JP3777703B2 - Battery pack and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack built in a portable electronic device or the like and a method for manufacturing the battery pack.
[0002]
[Prior art]
As portable electronic devices have become more compact in recent years, there is an increasing demand for smaller and lighter batteries (usually secondary batteries) used in these electronic devices. For example, recent PHS (Personal Handyphone System) telephones have a strong demand for miniaturization and weight reduction. Therefore, instead of using a secondary battery as a battery pack and attaching it to the telephone body, this secondary battery is built directly into the telephone. By connecting to the device body via a lead wire and a connector, an increase in volume and weight due to the battery pack itself and its mounting mechanism is avoided. However, even when the secondary battery is built into the phone body in this way, it is possible to replace the battery, so that the secondary battery cannot be easily disassembled or modified by the user. It is necessary to protect the battery by covering it with a cover. Moreover, since a protection circuit is always used in the case of a lithium secondary battery, the secondary battery and the protection circuit must be securely connected so that the protection circuit cannot be separated and used illegally or modified. It is necessary to integrate with and cover with a cover.
[0003]
Accordingly, as shown in FIG. 6, a lithium secondary battery built in a conventional PHS telephone is configured by wrapping an insulating exterior tape 8 around the unit cell 1 and the protection circuit 2 to form a battery unit 3, and this battery unit. 3 was covered with a contraction tube 9, and the contraction tube 9 was contracted and integrated as shown in FIG. Thereby, since the battery unit 3 is covered with the shrinkable tube 9 having a certain degree of hardness, the unit cell 1 and the protection circuit 2 cannot be easily separated or modified, and a thin film shape is obtained. Therefore, there is no possibility that the volume and weight of the battery unit 3 will increase more than necessary. This lithium secondary battery is used by connecting the connector 5 at the end of the lead wire 4 to the telephone body.
[0004]
[Problems to be solved by the invention]
However, since the shrinkable tube 9 is a synthetic resin film having a thickness of about 0.1 mm, it can be easily cut using a cutter knife or the like. For this reason, the lithium secondary battery built in the conventional PHS telephone has a problem that it is still insufficient to reliably prevent unauthorized use by the user. Moreover, since the battery unit 3 is only covered with the thin film-like shrinkable tube 9, there is a problem in that the single cell 1 and the protection circuit 2 cannot be sufficiently protected against an external impact.
[0005]
By the way, in a general portable electronic device, a battery is conventionally housed in a plastic box-shaped case, covered with a cover of the same shape, and the case and the cover are joined by ultrasonic waves or an adhesive. In some cases, the battery pack is configured to reliably prevent unauthorized use by the user and to provide sufficient protection against impact. However, when joining the case and the cover using ultrasonic waves, as shown in FIG. 8, the ultrasonic vibration is transmitted to the protruding portion 10 b provided at the lower end of the side wall 10 a of the cover 10, and the side wall of the case 11. The cover 10 and the case 11 need to be at least about 1.5 mm to 2 mm in thickness because they are fused to the joint surface 11b provided on 11a. Further, even when an adhesive is used, as shown in FIG. 9, for example, a structure in which the adhesive 12 having a high viscosity is applied to the side wall 11 a of the case 11 and the lower end of the side wall 10 a of the cover 10 is fitted is required. The thickness of the cover 10 and the case 11 must be increased as in the case of ultrasonic waves. For this reason, in the conventional cover 10 and case 11, since these thicknesses become too thick, a battery becomes large, and when using for a PHS telephone etc., for example, the request | requirement of size reduction and weight reduction cannot fully be satisfied. A problem occurs. In addition, particularly when using a lithium secondary battery, since the unit cell 1 itself and the protection circuit 2 are delicate, it is not preferable to join the cover 10 and the case 11 by applying ultrasonic vibration. It was.
[0006]
The present invention has been made in view of such circumstances, and in a battery pack in which a battery unit is housed in a plastic case and a cover, the step portions on the side walls of the case and the cover are fitted to each other and solvent injection is performed. It is an object of the present invention to provide a battery pack and a method for manufacturing the battery pack that reliably protects the internal battery unit and does not become too large by injecting a solvent into the fitting portion and joining them.
[0007]
[Means for Solving the Problems]
That is, in order to solve the above-mentioned problems, the present invention provides a battery pack in which a battery unit is housed in a plastic case and a cover. A stepped portion having a reduced thickness is provided, and a stepped portion having an inner peripheral surface that is fitted from the inner peripheral side to the outer peripheral surface of the stepped portion on the side wall of the case is formed at the lower portion of the side wall of the cover. A notch-shaped solvent injection part configured to be blocked by the outer peripheral surface of the step part on the side wall of the case is provided at an appropriate position of the step part on the side wall of the cover.
[0008]
According to the means of claim 1, the battery unit is housed in the case and the cover by fitting the inner peripheral surface of the step portion of the side wall of the cover to the outer peripheral surface of the step portion of the side wall of the case. Can do. Further, since the outer peripheral surface of the stepped portion on the side wall of the case is exposed at the solvent injection portion of the cover, if the solvent is injected here, the solvent can be easily soaked into the gap of the fitting portion and surely fused. be able to. Therefore, the battery unit can be protected by these cases and covers so that the user cannot easily disassemble or modify the battery unit. Moreover, since it is only necessary to provide a step portion on the side wall of these cases and covers, the thickness can be extremely reduced. Further, by covering with such a plastic case and cover, the impact resistance can be sufficiently enhanced.
[0009]
In the means of claim 1, the cover is covered from above with the case facing down, but the positional relationship between the case and the cover is relative and arbitrary. The battery unit may mean only a battery body such as a single battery, or may mean a combination of a protection circuit or the like with the battery body. Furthermore, the battery is generally a secondary battery, but there is no reason to eliminate the primary battery.
[0010]
In addition, a solvent injection portion in which the same thin thickness portion as the step portion is formed below the step portion at a position facing the solvent injection portion of the cover on the side wall of the case can be provided.
[0011]
According to the above, since the solvent injection part is also provided on the side wall on the case side, the solvent injection part is combined with the solvent injection part on the cover side, so that the solvent can be easily injected.
[0012]
Furthermore, a notch-shaped lead wire lead-out portion for drawing out the lead wire of the battery unit can be provided at a position facing each other on the side wall of the case and the cover.
[0013]
According to the above, when the battery unit is connected to the device main body via the lead wire, the lead wire can be pulled out from the lead wire lead-out portion of the case and the cover.
[0014]
Furthermore, in the invention according to claim 2, the battery pack manufacturing method uses the case and the cover, places the battery unit on the bottom plate of the case, and covers the battery unit with the ceiling plate of the cover. A step of fitting the inner peripheral surface of the step portion of the side wall of the cover to the outer peripheral surface of the step portion of the side wall of the case, and a step of injecting a solvent from the outside into the solvent injection portion of the cover and joining the cover and the case It is characterized by comprising.
[0015]
According to the second aspect of the present invention, the battery unit is placed in the case, covered with a cover, the stepped portions are fitted to each other, and the battery is easily accommodated simply by injecting the solvent from the solvent injecting portion. be able to.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
1 to 5 show an embodiment of the present invention. FIG. 1 is an assembled perspective view of a battery pack, FIG. 2 is a perspective view of a battery unit, and FIG. 3 is a longitudinal sectional view of a case and a cover. 4 is a perspective view showing a state in which a cover is put on a case containing a battery unit, and FIG. 5 is a longitudinal sectional view showing a state in which the cover is put on a case containing a battery unit. In addition, the same number is attached | subjected to the structural member which has the same function as the prior art example shown in FIGS.
[0018]
In the present embodiment, a battery pack using a lithium secondary battery built in a PHS telephone and a method for manufacturing the battery pack will be described. As shown in FIG. 2, the unit cell 1 of the lithium secondary battery of the present embodiment has a rectangular box shape, and the protection circuit 2 is mounted on an elongated printed board 2a. The protection circuit 2 is disposed on the side surface of the unit cell 1 and connected to the positive and negative terminals of the unit cell 1 via the positive electrode lead 2b and the negative electrode lead 2c, thereby forming the battery unit 3. A lead wire 4 is drawn out from the protection circuit 2 and can be connected to the telephone body via a connector 5 at the tip.
[0019]
The battery unit 3 including the unit cell 1 and the protection circuit 2 is housed between a case 6 and a cover 7 as shown in FIG. As shown in FIGS. 1 and 3, the case 6 includes a rectangular bottom plate 6a that is slightly larger than the battery unit 3, and a side wall 6b that protrudes upward from the periphery of the bottom plate 6a. This is a plastic box-shaped container provided. Further, the side wall 6b is provided with a stepped portion 6c whose thickness is reduced from the outer peripheral side at an upper portion of a predetermined height or more, and two steps on the long side of the square and one on the short side. A solvent injection portion 6d is provided in which the same thin wall portion as the portion 6c is recessed in a concave shape below the step portion 6c. Further, the side wall 6b is provided with a lead wire lead-out portion 6e by cutting out one end of the long side of the square.
[0020]
The cover 7 is a plastic upper / lower plate provided with a rectangular ceiling plate 7a having the same size as the bottom plate 6a of the case 6 and side walls 7b having the same height and projecting downward from the periphery of the ceiling plate 7a. It is a box container in the reverse direction. A stepped portion 7c having a reduced thickness from the inner peripheral side is provided at the lower portion of the side wall 7b below a predetermined height. At this time, the inner peripheral surface of the stepped portion 7 c is formed so as to substantially fit the outer peripheral surface of the stepped portion 6 c of the side wall 6 b of the case 6. Further, the stepped portion 7c is provided with solvent injection portions 7d that are concave cutouts at positions corresponding to the six solvent injection portions 6d of the case 6. Further, the side wall 7b is notched at one position corresponding to the lead wire lead-out portion 6e of the case 6, and a lead wire lead-out portion 7e is provided.
[0021]
A method for manufacturing a battery pack in which the battery unit 3 is housed in the case 6 and the cover 7 having the above-described configuration will be described. First, as shown in FIG. 1, the battery unit 3 is placed on the bottom plate 6 a of the case 6. Next, the ceiling plate 7a of the cover 7 is covered on the battery unit 3, and the inner peripheral surface of the stepped portion 7c of the side wall 7b is set to the outer periphery of the stepped portion 6c of the side wall 6b of the case 6 as shown in FIGS. Fit on the surface. Then, most of the outer peripheral surface of the stepped portion 6c is covered with the stepped portion 7c and is in contact with the inner peripheral surface of the stepped portion 7c with almost no gap. Further, each solvent injection portion 6d of the case 6 and each solvent injection portion 7d of the cover 7 face each other at the six surroundings, and these solvent injection portions 6d and 7d are combined to form a step portion 6c within a relatively wide range. The outer peripheral surface of the is exposed to the outside. At this time, the lead wire 4 of the battery unit 3 is drawn to the outside through the lead wire lead portions 6e and 7e.
[0022]
When the case 6 is covered with the cover 7 as described above, the solvent is infused into the gap between the step portions 6c and 7c by injecting the solvent into the outer peripheral surface of the step portion 6c exposed by the solvent injection portions 6d and 7d. . Since the solvent has a low viscosity unlike the adhesive, it can be easily infiltrated into the gap between the stepped portions 6c and 7c. The solvent soaked in this manner softens and melts the plastic on the outer peripheral surface of the stepped portion 6c and the inner peripheral surface of the stepped portion 7c and fuses them together, thereby securely bonding the case 6 and the cover 7 together. Can do. In addition, an appropriate amount of this solvent can be injected, for example, by supplying a constant amount by a metering pump from the tip of a needle having a through-hole formed in the shaft center.
[0023]
Here, as the plastic of the case 6 and the cover 7, for example, PC (polycarbonate), ABS resin, PC-ABS alloy or the like is preferably used. As the solvent, it is preferable to use MEK (methyl ethyl ketone), toluene, cyclohexane or the like, or a mixed solvent thereof, which can soften and fuse these plastics. Further, when vinyl chloride resin is used for the case 6 and the cover 7, THF (tetrahydrofuran) may be used as the solvent. Any combination of the plastic and the solvent may be used as long as the solvent can soften and fuse the plastic.
[0024]
As described above, according to the battery pack and the battery pack manufacturing method of the present embodiment, the battery unit 3 is housed in the plastic case 6 and covered by the cover 7 so as to be covered. The unit cell 1 and the protection circuit 2 cannot be disassembled or modified, and the impact resistance can be sufficiently enhanced. Moreover, since the case 6 and the cover 7 can be joined simply by fitting the step portions 6c and 7c of the side walls 6b and 7b and soaking the solvent into the gap, the step portions 6c and 7c are set to about 0.4 mm, for example. The side walls 6b and 7b can be formed to be very thin with a thickness of about 0.8 mm, and do not occupy more space than necessary when built in a PHS telephone, contributing to a reduction in size and weight of the battery. Can do.
[0025]
In the above embodiment, the lithium secondary battery built in the PHS telephone has been described. However, the types of electronic devices and batteries to be used are not limited to this. Moreover, although the above-mentioned embodiment used the substantially rectangular box type battery unit 3, the shape of the battery unit 3 is not limited. The shapes of the case 6 and the cover 7 can also be in accordance with the shape of the battery unit 3. Furthermore, in the above embodiment, the case 6 is provided with the solvent injection portion 6d, but the cover 7 may be provided with the solvent injection portion 7d. Moreover, the shapes of the solvent injection portions 6d and 7d are not limited to the concave shape and are arbitrary.
[0026]
【The invention's effect】
As is clear from the above description, according to the battery pack and the battery pack manufacturing method of the present invention, the step portions of the case and the side wall of the cover are fitted to each other and the solvent is injected from the solvent injection portion. Since the part can be reliably fused, it is possible to prevent the user from easily disassembling or modifying the battery unit. Further, since the case and the cover only need to be provided with a stepped portion on the side wall, the thickness of the case and cover can be made extremely thin, and the reduction in size and weight of the battery is not impaired. Furthermore, by securely covering the battery unit with the case and the cover, the impact resistance can be sufficiently enhanced.
[Brief description of the drawings]
FIG. 1 is an assembled perspective view of a battery pack according to an embodiment of the present invention.
FIG. 2 is a perspective view of a battery unit according to an embodiment of the present invention.
FIG. 3 is a longitudinal sectional view of a case and a cover, showing an embodiment of the present invention.
FIG. 4 is a perspective view showing an embodiment of the present invention and showing a state where a cover is put on a case containing a battery unit.
FIG. 5 is a longitudinal sectional view showing a state in which a cover is placed on a case containing a battery unit according to an embodiment of the present invention.
FIG. 6 is a perspective view showing a conventional example, in which a single cell and a protection circuit are covered with a shrinkable tube.
7 is a perspective view showing a conventional example and showing a state in which the contraction tube of FIG. 6 is contracted. FIG.
FIG. 8 shows another conventional example, and is a partially enlarged longitudinal sectional view of a joining portion of a case and a cover for joining using ultrasonic waves.
FIG. 9 is a partially enlarged longitudinal sectional view of a joint portion between a case and a cover, which is another conventional example and is joined using an adhesive.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 Battery unit 4 Lead wire 6 Case 6a Bottom plate 6b Side wall 6c Step part 6d Solvent injection part 6e Lead wire extraction part 7 Cover 7a Ceiling board 7b Side wall 7c Step part 7d Solvent injection part 7e Lead wire extraction part

Claims (2)

  In a battery pack in which a battery unit is housed in a plastic case and cover, a stepped portion having a thickness reduced from the outer peripheral side is provided on the upper side wall of the case, and a thickness is provided on the lower side of the cover from the inner peripheral side. The stepped portion is formed with an inner peripheral surface that is fitted to the outer peripheral surface of the stepped portion on the side wall of the case, and the outer periphery of the stepped portion on the side wall of the case is provided at an appropriate position on the stepped portion on the side wall of the cover. A battery pack comprising a notch-shaped solvent injection portion configured to be blocked by a surface. Using the case and cover according to claim 1,
The battery unit is placed on the bottom plate of the case, and the ceiling plate of the cover is placed on the battery unit, and the inner peripheral surface of the stepped portion of the side wall of the cover is fitted to the outer peripheral surface of the stepped portion of the side wall of the case. Process,
A method for manufacturing a battery pack, comprising: injecting a solvent from outside into a solvent injection portion of the cover, and joining the cover and the case.

Images