JPH09320643A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lithium ion battery from deteriorating as to its maximum charge capacity and cycle characteristic by appropriately performing an emergency stop of current in the event of some failure while current is passed to the battery, to make effective use of components in use, and to enable reduction in manufacturing cost and miniaturization of a battery pack. SOLUTION: A temperature fuse 18 which melts at a set temperature is put in a current carrying circuit which connects a battery main body 12 to a control part 14 which performs charge and discharge control of the battery main body 12, and the temperature fuse 18 is sandwiched between the circumferential surface of the battery main body 12 and that of a semiconductor device 36 in the control part 14, so that an overcurrent flowing in the control part 14 and any failure inside the battery are simultaneously detected by use of one temperature fuse 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery, such as a lithium ion secondary battery, which can be charged and discharged a plurality of times, and a battery integrally provided with means for controlling the charging / discharging state of the battery. Regarding the pack.

[0002]

2. Description of the Related Art Conventionally, in this type of battery pack, charge / discharge control is often performed while monitoring changes in the battery voltage. However, this charge / discharge control is not properly performed, and an overcurrent state may occur for a long time. It is known that when an abnormality such as a short circuit occurs inside the battery, the surface temperature of the battery abnormally rises, which may adversely affect not only the battery itself but also the device housing the battery.

In order to cope with such inconvenience, the control circuit is provided with a protection means for detecting and operating an overcurrent, and a temperature fuse is provided in the wiring between the control circuit and the battery so that the surface temperature of the battery exceeds the set value. When the temperature rises, the thermal fuse detects it and blows it off, forcibly stopping the current flowing through the battery, and an attempt has been made to prevent an accident due to the rise in the battery temperature.

[0004]

However, in the above-mentioned conventional example, when the overcurrent detection in the control circuit malfunctions, it is necessary to maintain the overcurrent state for the battery for a long time before the thermal fuse operates. However, deterioration or damage of the characteristics of the battery itself cannot be avoided.

As a result of studies made by the present inventors on such an inconvenience, when an overcurrent state occurs, the temperature of the semiconductor element provided for switching in the control circuit first rises. By monitoring the battery temperature at the same time as the conventional battery temperature, it was discovered that abnormalities in the charge / discharge state of the battery can be detected more quickly.

The present invention has been made on the basis of the above-mentioned findings, and by constructing the thermal fuse so as to contact the battery body and the semiconductor element at the same time, it is possible to use the single thermal fuse to simultaneously prevent an overcurrent. A battery abnormality can be detected, and the power supply can be stopped as soon as possible in the event of an abnormality, preventing the deterioration of the maximum charge capacity and cycle characteristics of a lithium-ion battery, and effectively using the parts used for manufacturing. It is an object of the present invention to provide a battery pack whose cost is gradually reduced and miniaturized.

[0007]

As shown in FIGS. 1 and 2, a battery pack 10 according to the present invention has a battery body 12 and a semiconductor device 36 for regulating on / off the charging / discharging timing of the battery body 12. A control unit 14 including
A temperature fuse 18 is integrally provided between the battery body 12 and the control unit 14 and blows when the temperature rises above a set temperature to forcibly cut off the energization of the battery body 12. The present invention is further characterized in that the thermal fuse 18 is brought into contact with the battery body 12 and the semiconductor element 36 at the same time.

The battery body 12 is a lithium-ion secondary battery, and the control unit 14 is an integrated circuit that monitors the charging / discharging timing and generates a predetermined control signal. A semiconductor element 36 for switching that turns on and off an energizing circuit for the battery body 12 is provided, and the temperature fuse 18 is sandwiched between the peripheral surface of the battery body 12 and the peripheral surface of the semiconductor element 36.

The battery body 12 described above is formed into a tubular shape having positive and negative electrodes 20 and 22 on both end surfaces 13a and 13b in the longitudinal direction, and the above-mentioned control portion 14 is formed into a shape substantially the same as the cross section of the battery body 12. The semiconductor element 36 is disposed on the first surface 25 a of the circuit board 24, and the peripheral surface of the semiconductor element 36 is connected to the first end surface 1 of the battery body 12 via the thermal fuse 18.
3a while being in contact with the second surface 25 of the circuit board 24.
b and the second end surface 13b of the battery main body 12 are provided with positive and negative electrode terminals 26a and 26b, respectively, and the periphery of the battery main body 12 and the control unit 14 can be covered with the protective cover 16 by exposing the electrode terminals 26. preferable.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The battery pack according to the present invention will be described below based on an example in which it is applied to a lithium ion secondary battery. However, the present invention is not limited to this, and can be applied to various secondary batteries in a similar manner. Is.

The battery pack 10 according to the present invention has a battery main body 12, a control unit 14 for restricting the charging / discharging state of the battery main body 12, and a battery main body 12 as shown in FIG. The protective cover 16 that integrally covers the control unit 14 and the temperature control unit 18 and the thermal fuse 18 that melts between the battery body 12 and the control unit 14 and blows when the heat exceeds the set temperature.
It is composed of

The battery body 12 is a lithium ion secondary battery formed in a cylindrical shape, and has one end 13 in the longitudinal direction thereof.
The positive electrode 20 is provided at b and the negative electrode 22 is provided at the other end 13a, and charging and discharging can be performed a plurality of times via the control unit 14.

The controller 14 connects the circuit board 24 to the battery main body 1
2 is formed into a disk shape having a diameter substantially equal to that of the circuit board 24.
While the electrode terminal 26a is provided on one surface 25b of the above, the necessary electronic circuit is formed on the other surface 25a.

The electronic circuit, as shown in FIG.
2 and a switching circuit 28 that is interposed in series in the energization path for 2 to regulate the energization timing, and the switching circuit 2
8 and a control circuit 30 that regulates the operation timing.

The control circuit 30 is a one-chip integrated circuit, and simultaneously detects the voltage application state from the outside to the battery pack 10 and the change in the terminal voltage of the battery body 12 itself, and applies the applied voltage. Is detected to exceed the set value, a control signal for instructing charging is output to the switching circuit 28 to enter the charging mode, while a control signal for instructing discharging is switched when the applied voltage falls below the set value. It is sent to the circuit 28 and switched to the discharge mode.

Further, during the charging mode, for example, the battery main body 12
A predetermined charge state is detected by, for example, detecting a change in the terminal voltage or the charge current, and when the completion of charging the battery main body 12 is detected, a control signal for stopping the charge is sent to the switching circuit 28. Further, a change in current during the energization of the battery body 12 is detected, and when a current exceeding a set value is detected, a control signal for stopping the energization is sent to the switching circuit 28.

The switching circuit 28 includes first and second switching circuits.
The two FETs 32 and 34 are used as a semiconductor element 36 for switching.
The anode and drain of 34 are connected in series, and the first and second diodes 38 and 40 are connected in parallel with the anode and drain of each FET 32 and 34 so that the cathode side faces the center.

Therefore, when a predetermined ON signal is applied to the gate of the first FET 32, as shown in FIG.
A second FET 34 connected in parallel with the second FET 34 from the second positive electrode 20 through the load 42 connected to the outside of the battery pack 10.
Battery body 1 from diode 40 through first FET 32
A discharge path 44 returning to the negative electrode 22 side of No. 2 is formed.

Contrary to the above, when the ON signal is applied only to the gate of the second FET 34, the charging power source 46 connected to the outside of the battery pack 10 as shown in FIG. 3B.
A charging path 48 that returns from the first diode 38 in parallel with the first FET 32 to the charging power supply 46 through the second FET 34 is formed from the first diode 38 in parallel with the first FET 32.

Further, when the current flowing in the current-carrying path for the battery body 12 becomes an overcurrent state, the first and second F
As a result of sending off signals to both ETs 32 and 34, FIG. 4 (a)
As described above, both FETs 32 and 34 are turned off at the same time, so that the first diode 38 or the second diode 40 blocks the power supply path to the battery body 12 forcibly.

The present invention has the above-mentioned structure, and further, the temperature fuse 18 is interposed between the first FET 32 side of the switching circuit 28 and the negative electrode 22 of the battery body 12, and
The temperature fuse 18 is sandwiched between the negative electrode side end surface 13a of the battery body 12 and the electronic circuit forming surface 25a of the circuit board 24.

The thermal fuse 18 is formed, for example, in the shape of a strip and is blown at a preset temperature. Further, one surface of the thermal fuse 18 is brought into close contact with the peripheral surface of the battery main body 12, and the other surface is provided with the switching circuit 28. It is in close contact with the peripheral surface of the semiconductor element 36 that constitutes it.

Therefore, if the control circuit 30 of the control unit 14 malfunctions and the overcurrent state continues, the current passing through the semiconductor element 36 of the switching circuit 28 also rises and its surface temperature also rises sharply. At the same time, the temperature rise of the battery body 12 also helps, and the temperature fuse 1
As a result that the temperature applied to the battery 8 also rises sharply, the temperature of the thermal fuse 18 exceeds the set value and melts down as shown in FIG. Protect.

The configuration or shape of the battery pack 10 as a whole can be appropriately changed according to its use or purpose. The configuration of the protective cover 16 may be changed, such as one that seals the entire body or one that covers only the connecting portion between the battery body 12 and the control unit 14. Furthermore, the shape of the thermal fuse 18,
The material or the location may be arbitrarily changed as long as it can simultaneously contact the semiconductor element 36 forming the electronic circuit and the peripheral surface of the battery body 12. Further, it goes without saying that the configurations of the electronic circuit and the electrode terminal 26 can be arbitrarily changed as long as the battery main body 12 can be charged and discharged.

[0025]

As described above, the present invention provides the thermal fuse 18
Is configured to contact the battery main body 12 and the semiconductor element 36 at the same time, overcurrent and battery abnormality can be detected at the same time by using one temperature fuse 18, and the energization can be accurately stopped at the time of abnormality. Prevents deterioration of the maximum charge capacity and cycle characteristics of ion batteries.
Further, the used parts are effectively utilized, and the manufacturing cost of the battery pack is gradually reduced and the size is reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view schematically showing an assembled state of a battery pack according to the present invention.

FIG. 2 is an electric circuit diagram showing an example of an electronic circuit provided in a battery pack.

FIG. 3 is an explanatory diagram showing an operating state of the battery pack,
The case where the control circuit is operating normally is shown.

FIG. 4 is an explanatory diagram showing an operating state of the battery pack,
The case where the operation of the control circuit becomes abnormal is shown.

[Explanation of symbols]

 10 Battery Pack 12 Battery Main Body 13 End Surface of Battery Main Body 14 Control Part 16 Protective Cover 18 Thermal Fuse 20 Positive Electrode 22 Negative Electrode 24 Circuit Board 25 Surface of Circuit Board 26 Electrode Terminal 28 Switching Circuit 30 Control Circuit 32 First FET 34 Second FET 36 Semiconductor Element 38 1st diode 40 2nd diode 42 Load 44 Discharge path 46 Charging power source 48 Charging path

Claims (3)

[Claims] 1. A control unit (14) comprising a battery body (12), a switching semiconductor element (36) for controlling on / off of charging / discharging timing with respect to the battery body (12), and a battery body (12). A battery pack integrally provided with a temperature fuse (18), which is located between the control units (14) and melts when the temperature rises above a set temperature to forcibly cut off the energization of the battery body (12). A battery pack characterized in that the fuse (18) is brought into contact with the battery body (12) and the semiconductor element (36) at the same time. 2. The battery body (12) is a lithium ion secondary battery, and the control unit (14) is an integrated circuit that monitors a charge / discharge timing and generates a predetermined control signal, and a control signal. And a semiconductor element (36) for switching which turns on and off the energizing circuit for the battery body (12) in cooperation with the input of the thermal fuse (18), and the thermal fuse (18) includes the semiconductor element (36) and the peripheral surface of the battery body (12). The battery pack according to claim 1, wherein the battery pack is sandwiched between the peripheral surfaces. 3. The battery body (12) is in the form of a cylinder having positive and negative electrodes (20) (22) on both end faces in the longitudinal direction, and the control unit (14) is a battery body (12). 12) the first surface (25) of the circuit board (24) formed in substantially the same shape as the cross section.
The semiconductor element (36) is provided in (a), and the surface of the semiconductor element (36) is brought into contact with the first end face (13a) of the battery body (12) through the thermal fuse (18), while the circuit described above is provided. Positive and negative electrode terminals (26a) and (26b) are provided on the second surface (25b) of the substrate (24) and the second end surface (13b) of the battery body (12), and the battery body (12) and the control unit are further provided. The battery pack according to claim 2, wherein the periphery of (14) is covered with a protective cover (16) with the electrode terminals (26) exposed.