JP2008288046A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack capable of surely stopping charge/discharge when the temperature of the battery pack is abnormally raised by battery temperature or the like. <P>SOLUTION: The battery pack is equipped with a heat sensitive body 5 changing from a non-conductive state to a conductive state when temperature of the battery pack including a secondary battery is abnormally raised; heating resistances R, R connected to the heat sensitive body 5 and the battery in series, and making flow current when the heat sensitive body is made conductive; and fuses H, H arranged in a position heated with the heating resistances R, R when current flows, connected to the battery in series, fused with the heating resistances R, R raising temperature by flow of current to shut off current. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery pack.

  The following Patent Documents 1 and 2 disclose detection of various battery abnormalities, such that secondary batteries deteriorate, characteristics of each battery greatly vary, or one of the batteries is short-circuited. The fuse connected in series to the battery is detected by being in a state where it cannot be used, and the current is passed through a heating resistor disposed at a position where the fuse can be heated, so that the fuse is thermally melted. It describes that the battery pack cannot be used. Patent Document 2 describes that the current flowing through the heating resistor is controlled to a constant current to optimize the heating current.

  Moreover, in such a battery pack, a thermistor for measuring the battery temperature is installed, and when the battery temperature becomes abnormally high, as a control means, it is connected in series with the battery by the function of a built-in protection circuit or microcomputer. Usually, charging and discharging are stopped by turning off an installed switching element.

Furthermore, in the following Patent Document 3 filed by the present applicant, a thermal sensor that changes from a non-conduction state to a conduction state when a temperature abnormal state occurs is disclosed, and the current between the battery and the input / output terminal is disclosed. When the electric signal acquired from the heat sensing element is input as a control signal to the interruption circuit inserted in the road, and the unit cell reaches an abnormal temperature in any part of the heat sensing region of the heat sensing element, A configuration is disclosed in which a cutoff circuit that receives an electrical signal in a conductive state related to the thermal result from the thermal body interrupts the current path.
Japanese Patent Laid-Open No. 9-261883 JP 2000-340267 A JP-A-2005-346943

  In the above-mentioned Patent Documents 1 and 2, by using a switching element that is switched from off to on when a battery pack including a secondary battery is in a temperature abnormal state by a built-in protection circuit, current is supplied to the heating resistor. The fuse is heated and heated to blow the fuse. However, in such a battery pack, when a failure such as a failure occurs in the protection circuit or the switching element, the fuse cannot be blown out and charging / discharging cannot be stopped.

  In addition, in the battery pack which stops charging and discharging by turning off the switching element installed in series when the battery temperature becomes abnormally high using the control means as described above. In the case where a failure such as a failure occurs in the control means and the switching element, charging / discharging cannot be stopped.

  The present invention has been made to solve such problems, and in the case where a failure such as a failure occurs in a protection circuit, a microcomputer, various switching elements, etc. as a control means in the battery pack, An object of the present invention is to provide a battery pack that can reliably stop charging and discharging when the battery pack becomes abnormally hot due to battery temperature or the like.

  The present invention provides a heat sensitive body that changes from a non-conductive state to a conductive state when a battery pack including a secondary battery is in an abnormal temperature state, and is connected in series to the heat sensitive body and the battery, and the heat sensitive body is in a conductive state. The heating resistor through which a current flows and the heating resistor through which the current flows is arranged at a position heated by the heating resistor, and is connected in series with the battery so that the current flows and the heating resistor is heated to a high temperature. And a fuse that cuts off a current that flows through the battery.

  Further, the heat sensitive body has a structure in which a heat-soluble member is interposed between a plurality of parallel conductive wires biased in a direction approaching each other, and the conductive wires are separated from each other, and the temperature abnormal state is obtained. When it reaches, the conductive wires come into close contact with each other as the heat-soluble member melts, and the heat sensitive body is configured to short-circuit the close contact between the conductive wires.

  The conductive wire includes a first metal wire and a second metal wire, and the heat sensitive body is provided with a heat-soluble member so as to cover the first metal wire, and the first The battery pack according to claim 2, wherein two metal wires are spirally wound around the surface of the heat-soluble member.

  Furthermore, the heat-soluble member is polyethylene or PET that dissolves in a range of 90 ± 10 ° C.

  Further, the battery pack includes a plurality of electrically connected unit cells, and a substantially entire region in a longitudinal direction is a heat sensitive region, and a heat sensitive result at an arbitrary portion of the heat sensitive region is obtained as an electric signal. The long heat-sensitive body which can be formed is provided in the surrounding surface across two or more of the said unit cells, It is characterized by the above-mentioned.

  In the present invention, the battery pack including the secondary battery is provided with a heat sensitive body that changes from a non-conductive state to a conductive state when the battery is in an abnormal temperature state. Since the fuse is blown, charging / discharging can be reliably stopped. As described above, in the present invention, even when a failure such as a failure occurs in the protection circuit, the microcomputer, various switching elements, etc. as the control means in the above-described conventional battery pack, the battery pack becomes abnormally hot. In this case, charging / discharging can be stopped reliably.

  FIG. 1 is a diagram showing the configuration of the battery pack 1 according to the first embodiment. In the figure, A is a tape cutout region for directly showing the heat sensitive body 5 between the tape 6 and the unit cell 2.

  The battery pack 1 includes a total of six unit cells 2 (2a to 2f), a circuit board 3, a connection member 4, input / output lines 7a and 7b, a connector 8, and the like.

  The unit cell 2 and the circuit board 3 are actually packed with PP, PE, PET film or heat-shrink film, but the film is not shown here to show the internal configuration.

  The battery pack 1 of the first embodiment has a main feature in that the heat sensitive body 5 is arranged.

  The unit cell 2 (2a to 2f) is a cylindrical alkaline secondary battery (nickel-hydrogen battery, nominal capacity 3000 mAh, 1.2 V, pack) configured in the size of a C cell (single-type battery) in a known JIS standard. An output of 7.2 V) or a lithium ion battery can be used.

  Each unit cell contains a predetermined power generation element, the positive electrode plate of the power generation element is at the positive terminal (front end in 2a), and the negative electrode plate is at the bottom of the outer can (at the rear end in 2a) Each is connected. Depending on the type of battery, the positions of the positive electrode and the negative electrode may be reversed.

    The unit cells 2 (2a to 2f) shown in FIG. 1 are provided side by side in the reverse direction for each adjacent cell, and are connected to the adjacent cells by connection members 4a to 4e.

  Among these, lead wires 7c and 7d are connected to the negative electrode of the unit cell 2a and the positive electrode of 2f, respectively. The lead wires 7 c and 7 d are connected to the external input / output lines 7 a and 7 b that also serve as the external input path and the external output path of the battery pack 1 via the circuit board 3. A connector 8 which is an input / output terminal for connecting to the external device side is attached to the distal ends of the external input / output lines 7a and 7b.

  As will be described in detail later, the circuit board 3 has a substrate made of a composite material containing a known inorganic filler and a resin composition. On the board | substrate, the predetermined | prescribed circuit element etc. which monitor the energization state of the unit cell 2 (2a-2f), and each value of a voltage and an electric current are provided. Here, the battery pack 1 is characterized in that a thermal element 5 and a resistance heating type fuse 10 are provided as a safety mechanism when the abnormal temperature of the unit cell 2 (2a to 2f) rises.

  FIG. 2 is a partially enlarged view of the heat sensitive body 5 and the unit cell (in this figure, the outer peripheral portion of 2a is shown).

  As shown in the figure, the heat sensitive element 5 operates as an abnormal temperature detection line of the unit cell 2 (2a to 2f), and as a whole, the metal wire (A line) 50, the metal line ( (B line) 51 is formed by interposing a soluble body 52 between them and separating the metal wires 50 and 51 from each other.

  As the metal wires 50 and 51, for example, single wires having a diameter of about 0.5 mm are used. Here, the metal wire 50 is a straight line, and the metal wire 51 is a spiral. Both of these metal wires 50 and 51 may be used in the form of a straight line, but both of them may be formed in a spiral shape and are not limited to this form. As a material, it is desirable to use a copper wire having excellent conductivity.

  The fusible body 52 normally maintains a solid, but is made of a material that exhibits solubility at a predetermined high temperature. Here, a general abnormal temperature of the battery is set to 90 ± 10 ° C., and a resin such as polyethylene or PET is used as a material having solubility in this temperature range. Moreover, as the soluble body 52, a sublimable temperature pellet can also be used. With this configuration, the heat sensitive area of the heat sensitive body 5 covers almost the entire area in the length direction.

  In addition, when a secondary battery is used as the unit cell 2 (2a to 2f), the temperature may rise to around 60 ° C. even during normal driving during large current discharge. Considering this, it is necessary to set a temperature range higher than this so that the thermal element 5 can detect the abnormal temperature.

  The soluble body 52 in the heat sensitive body 5 can be formed by insert molding, for example, with the metal wire 50 as a core body. Alternatively, the linear fusible body 52 may be formed in advance, a cut may be made in the radial direction along the longitudinal direction, and the metal wire 50 may be inserted into the cut portion later. An example of the size of the fusible body 52 is 1.2 mm in diameter (including the diameter of the metal wire 50). The fusible body 52 may be set to a size other than this, but is thin in order to obtain adhesion to the unit cell 2 (2a to 2f) and has a small insulation distance from the metal wires 50 and 51. It is desirable to obtain a good operation of the heat sensitive body 5.

  In the specific example shown in FIG. 2, the metal wire 51 is spirally wound around the surface of the fusible body 52 with an appropriate winding strength. At this time, it is desirable to bias the end of the metal wire 51 in the extending direction. The metal wires 50 and 51 are normally kept in an insulated state by the interposition of the fusible body 52.

  In the drawing, the structure is schematically illustrated so that the internal structure of the heat sensitive body 5 can be seen. However, in reality, a soluble body 52 and a metal wire 51 are provided over the entire heat sensitive body 5.

  The ends of the metal wires 50 and 51 are connected to the heating resistance R of the resistance heating type fuse 10 provided on the circuit board 3 and the negative side of the unit cell 2.

The heat sensitive body 5 having the above configuration is formed in a wire shape as a whole, and is arranged so as to be wound in common over the outer peripheral surface of each unit cell 2 (2a to 2f) as shown in FIG. . The heat sensitive body 5 may be wound once or more times. At this time, it is necessary to wind so that the whole heat sensitive body 5 contacts each unit cell 2 (2a to 2f) and maintains an appropriate tension. In this way, the heat sensitive body 5 is provided on the peripheral surface across at least one unit cell, preferably two or more unit cells.
However, such a heat sensitive body 5 may be disposed in contact with one unit cell, or may be disposed in a state of being thermally coupled to the unit cell without contacting. In addition, the battery pack of FIG. 1 may be provided with a resin outer case, and the battery pack of FIG. At this time, the heat sensitive body 5 may be arranged in a place where the temperature of the circuit board 3 including the unit cell or the electronic element can be detected.

  Thus, the heat sensitive body 5 arranged with respect to each of the unit cells 2 (2a to 2f) covers the tape and the tape 6 (here) so as to cover and press the unit 2 (2a to 2f). In this case, a glass tape excellent in strength and resistance is used) and is bonded to the surface of the unit cell 2 (2a to 2f) and thermally bonded.

* Block circuit diagram of FIG. 4 An embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 4, the present embodiment includes a battery pack 1 and a portable device PC that is an electronic device including a power source for charging the battery pack 1. The portable device PC is a portable personal computer such as a notebook computer. The battery pack 1 is normally structured to be detachably attached to the mobile device PC. The portable device PC is supplied with DC power output from an adapter (not shown) that converts AC commercial power from the outlet into DC power. S is provided. The power output from the control / power supply means S is used to charge the battery pack 1 or is supplied to the load L of the portable device PC. When there is no power supply from commercial power, power is supplied from the battery pack 1 to drive the power supply circuit S and the load L.

  In the battery pack 1, a secondary battery A composed of a unit cell 2 such as a lithium ion battery or a nickel metal hydride battery, a current detection unit 12 comprising a resistor or the like for detecting a current during charging / discharging of the battery A, a battery And a microprocessor unit (hereinafter referred to as MPU) that monitors and controls charging / discharging of A. In the battery pack 1, a temperature detection unit 13 including a thermistor arranged in close contact with the battery A is provided.

  In the present embodiment shown in FIG. 4, the battery A has three parallel battery cells 11, 12, 13, battery cells 21, 22, 23, and battery cells 31, 32, 33 as illustrated. Are electrically connected to each other to form blocks P1, P2, and P3, and these blocks P1, P2, and P3 are connected in series. In such electrical connection, tabs, which are flat metal pieces, are connected to the positive electrode and negative electrode of the battery cell by spot welding or the like, and are electrically connected. In the case of a lithium ion secondary battery, a battery cell having a capacity of about 2000 mAh / cell is used.

  In the MPU, the total battery voltage (measurement point d), the voltages of the blocks P1 to P3, the output from the current detection unit 12, and the analog voltage of the output from the temperature detection unit 13 are input, converted into digital signals, and the actual voltage [ An A / D conversion unit 14 is provided for conversion into mV], actual current value [mA], or the like. Then, the output from the A / D conversion unit 14 is input to a charge / discharge control / calculation unit 15 as a control means, and calculation, comparison, determination, etc. are performed, and a signal from the control / calculation unit 15 is used. The control element 17 composed of a switching transistor or the like is on / off controlled. Then, such electronic parts as MPU and control element 17 are arranged on the circuit board 3 of FIG.

  In other words, the control / calculation unit 15 calculates the remaining capacity by accumulating the charge / discharge current, detects the full charge of the battery A, or detects the abnormal current, abnormal temperature, abnormal voltage, etc. Control the discharge. The control element 7 composed of a switching transistor or the like is ON / OFF controlled, and cuts off the current with a control signal from the control / calculation unit 15 when detecting an abnormal current, abnormal temperature, or abnormal voltage. Using a well-known technique, the control / calculation unit 15 integrates the value obtained by multiplying the charging / discharging current converted by the A / D conversion unit 14 by the measurement unit time (for example, 250 msec), and is satisfied during discharge. The integrated amount is subtracted from the charge, or, at the time of charging, the integrated amount is added from the remaining capacity at the start of charging. The remaining capacity (Ah) of the battery A is calculated by such calculation. Instead of the remaining current accumulated capacity, the accumulated power (Wh) obtained by integrating the value obtained by multiplying the voltage at the time of measurement, the current, and the measurement unit time may be used as the remaining capacity.

  Further, the control / calculation unit 15 records various data in a memory. The control / arithmetic unit 15 including a CPU (Central Processing Unit) includes various memories. A program memory for storing a program for controlling the operation of the battery pack 1 is provided, and the program memory is a nonvolatile storage medium. A ROM (Read Only Memory) stores data necessary for executing the program in advance. A RAM (Random Access Memory) temporarily stores a part of a program and various data. In addition, EEPROM (Electrically Erasable Programmable ROM) or FlashMemory is provided as non-volatile memory, and EEPROM or FlashMemory needs to be saved even if software or setting data executed by the CPU or MPU shuts down. Data (for example, learning capacity, number of cycles, data at the time of abnormality, etc.) and the like are stored before shutdown, and these can be rewritten as needed.

  Further, the control / arithmetic unit 15 includes various timers and counters, and is used for time measurement, frequency measurement, and the like.

  Further, in the control / calculation unit 15, when the battery A is a nickel metal hydride battery or the like, the peak voltage is detected, the battery voltage −ΔV (= voltage drop) is detected, or the calculation is performed. It is detected by a known method such as using the remaining capacity. When battery A is a lithium-ion battery, it uses constant current (MAX current 0.5-1C) / constant voltage (MAX4.2V / cell) charging with regulated current and voltage. When the condition is below the predetermined value, the battery is fully charged. When full charge is detected, the control / calculation unit 15 outputs information indicating the remaining capacity as 100%. The full charge information can also be transmitted to the electronic device via the communication line.

  Here, the control / calculation unit 5 is a control element 17 for cutting off the charging current and the discharging current, the charging FET element 71 being a p-channel FET as the charging control element, and the discharging control element. A signal for on / off control is issued to the discharging FET element 72 which is a p-channel FET. Instead of the p-channel FET, it is also possible to use an n-channel FET charging FET element and a discharging FET element using a charge pump. 74 uses a p-channel FET.

  In the control / arithmetic unit 15, when the voltage of the battery A becomes lithium ion or higher than the overcharge voltage (for example, 4.2 V or higher), an off signal (element Since 71 is applied to the gate of the p-channel FET, the voltage of the off signal is equivalent to a high voltage signal) from the port CH. Further, when the voltage of the battery A becomes equal to or lower than the overdischarge voltage (for example, 2.7 V / Cell or lower), an off signal (the element 72 is applied to the gate of the p-channel FET) in order to turn off the discharging FET element 72. In order to apply, the voltage of the off signal is equivalent to the signal of the high voltage) from the port DSC. As described above, since the voltage is applied to the gates of the p-channel FETs of the elements 71 and 72, the voltage of the off signal corresponds to a high voltage signal, and the voltage of the on signal corresponds to a low voltage signal. . In the overcharge state, charging is stopped by the control / calculation unit 15 issuing an off signal to the port CH. At this time, when the portable device PC is discharged, the DSC is an ON signal, so that the discharging FET element 72 can be discharged through the parasitic diode 71B of the charging FET element 71 in the OFF state. Further, in the overdischarge state, the discharge is stopped by the control unit 15 issuing an off signal to the port DSC. At this time, when the portable device PC is charged, CH is an ON signal, so that the charging FET element 71 is in the ON state and can be charged via the parasitic diode 72B of the discharging FET element 72 in the OFF state.

  Further, in the battery pack 1 of the present embodiment, when the lithium ion battery A is held in the state of the overdischarge voltage or lower, the battery is preliminarily charged with the reduced current value instead of the above-described normal charging. A preliminary charging circuit 73 is provided. The preliminary charging circuit 73 includes a resistor 75 for reducing the charging current and a preliminary charging FET element 74 controlled by an on / off signal from the port PCH according to an instruction from the control / calculation unit 15. When the battery voltage at the time of disclosure of charge is equal to or lower than the overdischarge voltage, the control / calculation unit 15 issues an off signal from the port CH to turn off the charging FET element 71 by such a preliminary charging circuit 73. An on signal is issued from the port PCH to turn on the precharging FET element 74. With this operation, when a charging current is supplied from the portable device PC, the charging current is reduced by the resistor 75, and the battery A is charged through the precharging FET element 74 in the on state. If the battery voltage becomes equal to or higher than a predetermined value (for example, 3.0 V / cell) within a predetermined time (for example, 90 minutes) from the start of charging, the control / calculation unit 15 turns off the preliminary charging FET element 74. Then, the charging FET element 71 is turned on to perform normal charging as described above. In addition, if the battery voltage is less than a predetermined value (for example, 3.0 V / cell) within a predetermined time (for example, 90 minutes) from the start of charging, it is determined that the battery has deteriorated and cannot be charged normally and is abnormal. , Stop charging. Such abnormality determination result is appropriately transmitted to the mobile device PC side by communication processing.

  The MPU also includes a communication unit 9 that transmits various battery information such as battery voltage, remaining capacity, charge / discharge current value, and various command information to the control / power supply means S of the portable device PC. Communication processing between the battery pack 1 and the portable device PC is performed by the communication unit 9 as follows. The communication unit 9 includes a communication data generation unit that generates various battery information such as a battery voltage, a remaining capacity, and a charge / discharge current value as signal data that can be received by the portable device PC, and a driver unit that performs actual communication. The memory in the control / arithmetic unit 15 for storing various parameters for calculating the remaining capacity and various data is used. In addition, the driver unit receives a request for transmission of various information of the battery pack from the electronic device, and transmits the data created by the communication data creation unit to the electronic device from the driver unit. As a communication system, a well-known technique such as the SMBus system can be used, and it has a function of transmitting and receiving data signals and the like via two communication lines, a data line SDA and a clock line SCL.

  Since the battery pack 1 is used when the commercial power cannot be used such as when it is carried, the battery A is normally stored in a state close to full charge when the commercial power can be supplied to the portable device PC. Moreover, since the occurrence of a power failure is usually very small, the decrease in the remaining capacity of the battery A occurs due to the self-discharge of the battery and the power consumption in the battery pack 1. The charge / discharge control / calculation unit 15 starts recharging when the remaining capacity of the battery A reaches the recharge capacity due to self-discharge, circuit power consumption, and the like. The recharge capacity may be obtained by subtracting the integration of the current value per predetermined time from the full charge capacity, or may be obtained from the battery voltage corresponding to the recharge capacity. Further, the recharge capacity is 90%.

  In the present embodiment, the control / arithmetic unit 15 performs the following processing to obtain the remaining capacity. The control / arithmetic unit 15 discharges the battery A, subtracts the discharge capacity from the total discharge amount (= learning capacity), which is the total capacity of the battery A, which will be described later, and determines the remaining amount of the battery A as an integrated current amount or Calculated as the integrated amount (Ah). Further, the control / calculation unit 15 calculates the remaining capacity rate (%) of the battery A from the relational expression of (total capacity−integrated amount) / (total capacity) = remaining capacity rate during discharging. The charging capacity is calculated by the integrated amount of the charging current of the battery A or by multiplying this by the charging efficiency. The discharge capacity is calculated in consideration of the integrated amount of discharge current or discharge efficiency. The control / calculation unit 15 can also calculate the remaining amount by the integrated amount of electric power (Wh) instead of integrating the current. The integrated value of power is calculated by subtracting discharge power from charge power.

  Here, the total capacity (= learning capacity) of the battery at that time is the state in which the battery A is completely discharged even with the accumulated capacity (Ah or Wh) of the discharge from the fully charged state to the fully discharged state. The accumulated capacity (Ah or Wh) of charging from full charge to full charge may be used. If the total capacity can be obtained by other methods, the total capacity of the battery at that time may be used.

  As the discharge progresses, the control / calculation unit 15 corrects the remaining amount with the voltage signal input from the A / D conversion unit 14. When a signal indicating that the voltage of the battery A has reached and decreased to the first voltage is input from the A / D conversion unit 14, the control / calculation unit 5 causes the first voltage (for example, the lithium ion battery 3.6V / The calculated remaining capacity rate is corrected by a first remaining capacity (rate) Ya1 (for example, 8%) set in advance corresponding to the cell.

  That is, assuming that the first remaining capacity Ya1 is 8%, the control / calculation unit 5 causes the remaining capacity until the battery voltage of the secondary battery A decreases to the first voltage V1 when the calculated remaining capacity reaches 9%. Hold 9% as capacity. On the other hand, when the calculated remaining capacity is 9% or more and the battery voltage of the secondary battery A decreases to the first voltage V1, at that time, the control / calculation unit 5 sets the calculated remaining capacity value to 8%. To correct.

  Further, when the discharge progresses and a signal indicating that the voltage of the battery A has decreased to a predetermined discharge end voltage is input, the control / calculation unit 5 corrects the calculated remaining amount to zero. This is because when the battery voltage decreases to the discharge end voltage, the actual capacity of the battery 1 becomes 0 as the lower limit capacity. Then, the control / calculation unit 5 calculates and stores the discharge current integrated amount from the start of discharge to the discharge end voltage as a total discharge amount (= total capacity).

  After obtaining the total discharge amount (= learning capacity), the control / calculation unit 5 uses this total discharge amount until the next total discharge amount is obtained. Further, in addition to the first voltage corresponding to the first remaining capacity (rate), the calculated remaining capacity is also calculated with the second voltage corresponding to the second remaining capacity (rate) with a smaller capacity (for example, 3%). The rate may be corrected. In addition, the first voltage, discharge end voltage, etc. corresponding to the above-mentioned remaining capacity (rate) depend on the current and temperature, so it is possible to use a voltage corrected based on the current and temperature in use. is there.

* Characteristics of the present embodiment In the present embodiment, as shown in FIG. 4, the resistance heating type fuse 10 is arranged in series on the plus side of the battery A in the charge / discharge path of the battery A.

  The resistance heating type fuse 10 is generally sold, and has a structure in which heating resistors R and R connected in parallel are connected to an intermediate point between the fuses H and H, as shown in FIG. In order to cut off the fuses H and H, they are thermally coupled to the heating resistors R and R and the fuses H and H.

  The ends of the metal wires 50 and 51 of the heat sensitive body 5 are connected to the heating resistance R of the resistance heating type fuse 10 and the negative side of the battery A.

    According to the battery pack 1 having the above configuration, since the metal wires 50 and 51 of the heat sensitive body 5 are normally in an insulated state, the gap between both output end portions (end portions of the metal wires 50 and 51) of the heat sensitive body 5 is In the non-conductive state, no current flows through the heating resistor R of the resistance heating type fuse 10, and the fuse H is not thermally blown. At this time, the battery pack 1 is normally charged and discharged.

In the battery pack 1 as shown in FIG. 1, when at least one of the unit cells 2 (2a to 2f) fails and an abnormal increase in temperature occurs,
Alternatively, in the heat sensitive body 5 arranged in the outer case of the battery pack as described above, when an abnormal increase in the temperature of the circuit board 3 including the unit cell or the electronic element occurs,
As shown in FIG. 3, the heat sensitive body 5 is melted in an arbitrary part wound so as to be thermally coupled to the unit cell 2 (2 a to 2 f) where the abnormal temperature is generated or in the battery pack 1. Thus, if the soluble body 5 melt | dissolves and raise | generates a state change, the metal wires 50 and 51 will adjoin by the pressing force from the tape 6, will short-circuit, and a conduction | electrical_connection state will be reversed. That is, the two output end portions (end portions of the metal wires 50 and 51) of the heat sensitive body 5 are in a conductive state. Here, the metal wires 50 and 51 can be short-circuited even if the tape 6 is not essential when the metal wires 50 and 51 themselves are sufficiently biased in the direction of short-circuiting each other.

  When both the output end portions (end portions of the metal wires 50 and 51) of the heat sensitive body 5 are in a conductive state, a current flows from the battery A or the portable device PC to the heating resistors R and R for heating. Therefore, the heating resistors R and R generate heat, and the fuses H and H are thermally blown. Thereby, the use of the battery pack 1 can be disabled thereafter. Therefore, in this embodiment, even when a failure such as a failure occurs in the protection circuit, the microcomputer, various switching elements, etc. as the control means in the above-described conventional battery pack, the battery temperature rises or the electronic elements generate heat. For example, when the battery pack becomes abnormally hot, charging / discharging can be reliably stopped.

* 1-4. Variations of the thermal body The thermal body used in the present invention is not limited to the wire configuration shown in FIG. 2, but two or more in other forms as shown below. It only has to be formed in a long shape to the extent that it can be installed commonly in the unit cell.

  FIG. 5 is a partially enlarged view showing specific variations of other configuration examples of the heat sensitive body.

  FIG. 5A shows a configuration of a heat sensitive body in which the A line and the B line formed in a twisted line shape are close to each other and insulated by a fusible body, and both lines are held in the fusible body.

  Even when such a heat sensitive body is pressed against the unit cell with the glass tape, the fusible body melts when the abnormal temperature of the battery is generated, and the A line and the B line can be short-circuited. In particular, if the fusible body is molded in a state in which it is tightly tightened when the A line and the B line are rolled, it is considered that the short circuit can be more reliably short-circuited when the fusible body is melted. Further, if the tension applied to the A line and the B line is sufficiently strong, it is possible to detect a short circuit without providing the tape as the pressing means. In this case, the end portions of the A line and the B line are connected to the heating resistance R and the negative side of the battery A as in the above-described embodiment.

  FIG.5 (b) shows the structure of the heat sensitive body which coat | covers the A line on a straight line, and the helical B line | wire arranged with respect to this in the state insulated with the soluble body together. . Even with such a configuration, substantially the same effects as those of the first embodiment can be obtained during operation. Further, in this example, since the B line is not exposed to the outside, there is an effect that it is usually protected by a soluble material. In this case, the end portions of the A line and the B line are connected to the heating resistance R and the negative side of the battery A as in the above-described embodiment.

    FIG.5 (c) shows the structure which has arrange | positioned the strip | belt-shaped A member and B member so that a strip | belt-shaped soluble body may be pinched | interposed similarly. The heat-sensitive body having such a configuration can be held by being pressed with a tape as in the first embodiment, with the surface of either the A member or the B member being in contact with the unit cell. According to this configuration, since the contact area is ensured, it is possible to further improve the thermal coupling to the unit cell. Furthermore, by reducing the thickness of the tape, it is possible to arrange it more slimly with respect to the battery pack as compared to a wire-like soluble body. For this reason, if the heat sensitive body of this form is utilized, it can contribute to thickness reduction of a battery pack. In this case, the end portions of the A member and the B member are connected to the heating resistance R and the negative side of the battery A as in the above-described embodiment.

  Moreover, since the area which can be detected can be increased by widening the width | variety of a soluble body belt | band | zone, higher detection accuracy can be anticipated.

It is a block diagram of a battery pack. It is a figure which shows the structure of the structure (normal time) of a heat sensitive body. It is a figure which shows the structure of the structure (at the time of operation | movement) of a heat sensitive body. It is a circuit block diagram of the battery pack of one Example of this invention. It is a figure which shows the variation of a heat sensitive body.

Explanation of symbols

1 pack battery 2 unit cell (= battery A)
3 Protection circuit board 4 Connection member 5 Heat sensitive body 6 Glass tape 7a, 7b External input / output line 7c, 7d Lead wire 8 Connector 50 Metal wire (A line)
51 Metal wire (B wire)
52 Soluble PC Mobile device (= Electronic device)
S control / power supply means L load MPU microprocessor unit A battery 12 resistance (current detection unit)
DESCRIPTION OF SYMBOLS 13 Temperature detection part 14 A / D conversion part 15 Control and calculating part 17 Control element 71 FET element for charge 72 FET element for discharge 19 Communication part 10 Resistance heating type fuse H Fuse R Heating resistance

Claims (5)

A heat sensitive body that changes from a non-conductive state to a conductive state when the battery pack including the secondary battery is in an abnormal temperature state; and
A heating resistor that is connected in series to the heat sensitive body and the battery, and a current flows when the heat sensitive body becomes conductive, and
It is disposed at a position heated by the heating resistor through which current flows, and is connected in series with the battery, so that the current flowing through the battery is cut off by being thermally blown by the heating resistor that is heated by flowing current. A battery pack comprising a fuse. The heat sensitive body is:
It has a structure in which each conductive wire is separated by interposing a heat-soluble member between a plurality of parallel conductive wires biased in directions approaching each other,
2. When the abnormal temperature state is reached, the conductive wires come into close contact with each other as the heat-soluble member melts, and the heat sensitive body is configured to short-circuit the close contact between the conductive wires. The battery pack described in 1. The conductive wire consists of a first metal wire and a second metal wire,
The heat-sensitive body has a heat-soluble member disposed so as to cover the first metal wire, and the second metal wire is spirally wound around the surface of the heat-soluble member. The battery pack according to claim 2, wherein the battery pack is a battery pack.   The battery pack according to claim 2 or 3, wherein the heat-soluble member is polyethylene or PET that melts in a range of 90 ± 10 ° C. A battery pack incorporating a plurality of electrically connected unit cells,
A substantially entire region in the longitudinal direction is a heat sensitive region, and a long heat sensitive body capable of acquiring a heat sensitive result at an arbitrary portion of the heat sensitive region as an electric signal is formed across two or more of the unit cells. The battery pack according to claim 1, wherein the battery pack is provided on a peripheral surface.

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