JP2008130404A - Battery protector and protection method of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuse with a plurality of types of membrane resistances with different membrane resistance values only by manufacturing a fuse with one type of a membrane resistance by using one type of resistance paste as a battery protector formed by providing a fuse element interposed between a battery group with the number of cells n (n≥2) or less and a load circuit, and the membrane resistance which fuses the fuse element by the heat generated by energizing and generating heat by a battery group voltage at an abnormal time of the battery on a surface of a substrate. <P>SOLUTION: A resistance value of a total length of the membrane resistance 5 is set with respect to a battery voltage with the number of cells n. A head electrode 51 is provided on a membrane resistance end. A tap electrode 52 is provided in an intermediate position of the membrane resistance which achieves a resistance value corresponding to the battery voltage in response to the number of battery cells (less than n), and a lead conductor 71 or 72 is held on the head electrode 51 or the one tap electrode 52 selected for obtaining the resistance value corresponding to the number of cells of the battery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a protector for a secondary battery used as a power source for a portable device such as a notebook personal computer.

Resistive fuses are used to shut off between the secondary battery and the load when a secondary battery used as a power source for a portable device such as a notebook computer is abnormal, for example, when overcharged.
FIG. 5 (a) shows an example of a conventional fuse with resistance, and FIG. 5 (b) shows an equivalent circuit diagram of the resistor fuse.
In FIG. 5, 1 ′ is a heat-resistant insulating substrate, for example, a ceramic plate, 21 ′ and 22 ′ are film-shaped fuse end electrodes, 23 ′ is a film-shaped fuse intermediate electrode, and 3 ′ is fuse both-end electrodes 21 ′ and 22 ′. And a fuse element (low melting point soluble alloy piece) connected to the fuse intermediate electrode 23 ′, 51 ′ is a film-like film resistance electrode, and 5 ′ is between the film resistance electrode 51 ′ and the fuse intermediate electrode 23 ′. The film resistors 61 ′ and 62 ′ are connected to the fuse end electrodes 21 ′ and 22 ′, and 71 ′ is a lead conductor connected to the film resistance electrode 51 ′.
The film resistor 5 'is formed by printing and baking a resistance paste, and the film electrodes 21', 22 ', 23' and 51 'are formed by printing and baking a conductive paste.
FIG. 6 shows a battery-load circuit using the above-mentioned resistor-equipped fuse as a protector, and a circuit fuse can be constantly passed through the fuse element 3 ′ between the resistor-fused P ′ between the battery E ′ and the load circuit Z ′. A control circuit S ′ that detects an abnormality of the battery E ′ and transmits a transistor operation signal, and a transistor Tr ′ that is turned on by this signal to cause the resistor 5 ′ of the resistor-equipped fuse P ′ to generate heat. It has been added. (For example, see Patent Document 1)

  In the state shown in FIG. 6, if the load circuit is switched to the charger V ′ to charge the battery E ′ and overcharge occurs, an overvoltage occurs in the battery E ′, and the abnormality detection element of the control circuit S ′ For example, a reverse voltage higher than the breakdown voltage acts on the Zener diode D ′, a base current flows through the transistor Tr ′, a collector current flows according to the base current, and the film resistance 5 ′ generates heat, The fuse element 3 ′ of the fuse P ′ with resistance is melted and the battery E ′ and the charger V ′ are disconnected. At the same time, the film resistor 5 ′ of the fuse P ′ with resistance is cut off from both the battery E ′ and the charger V ′ by the fusing of the fuse element portions 3a ′ and 3b ′, and the conduction heat generation of the film resistor 5 ′ is stopped. .

JP-A-7-153367

In the above, when the resistance value of the film resistance of the fuse with film resistance is R, the number of battery shells is n, and the battery voltage per cell is V, the energization heat generation amount W of the film resistance is W = n ² V ² / R
Given in.
As described above, the film resistance is formed by printing and baking the resistance paste, and the resistance base is a mixture of a resistance powder such as metal oxide powder or carbon powder, a binder such as glass powder, and a solvent such as water. When the printed fired film is heated to a specific temperature, for example, 800 ° C., it is thermally degraded and broken.
Therefore, the melting point of the fuse element is selected and the resistance value R of the film resistance is set so that the fuse element can be blown when the film resistance temperature becomes about 600 ° C., for example. For example, the resistance value R of the membrane resistance is set to 20Ω for a 3-cell battery, and the resistance value R is set to 40Ω for a 4-cell battery.
In this case, conventionally, a resistance paste for a resistance value of 20Ω and a resistance paste for a resistance value of 40Ω have different compositions, and a common printing / baking apparatus is used to form a film resistance having the same film thickness and the same pattern. Yes.

However, in such a correspondence, when the number of battery cells is varied, it is necessary to increase the types of resistance paste, which is difficult to manage.
For example, it is conceivable to use one type of resistance paste for 20Ω and trim the resistance value of the film resistance to 40Ω by trimming. It is inevitable that the fuse element will not be blown, and this trimming part will reach the above-mentioned heat deterioration break temperature (800 ° C.), the heat deterioration break will stop, the heat generation of the film resistance will be stopped, and the fuse element will not be blown. Arise.

  An object of the present invention is to provide a fuse element interposed between a battery group having n cells or less (n ≧ 2) and a load circuit, and to generate current by heat generated by the battery group voltage when the battery is abnormal. As a battery protector with a film resistor that melts the element on the surface of the substrate, multiple types of film resistors with different film resistance values can be obtained by manufacturing only one type of fuse with one type of resistor paste. The purpose is to provide a fuse.

The battery protector according to claim 1 is configured such that a fuse element interposed between a battery group having n cells or less (n ≧ 2) and a load circuit and a heat generated by the battery group voltage when the battery is abnormal. The film resistance for fusing the fuse element is provided on the surface of the substrate, the total resistance of the film resistance is set for the battery voltage of the number of cells n, and the head electrode is connected to the end of the film resistance. A head electrode selected to obtain a resistance value according to the number of battery cells by providing a tap electrode at the middle position of the membrane resistance that has a resistance value corresponding to the battery voltage according to the number of battery cells (less than n) Alternatively, the lead conductor is held in one tap electrode.
According to a second aspect of the present invention, a battery protector according to claim 2 is configured to generate and heat generated by a battery group voltage when the battery is abnormal and a fuse element interposed between a battery group having n cells or less (n ≧ 2) and a load circuit. The film resistance for fusing the fuse element is provided on the surface of the substrate, the total resistance of the film resistance is set for the battery voltage of the number of cells n, and the head electrode is connected to the end of the film resistance. A tap electrode is provided at the middle position of the membrane resistance that has a resistance value corresponding to the battery voltage according to the number of battery cells (less than n), and a lead conductor is connected to each of the head electrode and the tap electrode for use. One lead conductor is selectively held according to the number of cells of the battery, and other lead conductors are cut and removed.
A battery protector according to a third aspect is the battery protector according to the first or second aspect, wherein the head electrode and the tap electrode are exposed by a through conductor on the other surface side of the substrate.
The battery protector according to claim 4 is the battery protector according to claim 1, wherein the fuse element is provided on one side of the substrate, the film resistance is provided on the other side of the substrate, and the both are communicated by a through conductor. And
The battery protector according to a fifth aspect is the battery protector according to any one of the first to fourth aspects, characterized in that the number of the intermediate positions of the film resistance is one.
According to a sixth aspect of the present invention, there is provided a battery protection method that uses the battery protector according to any one of the first to fifth aspects to protect the battery.

By selecting the one to be connected to the battery from the head electrode provided at the end of the film resistance or the tap electrode provided in the middle of the film resistance according to the film resistance value to be obtained, the film with one type of film resistance fuse is used. Several types of fuses with film resistors having different resistance values can be obtained. Accordingly, by forming the film resistance of the fuse with film resistance by using one type of resistance paste, the battery groups having different numbers of cells, that is, the batteries having different battery voltages for energizing and generating the film resistance of the film resistance fuse. Several types of film resistance fuses can be provided that can be used appropriately for groups. Thus, it is possible to simplify the production management of the fuse with film resistance.
In addition, since there is no need to adjust the film resistance by trimming, it is possible to eliminate thermal degradation breakage due to local heat generation at the film resistance trimming part without blowing the fuse element, and to guarantee the correct operation of the fuse with film resistance. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Usually, the battery voltage of a battery pack containing 3 cells is 9 to 13.5 V. In order to normally operate a fuse with a film resistance for this battery pack, it is necessary to set the film resistance value to 20Ω. On the other hand, the battery voltage of the battery pack containing 4 cells is 13.5 to 18v, and the film resistance value needs to be 40Ω in order to normally operate the fuse with film resistance for this battery pack.
An embodiment shared for the 3-cell battery and 4-cell battery will be described.
FIG. 1A is a partially cutaway top view showing an embodiment of the battery protector according to the present invention, and FIG. 1B is a cross-sectional view of FIG.
In FIG. 1, 1 is a heat-resistant insulating substrate, for example, a ceramic plate. 21 and 22 are film-like fuse end electrodes formed by printing and baking conductor paste, and 23 is also a film-like fuse intermediate electrode. 3 is a fuse element, which is connected between the fuse end electrodes 21 and 22 and the middle is connected to the fuse middle electrode 23. Usually, a low melting point soluble alloy piece having a melting point of 75 ° C. to 300 ° C. is used, and the flux 4 is applied.
Reference numeral 51 denotes a film-like resistance head electrode, 5 denotes a film resistance formed over the resistance head electrode 51 and the fuse intermediate electrode 23, and 52 denotes a tap electrode formed in the middle of the resistance 5. Reference numerals 61 and 62 denote lead conductors connected to the fuse end electrodes 21 and 22, respectively. Reference numerals 71 and 72 denote lead conductors connected to the resistance head electrode 51 and the resistance tap electrode 52, respectively.
Reference numeral 81 denotes a heat-resistant sealing plate such as a ceramic plate, and reference numeral 82 denotes an adhesive that seals between the substrate 1 and the sealing plate 81, such as an epoxy resin.

  In order to manufacture the fuse with film resistance, (a) a first step of forming the film resistance 5 by printing / baking a resistance paste, (b) each film electrode 21, 22, 23, A second step of forming 51 and 52; (c) a third step of connecting the fuse element 3 to the fuse end electrodes 21 and 22 and the fuse intermediate electrode 23 and applying flux 4; (d) lead conductors 61 and 62; It is manufactured through a fourth step of connecting 71 and 72 to each electrode, and (5) a fifth step of sealing with a sealing plate 81 and a sealing material 82.

The insulating substrate 1 may be a ceramic plate having a thickness of 100 to 1200 μm, for example, a 96% alumina ceramic plate. In addition, it is possible to use a metal base material that has been insulated. The planar dimensions of the insulating substrate are usually (3 mm to 20 mm) × (3 mm to 20 mm) square or rectangular.
The fuse element 3 may be a low melting point alloy round wire having a liquidus temperature of 75 ° C. to 300 ° C. and a diameter of 100 μm to 1200 μm, and a low melting point alloy square wire or a low melting point alloy foil having the same cross-sectional area.
The conductor paste is a mixture of conductor powder and glaze, and silver-platinum, silver-palladium, and copper can be used for the conductor powder.
For the resistance paste, for example, ruthenium oxide powder or a mixture of carbon powder and glaze can be used.
The flux is used to prevent oxidation of the low melting point soluble alloy piece and to dissolve some of the oxide film of the low melting point soluble alloy piece to facilitate the division of the molten alloy. Usually, the main component is rosin. If necessary, an activator (for example, diethylamine hydrochloride) added can be used.

  FIG. 2 shows a use state of the battery protector P according to the present invention, and a battery protector P and a control circuit S (for example, a Zener diode D and a transistor Tr) are incorporated between the load circuit Z and the battery E. Depending on the number of cells of the battery E (according to the battery voltage), the lead conductor 71 of the membrane resistance head electrode 51 or the lead conductor 72 of the membrane resistance tap electrode 52 is connected to the collector of the transistor Tr, and the high voltage side of the load Z One of the lead conductors 61 and 62 at both ends of the fuse element 3 of the fuse P with film resistance is connected to the other terminal, the other lead conductor 61 is connected to the high voltage side terminal of the battery E, and the emitter of the transistor Tr is grounded. . The lead conductor 71 of the film resistance head electrode 51 or the lead conductor 72 of the film resistance tap electrode 52 that is not connected to the collector of the transistor Tr is preferably cut off from the root.

  In FIG. 2, when an abnormal overvoltage occurs in the battery E, the Zener diode D breaks down and a base current flows through the transistor Tr. A large collector current flows along with this, and the membrane resistor 5 is energized and heated. Due to the generated heat, the fuse element 3 is melted, the load circuit Z is cut off from the battery E, and the membrane resistance of the battery protector P is cut off from the battery.

  In this case, when the number of cells of the battery E is three (or four), for example, the resistance value of the film resistor 5 of the fuse P with film resistance is set to 20Ω (or 40Ω). Therefore, the total resistance of the membrane resistor 5 is 40Ω, the lead conductor 72 of the resistance tap electrode 52 (or the lead conductor 71 of the resistance head electrode 51) is connected to the collector of the transistor Tr, and the lead conductor 71 of the resistance head electrode 51 is connected. (Or the lead conductor 72 of the resistance tap electrode 52) is cut and removed.

3A is a partially cutaway top view showing another embodiment of the battery protector according to the present invention, and FIG. 3A is a back view of the embodiment shown in FIG. On the other hand, the resistance head electrode 51 and the resistance tap electrode 52 are made to appear on the back side of the substrate as indicated by 510 and 520 by a through-hole such as a through hole, and the appearing resistance head electrode 510 depends on the number of cells in the battery group. Or a lead conductor 72 is connected to the appearing resistance tap electrode 520 as shown in FIG. 3-2, and the lead conductor 71 or 72 is connected to the collector of the transistor Tr as described above. Connected to.
In the embodiment shown in FIGS. 3A and 3B, the fuse end electrodes 21 and 22 are made to appear on the back side of the substrate by through conductors such as through holes as shown by 210 and 220. Although the lead conductors 61 and 62 are connected to 220, the lead conductors 61 and 62 can also be connected to the fuse both-end electrodes 21 and 22 on the surface side of the substrate as in the embodiment of FIG.
3A and 3B, the same reference numerals as those in FIG. 1 denote the same components.
In the embodiment shown in FIGS. 3A and 3B, the back side of the substrate 1 can be sealed and insulated.

The battery protector according to the present invention is used by being incorporated in a battery pack.
4 (a) or (b) is a partially cut-away top view showing another embodiment of the battery protector according to the present invention, and FIG. 4 (c) is FIG. 4 (a) or (b). FIG. 4 is a cross-sectional view of the lead wire 72 connected to the resistance tap electrode 52 according to the number of cells in the battery group when assembled in the battery pack, as shown in FIG. 4 (b), a lead conductor 71 is connected to the resistance head electrode 51, and the substrate 1 is sealed with a sealing cover 80, for example, an adhesive sheet, as shown in FIG. 4 (c). is there. 4, the same reference numerals as those in FIG. 1 denote the same components.
In this battery protector, the lead conductor 72 or 71 that is brought into the battery pack by the circuit shown in FIG. 2 and connected to either the resistance tap electrode 52 or the resistance head electrode 51 is the transistor Tr as described above. Connected to the collector.

  In the above embodiment, the three-cell battery and the one used for the four-cell battery are described. However, in order to share the three-cell battery, the four-cell battery, the five-cell battery,. Tap electrodes can also be provided at (n-3) locations in the middle of the membrane resistance.

  In the above embodiment, the fuse element and the film resistance are both provided on one side (front surface) of the substrate, but the film resistance is provided on the other surface (back surface) side of the substrate, and the film resistance and the electrical conduction between the fuse element are provided. Can be performed by a through conductor such as a through hole, and the membrane resistance head electrode and the tap electrode can be provided on the other side of the substrate. In this embodiment, it is necessary to provide an insulating layer also on the other side of the substrate, and the insulation on the front side and the back side of the substrate can be performed collectively by immersion coating.

1 is a view showing an embodiment of a battery protector according to the present invention. It is drawing which shows the use condition of the battery protector shown in FIG. It is drawing which shows the Example different from the above of the battery protector which concerns on this invention. It is drawing which shows the different use condition of another Example of FIGS. It is drawing which shows the Example different from the above of the battery protector which concerns on this invention. 1 is a diagram illustrating a conventional battery protector. 1 is a diagram illustrating a battery protection circuit using a conventional battery protector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation board | substrate 21, 21 Fuse both-ends electrode 23 Fuse intermediate electrode 3 Fuse element 4 Flux 51 Film resistance head electrode 52 Film resistance tap electrode 5 Film resistance 61,62 Lead conductor 71,72 Lead conductor 80 Sealing sheet 81 Sealing plate 82 adhesive

Claims (6)

A fuse element interposed between a battery group having n cells or less (n ≧ 2) and a load circuit, and a membrane resistance that heats current by a battery group voltage when the battery is abnormal and blows the fuse element by the generated heat Is provided on the surface of the substrate, the resistance value of the total length of the membrane resistance is set with respect to the battery voltage of the number of cells n, the head electrode is provided at the end of the membrane resistance, and the number of battery cells (less than n) ) Is provided with a tap electrode at the middle position of the membrane resistance, which has a resistance value corresponding to the battery voltage, and a lead conductor is attached to the selected head electrode or one tap electrode in order to obtain a resistance value according to the number of battery cells. A battery protector characterized by possession. A fuse element interposed between a battery group having n cells or less (n ≧ 2) and a load circuit, and a membrane resistance that heats current by a battery group voltage when the battery is abnormal and blows the fuse element by the generated heat Is provided on the surface of the substrate, the resistance value of the total length of the membrane resistance is set with respect to the battery voltage of the number of cells n, the head electrode is provided at the end of the membrane resistance, and the number of battery cells (less than n) ) According to the battery voltage, a tap electrode is provided at the middle position of the membrane resistance, and a lead conductor is connected to each of the head electrode and the tap electrode. A battery protector characterized by selectively holding lead conductors and cutting and removing other lead conductors. 3. The battery protector according to claim 1, wherein the head electrode and the tap electrode are exposed by a through conductor on the other surface side of the substrate. 3. The battery protector according to claim 1, wherein the fuse element is provided on one side of the substrate, the film resistance is provided on the other side of the substrate, and the both are communicated by a through conductor. The battery protector according to any one of claims 1 to 4, wherein the number of intermediate positions of the membrane resistance is one. A battery protection method comprising protecting a battery using the battery protector according to claim 1.

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