JP2013188107A - Current interruption device, power storage device, secondary battery, and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which is robust against rapid changes of a charging voltage and properly protects a battery element from overcharge in a current interruption device used in a power storage device.SOLUTION: This specification discloses a current interruption device. The current interruption device includes: a voltage detection part; an interruption part interrupting electrical conduction from a battery terminal to a battery element when a voltage exceeding an upper limit voltage is detected by the voltage detection part; a capacitor parallely connected with the voltage detection part; and a resistor serially connected with a parallel circuit composed of the voltage detection part and the capacitor. In the current interruption device, the parallel circuit composed of the voltage detection part and the capacitor and a serial circuit of the resistor are parallely connected with the battery element.

Description

  The present invention relates to a current interrupt device, a power storage device, a secondary battery, and a vehicle.

  In a secondary battery such as a lithium ion secondary battery, a current interrupt device may be provided to protect the battery element from overcharging. Patent Document 1 discloses a power storage device in which a current interrupting device is incorporated. In the technique of Patent Document 1, a Zener diode is provided in parallel with the battery element, and a thermal fuse is provided between the battery element and the battery terminal. In the technique of Patent Document 1, when the voltage applied to the battery terminal exceeds the upper limit voltage, the thermal fuse is blown by the heat generated by the Zener diode, and the conduction between the battery element and the battery terminal is cut off. Prevent overcharge.

JP 2003-284237 A

  When a power storage device is mounted on a vehicle such as a hybrid vehicle or an electric vehicle, the power storage device is charged with electric power generated by regenerative power generation of the motor. When charging the power storage device using regenerative power, the charging voltage may fluctuate rapidly, and the charging voltage may momentarily exceed the upper limit voltage. If the upper limit voltage of the current interrupting device is set so as to allow such a momentary large voltage, the battery element cannot be properly protected from overcharging. Further, if the current interruption device cuts off the conduction every time such a momentary large voltage is applied, it is necessary to frequently replace the power storage device, which requires much labor for maintenance. . A technique that is robust against sudden fluctuations in charging voltage and that can appropriately protect battery elements from overcharging is expected.

  The present specification provides a technique for solving the above problems. In this specification, in the current interrupting device used for an electrical storage apparatus, the technique which is robust with respect to the rapid fluctuation | variation of a charging voltage, and can protect a battery element from overcharge appropriately is provided.

  The present specification discloses a current interrupting device. The current interrupting device is connected in parallel to the voltage detection unit and the voltage detection unit, and when the voltage detection unit detects a voltage exceeding the upper limit voltage, the current detection unit interrupts the conduction from the battery terminal to the battery element. A capacitor and a resistor connected in series to a parallel circuit of the voltage detector and the capacitor are provided. In the current interrupt device, a parallel circuit of a voltage detector and a capacitor and a series circuit of a resistor are connected in parallel to the battery element.

  In the above current interrupting device, when the charging voltage applied to the battery terminal exceeds the upper limit voltage, it is detected by the voltage detection unit, and the conduction from the battery terminal to the battery element is interrupted at the interrupting unit. The battery element can be protected from overcharging.

  In the above current interrupting device, a resistor and a capacitor form a low-pass filter, which suppresses fluctuations in the voltage applied to the voltage detector even when a sudden fluctuation occurs in the charging voltage applied to the battery terminal. Is done. By adopting such a configuration, even when the charging voltage momentarily exceeds the upper limit voltage, the voltage applied to the voltage detection unit does not exceed the upper limit voltage, and the blocking unit is a battery. The conduction from the terminal to the battery element is not interrupted. The current interrupt device is robust against sudden fluctuations in the charging voltage, and can appropriately protect the battery element from overcharging.

  In the above current interrupting device, the voltage detection unit preferably includes a Zener diode.

  According to the current interrupting device, it is possible to detect whether or not the charging voltage exceeds the upper limit voltage by utilizing the breakdown phenomenon of the Zener diode. The voltage detection unit can be configured with a simple configuration.

  In the above current interrupting device, the interrupting unit includes a connecting member that electrically connects the battery terminal and the battery element, and an actuator that switches the connecting member between a connected state and a non-connected state. When a voltage exceeding the upper limit voltage is detected by the unit, it is preferable that electric power is supplied to the actuator, and the actuator switches the connecting member from the connected state to the non-connected state.

  According to said electric current interruption apparatus, an interruption | blocking part can be comprised by simple mechanical structure.

  In the above current interrupting device, the actuator preferably includes a piezoelectric element.

  According to the above current interrupting device, the actuator can be miniaturized and the entire device can be miniaturized.

  Alternatively, the current interrupting device includes a thermal fuse that electrically connects the battery terminal and the battery element, and a heating unit that heats the thermal fuse, and the voltage detection unit exceeds the upper limit voltage. When the voltage is detected, it is preferable that electric power is supplied to the heating unit and the thermal fuse is blown.

  According to said electric current interruption apparatus, an interruption | blocking part can be comprised by a very simple structure.

  The present specification also discloses a power storage device including the above-described current interrupting device, a battery element, and a battery terminal.

  The present specification also discloses a secondary battery including the structure of the above power storage device.

  The present specification also discloses a vehicle on which the power storage device described above is mounted.

  According to the technology disclosed in this specification, in a current interrupt device used in a power storage device, it is possible to appropriately protect battery elements from overcharging while ensuring robustness against a rapid change in charging voltage.

The circuit structure of the electrical storage apparatus 2 of Example 1 is shown. A part of mechanical structure of the electrical storage apparatus 2 of Example 1 is shown. A part of mechanical structure of the electrical storage apparatus 2 of Example 1 is shown. The circuit structure of the electrical storage apparatus 62 of Example 2 is shown.

Example 1
As shown in FIG. 1, the power storage device 2 of this embodiment includes battery terminals 4 a and 4 b, a battery element 10, and a current interrupt device 12. The current interrupt device 12 includes an interrupt circuit 14 and a switching circuit 16. The battery element 10 of the present embodiment is a secondary battery such as a nickel metal hydride battery or a lithium ion battery. The power storage device 2 is mounted on a vehicle such as a hybrid vehicle or an electric vehicle, and supplies the electric power of the battery element 10 to a motor that rotationally drives wheels. In addition, the power storage device 2 charges the battery element 10 with electric power regenerated by the motor.

  The interruption circuit 14 includes main terminals 18a and 18b through which a current for charging and discharging the battery element 10 flows, and control terminals 20a and 20b for switching between conduction and interruption between the main terminals 18a and 18b. When no control voltage is applied between the control terminals 20a and 20b, the main terminals 18a and 18b are electrically connected. When a control voltage is applied between the control terminals 20a and 20b, the conduction between the main terminals 18a and 18b is cut off and the cut-off state is maintained.

  The switching circuit 16 switches input to the control terminals 20 a and 20 b of the cutoff circuit 14 according to the magnitude of the charging voltage to the power storage device 2. When the charging voltage to power storage device 2 is less than the predetermined upper limit voltage, switching circuit 16 does not apply a control voltage between control terminals 20a and 20b. When the charging voltage to power storage device 2 exceeds the upper limit voltage, switching circuit 16 applies a control voltage between control terminals 20a and 20b.

  More specifically, the switching circuit 16 includes a Zener diode 22, resistors 24a, 24b, 24c, and 24d, a transistor 26, a capacitor 50, and a resistor 52. One end of the resistor 52 is connected to the positive electrode of the battery element 10. The capacitor 50 connects between the other end of the resistor 52 and the negative electrode of the battery element 10. The cathode of the Zener diode 22 is connected to the connection between the resistor 52 and the capacitor 50. The resistor 24 a connects between the anode of the Zener diode 22 and the negative electrode of the battery element 10. The control terminal 20a of the interruption circuit 14 is connected to the positive electrode of the battery element 10, and the resistor 24d is connected between the control terminal 20b of the interruption circuit 14 and the collector of the transistor 26. The emitter of the transistor 26 is connected to the negative electrode of the battery element 10. The resistor 24 b connects between the anode of the Zener diode 22 and the base of the transistor 26. The resistor 24 c connects between the base of the transistor 26 and the emitter of the transistor 26.

  In the switching circuit 16 configured as described above, when the charging voltage to the power storage device 2 is smaller than the breakdown voltage of the Zener diode 22, no current flows through the Zener diode 22. Therefore, the base and emitter of the transistor 26 are kept at the same potential, and no current flows between the collector and emitter of the transistor 26. Therefore, no control voltage is applied between the control terminals 20a and 20b of the cutoff circuit 14, and the conduction between the main terminals 18a and 18b is maintained.

  When the charging voltage to the power storage device 2 exceeds the breakdown voltage of the Zener diode 22, a current flows through the Zener diode 22. As a result, a potential difference is generated between the base and emitter of the transistor 26, and a current also flows between the collector and emitter of the transistor 26. Thereby, a control voltage is applied between the control terminals 20a and 20b of the cutoff circuit 14, and the conduction between the main terminals 18a and 18b is cut off.

  As described above, in the power storage device 2 of the present embodiment, the voltage is detected by the zener diode 22 and the resistor 24a of the switching circuit 16, and when the voltage exceeding the upper limit voltage is detected, the main circuit 18a, The conduction between 18b is cut off. Therefore, the Zener diode 22 and the resistor 24a can be referred to as a voltage detection unit, and the cutoff circuit 14 can be referred to as a cutoff unit.

  In the switching circuit 16, a capacitor 50 is connected in parallel to the Zener diode 22 and the resistor 24 a that are voltage detectors, and a resistor 52 is connected in series to the parallel circuit. A circuit is connected in parallel to the battery element 10. In the switching circuit 16 having the above configuration, a low-pass filter is formed by the resistor 52 and the capacitor 50. Therefore, even when a sudden change occurs in the charging voltage applied to the battery terminals 4a and 4b, the voltage detector Variations in the voltage applied to a certain Zener diode 22 and resistor 24a can be suppressed. By adopting such a configuration, even when the charging voltage instantaneously exceeds the upper limit voltage, the voltage applied to the Zener diode 22 and the resistor 24a as the voltage detection unit exceeds the upper limit voltage. Therefore, it is possible to continue to maintain the conduction in the cutoff circuit 14.

  FIG. 2 shows a part of the mechanical configuration of the power storage device 2. In this embodiment, the power storage device 2 includes an electrode structure 30, a current collector plate 32, an insulating plate 34, a conductive plate 36, a battery terminal 38, an insulating gasket 40, and a case 42. . The electrode structure 30 and the current collector 32 constitute a part of the battery element 10, and the current collector 32 corresponds to the positive electrode of the battery element 10. The battery terminal 38 corresponds to the battery terminal 4a of FIG. The electrode structure 30 is accommodated in the case 42. The current collecting plate 32 extends from the electrode structure 30 directly above, and is bent sideways while contacting the lower surface of the insulating plate 34. The insulating plate 34, the conductive plate 36, and the battery terminal 38 are fitted into an opening formed in the upper portion of the case 42 through a gasket 40. The conductive plate 36 and the battery terminal 38 are in contact with each other at the end of the conductive plate 36. An opening is formed in the center of the insulating plate 34. A convex portion protruding downward is formed at the center of the conductive plate 36, and the convex portion is in contact with the current collector plate 32 through the opening of the insulating plate 34. The conductive plate 36 and the current collector plate 32 are fixed at the contact portion. The electrode structure 30 and the battery terminal 38 are electrically connected via the current collector plate 32 and the conductive plate 36.

  A piezoelectric element 44 is disposed between the insulating plate 34 and the conductive plate 36. The piezoelectric element 44 is connected to the control terminals 20a and 20b (see FIG. 1). When a control voltage is applied to the control terminals 20a and 20b, the piezoelectric element 44 urges the conductive plate 36 away from the insulating plate 34 (upward in FIG. 2), and deforms the conductive plate 36. The current collecting plate 32 and the conductive plate 36 can be referred to as a connecting member that electrically connects the electrode structure 30 and the battery terminal 38, and the piezoelectric element 44 can be referred to as an actuator.

  As shown in FIG. 2, when the control voltage is not applied to the control terminals 20a and 20b, the piezoelectric element 44 is not driven and the conductive plate 36 is not deformed, so that the contact between the current collector plate 32 and the conductive plate 36 is maintained. Is done. In this case, the conductivity between the electrode structure 30 and the battery terminal 38 is ensured. In other words, the conductivity between the battery element 10 and the battery terminal 4a in FIG. 1 is ensured.

  As shown in FIG. 3, when a control voltage is applied to the control terminals 20 a and 20 b, the piezoelectric element 44 is driven to deform the conductive plate 36 in a direction away from the insulating plate 34. The convex portion of the conductive plate 36 is pulled out from the opening of the insulating plate 34, and the portion of the current collector plate 32 that is fixed to the conductive plate 36 is broken. Thereby, the conduction between the electrode structure 30 and the battery terminal 38 is cut off, in other words, the conduction between the battery element 10 and the battery terminal 4a in FIG. 1 is cut off. In the present embodiment, the current collecting plate 32 is broken, so that the conduction between the electrode structure 30 and the battery terminal 38 is cut off even when the control voltage is not applied to the piezoelectric element 44 thereafter. Maintained.

  As described above, according to the present embodiment, when the charging voltage to the power storage device 2 exceeds the upper limit voltage, the conduction between the battery element 10 and the battery terminal 4a is interrupted. By setting it as such a structure, the overcharge to the battery element 10 can be prevented. Further, according to this embodiment, when the charging voltage to the power storage device 2 exceeds the upper limit voltage only momentarily, the conduction between the battery element 10 and the battery terminal 4a is maintained without being cut off. . The current interrupting device 12 of the present embodiment is robust against sudden fluctuations in the charging voltage, and can appropriately protect the battery element 10 from overcharging.

  In the above-described embodiment, the case where the voltage detection unit is configured by the Zener diode 22 and the resistor 24a has been described. However, when the voltage exceeding the upper limit voltage is detected, the cutoff circuit 14 can block the conduction. If so, a voltage detector having a configuration other than this may be used.

  In the above embodiment, the configuration in which the conduction between the main terminals 18a and 18b is cut off by the actuator using the piezoelectric element 44 in the cutoff circuit 14 has been described. However, for example, the main terminals 18a, It is good also as a structure which interrupts | blocks the electric conduction between 18b. Further, in the interruption circuit 14, instead of using an actuator, the main terminals 18a and 18b are connected by a thermal fuse, and when a control voltage is applied between the control terminals 20a and 20b, a heating unit ( For example, a resistor may be provided, and the conduction between the main terminals 18a and 18b may be cut off by melting the thermal fuse.

(Example 2)
In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. As shown in FIG. 4, in the power storage device 62 of the present embodiment, the positions of the battery terminals 4 a and 4 b and the battery element 10 are interchanged with the current interrupt device 12 interposed therebetween. In other words, the power storage device 62 of the present embodiment differs from the power storage device 2 of the first embodiment in that the battery terminal 4a is connected to the main terminal 18a and the positive electrode of the battery element 10 is connected to the main terminal 18b. .

  In the power storage device 62 of this embodiment, when the conduction between the main terminals 18a and 18b is interrupted in the interruption circuit 14, no current flows through the battery element 10, but the resistor 52 and the zener diode 22 of the switching circuit 16 are provided. , Current paths are formed between the battery terminals 4a and 4b via the resistors 24a, 24b and 24c. Therefore, when the power storage device 62 is used as an assembled battery, it is possible to ensure the conductivity between the battery terminals 4a and 4b even after the current interrupting device 12 operates and the conduction in the interruption circuit 14 is interrupted. Can continue to be used with the output reduced.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in the present specification or the drawings can achieve a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2 Power storage device 4a, 4b Battery terminal 10 Battery element 12 Current interrupt device 14 Interrupt circuit 16 Switching circuit 18a, 18b Main terminal 20a, 20b Control terminal 22 Zener diodes 24a, 24b, 24c, 24d Resistor 26 Transistor 30 Electrode structure 32 Current collecting plate 34 Insulating plate 36 Conductive plate 38 Battery terminal 40 Gasket 42 Case 44 Piezoelectric element 50 Capacitor 52 Resistor 62 Power storage device

Claims (8)

A voltage detector;
When a voltage exceeding the upper limit voltage is detected by the voltage detection unit, a blocking unit that blocks conduction from the battery terminal to the battery element,
A capacitor connected in parallel to the voltage detector;
Comprising a resistor connected in series to a parallel circuit of the voltage detector and the capacitor;
A current interrupting device in which a parallel circuit of the voltage detector and the capacitor and a series circuit of the resistor are connected in parallel to the battery element.   The current interrupting device according to claim 1, wherein the voltage detection unit includes a Zener diode. The blocking section includes a connecting member that electrically connects the battery terminal and the battery element, and an actuator that switches the connecting member between a connected state and a non-connected state;
3. The current interrupting device according to claim 1, wherein when the voltage detection unit detects a voltage exceeding an upper limit voltage, electric power is supplied to the actuator, and the actuator switches the connecting member from a connected state to a non-connected state.   The current interrupting device according to claim 3, wherein the actuator includes a piezoelectric element. The interrupting unit includes a thermal fuse that electrically connects the battery terminal and the battery element, and a heating unit that heats the thermal fuse,
3. The current interrupting device according to claim 1, wherein when the voltage detection unit detects a voltage exceeding an upper limit voltage, electric power is supplied to the heating unit and the thermal fuse is blown.   A power storage device comprising the current interrupting device according to claim 1, the battery element, and the battery terminal.   A secondary battery comprising the structure of the power storage device according to claim 6.   A vehicle equipped with the power storage device of claim 6.

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