(19)
(11)EP 3 525 309 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
04.11.2020 Bulletin 2020/45

(21)Application number: 19163089.6

(22)Date of filing:  06.09.2005
(51)International Patent Classification (IPC): 
H02H 7/18(2006.01)
H01H 85/46(2006.01)
H02J 7/00(2006.01)

(54)

PROTECTION CIRCUIT

SCHUTZSCHALTUNG

CIRCUIT DE PROTECTION


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR

(30)Priority: 04.10.2004 JP 2004291756

(43)Date of publication of application:
14.08.2019 Bulletin 2019/33

(62)Application number of the earlier application in accordance with Art. 76 EPC:
05778471.2 / 1798833

(73)Proprietor: Dexerials Corporation
Tokyo 141-0032 (JP)

(72)Inventors:
  • FURUUCHI, Yuji
    Kanuma-shi, Tochigi 322-8502 (JP)
  • FURUTA, Kazutaka
    Kanuma-shi, Tochigi 322-8502 (JP)
  • KAWAZU, Masami
    Kanuma-shi, Tochigi 322-8502 (JP)

(74)Representative: TBK 
Bavariaring 4-6
80336 München
80336 München (DE)


(56)References cited: : 
EP-A2- 1 289 096
US-B1- 6 208 117
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    TECHNICAL FIELD



    [0001] The present invention relates to a protection circuit which protects a battery pack from overcurrents and overvoltages using a protection device having heating resistors and fuse elements provided on a circuit board.

    BACKGROUND ART



    [0002] As mobile electronic devices such as cellular telephones or notebook PCs have been widely used, the lithium-ion battery market has been expanded. These mobile electronic devices typically employ a battery pack, as its power supply, which has one to four lithium-ion batteries connected in series. Such a battery pack may ignite or cause smoke when the lithium-ion battery is overcharged (i.e., becomes under an overvoltage) during recharging, and is thus provided with a protection circuit to avoid overcharges.

    [0003] This protection circuit is required to protect the batteries from both overcurrents and overvoltages. To this end, employed is a protection circuit which includes a protection device having heating resistors and fuse elements provided on a circuit board, and a sensing device for detecting an overvoltage and switching a current flowing into the protection device. This protection circuit is designed such that the fuse element is melted in an overcurrent condition, while in an overvoltage condition, the sensing device allows a current to suddenly flow through the heating resistor, thereby causing the heating resistor to generate heat by which the fuse element is melted (Patent Document 1).

    [0004] Patent Document 1: JP 2 790 433 B2

    [0005] In recent years, as the market for mobile electronic devices that operate on a large current has been expanded, such a battery pack has come into use that operates at a rated voltage for about 10 serially connected lithium-ion batteries, which is well over previous rated voltages for four or less serially connected lithium-ion batteries.

    [0006] On the other hand, in the aforementioned battery pack protection circuit, the voltage applied across the heating resistor of the protection device is dependent on the number of serially connected batteries that are included in the battery pack. Accordingly, to ensure that the fuse element of the protection device is melted in an overcharge condition, a lineup of protection devices has to be prepared each of which is provided with a heating resistor having an appropriate resistance value for each number of serially connected batteries. However, now that battery packs have a variety of voltage ratings for four or less to about ten serially connected lithium-ion batteries, this has become problematic due to an increase in costs or prices resulting from many different protection devices being produced.

    [0007] For example, in a protection circuit 1X of Fig. 6 and a protection circuit 1Y of Fig. 7, suppose that protection devices 2A and 2B each include heating resistors 3 and fuse elements 4 which are provided on a circuit board, its operable power is 10 to 20W, one battery 6 within a battery pack 5 has the maximum voltage of 4V, and a voltage sensing IC 8 and an FET 9 are provided as sensing means 7. In this case, the protection devices 2A and 2B have to be prepared such that the heating resistor 3 has the resistance values of Table 1 for each number of serially connected batteries 6 that are included in the battery pack 5.
    [Table 1]
    Number of serially connected batteriesResistance value (Ω)
    1 0.8 - 1.6
    2 3.2 - 6.4
    3 7.2 - 14
    4 13 - 26
    5 20 - 40
    ... ...
    10 80 - 160


    [0008] Suppose that in a battery pack 5 having ten serially connected batteries, the protection circuit 1X of Fig. 6 is formed using a 25 Ω heating resistor corresponding to a battery pack 5 having four serially connected batteries. In this case, in an overcharge condition, the voltage sensing IC 8 detects an overvoltage across the battery pack 5 resulting in a change in the gate potential of the FET 9. The power consumption W at the heating resistor 3 when a large current flows through the heating resistor 3 is given by the following equation:

    This thus amounts to 64 W, which is well beyond the operable range of from 10 to 20 W. For this reason, before the fuse element 4 is melted, the heating resistor 3 will be burned out.

    [0009] As can be seen from the foregoing, it is necessary to use such a heating resistor 3 of the protection devices 2A and 2B that has a resistance value corresponding to the voltage on the battery pack 5.

    [0010] On the other hand, a battery pack used in a mobile electronic device operating on a large current requires the protection device to include a large-current fuse element. From this point of view, a lineup of protection devices with fuse elements of various ratings is required, which has become problematic due to an increase in costs or prices of the protection device.

    [0011] Further background art is known from the document US 6 208 117 B1 relating to a battery pack and an electronic apparatus using the same, and the document EP 1 289 096 A2 relating to a battery apparatus for controlling plural batteries and a control method of plural batteries.

    SUMMARY OF INVENTION



    [0012] It is therefore an object of the present invention to provide a protection circuit which protects a battery pack from overcurrents and overvoltages using sensing means and a protection device having heating resistors and fuse elements provided on a circuit board. This protection circuit is intended to share a protection device regardless of the current rating of the battery pack or regardless of the number of serially connected batteries in the battery pack.

    [0013] The inventors have completed the present invention by finding the following facts in a protection circuit, which protects a battery pack having a plurality of rechargeable batteries connected in series from overcurrents and overvoltages, in an attempt to allow a voltage to be applied to heating resistors of the protection device within an operable range of the protection device when the protection circuit is activated due to an overvoltage. That is, (1) it is effective to allow the voltage of not the total number of serially connected batteries in the battery pack but a predetermined number of batteries to be applied to the heating resistor in an overvoltage condition. (2) In detecting an overvoltage using the sensing means, the voltage to be detected needs not always to be the voltage of the total number of serially connected batteries in the battery pack but may be the voltage of a predetermined number of serially connected batteries. It was also found that to allow the shared use of a protection device, which has a rating for normal applications, in large-current applications, the protection devices should be arranged in parallel in a plurality of stages.

    [0014] According to the present invention, there is provided a protection circuit, as defined in the claims.

    [0015]  Generally, a first aspect of the present disclosure relates to a protection circuit for protecting a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages. The protection circuit comprises: a protection device having a heating resistor and a fuse element provided on a circuit board; and sensing means for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor. The protection circuit is designed such that the fuse element is melted in an overcurrent condition, and in an overvoltage condition on any of the batteries, the sensing means switches on the current flowing into the heating resistor, thereby causing the heating resistor to generate heat and the fuse element to be melted. In particular, the protection circuit may be provided with a plurality of sensing means for detecting an overvoltage between different batteries.

    [0016] Generally, a second aspect of the present disclosure relates to a protection circuit for protecting a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages. The protection circuit comprises: protection devices each having a heating resistor and a fuse element provided on a circuit board; and sensing means for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor. The plurality of protection devices are connected in parallel. In an overcurrent condition, the fuse element is melted at each protection device. Additionally, in an overvoltage condition on any of the batteries, the sensing means switches on the current flowing into the heating resistor, thereby causing a voltage across a predetermined number of the batteries in the battery pack to be applied to the heating resistor of each protection device, the heating resistor to generate heat, and the fuse element to be melted.

    [0017] The first and second aspects of the present disclosure are each to provide a protection circuit which protects a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages. The protection circuit includes a protection device having heating resistors and fuse elements provided on a circuit board, and overvoltage sensing means.

    [0018] In the first one of these protection circuits, the sensing means senses an overvoltage to switch on a current flowing into the heating resistor of the protection device and apply a voltage to the heating resistor of the protection device. At this time, the sensed voltage is not the voltage of the total number of serially connected batteries in the battery pack but the voltage across any of the serially connected batteries. For this reason, the heating' resistor can be shared between a protection device used in a protection circuit for a battery pack having a larger number of serially connected batteries and a protection device used in a protection circuit for a battery pack having a smaller number serially connected batteries. This makes it possible to avoid producing many different protection devices, thereby reducing the manufacturing costs of the protection circuit. Furthermore, according to this protection circuit, a voltage sensing IC having a low voltage rating can detect an overvoltage on a battery pack having a high voltage rating. Here, assuming that the sensed voltage is a voltage across an individual battery between any batteries, it is possible to observe a charged condition according to a variation in the characteristics of each individual battery in the battery pack. On the other hand, in this protection circuit, a plurality of sensing means can be provided to detect an overvoltage between different batteries in the battery pack. In this case, even when such a voltage sensing IC is not available which has a high voltage rating and detects an overvoltage on the whole battery pack due to its larger number of serially connected batteries, it is possible to form a protection circuit using an existing voltage sensing IC having a low voltage rating corresponding to a battery pack having a smaller number of serially connected batteries.

    [0019] In the second one of these protection circuits, the protection devices are connected in parallel, and thus the fuse elements are also connected in parallel. For this reason, the fuse element of the protection device can be shared between a protection circuit allowing a larger current to flow through the battery pack and a protection circuit allowing a smaller current to flow through the battery pack, thereby reducing the manufacturing costs of the protection device. Accordingly, the protection circuit can be manufactured at reduced costs as a whole.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0020] 

    Fig. 1 shows a protection circuit according to one embodiment of the present invention;

    Fig. 2 shows a protection circuit according to another embodiment of the present invention;

    Fig. 3 shows a protection circuit according to an example useful for understanding the present invention;

    Fig. 4 is an explanatory view showing a conduction path where a fuse element is melted in a circuit having protection devices arranged in parallel;

    Fig. 5 is an explanatory view showing a conduction path where a fuse element is melted in a circuit having protection devices arranged in parallel;

    Fig. 6 is an explanatory view showing a problem with a conventional protection circuit; and

    Fig. 7 is an explanatory view showing a problem with a conventional protection circuit.


    EXPLANATION OF SYMBOLS



    [0021] 
    1X, 1Y:
    Conventional protection circuit
    1A, 1B, 1C:
    Protection circuit
    2A, 2B:
    Protection device
    3:
    Heating resistor
    4:
    Fuse element
    5:
    Battery pack
    6, 6-1 to 6-10:
    Battery
    7:
    Sensing means
    8, 8-1, 8-2, 8-3:
    Voltage sensing IC
    9, 9-1, 9-2, 9-3:
    FET

    DETAILED DESCRIPTION



    [0022]  Now, the present invention will be described below in more detail with reference to the accompanying drawings. In each of the drawings, like symbols indicate the same or equivalent components.

    [0023] Fig. 1 shows a protection circuit 1A according to one embodiment of the first aspect of the present invention. The protection circuit 1A protects a battery pack 5 having ten serially connected rechargeable batteries 6-1 to 6-10 from overcurrents and overvoltages, and includes a protection device 2A and sensing means 7.

    [0024] As described in the publication of Japanese Patent No. 2790433 (Patent Document 1) and Japanese Patent Laid-Open Publication No. 2000-285778, the protection device 2A is designed to have heating resistors 3 and fuse elements 4 provided on a circuit board, so that a current flows through the heating resistors 3 to generate heat thereby causing the fuse element 4 to be melted.

    [0025] The sensing means 7 includes a voltage sensing IC 8 and an FET 9. The voltage sensing IC 8 is connected so as to sense a voltage between the first battery 6-1 and the fourth battery 6-4, and output the sensed signal to the gate of the FET 9. By connecting the voltage sensing IC 8 in this manner, the voltage sensing IC 8 suitable for sensing the serial voltage of four batteries can be used to detect an overvoltage on the battery pack 5 having ten serially connected batteries. In particular, in this protection circuit 1B, the voltage sensing IC 8 is connected so as to also detect a voltage on individual batteries between the first battery 6-1 and the fourth battery 6-4. Accordingly, it is possible to detect an overvoltage on each battery even in the presence of variations in characteristics of the individual batteries accommodated in the battery pack 5 and variations in voltage on the individual batteries during charging.

    [0026] In the protection circuit 1A, an overcurrent flowing through the battery pack 5 would cause the fuse element 4 of the protection device 2A to be melted. Furthermore, an overvoltage on the battery pack 5 would cause the FET 9 to have a gate potential above a predetermined voltage and to be thereby switched on. This in turn causes a current to suddenly flow through the drain - source of the FET 9 and thus a current to suddenly flow through the heating resistor 3 of the protection device 1A, thereby causing the heating resistor 3 to generate heat and the fuse element 4 to be melted.

    [0027] Here, since the source terminal of the FET 9 is connected between the battery 6-4 and the battery 6-5 in the battery pack 5, a voltage across the heating resistor 3 under the switched-on condition is not the voltage across the battery pack 5 but a serial voltage across four batteries that is defined by the position of this connection. Thus, according to this protection circuit, the heating resistor 3 suitable for a serial voltage across four batteries applied to the heating resistor 3 under the switched-on condition can also be used to cope with an overvoltage on the battery pack 5 having ten serially connected batteries, thereby providing the protection circuit at reduced costs.

    [0028] In consideration of troubles caused by a short circuit between batteries, a voltage across as many serially connected batteries as possible is preferably applied to the heating resistor 3 under the switched-on condition. However, since there is an extremely low possibility of a short circuit between batteries, a voltage across two or more serially connected batteries may be applied to the heating resistor 3 in practice.

    [0029] Furthermore, the protection circuit 1A of Fig. 1 is provided with a resistor R between the gate and the source of the FET 9. This is because the gate potential of the FET 9 needs to be made higher to a certain extent than the source potential in order to switch on the N-channel TFT when the voltage sensing IC 8 has detected an overvoltage.

    [0030] Like the protection circuit 1A of Fig. 1, a protection circuit 1B of Fig. 2 is designed such that a voltage sensing IC 8-1 is connected so as to sense a voltage between the first battery 6-1 and the fourth battery 6-4, and a voltage sensing IC 8-2 is also connected between the remaining battery 6-5 and the seventh battery 6-7, thus providing two voltage sensing ICs. When either the voltage sensing IC 8-1 or 8-2 has sensed an overvoltage, the fuse element 4 of the protection device 2A is melted to thereby protect the battery pack 5 from being overcharged.

    [0031] That is, when there occurs an overvoltage on any one battery between the first battery 6-1 and the fourth battery 6-4, the voltage sensing IC 8-1 raises the gate potential of an FET 9-3 causing the FET 9-3 to be switched on. This in turn causes a current to suddenly flow through the heating resistor 3 of the protection device, thereby allowing the heating resistor 3 to generate heat and the fuse element 4 to be melted.

    [0032] On the other hand, when there occurs an overvoltage on any one battery between the fifth battery 6-5 and the seventh battery 6-7, the voltage sensing IC 8-2 raises first the gate potential of an FET 9-1 causing a current to suddenly flow through the drain - source of the FET 9-1 and thereby lowering the gate potential of a FET 9-2. Since this FET 9-2 is a P-channel FET, the FET 9-2 is switched on due to a drop in the gate potential, causing a current to suddenly flow through the drain - source. This raises the gate potential of the FET 9-3 causing the FET 9-3 to be switched on, thus allowing a current to suddenly flow through heating resistor 3 of the protection device. The heating resistor 3 thus generates heat to melt the fuse element 4. Here, diodes D-1 and D-2 are provided in order to prevent the raised gate potential of the FET 9-3 from being lowered via other parts of the circuit.

    [0033] Thus, according to the protection circuit 1B, the voltage sensing ICs 8-1 and 8-2 corresponding to, for example, three or four serially connected batteries can be used to perfectly prevent an overvoltage occurring on the battery pack having ten serially connected batteries. In other words, even when such a voltage sensing IC is not available which has a high voltage rating and detects an overvoltage on the whole battery pack due to its larger number of serially connected batteries, it is possible to form a protection circuit using an existing voltage sensing IC having a low voltage rating corresponding to a battery pack having a smaller number of serially connected batteries.

    [0034] Fig. 3 is a protection circuit 1C according to an example useful for understanding the present invention directed to a large-current battery pack. The protection circuit 1C is provided with four protection devices 2A in parallel, which are the same as the one described above. Accordingly, even when a large current flows into the battery pack 5 in its normal conducting condition and the fuse element 4 would be melted in a case of the protection device 2A being singly provided, the protection circuit 1C allows the conduction path to be branched into four shunts in the protection device 2A, thus preventing the fuse element 4 from being melted.

    [0035] On the other hand, in an overcurrent condition, the fuse element 4 of each protection device 2A is melted. Thus, according to the protection circuit 1C, the fuse element of the protection device can be shared between a protection circuit allowing a larger current to flow into the battery pack and a protection circuit allowing a smaller current to flow into the battery pack, thereby reducing the manufacturing costs of the protection device.

    [0036]  Suppose that in a circuit having protection devices arranged in parallel, an overcurrent causes the fuse element 4 to be melted, for example, in a way as shown in Fig. 4 or Fig. 5. In this case, there will remain conduction paths in the circuit as shown by the arrows even after the fuse element 4 has been melted. In order to prevent such a conduction path from remaining after the fuse element 4 has been melted, a rectifier element is preferably connected to the heating resistor, and thus in the protection circuit 1C shown in Fig. 3, a diode is connected to the protection device 2A. Alternatively, an FET may also be connected as the rectifier element to the protection device 2A.

    [0037] Furthermore, pursuant to the two voltage sensing IC stages provided in the protection circuit 1B of Fig. 2, the protection circuit 1C is provided with three voltage sensing IC stages, and each of voltage sensing ICs 8-1, 8-2, and 8-3 employed is suitable for sensing the voltage of two to four serially connected batteries. Each of the voltage sensing ICs 8-1, 8-2, and 8-3 senses not only the voltage across a row of batteries respectively but also the voltage on individual batteries. Thus, according to the protection circuit 1C, even when any one of the ten batteries 6-1 to 6-10 is overcharged, any one of the three voltage sensing ICs 8-1, 8-2, and 8-3 senses it, causing the FET 9-3 to be switched on. This in turn allows a serial voltage of the four batteries 6-1 to 6-4 to be applied to each heating resistor 3 of the protection device 2A, thereby causing the heating resistor 3 to generate heat and the fuse element 4 to be melted. As described above, according to the protection circuit 1C, it is possible to form a protection circuit good for a battery pack having ten serially connected batteries, by using the voltage sensing IC and the protection device which are suitable for sensing the voltage across two to four serially connected batteries.

    INDUSTRIAL APPLICABILITY



    [0038] The protection circuit according to the present invention is useful as the protection circuit for battery packs with various voltage ratings or current ratings, such as those used with cellular telephones, notebook personal computers, electric cars, or electric motorcycles. As evident from the above, the following subjects form part of the content of the present disclosure.

    [0039] According to a 1st subject, there is provided a protection circuit for protecting a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages,
    the protection circuit comprising:

    a protection device having a heating resistor and a fuse element provided on a circuit board; and

    sensing means for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor, wherein

    the fuse element is melted in an overcurrent condition, and in an overvoltage condition on any of the batteries, the sensing means switches on the current flowing into the heating resistor, thereby causing the heating resistor to generate heat and the fuse element to be melted.



    [0040] According to a 2nd subject, the protection circuit according to the 1st subject comprises a plurality of sensing means for sensing an overvoltage between different batteries, wherein in an overvoltage condition on any of the batteries, the sensing means switches on a current flowing into the heating resistor.

    [0041] According to a 3rd subject, in the protection circuit according to the 1st or 2nd subjects, in the overvoltage condition on any of the batteries, a voltage across a predetermined number of the batteries in the battery pack is applied to the heating resistor.

    [0042] According to a 4th subject, there is provided protection circuit for protecting a battery pack having rechargeable batteries connected in series from overcurrents and overvoltages,
    the protection circuit comprising:

    protection devices each having a heating resistor and a fuse element provided on a circuit board; and

    sensing means for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor, wherein:

    the plurality of protection devices are connected in parallel;

    in an overcurrent condition, the fuse element is melted at each protection device; and

    in an overvoltage condition on any of the batteries, the sensing means switches on the current flowing into the heating resistor, thereby causing a voltage across a predetermined number of the batteries in the battery pack to be applied to the heating resistor of each protection device, the heating resistor to generate heat, and the fuse element to be melted.



    [0043] According to a 5th subject, in the protection circuit according to the 4th subject, the heating resistor is connected with a rectifier element to prevent conduction resistance from remaining via the heating resistor when an overcurrent has caused the fuse element to be melted incompletely.


    Claims

    1. A protection circuit (1A, 1B) for protecting a battery pack (5) having rechargeable batteries (6-1, 6-2, ...) connected in series from overcurrents and overvoltages,
    the protection circuit (1A, 1B) comprising:

    a protection device (2A) having a heating resistor (3) and a fuse element (4) provided on a circuit board; and

    sensing means (7) for detecting an overvoltage across any of the batteries in the battery pack and switching a current flowing into the heating resistor, wherein
    the sensing means (7) includes a voltage sensing IC (8) and a FET (9), wherein
    the FET (9) is configured to flow a current through drain - source of the FET, when the sensed voltage at its gate is above a predetermined voltage, thereby causing the current flowing into the heating resistor to be switched on,
    characterised in that

    the fuse element (4) is configured to be melted in an overcurrent condition, and the sensing means (7) is configured to switch on the current flowing into the heating resistor (3) in an overvoltage condition on any of the batteries, thereby causing the heating resistor to generate heat and the fuse element to be melted, wherein

    the voltage sensing IC (8) is configured to sense a voltage across a predetermined number out of the batteries in the battery pack and each individual battery of said predetermined number out of the batteries in the battery pack, and to output the sensed voltage to a gate of the FET.


     
    2. The protection circuit according to claim 1, comprising a plurality of sensing means (7) for sensing an overvoltage between different batteries, wherein each of the sensing means (7) is configured to switch on a current flowing into the heating resistor (3) in an overvoltage condition on any of its sensed batteries.
     
    3. The protection circuit according to claim 1 or 2, wherein a voltage across a predetermined number of the batteries in the battery pack is applied to the heating resistor (3) in the overvoltage condition on any of the batteries.
     


    Ansprüche

    1. Schutzschaltung (1A, 1B) zum Schützen einer Batteriepackung (5) mit in Reihe geschalteten wiederaufladbaren Batterien (6-1, 6-2, ...) vor Überströmen und Überspannungen,
    wobei die Schutzschaltung (1A, 1B) aufweist:

    eine Schutzvorrichtung (2A) mit einem Heizwiderstand (3) und einem Sicherungselement (4), die auf einer Leiterplatte bereitgestellt sind; und

    einer Fühleinrichtung (7) zum Detektieren einer Überspannung über einer der Batterien in der Batteriepackung und Schalten eines in den Heizwiderstand fließenden Stroms, wobei

    die Fühleinrichtung (7) einen Spannungsfühlung-IC (8) und einen FET (9) umfasst, wobei

    der FET (9) konfiguriert ist, einen Strom über Drain-Source von dem FET fließen zu lassen, wenn die gefühlte Spannung an seinem Gate über einer vorbestimmten Spannung ist, wodurch bewirkt wird, dass der in den Heizwiderstand fließende Strom eingeschaltet wird,

    dadurch gekennzeichnet, dass

    das Sicherungselement (4) konfiguriert ist, in einer Überstrombedingung geschmolzen zu werden, und die Fühleinrichtung (7) konfiguriert ist, den in den Heizwiderstand (3) fließenden Strom in einer Überspannungsbedingung bezüglich einer der Batterien einzuschalten, wodurch bewirkt wird, dass der Heizwiderstand Wärme erzeugt und das Sicherungselement geschmolzen wird, wobei

    der Spannungsfühlung-IC (8) konfiguriert ist, eine Spannung über einer vorbestimmten Anzahl aus den Batterien in der Batteriepackung und jeder einzelnen Batterie der vorbestimmten Anzahl aus den Batterien in der Batteriepackung zu fühlen, und die gefühlte Spannung an ein Gate von dem FET auszugeben.


     
    2. Schutzschaltung gemäß Anspruch 1, mit einer Vielzahl von Fühleinrichtungen (7) zum Fühlen einer Überspannung zwischen unterschiedlichen Batterien, wobei jede der Fühleinrichtungen (7) konfiguriert ist, einen in den Heizwiderstand (3) fließenden Strom in einer Überspannungsbedingung bezüglich einer von ihren gefühlten Batterien einzuschalten.
     
    3. Schutzschaltung gemäß Anspruch 1 oder 2, wobei eine Spannung über einer vorbestimmten Anzahl der Batterien in der Batteriepackung in der Überspannungsbedingung bezüglich einer der Batterien an den Heizwiderstand (3) angelegt wird.
     


    Revendications

    1. Circuit de protection (1A, 1B) destiné à protéger un bloc-batterie (5) ayant des batteries rechargeables (6-1, 6-2, ...) reliées en série, contre des surintensités et des surtensions,
    le circuit de protection (1A, 1B) comprenant :

    un dispositif de protection (2A) comportant une résistance chauffante (3) et un élément fusible (4) placés sur une carte de circuit ; et

    un moyen de détection (7) destiné à détecter une surtension aux bornes de l'une quelconque des batteries du bloc-batterie et à commuter un courant circulant dans la résistance chauffante, dans lequel :
    le moyen de détection (7) comporte un circuit intégré de détection de tension (8) et un transistor FET (9), dans lequel :

    le transistor FET (9) est configuré pour faire circuler un courant à travers les drain-source du transistor FET, lorsque la tension détectée au niveau de sa grille est supérieure à une tension prédéterminée, en faisant ainsi passer le courant circulant dans la résistance chauffante,

    caractérisé en ce que :
    l'élément de fusible (4) est conçu pour être fondu dans un état de surintensité, et le moyen de détection (7) est configuré pour faire passer le courant circulant dans la résistance chauffante (3) dans un état de surtension sur l'une quelconque des batteries, en amenant ainsi la résistance chauffante à produire de la chaleur et l'élément fusible à être fondu, dans lequel :
    le circuit intégré de détection de tension (8) est configuré pour détecter une tension aux bornes d'un nombre prédéterminé de batteries du bloc-batterie et de chaque batterie individuelle dudit nombre prédéterminé de batteries du bloc-batterie, et pour délivrer la tension détectée à une grille du transistor FET.


     
    2. Circuit de protection selon la revendication 1, comprenant une pluralité de moyens de détection (7) destinés à détecter une surtension entre des batteries différentes, dans lequel chacun des moyens de détection (7) est configuré pour faire passer un courant circulant dans la résistance chauffante (3) dans un état de surtension sur l'une quelconque de ses batteries soumises à détection.
     
    3. Circuit de protection selon la revendication 1 ou 2, dans lequel une tension aux bornes d'un nombre prédéterminé de batteries du bloc-batterie est appliquée à la résistance chauffante (3) dans l'état de surtension sur l'une quelconque des batteries.
     




    Drawing

















    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description