JP2002245993A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack provided with a box body in which a split type case made of resin is joined/integrated by a supersonic deposition and having a constitution capable of stably carrying out a joining/integration at a desired joint strength even if a thickness of the case is thin. SOLUTION: In the split type case made of resin, one of the case has a rib 4 having a cross section of V shape at a tip end of a deposited rib and the other case has a V-shaped groove 6 to which the V-shaped rib is fitted. The V-shaped rib and the V-shaped groove are fitted and deposited by a supersonic wave.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack in which a battery and a wiring circuit are housed in a housing composed of a divided resin case, and the divided cases are joined and integrated by ultrasonic welding. For details, use a thin split case,
The present invention relates to a battery pack having a joining structure having excellent joining accuracy during ultrasonic welding.

[0002]

2. Description of the Related Art A battery pack composed of a plurality of batteries is widely used as a power supply for driving various mobile devices such as mobile communication devices and notebook PCs. A general battery pack includes, in a housing having electrical insulation, a control circuit for controlling a charge / discharge state of a battery, in addition to a plurality of batteries,
It has a built-in safety element such as a thermal fuse and a PTC element, and a contact terminal for connecting to a main unit.
On the other hand, the casing of the battery pack is formed by combining a half-shell-shaped split case made of synthetic resin. After the above-described components are housed in one split case, both split cases are welded by ultrasonic welding or the like. Are integrated.

[0003] A split case made of a synthetic resin is provided on a joint surface of one split case, that is, a welding rib formed on a peripheral portion of an opening in each half shell-shaped split case, on a joint surface of the other split case. After the combination, the parts are joined and integrated by ultrasonic welding at the joint surface of the divided cases. More specifically, components such as a battery are housed in a half-shell-shaped split case, and the joining surfaces of the split cases are aligned,
After assembling the casing into a predetermined shape, ultrasonic welding is performed. In the ultrasonic welding, a horn is brought into contact with one of the divided cases, and ultrasonic vibration of about 20 kHz is intensively applied to the welding rib via the horn. Longitudinal vibration is applied to the welding rib by the energy of the ultrasonic wave, and the welding rib generates heat and melts on the surface in contact with the other split case. By stopping the application of the ultrasonic vibration and solidifying the molten resin, a joining action with the other split case is exhibited, and the two cases are joined and integrated.

[0004] In recent years, battery packs used as power supplies for portable electronic devices have been required to be smaller and lighter as the devices become lighter and thinner. To reduce the size and weight of the battery pack, in addition to reducing the size and weight of the components to be housed, it is also necessary to reduce the size of the housing.Thus, the thickness of each of the divided cases that make up the housing must be reduced. Is supported. In addition, in order to reduce the size and cost of the entire device, the battery pack itself is often installed outside the device and takes part of the external appearance, and the external appearance of the battery pack is also an important characteristic. Is coming.

[0005]

However, setting the thickness of the divided case to be thinner not only reduces the joint area of the two cases, but also causes the joint / integration strength to be reduced, and also causes the joint to be unified. In this case, the accuracy of the bonding position at the time is deteriorated, and the surface properties of the pack are also adversely affected, thereby greatly reducing the marketability.

[0006] The lowering of the joint strength of the housing in the battery pack is caused by the peeling of the joint and the joint breakage when the battery pack is dropped or dropped during transportation and handling in a state where the battery pack is attached to the device. This may cause cracking of the housing. Such inconvenience is such that the joint surface of the split case is displaced to cause peeling or cracking, and the occurrence frequency of inconvenience tends to increase in a battery pack using a thin case having a low joint strength. .

A configuration using a thinner divided case is as follows.
The area of the fitting portion for fitting the split case at the predetermined position is also reduced, and assembling workability is deteriorated. Furthermore, in the stage of applying ultrasonic welding to the split case fitted to the predetermined position, the area of the fitting portion is small, so that the displacement of the joining position is likely to occur at the time of ultrasonic welding. Is also reduced.

[0008] The split case is provided with a concave rib receiving surface into which the welding rib is fitted. The resin material melted during the ultrasonic welding flows into the rib receiving surface and joins the split cases. As the joining area decreases, the volume of the rib receiving surface also decreases, and depending on the conditions of ultrasonic welding and the shape of the welding rib, a resin material exceeding the volume of the rib receiving surface may be melted. At this time, the resin material in a molten state is extruded from the joining surface and solidified, so that a raised portion of the resin material is formed on the housing surface of the battery pack, which has an adverse effect on the appearance.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to reduce the thickness and weight of a battery pack while solving these inconveniences. It is an object of the present invention to provide a battery pack having a structure capable of stably joining and integrating with strength.

[0010]

In order to achieve the above object, a battery pack according to claim 1 of the present application has a battery and a wiring circuit housed in a housing composed of a divided resin case, and a divided case. Are joined and integrated by ultrasonic welding of welding ribs provided on the joining surface, and one of the divided cases has a cross section V at the tip of the welding rib.
The V-shaped rib and the V-shaped rib are fitted into the other divided case, and the V-shaped rib and the V-shaped groove are fitted and ultrasonically welded. Features.

The inventors of the present invention have conducted various studies in response to the above-mentioned conventional problems. As a result, the cross-sectional shape of the welding rib to be subjected to ultrasonic welding is V-shaped, and the rib into which the rib is fitted is set. When the cross-sectional shape of the receiving surface is a V-shaped groove, it has been found that required ultrasonic welding is easily performed. That is, the welding ribs provided on one of the split cases are fitted to the rib receiving surfaces provided on the other split case, and are joined and joined by ultrasonic welding.
At the time of integration, a split case is fitted by fitting a welding rib having a V-shaped cross-section and a V-shaped groove corresponding to the shape of the welding rib, and both cases are arranged at predetermined positions. The ultrasonic welding can be performed in the state of being welded, and the displacement during the welding hardly occurs. In addition, in the conventional case, a stopper rib for fitting and positioning the two was arranged in parallel with the welding rib to be subjected to ultrasonic welding, but fitted with a V-shaped welding rib, By adopting the configuration of performing the ultrasonic welding, not only the stopper rib is not required, but also the effect of further reducing the thickness of the welding rib and the size and weight of the battery pack accompanying this can be obtained. Furthermore, the shape of the V-groove is set in accordance with the shape of the V-shaped welding rib. Specifically, in consideration of the thickness of the welding rib, the angle of the V-shape, the molten state during ultrasonic welding, and the like, the V-groove is set. The angle is determined. As a result, it has also been found that even when a thin divided case is used, the welding area is increased, and a stable portion in a welded state is easily formed.

As described above, the invention according to claim 1 is based on the above findings, and a required joining strength can be obtained even by using a thin divided case, and a highly reliable battery pack can be mass-produced. In addition, it has a specific effect that it can be manufactured with a high yield.

On the other hand, in the battery pack according to claim 2 of the present application, a battery and a wiring circuit are housed in a divided resin housing, and opposed surfaces to be joined of the housing are provided on the joined surfaces. At least one of the divided cases is ultrasonically welded to the joining surface of the other divided case, and a stopper is fitted to the joining surface. A rib portion, and the welding rib portion and the stopper rib portion are alternately arranged on the welding rib.

According to this structure, the portions where ultrasonic welding is performed and the portions where the fitting connection is made are alternately arranged on the series of welding ribs, and the split case is fitted at the stopper rib portion. Since it is arranged at a predetermined position, displacement during ultrasonic welding is unlikely to occur. Further, it is necessary to determine the arrangement of the welding rib portion and the stopper rib portion in consideration of the thickness, shape, and the like of the divided case. Therefore, it is preferable that the stopper rib portion is arranged so as to obtain a fitting strength sufficient to hold the divided case at a predetermined position during ultrasonic welding, and that the remaining portion is a welding rib portion. In addition, compared with the conventional case in which both are arranged in parallel on the welding rib, not only the thickness of the welding rib can be reduced, but also the effect of improving the bonding strength because the welding area of the entire battery pack is increased. Play.

Further, since the stopper rib portion is located adjacent to the welding rib portion, the excessive welding rib in a molten state at the time of ultrasonic welding flows into the stopper rib portion where ultrasonic welding is not performed. For this reason, the raised portion of the resin does not occur on the outer surface of the housing of the battery pack, and an effect of significantly reducing appearance defects is also achieved.

In a battery pack according to a third aspect of the present invention, a battery and a wiring circuit are housed in a housing made of a divided resin case, and opposed joint surfaces of the divided case are provided on the joint surface. The welding ribs are joined and integrated by ultrasonic welding, and at least one of the split cases is a welding rib portion ultrasonically welded to the joining surface of the other split case and a stopper rib fitted to the joining surface. And a rib having a V-shaped cross section formed at the end of the welding rib portion, and the V-shaped rib is fitted into a V-shaped groove formed on the joint surface of the other split case facing the other. In this case, it is characterized by being ultrasonically welded. That is, the battery pack according to the third aspect has a configuration according to the second aspect, in which a portion where ultrasonic welding is performed and a portion where fitting connection is performed are alternately arranged on a series of welding ribs. It is a combination of the configuration according to claim 1 in which the tip is V-shaped and a V-shaped groove is formed in a portion facing the V-shape. The effects obtained by each configuration are synergistically exhibited, and the required joining strength is obtained. Thus, there is an effect that a highly reliable battery pack can be mass-produced and manufactured with high yield.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below exemplifies a battery pack for embodying the technical idea of the present invention, and the present invention does not specify a battery pack and a divided case constituting the battery pack in the following structure.

(First Embodiment) FIG. 1 is a schematic sectional view showing a configuration of an ultrasonic welding portion of a battery pack according to a first embodiment, and shows an upper case 1 and a lower case before ultrasonic welding. 2 is a drawing in a state of being fitted. Reference numeral 3 denotes a battery block in which a secondary battery such as a lithium ion battery and a connection plate of circuit components necessary for a battery pack, a safety element, a safety circuit board, a control circuit board, and the like are assembled.

FIG. 2 is an enlarged view of the ultrasonic welding portion in FIG. Reference numeral 4 denotes an ultrasonic welding rib, and reference numeral 5 denotes an energy director provided at the tip. Reference numeral 6 denotes an ultrasonic welding rib receiving surface. 8a is upper case 1 and lower case 2
Is an outer gap necessary for the ultrasonic welding of, and is set to 0.1 mm in the present embodiment. “a” indicates the thickness dimension of the ultrasonic welding rib, which was similarly set to 0.6 mm.
b is the thickness dimension of the side wall of the upper case 1 1.2 mm. c
Is the width dimension of the ultrasonic welding rib receiving surface, which was set to 0.7 mm. In addition, d is the thickness dimension of the side wall of the lower case 2, which is set to 1.2 mm in the present embodiment.

FIG. 3 is an enlarged detailed view of the ultrasonic welding rib and the receiving surface portion in FIG. e indicates the tip angle of the energy director 5, and when set at 60 °, the receiving surface 6 is aligned and positioned at a predetermined position when the energy director is combined with the case 2 which is the upper case 1. Therefore, it is preferable to have a V-shape, and the angle f is set to an angle 90 ° larger than e.

FIG. 4 is an enlarged view of the ultrasonic welding portion in the conventional configuration. A cap rib 7 is provided on the inner surface of the battery pack.
Are provided to prevent the welding ribs 4 from dropping into the inner surface of the pack during ultrasonic welding. Also rib receiving surface 6
Is formed in a concave portion, and its lower end surface is flat.

Comparing FIG. 2 with FIG. 4, in the present embodiment, the drop-off prevention rib 7 is unnecessary, and at the same time, the gap 8b inside the upper case 1 and the lower case 2 is also unnecessary. Instead, it has a V-shaped ultrasonic receiving rib receiving surface which is not applied in the conventional configuration.

As a result, the width c of the ultrasonic welding rib receiving surface in the present embodiment can be set to 0.7 mm, which is almost the same as the ultrasonic welding rib. On the other hand, the thickness d of the side wall of the lower case can be reduced to 0.5 mm. Looking at this in terms of the external dimensions of the battery pack, a reduction of 1.0 mm in the left-right direction and the front-back direction is possible,
The effect of miniaturization can be obtained. In addition, in a structure having the same external dimensions, the entire side wall can be thickened by an amount that can be reduced in thickness, thereby contributing to improvement in overall strength and appearance.

(Second Embodiment) FIG. 4 is a perspective view showing a state before ultrasonic welding is performed on a battery pack according to a second embodiment. The upper case 1 has an end face serving as a welding rib 1a and is ultrasonically welded to the lower case 2.
An ultrasonic director 1b having a V-shaped cross section is formed at the tip of the welding rib 1a. A notch 1c is provided adjacent to the ultrasonic director 1b, and no ultrasonic welding is performed on this portion. The lower case 2 is provided with a connecting surface 2b to which the ultrasonic director 1b of the upper case 1 is welded, and a stopper rib 2d fitted with the notch 1c. This stopper rib 2d is
It is provided on the inner surface side of the lower case 2, and a standing wall 2a is provided on the outer surface side. In response to this standing wall 2a,
The outer surface side of the welding rib 1a of the upper case 1 is cut out, and is fitted to the notch 1c of the upper case 1. The upper case 1 and the lower case 2 are fitted by the notch 1c, the standing wall 2a, and the stopper rib 2d, and are held at a predetermined position during ultrasonic welding to prevent the occurrence of displacement during ultrasonic welding. It is to prevent.

The ultrasonic director 1b of the upper case 1 has a V-shaped cross section, and its tip is melted during ultrasonic welding, and is joined to the connecting surface 2b of the lower case 2. Ultrasonic director 1b and notch 1 in upper case 1
The arrangement of “c” is set in consideration of the bonding strength between the upper case 1 and the lower case 2 required for the battery pack and the fitting strength required for ultrasonic welding. In the present embodiment, since the ultrasonic welding rib 1a has a relatively large thickness and the joining strength between the upper case 1 and the lower case 2 is high, the stopper rib is taken into consideration in consideration of workability during ultrasonic welding and the like. The ratio of the fitting portion composed of 2d and the cutout portion 1c is increased.

FIG. 6 is a diagram showing a cross-sectional structure at a welding portion after ultrasonic welding. The ultrasonic director 1b of the upper case 1 is welded to the connecting surface 2b of the lower case 2, and the excess material 2d, which has been solidified by the resin material in the molten state at the time of ultrasonic welding, and the direction of the stopper rib 2d and the direction of the lower case 2 It flows to the inner surface side and does not leak to the outer surface side of the battery pack along the gap between the standing wall 2a and the welding rib 1a. As described above, according to the present embodiment, by fitting the lower case and the upper case and then performing ultrasonic welding, it is possible to manufacture a battery pack having a stable and accurate welding state.

In this embodiment, the connecting surface 2b of the lower case is provided.
Has a V-shaped groove corresponding to the shape of the ultrasonic director 1d having a V-shaped cross section, and is ultrasonically welded in a state where both are fitted. May be applied. At this time, the stopper rib 2 and the notch 1c are fitted by the ultrasonic director 1d and the V-shaped groove. In such a configuration, since the fitting by the standing wall 2a is not required, there is no need to provide the standing wall 2a, and the thickness of the lower case 2 corresponding to the standing wall 2a can be reduced.

[0028]

As described above, according to the structure of the present invention, it is possible to stably join and integrate the divided cases constituting the battery pack with a required joining strength. Its industrial value is great because it allows weight reduction to be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a battery pack according to a first embodiment.

Fig. 2 Enlarged view of the ultrasonic welding part

FIG. 3 is an enlarged view of the ultrasonic welding rib and a receiving surface portion.

FIG. 4 is an enlarged view of an ultrasonic welding portion in a battery pack having a conventional configuration.

FIG. 5 is a perspective view showing a configuration of a battery pack according to a second embodiment before ultrasonic welding.

FIG. 6 is a cross-sectional view showing a configuration of a welding portion after the ultrasonic welding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper case 2 Lower case 3 Battery block 4 Ultrasonic welding rib 5 Energy director 6 Ultrasonic welding rib receiving surface

Continuing on the front page (72) Inventor Rinnobu Ohno 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Reference) 5H040 AA03 AS11 AY08 CC05 CC13 JJ03

Claims (3)

[Claims] 1. A battery and a wiring circuit are housed in a housing composed of a split type resin case, and opposed joining surfaces of the divided case are joined by ultrasonic welding of welding ribs provided on the joining surface. One divided case has a rib having a V-shaped cross section at the tip of a welding rib, and the other divided case has a V-shaped groove into which the V-shaped rib is fitted. A battery pack characterized in that the V-shaped rib and the V-shaped groove are fitted and ultrasonically welded. 2. A battery and a wiring circuit are housed in a divided resin housing, and opposed surfaces of the housing are joined and integrated by ultrasonic welding of welding ribs provided on the joined surfaces. Wherein at least one of the divided cases has a welding rib portion ultrasonically welded to the joining surface of the other divided case, and a stopper rib portion fitted to the joining surface, A battery pack characterized in that the welding ribs and the stopper ribs are alternately arranged on the welding ribs. 3. A battery and a wiring circuit are housed in a housing composed of a split type resin case, and opposing joint surfaces of the split case are joined by ultrasonic welding of welding ribs provided on the joint surface. An integrated battery pack, wherein at least one of the split cases has a welding rib portion that is ultrasonically welded to a bonding surface of the other split case and a stopper rib portion that is fitted to the bonding surface. A rib having a V-shaped cross section is formed at the tip of the welding rib portion, and the V-shaped rib is fitted into a V-shaped groove formed on the joint surface of the other split case facing and ultrasonically welded. A battery pack characterized in that: