JP4596898B2 - Pack battery - Google Patents

Description

  The present invention relates to a battery pack having excellent waterproofness and cooling performance.

  It is important for the battery pack to have a waterproof structure while allowing the battery to cool efficiently. Battery packs that cannot cool the batteries efficiently will shorten their lifespan when the battery temperature rises, or when the battery temperature becomes abnormally high, stop charging / discharging and stop using electric devices. It is necessary to stop temporarily. In addition, a battery pack that cannot be housed in a case with a waterproof structure has a problem that water enters the battery from the hole of the safety valve and the battery cannot be used. In particular, a lithium ion secondary battery or the like having a large capacity cannot be used because the electrolyte leaks when water enters through the hole of the safety valve and corrodes the safety valve with a thin metal film.

  However, storing the battery in a case with a waterproof structure and efficiently cooling the battery are contradictory properties, and it is difficult to satisfy both. For example, in order to cool the battery efficiently, if a vent hole is opened in the case, water cannot penetrate into the case to make an effective waterproof structure. In addition, if the case is completely water-tightly sealed for a waterproof structure, the battery cannot be cooled efficiently. In particular, the case of a battery pack is required to have an impact strength that is not damaged by an impact. Therefore, when the case is completely sealed, the cooling of the battery becomes extremely poor.

The harmful effects caused by the rapid temperature rise of the battery can be prevented by putting a heat storage material in the case of the battery pack as described in Patent Document 1, for example. This battery pack can absorb the heat generated by the battery with a heat storage material to reduce the temperature rise. This battery pack is effective when the amount of heat generated by the battery is small. However, if the heat generation amount of the battery is large and the heat storage material does not absorb heat, there is a problem that the temperature of the battery rises. For example, a battery pack used for a power tool may be quickly charged and fully charged, and then immediately used with a large current. The battery pack becomes hot when fully charged. Therefore, if the heat storage material cannot absorb heat in this state, it cannot absorb the heat generated when discharging with a large current thereafter. The total amount of heat that can be absorbed by the heat storage material is proportional to the amount of heat storage material used. Therefore, the amount of heat storage material stored in the battery pack can be increased to increase the amount of heat storage. However, if a large amount of heat storage material is housed inside the battery pack, the battery pack becomes large and expensive, and this limits the amount of heat storage material used.
JP 2002-291670 A

  The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide a battery pack in which the battery can be housed in a case with a reliable waterproof structure while the battery is effectively cooled without limitation of the amount of cooling heat.

The battery pack of the present invention has the following configuration in order to achieve the aforementioned object.
The battery pack stores a plurality of secondary batteries 2 in a case 1. The case 1 includes an outer case 3 and an inner case 4 provided inside the outer case 3. Case 1 has inner case 4 sealed in a watertight structure, and secondary battery 2 is housed inside. Further, a hollow layer 5 is provided between the outer case 3 and the inner case 4, and a vent hole 6 that opens the hollow layer 5 to the outside is opened in the outer case 3. The battery pack ventilates the air in the hollow layer 5 to the outside through the vent hole 6 and cools the secondary battery 2 through the inner case 4.

  The case 1 can be provided with a hollow layer 5 around and on the upper surface of the inner case 4. The case 1 can include a plastic lower case 1A and an upper case 1B. The lower case 1A is integrally formed with an inner case 4 that opens upward inside the outer case 3 that opens upward, and the upper case 1B closes the upper opening of the outer case 3. By connecting to the lower case 1A, the inner case 4 of the lower case 1A can be closed by the inner lid 7. In this case, the vent hole 6 can be opened in the upper case 1B. Further, in this case, the circuit board 8 can be disposed above the inner lid 7.

  The battery pack of the present invention has an advantage that the battery can be housed in a case with a reliable waterproof structure while the battery is effectively cooled without limitation of the amount of cooling heat. In the battery pack of the present invention, the case is composed of an outer case and an inner case, the inner case is sealed in a watertight structure and the secondary battery is accommodated therein, and between the outer case and the inner case. This is because a hollow layer is provided and the air in the hollow layer is ventilated to the outside through a vent hole opened in the outer case.

  Since the battery pack with this structure houses the battery in an inner case sealed in a watertight structure, it is possible to reliably prevent water from entering the inside of the battery and prevent adverse effects such as the battery becoming unusable. Furthermore, the battery pack with this structure ventilates external air through a hollow layer provided between the outer case and the inner case, so the secondary battery is cooled via the inner case to efficiently cool the battery. it can. In particular, unlike conventional battery packs, the battery is cooled with air that ventilates the hollow layer without storing the amount of heat storage material in the case. There is. In addition, since the battery pack having this structure does not require a space for storing the heat storage material, there is also a feature that the whole can be made compact without increasing the outer shape of the case.

  Furthermore, the case of the battery pack is required to have an impact strength that is not damaged by an impact, but the battery pack of the present invention can improve the impact strength by providing the case with a two-layer structure of an outer case and an inner case. Features are also realized. In particular, since the case with a two-layer structure has improved impact resistance, the inner case can be made thinner to improve heat conduction, and the cooling efficiency of the battery can be increased. That is, the battery pack according to the present invention can improve the cooling efficiency by reducing the thickness of the inner case while improving the impact resistance with the two-layer structure of the outer case and the inner case.

  As described above, the battery pack according to the present invention has both anti-impact strength while satisfying both the case where the battery is housed in a case with a waterproof structure and the battery is efficiently cooled, which are mutually contradictory characteristics. Really ideal features that can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. However, the example shown below illustrates the battery pack for embodying the technical idea of the present invention, and the present invention does not specify the battery pack as follows.

  Further, in this specification, in order to facilitate understanding of the scope of claims, numbers corresponding to the members shown in the examples are indicated in the “claims” and “means for solving problems” sections. It is added to the members. However, the members shown in the claims are not limited to the members in the embodiments.

  The battery pack shown in the cross-sectional view of FIG. 1 and the plan view of FIG. 2 houses a plurality of secondary batteries 2 in a case 1. The case 1 includes an outer case 3 and an inner case 4 provided inside the outer case 3. The illustrated case 1 includes a plastic lower case 1A and an upper case 1B. In the lower case 1A, an inner case 4 that opens upward is integrally formed inside an outer case 3 that opens upward. The upper case 1B is connected to the lower case 1A so as to close the upper opening of the outer case 3. The opening of the inner case 4 is closed with an inner lid 7.

  As shown in FIGS. 1 and 3, the lower case 1 </ b> A is formed by integrally forming an outer peripheral wall 11 of the outer case 3 and an inner peripheral wall 12 of the inner case 4 on a single bottom plate 10. The outer peripheral wall 11 forms the outer case 3, and the inner peripheral wall 12 constitutes the inner case 4. The lower case 1A in the figure has one bottom plate 10. However, in the battery pack of the present invention, the bottom plate of the lower case can be a double bottom, and separate bottom plates can be provided for the inner case and the outer case.

  In the lower case 1 </ b> A, a gap is provided between the outer peripheral wall 11 and the inner peripheral wall 12, and the hollow layer 5 is provided between the outer case 3 and the inner case 4. The inner peripheral wall 12 of the lower case 1A serving as the inner case 4 has a size that can accommodate the battery core 9 and has a rectangular box shape that opens upward. The battery core 9 is formed in a block shape by connecting both ends of a plurality of secondary batteries 2 with lead plates 16. In the illustrated battery core 9, two sets of blocks in which four cylindrical batteries are connected in series are connected in parallel. The inner peripheral wall 12 of the lower case 1A accommodates the battery core 9 therein, and is sealed in a watertight structure by closing the opening on the upper surface in a watertight manner with the inner lid 7.

  The inner lid 7 is ultrasonically welded and watertightly connected to the opening edge of the inner peripheral wall 12 of the lower case 1A. However, the inner lid can be bonded and connected to the opening edge of the inner peripheral wall, or can be fixed by screwing to the opening edge of the inner peripheral wall via packing. The lead plate 16 of the battery core 9 connected to the electrode of the secondary battery 2 penetrates the inner lid 7 in a watertight manner and protrudes above the inner peripheral wall 12. Therefore, the inner lid 7 is provided with a slit (not shown) through which the lead plate 16 passes. The lead plate 16 is inserted into the slit, and the gap between the slit and the lead plate 16 is watertightly closed with a sealing material or the like. In the illustrated battery pack, the opening of the inner peripheral wall 12 of the lower case 1A is water-tightly closed with the inner lid 7, but the opening of the inner peripheral wall of the lower case can be water-tightly closed with the upper case. The upper case is ultrasonically welded or adhered in the same manner as the inner lid, or is screwed through a packing to close the opening of the inner peripheral wall in a watertight manner.

  The outer peripheral wall 11 is formed lower than the inner peripheral wall 12. This is because the peripheral wall 14 of the upper case 1B is connected. The outer peripheral wall 11 is also formed in a rectangular box shape that opens upward. The hollow layer 5 is provided between the inner peripheral wall 12 and the outer peripheral wall 11 with both the inner peripheral wall 12 and the outer peripheral wall 11 being quadrangular. The hollow layer 5 ventilates outside air here, and cools the secondary battery 2 accommodated inside the inner peripheral wall 12.

  The upper case 1 </ b> B is provided with a peripheral wall 14 integrally formed around the top plate 13. The peripheral wall 14 constitutes the outer case 3 by connecting the lower end edge thereof to the upper end edge of the outer peripheral wall 11 of the lower case 1A. The peripheral wall 14 of the upper case 1B and the outer peripheral wall 11 of the lower case 1A are connected by ultrasonic welding or are bonded together. However, the lower case and the upper case can be connected with screws. Since the lower case 1A has a rectangular outer peripheral wall 11, the peripheral wall 14 of the upper case 1B has a rectangular box shape. The peripheral wall 14 and the outer peripheral wall 11 are connected by ultrasonic welding or bonding with the contact edges connected to each other having the same shape.

  The upper case 1 </ b> B has a vent hole 6 for ventilating the outside air in the hollow layer 5. The upper case 1 </ b> B in the figure has slit-shaped vent holes 6 on both sides of the top plate 13. Further, the upper case 1 </ b> B in the figure has a ventilation hole 6 opened above the hollow layer 5. In this case 1, the outside air is smoothly ventilated from the hollow layer 5 to the hollow layer 5, and the secondary battery 2 housed in the inner case 4 is efficiently cooled with the outside air.

  Although the battery pack is not shown, the battery pack can be forcibly blown from the vent hole 6 in a state where the battery pack is set in the charger to effectively cool the built-in secondary battery 2. Further, the charger for forcibly blowing the battery pack forcibly supplies the outside air to one of the vent holes 6 to forcibly cool the built-in secondary battery 2. The air supplied from one vent hole 6 to the hollow layer 5 passes through the hollow layer 5 to cool the secondary battery 2 through the inner case 4, and then is exhausted to the outside from the other vent hole 6. . The battery pack in which a plurality of vent holes 6 are opened in the case 1 forcibly blows and supplies outside air from specific vent holes 6 and exhausts the internal air from the remaining vent holes 6 to efficiently recharge the secondary battery 2. Can be cooled. However, the battery pack of the present invention can also open one vent hole. Further, it is not always necessary to cool by forcedly blowing air from the vent hole, and the secondary battery can be cooled by naturally ventilating outside air from the vent hole.

  Further, the battery pack shown in the figure is provided with an integrally formed connecting convex portion 15 protruding upward from the upper case 1B and connected to an electric device. The battery pack having the connecting projection 15 can be reliably connected to a fixed position of the electric device or the charger.

  Further, as shown in FIGS. 1 and 4, the battery pack shown in the figure has a circuit board 8 disposed on the upper case 1 </ b> B. The circuit board 8 is put in the board holder 17 and fixed on the inner lid 7. The circuit board 8 is mounted with a protection circuit (not shown) for the secondary battery 2 that controls the current for charging and discharging the battery pack. The protection circuit prevents overcharge and overdischarge of each secondary battery 2 and prevents overcurrent and charges and discharges. Therefore, the protection circuit detects the remaining capacity of each secondary battery 2 and detects the voltage of each secondary battery 2 to control charging / discharging of the battery pack. Further, a circuit that detects an overcurrent of the secondary battery 2 and interrupts the current is mounted. In particular, a battery pack in which the secondary battery 2 is a lithium ion secondary battery detects each battery voltage and controls the charge / discharge current of the battery pack. However, the battery pack of the present invention does not specify a secondary battery as a lithium ion secondary battery. This is because a nickel metal hydride battery or a nickel cadmium battery can be used as the secondary battery.

  The substrate holder 17 is made of plastic in a box shape with an upper opening that can accommodate the circuit board 8. After the circuit board 8 is accommodated, the substrate holder 17 is filled with uncured liquid or paste-like plastic, and is cured to embed the circuit board 8 and electronic components in the plastic to form a waterproof structure. The circuit board 8 is connected to the secondary battery 2 via the lead plate 16. The lead plate 16 penetrates the substrate holder 17 and the inner lid 7 with a waterproof structure and is connected to the secondary battery 2. The battery pack having this structure can be waterproofed in an ideal state while the circuit board 8 is disposed outside the inner case 4. For this reason, even if water enters the case 1 from the vent hole 6, this does not cause a failure such as corrosion of the circuit board 8.

The above battery pack is assembled in the following steps.
(1) A plurality of secondary batteries 2 are connected by a lead plate 16 to form a battery core 9.
(2) The battery core 9 is housed inside the inner peripheral wall 12 of the lower case 1A.
(3) The upper opening of the inner peripheral wall 12 of the lower case 1A is closed with the inner lid 7. The inner lid 7 is ultrasonically welded and connected to the upper edge of the inner lid 7 in a watertight manner. In this state, the secondary battery 2 is housed in the inner case 4 in a watertight structure.
(4) The substrate holder 17 and the circuit board 8 are set on the inner lid 7, and the lead plate 16 of the battery core 9 is connected to the circuit board 8.
(5) The substrate holder 17 is filled with an uncured plastic liquid and cured. The uncured plastic liquid is filled so as to completely embed the circuit board 8 and the electronic components mounted thereon.
(6) The upper case 1B is placed on the lower case 1A, and the lower edge of the peripheral wall 14 of the upper case 1B is ultrasonically welded to the upper edge of the outer peripheral wall 11 of the lower case 1A. In this state, the upper case 1 </ b> B and the lower case 1 </ b> A are connected, and the outer case 3 is provided outside the inner case 4.

It is sectional drawing of the battery pack concerning one Example of this invention. It is a top view of the battery pack shown in FIG. It is a disassembled perspective view of the lower part of the battery pack shown in FIG. It is a disassembled perspective view of the upper part of the battery pack shown in FIG.

Explanation of symbols

1 ... Case 1A ... Lower case
DESCRIPTION OF SYMBOLS 1B ... Upper case 2 ... Secondary battery 3 ... Outer case 4 ... Inner case 5 ... Hollow layer 6 ... Vent hole 7 ... Inner lid 8 ... Circuit board 9 ... Battery core 10 ... Bottom plate 11 ... Outer peripheral wall 12 ... Inner peripheral wall 13 ... Top plate 14 ... Peripheral wall 15 ... Connection convex part 16 ... Lead plate 17 ... Board holder

Claims (3)

A battery pack in which a plurality of secondary batteries (2) are stored in a case (1), the case (1) being provided inside the outer case (3) and the outer case (3) (4)
The inner case (4) is sealed in a watertight structure, and the secondary battery (2) is stored inside.
Further, a hollow layer (5) is provided between the outer case (3) and the inner case (4), and a vent hole (6) for opening the hollow layer (5) to the outside is provided in the outer case (3). opening to, Ri Na so as to cool the secondary battery (2) via the inner case (4) and ventilated hollow layer through the vent holes (6) of air (5) to the outside,
The case (1) includes a plastic lower case (1A) and an upper case (1B), and the lower case (1A) is inside the outer case (3) that opens upward, and the inner case (4 ) Are integrally molded,
The upper case (1B) is connected to the lower case (1A) so as to close the upper opening of the outer case (3), and the inner case (4) of the lower case (1A) is connected to the inner lid (7 ) Packed battery that is blocked. Battery pack as described in claim 1 which opens a vent hole (6) in the upper case (1B). Battery pack as described in claim 1 above the inner lid (7) are arranged a circuit board (8).

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