JPH08167433A - battery pack - Google Patents

Abstract

(57) [Summary] [Purpose] To facilitate the miniaturization of battery packs.
Also, prevent the risk of burns, etc. due to the heat generated by the overcurrent protection element. [Structure] A PTC thermistor 101 is provided in a battery case 1 in a state of being enclosed in a film heat insulating material so that Joule heat of the PTC thermistor 101 due to overcurrent is less likely to be transmitted to the case 1 and the battery 4. Further, a PTC thermistor 101 is arranged between the battery 4 and the inner surface of the battery case 1 on the side of attachment / detachment of a device that supplies power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack detachably attached to a mobile phone or the like.

[0002]

2. Description of the Related Art FIG. 5 (a) is a sectional view of a battery pack, in which a cylindrical battery 2 and 3 in a battery case 1 and a PTC thermistor (positive temperature) as a protection element for preventing an overcurrent in a charging / discharging circuit. coeficient
thermistor) 101 is provided, and the PTC thermistor 10 is provided.
1 is arranged in a space formed between the cylindrical batteries 2 and 3. The PTC thermistor is made of oxide semiconductor ceramic containing barium titanate as a main component, and generates Joule heat (I ² R) to keep the temperature at a predetermined temperature (switching temperature: eg, hundreds of degrees, etc.). It has a characteristic that the electric resistance value rises sharply when it reaches several tens to several hundreds of degrees), and it is used in various products such as electric heaters.

FIG. 1B is a simplified block diagram of the charging / discharging circuit of the battery pack, and FIG. 1C is a characteristic diagram of the PTC thermistor. When the circuit is short-circuited, the PTC thermistor 101 is discharged due to the large current discharged from the battery. When the temperature rises above a predetermined temperature a ° C., the resistance value suddenly rises and the overcurrent of the battery is prevented.

Here, as shown in FIG. 5A, the PTC
Only the corners of the bottom of the thermistor 101 are brought into contact with the cylindrical batteries 2 and 3 to position and fix them so that the PTC thermistor 101 is arranged in the air layer 5. This is because the battery surface is metal and has high thermal conductivity.
Since the PTC thermistor 101 emits high heat due to Joule heat, it is prevented that the Joule heat due to overcurrent is deprived from the PTC thermistor 101, the temperature rise of the PTC thermistor 101 is prevented, and the PTC thermistor 101 does not function normally. 1 has such a structure in order to prevent the risk of burns and the like due to overheating.

[0005]

Due to the miniaturization of devices such as mobile phones for attaching and detaching the battery pack, the battery pack is also miniaturized.

FIG. 6 shows a sectional view of a miniaturized battery pack, and the prismatic battery 4 is often used for miniaturization. As can be seen from the figure, in order to arrange the PTC thermistor 101 between the prismatic battery 4 and the battery case 1, a space 5 must be provided for it, but in order to miniaturize the battery pack, the PTC thermistor 101 is required. It is necessary to make the space 5 in which 101 is arranged as narrow as possible.

However, as described above, when the battery is short-circuited for some reason and heat is taken from the PTC thermistor 101 which generates heat due to overcurrent, the PTC
Since the temperature of the thermistor 101 does not rise normally, it is dangerous because it does not function properly. Further, when the battery case is overheated due to the heat generated by the PTC thermistor, there is a risk that the battery case molded with the molding resin will be melted or burned.

[0008]

In order to solve the above problems, the present invention provides a PTC thermistor in a battery case in a state of being wrapped with a film-like heat insulating material.
The PTC thermistor's Joule heat due to overcurrent is difficult to transfer to the case and battery. The film insulation is
Paper (excluding cardboard) or asbestos is preferable because it can be made thin like a film and has a low thermal conductivity, and aramid paper is particularly preferable because it has a low thermal conductivity. Note that cardboard is not suitable because it is thick and has a relatively high thermal conductivity.

Further, according to the present invention, the PTC thermistor is arranged between the battery and the inner surface of the battery case on the side of attachment / detachment to / from the device for supplying power, so that there is no risk of burns when the device is used. In particular, by selecting the position where the attachment piece for attaching the battery pack to the device is located on the outer surface of the case that is directly above the PTC thermistor, the attachment piece is present even when the battery pack is removed from the equipment. The risk of burns can be eliminated. Further, by enclosing the PTC thermistor in the film-like heat insulating material so as to be arranged between the inner surface of the case and the battery as described above, not only is there no fear of burns, but also the PTC thermistor due to overcurrent is removed. Makes it difficult for Joule heat to transfer to the case and battery.
The film heat insulating material is preferable because paper (excluding cardboard) or asbestos can be thinly formed in a film shape and has low thermal conductivity, and aramid paper is particularly suitable because it has low thermal conductivity.

Not only PTC thermistors made of oxide semiconductor ceramics containing barium titanate as a main component, but also those having the characteristic of generating Joule heat and rapidly increasing the electric resistance value when reaching a predetermined temperature. If so, it can be used in the present invention.

Summarizing the above, the present invention is as follows. : A battery pack comprising a battery in a case and a charging / discharging circuit interposing a protective element that generates Joule heat and suddenly increases an electric resistance value at a predetermined temperature or higher to prevent an overcurrent. A battery pack, which is provided in a case in a state of being wrapped in a heat insulating material.

In a battery pack having a battery inside a case and a charging / discharging circuit having a protection element for preventing Joule heat, which causes an electrical resistance value to rise sharply at a predetermined temperature or higher to prevent overcurrent, A battery pack, wherein the element is arranged between the inner surface of the case and the battery on the side of attachment / detachment of a device that supplies the battery. : The battery pack according to claim 1, wherein an engaging piece for attaching the battery pack to the device is provided on an outer surface of the case that is directly above the element arrangement portion.

[0013]: A battery pack according to the above item, wherein the element is enclosed in a film-like heat insulating material and is arranged between the inner surface of the case and the battery.

The film-like heat insulating material is paper (excluding cardboard) or asbestos,
Battery pack described.

[0015]: The battery pack according to the above, wherein the film-shaped heat insulating material is aramid paper.

[0016]

According to the above-mentioned items (1) to (3): The heat generated by the protective element is hardly transmitted to the battery case and the battery by the heat insulating material, and the temperature of the protective element rises normally. Therefore, the air layer surrounding the protection element can be narrowed, or the case, the protection element, and the battery can be brought into contact with each other via the film-shaped heat insulating material,
It is easy to downsize the battery pack. In addition, melting of the battery case can be prevented, and the risk of burns can be prevented.

Since the heat generated by the protective element heats the part of the battery case that is attached to and detached from the device, it is difficult to be transmitted to the part exposed to the outside. Therefore, since the risk of burns or the like can be prevented when the battery pack is attached to the device, the inner surface of the case and the protective element can be placed close to each other in the case, and the battery pack can be easily miniaturized.

The heat generated by the protective element is not easily transmitted to the engaging piece, and since the engaging piece is located above the heat generating position, there is no risk of burns or the like even when the battery pack is removed from the device. Therefore, the inner surface of the case and the protective element can be brought close to each other, and the battery pack can be easily downsized.

In addition, by wrapping the protective element in a film-like heat insulating material, it becomes difficult for the heat generated by the protective element to be transmitted to the battery and the battery case, so that not only the fear of burns can be prevented but also the protective element can be normally heated. To rise. Therefore, the air layer surrounding the protection element can be narrowed, or the case, the protection element, and the battery can be brought into contact with each other through the film-shaped heat insulating material, so that the battery pack can be easily downsized. Also, melting of the case can be prevented.

:, Both, paper (excluding cardboard)
Alternatively, asbestos has a low thermal conductivity and can be formed into a thin film, so that it does not hinder the miniaturization of the battery pack. : Aramid paper is particularly effective because it has a low heat conductivity and a high effect of preventing heat conduction to the battery and battery case.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a battery pack showing a first embodiment of the present invention. Inside the battery case 1 is a PTC thermistor 10 wrapped in a prismatic battery 4 and aramid paper 6.
1 is provided. Aramid paper is
It is widely known as an invention of DuPont, and is used as an insulating material for transformers.
It is used for various purposes due to its chemical properties. As the film heat insulating material constituting the present invention, thin and low thermal conductivity paper (excluding cardboard) or asbestos can be used, but aramid paper having particularly low thermal conductivity is the most suitable film heat insulating material. As described in this example. Table 1 is a thermal conductivity comparison table between aramid paper, which is published by DuPont in its product catalog, and other materials that are considered to have low thermal conductivity, and it can be seen that the thermal conductivity of aramid paper is low.

[0022]

[Table 1]

2A, 2B and 2C relate to the second embodiment of the present invention, and FIG. 2A is a side view of a mobile phone,
(B) is a side view showing a method of attaching the battery pack to the main body of the mobile phone, (c) is a perspective view of the battery pack, and the battery pack 12 first has an engaging portion (not shown) on the lower end side on the main body 11 side. When the upper end side is tilted toward the main body 11 side, the engaging portion 14 at the tip of the elastic piece 13 provided at the upper end fits into the main body 11 and is attached to the mobile phone main body 11 by the force of the elastic piece 13. In this installed state,
Almost half of the battery pack 12 is the mobile phone body 11
Hide inside.

FIG. 3 is a sectional view of the case of the battery pack according to FIG. 2, in which the hatched areas between the dotted lines A and B and the battery case 1 are the PTC thermistor 10 respectively.
The PTC thermistor 101 is arranged between the battery and the back surface of the case in this mounting area of No. 1.
The hatched area between the dotted line A and the case 1 is the detachable side hidden inside the mobile phone body 11, and an example of disposing the PTC thermistor 101 in this area is shown in FIG. Also,
The shaded area between the dotted line B and the case 1 is directly below the elastic piece 13 that engages with the mobile phone body 11 provided in the battery pack 12, and the PTC thermistor 1 is located in this area.
An example of arranging 01 is shown in FIG. FIG. 4A is a cross-sectional view of the battery pack according to FIG. 2, in which the PTC thermistor 101 is wrapped with aramid paper 6 on the bottom side of the battery case 1 and between the rectangular battery 4 and the inner surface of the case 1. In the example of the arrangement, in the present embodiment, the bottom side is the detachable side hidden inside the mobile phone body 11, so that the heat generated by the PTC thermistor 101 does not reach the exposed portion. In this embodiment, aramid paper 6
Since the PTC thermistor 101 is wrapped in, the prismatic battery 4 and the inner surface of the battery case 1 are made of aramid paper 6
The PTC thermistor 101 is sandwiched through the PTC thermistor 101, and even with this structure, the PTC thermistor 101 can generate heat to normally raise the temperature and reliably prevent an overcurrent.
In the figure, 15 is a charging terminal, 16 is a power supply terminal, 17 is a circuit board, and 18 is a conductive wire.

FIG. 4B is a cross-sectional view of another battery pack according to FIG. 2, in which the PTC is located directly below the elastic piece 13.
In the example in which the thermistor 101 is wrapped with the aramid paper 6 and arranged between the rectangular battery 4 and the inner surface of the case 1, the position where the elastic piece 13 for mounting the battery pack 12 on the mobile phone body 11 is arranged is shown. Select and P
Since the TC thermistor 101 is arranged on the inner surface of the battery case 1, the battery pack 12 is attached to the main body 11 of the mobile phone.
Even if the PTC thermistor 101 is short-circuited in the state where it is removed from the PTC thermistor 101 and the PTC thermistor 101 generates heat, the elastic piece 13 is interposed therebetween, so that there is no fear of burns or the like. Also in this embodiment, since the PTC thermistor 101 is wrapped with the aramid paper 6, the PTC thermistor 101 is sandwiched between the prismatic battery 4 and the inner surface of the battery case 1 with the aramid paper 6 interposed therebetween. In addition, the PTC thermistor 101 generates heat and the temperature can be raised normally, and overcurrent can be reliably prevented. In the PTC thermistor 101, a conductive wire 18 shown by a dotted line is connected to the circuit board 17 through the side surface of the prismatic battery 4.

As described above, since a film-like heat insulating material such as aramid paper is used without requiring a special heat insulating structure, the battery pack can be easily miniaturized.

[0027]

By wrapping the protective element for preventing overcurrent in the film-like heat insulating material and providing it in the battery case, the protective element generates heat and the temperature rises normally, so that the overcurrent can be surely prevented. No special heat insulation structure is required, the space required for arranging this protective element in the battery case can be reduced, the battery pack can be easily miniaturized, and the battery case can be prevented from melting.
Also effective in preventing burns.

Further, by disposing the protective element for preventing overcurrent between the battery and the inner surface of the case on the side of attachment / detachment to / from the device for supplying power, the risk of burns or the like is eliminated when the device is attached to the device. The gap between the protective element and the inner surface of the battery case can be narrowed, a special heat insulating structure is not required, and the battery pack can be easily downsized. Furthermore, the outer surface of the case, which is directly above the protective element placement part that prevents overcurrent, is equipped with an engaging piece for attaching the battery pack to the device, eliminating the risk of burns and the like even when removed from the device. be able to. In such a battery pack, the above-mentioned effects can be further enhanced by providing the protective element for preventing overcurrent in the battery case in the state of being wrapped with the film-shaped heat insulating material.

[Brief description of drawings]

FIG. 1 is a sectional view of a battery pack showing a first embodiment of the present invention.

2 (a), (b) and (c) relate to a second embodiment of the present invention, (a) is a side view of a mobile phone, and (b) is a method for attaching a battery pack to the mobile phone body. The side view shown, (c) is a perspective view of a battery pack.

FIG. 3 is a sectional view of the case of the battery pack according to FIG.

4A and 4B are cross-sectional views of a battery pack showing different embodiments according to FIG. 2 respectively.

FIG. 5 shows a conventional example, (a) is a cross-sectional view of a battery pack, (b) is a simplified block diagram of a charge / discharge circuit of the battery pack, and (c) is a characteristic diagram of a PCT thermistor.

FIG. 6 is a cross-sectional view of a miniaturized battery pack showing a conventional example.

[Explanation of symbols]

1: Battery case 2, 3: Cylindrical battery 4: Square battery 5: Space 6: Aramid paper 11: Mobile phone body 12: Battery pack 13: Elastic piece 14: Engagement part 15: Charging terminal 16: Power supply terminal 17 : Circuit board 18: Conductive wire 101: PTC thermistor

Claims (3)

[Claims] 1. A battery pack comprising: a battery in a case; and a charging / discharging circuit having a protection element that generates Joule heat and that suddenly increases an electric resistance value at a predetermined temperature or more to prevent overcurrent. A battery pack, wherein the device is provided in a case in a state of being wrapped in a film-like heat insulating material. 2. A battery pack provided with a battery in a case, and a charging / discharging circuit interposing a protective element which generates Joule heat and suddenly increases an electric resistance value at a predetermined temperature or higher to prevent an overcurrent. A battery pack, wherein the element is arranged between an inner surface of a case and a battery on an attachment / detachment side of a device that supplies power. 3. The battery pack according to claim 2, wherein an engaging piece for attaching the battery pack to the device is provided on an outer surface of the case which is directly above the element arrangement portion.