JP5031347B2 - Battery pack - Google Patents

Description

  The present invention relates to a chargeable / dischargeable nonaqueous electrolyte secondary battery, specifically a lithium ion secondary battery, which is mainly used as a power source for portable electronic devices such as a video camera, a mobile computer, a mobile phone, etc. It relates to the battery pack stored in the box.

  In recent years, as power sources for portable electronic devices such as video cameras, mobile computers, and mobile phones, which are rapidly spreading, chargeable / dischargeable rectangular parallelepiped nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries are mainly used. It has been. A lithium ion secondary battery is composed of an electrode group in which a positive electrode and a negative electrode are wound through a separator, and a nonaqueous electrolyte, which are made of aluminum or an aluminum alloy and housed in a rectangular parallelepiped case.

  On one side of this lithium ion secondary battery (unit cell), a protection circuit for controlling the battery voltage to prevent overcharge and overdischarge, and power is taken out from the unit cell or from the outside. A battery core is configured by arranging a circuit board having an external output terminal for capturing. The battery core is attached to an electronic device as a battery pack in a state of being housed in an insulating case made of, for example, a synthetic resin. The protective circuit board and the unit cell are electrically connected by a connecting lead plate.

In Patent Document 1, a box-shaped case integrally formed with a mold accommodates a battery core in which a protection circuit board is arranged vertically on a rectangular flat unit cell, and then the surface of the unit cell. And the invention of a battery pack in which the two long side plates facing the case are attached with an insulating sheet.
JP 2006-164559 A

FIG. 6 is a cross-sectional view showing a state in which a case 13 for a conventional battery pack such as Patent Document 1 is manufactured by a mold 8.
The mold 8 includes a movable mold 81 and a fixed mold 82.
The movable mold 81 and the fixed mold 82 are brought into contact with each other, and polycarbonate (PC) heated to approximately 320 ° C. and melted is injected into the cavity 84 generated at this time through the runner 83 and the gate 85.
In addition, as a material of the case 13, acrylonitrile butadiene styrene (ABS) and PC / ABS which are these synthetic materials can also be used.

FIG. 7 is a cross-sectional view showing a state where the mold 8 is opened.
The mold 8 is opened, the movable mold 81 is removed, and a case 13 having a box shape with a single-sided opening in which a side plate portion is provided around the bottom plate portion is taken out.
At this time, for example, when the movable mold 81 is sag, a burr 13 a is always generated on the side plate portion of the case 13.

FIG. 8 is a partial side view showing the case 13.
A unit cell (not shown) is accommodated in the case 13, the opening of the case 13 is closed, and an insulating sheet 14 is affixed across the side plate portion where the burr 13 a is generated.
When there is a burr 13a, the insulating sheet 14 stretches and breaks at the part where the burr 13a is present, or is formed by the fixed mold portion 13b formed by the fixed mold 82 of the side plate portion of the case 13 and the movable mold 81. There is a problem that the insulating sheet 14 may be peeled off after a finished product as a battery pack is obtained without being in close contact with the movable part 13c.

  The above-mentioned problem is a problem when the movable mold portion 13c formed by the movable mold 81 of the side plate portion of the case 13 and the fixed mold portion 13b are on the same plane. It is impossible in terms of manufacturing technology to make the dimensions of the fixed mold portion 13b completely the same. Actually, one of the fixed mold portions 13b protrudes outward, and one of them is recessed inward to cause a step.

FIG. 9 is a partial side view of the case showing a case where the fixed mold portion 13b to which the end portion of the insulating sheet 14 is attached is recessed inward from the movable mold portion 13c.
In this case, when the unit 13 is accommodated in the case 13 and the opening of the case 13 is closed, and the insulating sheet 14 is pasted over the fixed mold part, the insulating sheet 14 is fixed to the fixed mold part of the case 13. There is a problem that the insulating sheet 14 may be peeled off after a finished product as a battery pack is obtained without being in close contact with 13b.
As described above, when there is a step between the movable mold portion 13c and the fixed mold portion 13b, even if a slight sag occurs on the concave mold, the sag is within the range of the step size. There is no burr in the corresponding part of the case 13, and the occurrence probability of the burr is reduced.
However, since processing is usually performed with the aim of having the same dimensions, if a step occurs as a result, the step between the movable mold part and the fixed mold part occurs in the opposite direction on the side plate part facing the case. However, it cannot always be said that burr can be reduced.

  The present invention has been made in view of such circumstances, and at least one side plate portion to which the insulating sheet of the case is attached or wound is one of a fixed mold and a movable mold of the mold, The bottom plate side portion molded on the bottom plate portion side protrudes outward from the opening side portion formed by the other mold, and the insulating sheet is configured to be stuck or wound around the bottom plate side portion. Therefore, when molding the mold, even if a sag occurs in the other mold, burr is prevented from being generated in the opening side portion of the case, and the insulating sheet is securely adhered to the bottom plate side portion. An object is to provide a battery pack that is prevented from being peeled off.

  And this invention is comprised so that the level | step-difference dimension of a baseplate side part and an opening side part may be 0.05 mm or less, Even if a sagging arises in said other type | mold at the time of metal mold | die shaping | molding, Burr is prevented from occurring in the opening side portion, the end of the insulating sheet is securely adhered to the bottom plate side portion of the case when the insulating sheet is stuck, and the insulating sheet is prevented from peeling off after the battery pack is completed. It is an object of the present invention to provide a battery pack that does not feel uncomfortable due to a step, or that the step portion becomes a knife edge and is not injured.

  The battery pack according to the first invention uses a unit cell, a battery core having an external output terminal for taking out power from the unit cell to the outside, or taking in power from outside, and a fixed mold and a movable mold of the mold. The case is formed into a box shape having a single-side opening with a side plate portion provided around the bottom plate portion, the battery core is accommodated therein, the opening of the case is closed, and at least one side plate portion of the case is covered. In the battery pack including the insulating sheet that is attached or wound around, the one side plate portion is formed by one of the fixed die and the movable die, and the bottom plate side portion that is formed on the bottom plate portion side is the other. It protrudes outside from the opening side part shape | molded by this type | mold, The said insulating sheet is affixed over the said baseplate side part, or is wound, It is characterized by the above-mentioned.

In the present invention, since the bottom plate side portion protrudes outward from the opening side portion, even if the other die sags during mold forming, the bottom plate side portion has a burr on the opening side portion of the side plate portion formed by the die. Can be suppressed, and the occurrence probability of burrs can be reduced to about half of that in the prior art. Therefore, the insulating sheet is prevented from being broken or peeled off after the product is completed due to burrs.
Further, since the bottom plate side portion to which the end portion of the insulating sheet is stuck or wound protrudes outward, the insulating sheet is securely adhered to the bottom plate side portion and is prevented from peeling off after the product is completed.

  A battery pack according to a second invention is characterized in that, in the first invention, a step size between the bottom plate side portion and the opening side portion is 0.05 mm or less.

  In the present invention, since the step size between the bottom plate side portion and the opening side portion is 0.05 mm or less, there is no sense of incongruity due to this step, and the step portion becomes a knife edge and is not injured. And the bottom plate side part protrudes too much, and the insulating sheet does not float at the movable part, and when the battery pack is attached to the portable electronic device, there is no problem such as poor fit.

According to the first aspect of the present invention, at least one side plate portion of the case to which the insulating sheet is affixed or wound has the bottom plate side portion formed by one of the fixed mold and the movable mold of the mold, The insulating sheet protrudes outward from the opening side portion formed by the mold, and the insulating sheet is configured to be affixed or wound around the bottom plate side portion. Even if this occurs, the occurrence of burrs on the opening side portion of the case is suppressed, and the probability of occurrence of burrs is substantially halved. Therefore, it is suppressed that an insulating sheet peels after completion of a product.
Furthermore, since the insulating sheet is in close contact with the bottom plate side portion, peeling off after the product is completed is suppressed.

  According to the second aspect of the invention, the step size between the bottom plate side portion and the opening side portion is configured to be 0.05 mm or less. There is no need to do. And the bottom plate side part protrudes too much, and the insulating sheet does not float at the opening side part, and when the battery pack is attached to the portable electronic device, there is no problem such as poor fit.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment.
1 is an exploded perspective view showing a battery pack 1 according to an embodiment of the present invention, FIG. 2 is an enlarged perspective view showing a case 3 provided in the battery pack 1, and FIG. 3 is a partial side view showing the battery pack 1. is there.
The unit cell 21 of the battery core 2 of the battery pack 1 is a rectangular flat plate having a length of 36 mm, a width of 34 mm, and a thickness of 5.2 mm, and is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery, for example, a positive electrode and a negative electrode An electrode group wound with a separator and a non-aqueous electrolyte are housed in a case made of aluminum or aluminum alloy. A negative electrode terminal (not shown) is provided on one side surface of the unit cell 21 via an insulating plate (not shown), and a lead attachment plate 21a is provided on the other side surface facing this. The entire unit cell 21 other than the portion where the negative electrode terminal is provided is the positive electrode (terminal).

  A double-sided adhesive fixing tape (not shown) is affixed to the side surface adjacent to the other side surface where the negative electrode terminal of the unit cell 21 is provided, and the protective circuit portion 22 is supported on the fixing tape. In this state, the first side plate portion 23a of the substrate holder 23 is adhered. The second side plate portion 23b of the substrate holder 23 is in contact with one side surface of the unit cell 21 provided with the negative electrode terminal.

A protection circuit (not shown) for preventing overcharge or overdischarge of the unit cell 21 is provided on the surface of the protection circuit unit 22 facing the unit cell 21 of the substrate 22a. On the outer surface side of the substrate 22a, positive and negative external output terminals 22b, 22b and 22b for taking out electric power to the outside and taking in electric power from outside for charging are provided by gold plating.
The first lead plate 22c connects the electrode of the substrate 22a and the negative terminal. The second lead plate 22d connects the electrode of the substrate 22a and the other side surface of the unit cell 21 via the lead mounting plate 21a.

  As shown in FIG. 2, the case 3 made of synthetic resin has window portions 32 a, 32 a, 32 a for exposing external output terminals 22 b, 22 b, 22 b of the protection circuit portion 22 to a flat plate portion (bottom plate portion) 31. The side plate part 32 provided, the side plate part 33 which opposes this, and the side plate parts 34 and 34 which adjoin these are made the box shape of one surface opening.

The side plate portion 34 includes a movable mold part (opening side part) 34a formed by a movable mold 71 of the mold 7 described later, and a fixed mold part (bottom plate side part) 34b formed by the fixed mold 72. .
As shown in FIG. 3, the fixed mold portion 34b protrudes outward from the movable mold portion 34a, and a projecting surface portion 34c is provided at a boundary portion between the movable mold portion 34a and the fixed mold portion 34b.

FIG. 4 is a cross-sectional view showing a state in which the case 3 is manufactured by the mold 7.
The mold 7 includes a movable mold 71 and a fixed mold 72.
A convex portion 71a is provided on the central side of the movable mold 71, and groove portions 71b and 71b are formed on both sides of the convex portion 71a. A concave portion 72 a is provided on the center side of the fixed mold 72.
The cavity 74 generated when the movable mold 71 and the fixed mold 72 are attached to each other is such that the fixed mold portion 34b of the case 3 formed by filling the cavity 74 with a synthetic resin protrudes outside the movable mold portion 34a. Further, the side wall portion of the recess 72a is formed to be located outside the side wall portion outside the groove portions 71b and 71b.
Into the cavity 74, a molten PC heated to approximately 320 ° C. is injected through a runner 73 and a gate 75.
Note that ABS and PC / ABS can also be used as the material of the case 3.

FIG. 5 is a cross-sectional view showing a state where the mold 7 is opened.
The mold 7 is opened, the movable mold 71 is removed, and the case 3 is taken out.
At this time, even if sagging occurs in the movable mold 71, if the step between the movable mold portion 34a and the fixed mold portion 34b, that is, within the projecting width of the projecting surface portion 34c, a burr occurs in the movable mold portion 34a. Absent.

As shown in FIG. 1, the insulating sheet 4 includes a rectangular flat portion 41 and side portions 42, 42, 43, 44, 44 that hang down from the flat portion 41.
The side portion 42 includes a first side portion 42a attached to the movable mold portion 34a and a second side portion 42b attached to the fixed mold portion 34b.

  The battery core 2 obtained as described above is housed in the case 3 with the external output terminals 22b, 22b, and 22b exposed from the windows 32a, 32a, and 32a. And the flat part 41 of the insulating sheet 4 is stuck on the exposed surface of the battery core 2, and the side parts 42, 42, 43, 44, 44 are attached to the case 3 with the windows 32 a, 32 a, 32 a exposed. Affixed along the side plate portions 34, 34, 32, 33. Thereby, the battery pack 1 is configured.

In the present embodiment, the side plate portions 34 and 34 of the case 3 to which the insulating sheet 4 is affixed have fixed mold portions 34b and 34b protruding outward from the movable mold portions 34a and 34a. Since the side portions 42 and 42 are affixed over the fixed mold portions 34b and 34b, even if the movable mold 71 is sag during molding, the movable mold portions 34a and 34a are not burred. The probability of occurrence is almost halved. Therefore, the insulating sheet 4 is prevented from being broken by the burr, and the insulating sheet 4 is prevented from peeling off after the product is completed.
Furthermore, since the insulating sheet 4 is in close contact with the fixed mold portions 34b and 34b, it is possible to prevent the insulating sheet 4 from being peeled off after the product is completed.

Below, the target step size (projecting width of the projecting surface portion 34c) between the movable mold part 34a and the fixed mold part 34b of the case 3 on the mold processing is 0.000 mm, 0.010 mm, 0.020 mm, 0.030 mm, After changing to 0.040 mm, 0.050 mm, and 0.060 mm, the side plate portion 34 adjacent to the side plate portion 34 on the right side and the side plate portion 34 adjacent to the left side toward the side plate portion 32 of the case 3 after molding. Table 1 below shows the results of measurement of the actually measured step dimensions.
The unit cell 21 is 36 mm long, 34 mm wide, and 5.2 mm thick.

In the table, a negative numerical value indicates that the movable mold part 34a of the case 3 protrudes outside the fixed mold part 34b (reverse step).
From Table 1, it can be seen that when the target step size is 0.020 mm or more and 0.060 mm or less, the actually measured step size is over 0 for both the left and right side plate portions 34 and is about 0.05 mm or less.

  By processing so that the actually measured step dimension exceeds 0 and is equal to or less than 0.05 mm, the fixed mold part 34b of the case 3 protrudes outside the movable mold part 34a, and the movable mold 71 is sagged during molding. Further, the occurrence of burrs on the movable mold portion 34b of the side plate portion 34 of the case 3 is suppressed, and the second side portion 42b is securely adhered to the fixed mold portion 34b of the case 3 when the insulating sheet 4 is applied. That is, it is reliably suppressed that the insulating sheet 4 is peeled off after completion of the step.

When the level difference is 0.05 mm or less, it has been confirmed that the level difference does not cause a sense of incongruity, and the level difference portion does not become a knife edge and cause injury. Then, the fixed mold portion 34b protrudes too much, and the first side portion 42a of the insulating sheet 4 does not float on the movable mold portion 34a, and the fit becomes worse when the battery pack 1 is attached to the portable electronic device. There is no problem.
Therefore, it is preferable to process the mold with a target step size of 0.020 mm or more and 0.060 mm or less, and it is more preferable to process the mold with 0.020 mm or more and 0.040 mm or less. By performing molding using the mold machined as described above, the actually measured step size of the case 3 obtained can be controlled to exceed 0 and 0.05 mm or less.

In the above-described embodiment, the case where the fixed mold portion 34b of the two side plate portions 34, 34 of the case 3 protrudes outward from the movable mold portion 34a is described, but the present invention is not limited to this. .
Moreover, in the said embodiment, although the case where the part by the side of the flat plate part 31 of the height direction of case 3 was shape | molded by the fixed mold | type 72 of the metal mold | die 7 was demonstrated, it is not limited to this. The portion on the opening side in the height direction of the case 3 may be molded by the fixed mold 72. Also in this case, the bottom plate side portion of the side plate portion 34 is configured to protrude outward from the opening side portion.

It is a disassembled perspective view which shows the battery pack which concerns on embodiment of this invention. It is an expansion perspective view which shows the case with which a battery pack is equipped. It is a partial side view which shows a battery pack. It is sectional drawing which shows the state which manufactures a case with a metal mold | die. It is sectional drawing which shows the state which opened the metal mold | die. It is sectional drawing which shows the state which manufactures the case for conventional battery packs, such as patent document 1, by a metal mold | die. It is sectional drawing which shows the state which opened the metal mold | die. It is a partial side view which shows a case. It is a partial side view of a case which shows the case where the stationary mold | type part to which the edge part of an insulating sheet is affixed inside the movable mold | type part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery pack 2 Battery core 21 Unit cell 21a Lead mounting plate 22 Protection circuit part 22a Board | substrate 22b External output terminal 22c 1st lead board 22d 2nd lead board 23 Board | substrate holder 23a 1st side board part 23b 2nd side board part 3 Case 31 Flat plate Part 32, 33, 34 Side plate part 32a Window part 34a Movable part 34b Fixed mold part 34c Projecting surface part 4 Insulating sheet 41 Plane part 42, 43, 44 Side part 42a First side part 42b Second side part 7 Mold 71 Movable Mold 72 Fixed mold 73 Runner 74 Cavity 75 Gate

Claims (2)

A battery core having a unit cell and an external output terminal for taking out power from the unit cell or taking in power from outside;
Using a fixed mold and a movable mold of the mold, a case that is molded into a box shape with a single-sided opening in which a side plate portion is provided around the bottom plate portion, and accommodates the battery core;
A battery pack comprising: an insulating sheet that is attached or wound around at least one side plate portion of the case after closing the opening of the case.
The one side plate portion is protruded to the outside from the opening side portion formed by the other die, with the bottom plate side portion formed on the bottom plate portion side by one of the fixed die and the movable die.
The battery pack, wherein the insulating sheet is affixed or wound around the bottom plate side portion.   The battery pack according to claim 1, wherein a step size between the bottom plate side portion and the opening side portion is 0.05 mm or less.

Images