a position close to the upper lid case 20a, and the end of the circuit board 7 is adjacent to the inner surface of the upper lid case 20a. The mounting pins 4a of the connector 4 are inserted into the insertion holes 4b provided on the end side of the circuit board 7 and then soldered, whereby the connector 4 is mounted and fixed on the circuit board 7. As shown in FIG. 4, in order to secure the soldering area and firmly fix the connector 4 to the circuit board 7, the distance from the end of the circuit board to the connector 4 is separated, so the connector 4 and the upper lid case Since a gap is generated to some extent between 20a, a minute space 30 exists. On the Y direction negative direction side in the minute space 30, the partial area 200 a of the upper lid case 20 a is processed to be thick, thereby preventing dust, moisture, and the like from entering the minute space 30.
JP 2001-266817 A

Here, the micro space 30 is a so-called dead space, and by removing this, it is possible to increase the space efficiency, further reduce the thickness and size of the battery pack, or increase the mounting area on the circuit board. is there. Therefore, the present inventors have studied to omit the minute space 30.
In FIG. 4, the position where the insertion hole 4b is provided in the circuit board 7 is brought closer to the end side (Z direction positive direction side), that is, the distance b from the insertion hole 4b to the end of the circuit board is shortened. The partial region 200a is not thickly processed, and the distance a between the connector 4 and the upper lid case 20a is set to zero. With such a configuration, the minute space 30 can be omitted.

However, the solder space for mounting the mounting pins 4a on the circuit board 7 is reduced, and it becomes difficult to ensure sufficient bonding strength.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a battery pack with improved space efficiency while maintaining sufficient bonding strength when a connector is bonded to a circuit board.

Therefore, the present invention adopts the following configuration in order to solve the above problems.
A battery pack in which a circuit board is housed in a case together with a unit cell, a connector is mounted near an end of the circuit board, and an external connection part of the connector is exposed to the outside of the case, in the vicinity of the connector A recess is formed in the thickness direction on the inner surface of the case facing the end of the circuit board, and the end of the circuit board is inserted into the recess.

Further, the following configuration is desirable.
The recess is formed by penetrating the case, and the outer surface of the case including the recess is covered with a covering material. The connector is mounted on the circuit board with mounting pins. The circuit board has a shape in which a part of the end portion of the circuit board bulges outward along the connector mounting surface, and the bulged portion serves as an end portion of the circuit board in the recessed portion of the case. Has been inserted.

  As described above, a recess is provided on the inner surface of the case facing the storage area of the circuit board stored inside the case, and the end of the circuit board on which the connector is mounted is inserted into the recess. By doing so, the end of the circuit board can be moved to the outer surface side from the inner surface of the case. The connector can be brought closer to the inner surface of the case by the moving distance, and the minute space between the case and the connector in the battery pack can be reduced. Since the volume of the storage space inside the case can be reduced by the reduced amount, the battery pack can be reduced in size. Alternatively, even if the external shape of the battery pack cannot be changed due to the specifications of the external device, the circuit board can be expanded by the reduction, leading to an increase in the mounting area of electronic components on the circuit board. You can also.

  Furthermore, even if the position of the connector is moved in the same direction, the distance from the insertion hole to the end of the circuit board is secured, so the connector can be mounted by soldering the connector mounting pins to the board using this area. It can be easily fixed firmly to the circuit board. When the minute space can be omitted as in the present invention, there is no need to process the case end to be thick, and the manufacturing process is prevented from becoming complicated.

  In the case where the recessed portion is penetrating, the covering material is attached to the surface of the battery pack so as to cover the penetrating portion after the circuit board is inserted into the recessed portion. This makes it easy to specify the product name and logo on the battery pack.

Hereinafter, the best mode for carrying out a battery pack according to the present invention will be described with reference to the drawings.
(Overall configuration of battery pack)
First, the battery pack will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the battery pack 1, and FIG. 2 is a perspective view of the circuit board 7.

  The battery pack 1 used in the present embodiment is mainly a PC device as a target mounting device, and a circuit board 7 and a comb on a thin flat plate are connected to two unit cells 3 connected in series and two in parallel. A connector 4 having a tooth shape is connected, and the connector 4 is housed in the internal space of the case 2 formed by the upper lid case 2a and the lower lid case 2b. In the internal space, the insulating sheet 11, the lead wire 12, the lead plates 13, 13a, the circuit board 7, and the circuit board that are connected to the battery unit in which the four unit cells 3 are connected in two series and two in parallel A connector 4 connected to 7 is also housed, and a covering material is attached to a part of the upper lid case 2a. However, the circuit board 7 in which a part of the opening is provided in the case 2 so that only the comb-shaped surface of the connector 4 is exposed to the outside, and the connector 4 is joined to the bulging part of the lower lid case 2b. It is supported by being fitted by a provided fitting part (not shown).

Next, each of the constituent members of the battery pack 1 will be described.
The unit cell 3 is a cylindrical lithium ion battery. Lead wires 12 are connected via insulating sheets 11 to both ends of the battery unit composed of four unit cells 3 connected in two series and two in parallel. Of the two lead wires 12 connected to both ends, one lead wire 12 connected to the battery unit on the X direction positive direction side is on the X direction negative direction side and the X direction negative direction side The other lead wire 12 connected to the battery unit extends in the positive direction in the X direction. These are connected to a circuit board 7 on a thin flat plate at a substantially central portion in the X direction of the battery unit.

  The upper lid case 2a and the lower lid case 2b are made of a resin material, and as shown in FIG. 1, the cylindrical unit cells 3 are connected in series and in parallel in the internal space formed by them. The connector 4, the circuit board 7, and the like can be accommodated while corresponding to the shape of the battery unit. A rectangular projecting portion toward the Y direction negative direction side is provided at a substantially central portion in the X direction of the upper lid case 2a. The protruding portion is provided with a rectangular perforated portion 6 at a substantially central portion. The perforated portion 6 is formed on an area where the circuit board 7 is disposed, and is set to a size that allows a convex area 7a of the circuit board 7 described later to be sufficiently inserted. Further, the lower lid case 2b is provided with a notch at the substantially central portion in the X direction so that the comb-shaped surface of the connector 4 is exposed to the outside as described above.

  The connector 4 has a comb-shaped surface as shown in FIG. 1, the comb-shaped surface faces the Y direction negative direction side, and the opposite surface (Y direction positive direction side) faces the circuit board 7. It is joined to the substantially central portion of the circuit board 7 so as to be in contact, and the comb-shaped surface is disposed so as to be exposed to the outside from the opening provided in the case 2. The connector 4 is electrically connected to the circuit board 7, and after the battery pack 1 is formed, the connector 4 is electrically connected to an external device to be mounted on the comb-shaped surface.

  As shown in FIG. 2, the circuit board 7 is a thin plate having a substantially rectangular shape with the X direction as the longitudinal direction. A convex region projecting toward the positive side in the Z direction is present at the substantially central portion in the X direction of the flat plate 7, and is integrally formed with a circuit board main part 7 b that occupies the main part of the circuit board 7. The circuit board 7 is provided with three insertion holes 4b. A mounting pin (not shown) of the connector 4 is inserted into the insertion hole 4b and soldered, so that the connector 4 is provided at a substantially central portion of the flat plate main surface. Are mounted and electrically connected. Note that the number of the insertion holes 4b is not limited to three, and it is only necessary that the connector 4 described later is securely mounted on the circuit board 7. The circuit board 7 on which the connector 4 is mounted is located at a substantially central portion in the X direction of the battery unit in a state where the convex region 7a is inserted through the perforated portion 6. The bonding state between the circuit board 7 and the connector 4 and the positional relationship between the circuit board 7 and the upper lid case 2a will be described later. The circuit board 7 realizes a control circuit for distributing power between the battery pack 1 and an external device (not shown), a protective circuit for maintaining a good battery state by repeatedly charging and discharging. An electronic component (not shown) such as an IC is formed. Since the configuration and the like of these electronic components are known, illustration and description thereof are omitted.

The covering material 5 has a strip shape with the X direction as the longitudinal direction, and is made of a thin resin material. The covering material 5 has adhesiveness on the main surface in the Z direction, and is attached to the upper lid case 2a so as to cover the perforated portion 6, and prevents infiltration of suspended matter or moisture into the battery pack 1. Is. The above-mentioned use is not effective only for the perforated portion 6 and may be formed so as to cover other through holes and the like that are necessary for the configuration of the case 2. The covering material 5 can also be used as a rating label for the battery pack 1 or a caution label for alerting the user, and has the effect of clearly indicating the logo of the battery pack 1 or the like.
(Disposition to the upper cover case 2a of the circuit board 7)
The connection between the connector 4 and the circuit board 7 and the proximity of the circuit board 7 and the upper lid case 2a to which the connector 4 is bonded will be described with reference to FIGS. 3 (a) and 3 (b). 3 (a) is a top view of the battery pack 1, and FIG. 3 (b) is a BB cross-sectional view of the battery pack 1. Note that the wiring path from the substrate 7 to the unit cell 3 is omitted for the sake of convenience. On the contact surface between the connector 4 and the circuit board 7, the needle-like mounting pin 4a extends to the positive side in the Y direction. Is provided. This mounting pin 4a is inserted into the insertion hole 4b provided in the circuit board 7, and the connector 4 is connected to the circuit board 7 by soldering the mounting pin 4a in a state where the connector 4 is securely grounded to the circuit board 7. It is bonded and mounted on the substrate 7. The formation position of the insertion hole 4b in the circuit board 7 is on the main surface of the main part 7b of the circuit board 7 and in a range corresponding to the formation range of the convex region 7a in the X direction. Further, in the vicinity of the end of the circuit board 7 on the positive side in the Z direction, the circuit board 7 is spaced apart from the edge on the positive direction side in the Z direction. Due to this constant distance, the area ratio from the insertion hole 4b to the end of the circuit board 7 on the positive side in the Z direction is small relative to the entire area of the circuit board 7, but the soldering is performed. There is enough space to do this.

Next, the proximity state of the circuit board 7 on which the connector 4 is mounted by the above method to the case 2 will be described below.
The circuit board 7 on which the connector 4 is mounted is housed and fixed in the case 2 with the convex region 7a inserted through the perforated portion 6 provided in the upper lid case 2a from the negative side in the Z direction. ing. The main surface of the convex portion of the upper lid case 2a including the perforated portion 6 is covered with the covering material 5 from the Z direction positive direction side. It is desirable to arrange the circuit board 7 so that the convex region 7a inserted into the upper lid case 2a does not protrude from the outer surface of the upper lid case 2a.

  As described above, when the convex region 7a of the circuit board 7 is inserted into the perforated portion 6 of the upper lid case 2a, as shown in the enlarged view of FIG. The position of the edge of the convex region 7a has moved to the positive side in the Z direction by a distance a from the inner surface of the upper lid case 2a (see FIG. 4), and approximately 50% of the thickness of the upper lid case 2a. It enters the positive direction side in the Z direction from the inner surface of the upper lid case 2a. Here, if the distance from the end of the circuit board to the insertion hole 4b is substantially the same as the conventional case (distance b in FIG. 4), the dead space between the connector 4 and the upper lid case 2a is omitted by the distance a. . As a result, the internal space of the case 2 to be molded is reduced, which leads to downsizing of the battery pack. Alternatively, in the case where the case 2 is used without changing the external shape of the case 2 corresponding to the external device, the area of the circuit board 7 itself can be enlarged by the omitted distance a. As a result, more electronic components and the like can be mounted on the circuit board 7, which can lead to higher functionality of the battery pack.

  Since the connector 4 is in close contact with the inner surface of the upper lid case 2a, a space that faces the external space does not occur between the connector 4 and the upper lid case 2a. Therefore, it is not necessary to thicken part of the upper lid case 2a as in the conventional case. For example, when the upper lid case 2a is produced by injection molding, it is not necessary to use a complicated mold, which leads to suppression of yield reduction.

  In the present embodiment, the perforated portion is provided in the upper lid case 2a, but is not limited to this, the edge of the convex region 7a is more positive in the Z direction than the position of the inner surface of the upper lid case 2a If it is the structure fixed by the side, it can change suitably. For example, a recessed hole that does not pass through may be provided at the position where the perforated part 6 is formed instead of the perforated part 6, and the convex region 7a may be inserted into the recessed hole. Furthermore, as long as a sufficient space for soldering is secured, the end of the circuit board 7 may be fitted inside the recessed hole. When the recessed hole does not penetrate as described above, the covering material 5 may not be attached to the upper lid case 2a. Further, the length inserted into the recessed hole of the convex region 7a is not limited to approximately 50% with respect to the thickness of the upper lid case 2a. It is optimal if the space between the connector 4 and the upper lid case 2a can be omitted without the convex region 7a projecting from the outer surface of the upper lid case 2a. If the space capacity can be reduced even if a slight gap remains between the connector 4 and the upper lid case 2a, the effect of reducing the size of the battery pack can be obtained. It's okay because you can. However, in that case, it is desirable to thicken part of the upper lid case 2a so as to close the region facing the external space.

In addition, the method of joining the connector 4 and the circuit board 7 is not limited to soldering. For example, the connector 4 is electrically connected to the circuit board 7 by using a method such as welding, so that If it can be fixed, it can be changed as appropriate.
(Advantage of this embodiment)
As described above, the perforated part 6 is provided in the upper lid case 2a, and the convex region 7a of the circuit board 7 is inserted into the perforated part 6, so that the internal space of the battery pack 1 can be reduced. This leads to downsizing of the battery pack. According to the above configuration, the position of the insertion hole 4b on the circuit board 7 required for attaching the connector 4 to the circuit board 7 is not changed compared to the conventional case. Even if it is attached or detached, the above advantages can be maintained without reducing the strength of the circuit board 7.

Since the dead space of the internal space in the battery pack 1 is omitted, there is an effect of suppressing the heat generated in the battery pack 1 from staying in the battery pack 1, and the battery pack 1 is also improved in terms of heat dissipation. ing.
In addition, if it is impossible to change the external shape of the battery pack 1 with respect to the external device, the mounting area of the substrate 7 can be increased by the amount of movement of the substrate 7 to the perforated portion 6. Become. Thereby, since the interval between the elements mounted on the substrate 7 can be increased, the thermal influence between the elements can be reduced. In particular, as battery packs 1 and external devices tend to be more closely connected with higher performance, more functions, and smaller size required for external devices, heat generated from external devices also affects pack battery 1. Considering the fact that the possibility of exerting an increase is also considered, such improvement in heat dissipation is meaningful.
(Other matters)
The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment. For example, the present invention can be applied to the following cases.
(1) A unit cell is not limited to a cylindrical lithium ion secondary battery, For example, a square shape may be sufficient. In addition to the lithium ion secondary battery, an alkaline secondary battery such as a nickel metal hydride battery or a nickel cadmium battery, a nonaqueous secondary battery such as a lithium polymer battery, or a lead secondary battery may be used.
(2) The number of unit cells may be 3 or less or 5 or more, and all of them may be connected in series, in parallel, or in other combinations.
(3) The material of the covering material 5 may be other than the resin material as long as it has adhesiveness and insulating properties.
(4) The shape of the circuit board 7 is not limited to the present embodiment, and any shape can be used as long as it is inserted into the recessed hole provided in the upper lid case 2a and held in the battery pack.

  The present invention is particularly useful for the production of a battery pack that can be reduced in thickness and weight, and can stably distribute power over a long period of time.

1 is an exploded perspective view of a battery pack 1. FIG. 3 is a perspective view of a circuit board 7. FIG. (a) is a top view of the battery pack 1, and (b) is a BB cross-sectional view of the battery pack 1. 3 is a cross-sectional view showing a joint portion between the connector 4 and the circuit board 7 and a proximity portion with respect to the upper lid case 20a of the circuit board 7. FIG.

Explanation of symbols

1 pack battery
2 cases
3 unit cell
4 Connector
5 Coating material
6 Perforated part
7 Circuit board

Claims (4)

The battery pack is a battery pack in which a circuit board is housed in a case together with a unit cell, a connector is mounted near the end of the circuit board, and an external connection portion of the connector is exposed outside the case,
A battery pack, wherein a concave portion is formed in a thickness direction on an inner surface of the case, and an end portion of the circuit board is inserted into the concave portion. The recessed portion is processed through the case,
2. The battery pack according to claim 1, wherein an outer surface of the case including the recessed portion is covered with a covering material. 3. The battery pack according to claim 1, wherein the connector has a mounting pin and is inserted and mounted on the board. The circuit board has a shape in which a part of the end of the circuit board bulges outward along the mounting surface of the connector,
4. The battery pack according to claim 1, wherein the bulging portion is inserted into the recessed portion of the case as the end portion of the circuit board.

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