JP2002042752A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide information useful for analysis of a cause of failure of a battery pack and to improve safety of the battery pack when an abnormal state is caused. SOLUTION: The battery pack having a protective function when the abnormal state is caused is furnished with an abnormality detection means 11 to detect abnormality, heating control means Q1, Q2 to heat a heating resistant body 14 by detecting abnormality by the abnormality detection means 11 and a temperature fuse 12 inserted into an electric current route of charging and discharging and fused by heating of the heating resistant body 14, and it improves safety of the battery pack by controlling the electric current route of charging and discharging impossible to charge or to charge and discharge by cutting it by fusing the temperature fuse 12 at the time of immersion of liquid containing water and an electrolytic solution, overcharge and overvoltage, charging time abnormality, unbalance of a plural number of cell voltages connected in series and the abnormal state that the charging electric current flows at more than a specified value for a specified period of time though a switching element for charging is off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack having a protection function when an abnormal condition occurs.

[0002]

2. Description of the Related Art If a battery pack is used continuously after its life has expired, not only the capacity value will be extremely reduced, but also a battery which has been repeatedly overcharged and overdischarged will not be used. When lithium precipitates in the form of dendrite and breaks through the separator, and liquid enters the battery pack due to submergence or leakage of the electrolyte, the possibility of smoke or ignition increases due to a short circuit inside the battery. . Alternatively, a similar problem occurs when the battery pack is disassembled by a user's misuse or is exposed to an unexpected state such as being damaged by sharp metal.

[0003] Furthermore, batteries should be disposed of as industrial waste by a specific trader, but there is a possibility that the batteries may be disposed of together with combustible materials. In such a case,
In the current battery pack, for example, if the battery pack is exposed to a dangerous state in an overcharged state, the possibility of smoking or firing increases.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to improve the safety of a battery pack when an abnormal condition occurs and to be useful for analyzing the original cause of a battery pack failure. To provide information.

Therefore, the present invention relates to a battery pack having a protection function in the event of occurrence of an abnormal state, comprising an abnormality detecting means for detecting an abnormality, and a heat generation control for causing a heating resistor to generate heat by detecting the abnormality by the abnormality detecting means. Means, and a thermal fuse inserted into the charging / discharging current path and blown by the heat generated by the heating resistor. When an abnormality is detected, the charging / discharging current path is cut by blowing the temperature fuse to charge or charge. Characterized in that it is configured to be controlled to be unable to discharge, and further, a non-volatile memory that stores the abnormality detected by the abnormality detection unit, and a communication unit that outputs information of the abnormality stored in the non-volatile memory or A display means is provided as an output means, and when an abnormality is detected, the charging / discharging current path is cut by blowing the temperature fuse to disable charging or charging / discharging. Gyoshi and is characterized by being configured to output the abnormality information stored in the nonvolatile memory.

The abnormality detecting means includes means for detecting intrusion of a liquid containing water or electrolyte, means for detecting overcharge or overvoltage, means for detecting abnormality in charging time, and a plurality of cells connected in series. Means for detecting voltage imbalance,
It is a means for detecting that a charging current has flowed over a predetermined value for a predetermined period even though the charging switch element is off.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a battery pack according to the present invention, wherein 1 is a battery, 2 is a battery voltage monitoring IC, 3 is a charge / discharge control FET, 4 is a control microcomputer, 5 is a current detection resistor, 6 Is OPAMP, 7 is EEPR
OM, 8 denotes a liquid detection unit and a temperature fuse, and 9 denotes an LED display.

In FIG. 1, a battery 1 is a secondary battery in which cells are directly connected to each other. A current detection resistor 5 detects the charge / discharge current I, and an OPAMP 6 is detected by the current detection resistor 5. This is an amplifier that amplifies a very small voltage. The battery voltage monitoring IC 2 is a protection IC that detects battery voltage and performs charge / discharge control. The control microcomputer 4 performs various controls in the battery pack, abnormality detection, and the like, performs arithmetic processing therefor, and communicates with an external host device.
The EEPROM 7 is storage means for storing programs, control data, abnormal data, history / accumulated data, and the like. The charge / discharge control FET 3 is a switch element that controls charging / discharging on / off by a signal from the battery voltage monitoring IC 2 or the control microcomputer 4. Liquid detector and thermal fuse 8
When a liquid enters the inside of a battery pack due to submergence, leakage of an electrolyte, or the like, the liquid detection element detects the liquid and controls the FET, thereby causing, for example, a heating element to generate heat to blow the thermal fuse. The LED display 9 displays the remaining amount for capacity display, and automatically or separately provides a switch when the thermal fuse is blown, and presses this switch to display abnormality information, for example, a binary code of several bits. To display.

In the above-described liquid detecting section and the thermal fuse 8, the liquid detecting section is arranged near a location where liquid enters, such as a connector section, and the fuse blowing section is separated from the liquid detecting section by at least 10 mm or more. It is what was separated and arranged. When the liquid is detected, the fuse blowing section is blown, and each cell is forcibly discharged. Further, the fuse blown portion is sealed with a sealing material such as silicon so as not to come into contact with the liquid even when the liquid enters. This is because the fuse is not blown out if the liquid in the liquid detection part evaporates due to the heat generated by the fuse blowout part because the liquid detection part and the fuse blowout part are close to each other. This is to prevent that.

A voltage detecting lead wire connecting the battery 1 and the battery voltage monitoring IC 2 has a predetermined value or more, for example, 100Ω.
A lead wire having the above resistance value is used. This is because, if a normal lead wire is used, there is a possibility of short-circuiting after disconnection, and smoking or ignition. Since a particularly large current of, for example, about several μA does not need to flow through the voltage detection lead wire, there is no problem even if it has a resistance value of 1 kΩ, for example.

FIG. 2 is a diagram showing a specific configuration example of the liquid detecting section and the temperature fuse, wherein 11 is a liquid detecting section, 12 is a temperature fuse, 14 is a heating resistor, 15 is a control microcomputer, and Q1 and Q2 are 3 shows a control FET.

FIG. 2 shows a specific configuration example of the liquid detecting section and the thermal fuse. The thermal fuse 12 is inserted and connected in series to a current path for charging and discharging the battery 1. The heating resistor 14 is connected to the control FET Q1 or the control F
When the ETQ 2 is turned on, a current flows and heat is generated, and the thermal fuse 12 is blown. The liquid detection unit 11
When the liquid is detected, the resistance value decreases. At this time, the gate voltage of the control FET Q1 increases.
When TQ1 is turned on, the heat generating resistor 14 generates heat, and the thermal fuse 12 in the current path is blown. The control microcomputer 15 detects, for example, heat generation on the substrate, cell voltage, and other abnormalities, turns on the control FET Q2, and turns on the heating resistor 1
The control microcomputer 4 generates heat and blows the thermal fuse 12 in the current path, and may be the control microcomputer 4 shown in FIG. 1 or another. Thus, charging or charging / discharging is disabled by blowing the thermal fuse 12.

In the case of a normal thermal fuse, when the cell temperature rises above a predetermined temperature, the thermal fuse in the charging / discharging current path blows and charging and discharging become impossible. For example, when the number of cells is large, In this case, a large number of thermal fuses must be inserted into the current path, and the voltage drop increases. Therefore, only one thermal fuse 12 may be arranged in the current path for charging and discharging, and the other thermal fuses may be configured so that the control microcomputer 15 detects whether or not the thermal fuse has blown. As a configuration in which charging or charging / discharging is not possible, as described above, the charging / discharging control FET is permanently turned off, or a means for blowing the thermal fuse 12 inserted in the charging / discharging current path is used. Can be.

The present invention is not limited to the above-described embodiment, but can be variously modified. For example, in the above-described embodiment, the liquid detection unit and the temperature fuse in which the detection unit and the fuse for detecting liquid and fusing the current path are shown as an integral unit, but the detection unit, the temperature fuse, and the heating resistor are separately provided. Needless to say, the configuration may be made as follows. In addition, charging or charging / discharging is controlled by blowing the thermal fuse based on liquid detection and temperature detection.However, overcharging or overvoltage, charging time abnormality, cell voltage imbalance, and charging FET are turned on. Even if the charging current flows over a predetermined value for a predetermined period in spite of the above-mentioned operation, means for detecting other abnormalities may be provided, and the thermal fuse may be blown on the condition that the abnormality is detected. Good. Further, in such a case, the abnormality caused by the operation may be stored in the non-volatile memory, and may be transmitted by communication in response to a request from the external host device.

For example, when a reference value of the charging time is set, and the current is flowing though the value greatly exceeds the reference value,
In addition, a reference value of unbalance is set, and a difference between each cell voltage is obtained. When the difference is larger than the reference value and extremely unbalanced, a reference value of charging time and charging current is set, and charging is performed. The control microcomputer controls the control FET when a symptom that seems to be fatal occurs in the battery pack, for example, when the charging current flows for a predetermined time or more for a predetermined period even when the FET is off. Blow the fuse.

[0016]

As is apparent from the above description, according to the present invention, there is provided a battery pack having a protection function in the event of an abnormal state, comprising: an abnormality detecting means for detecting an abnormality; Heat generation control means for causing the heat generation resistor to generate heat upon detection; and a temperature fuse inserted into the charge / discharge current path and blown by the heat generated by the heat generation resistor. The system is configured to cut off the path and control charging or charging / discharging, so that intrusion of liquid including water and electrolyte, overcharging or overvoltage, abnormal charging time, and imbalance of multiple series-connected cell voltages Even if the charging switch element is off, the charging current flows for a predetermined period, for example, a predetermined value or more. It is possible to improve the safety of the pond pack.

Further, the nonvolatile memory includes a nonvolatile memory for storing the abnormality detected by the abnormality detecting means, and a communication means or a display means for outputting information of the abnormality stored in the nonvolatile memory as an output means. Since the stored abnormality information is configured to be output, it is possible to present useful information when analyzing the cause of the failure of the battery pack.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a battery pack according to the present invention.

FIG. 2 is a diagram illustrating a specific configuration example of a liquid detection unit and a thermal fuse.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery, 2 ... Battery voltage monitoring IC, 3 ... Charge / discharge control F
ET, 4 ... microcomputer, 5 ... current detection resistor, 6 ... OPAM
P, 7: EEPROM, 8: Liquid detection unit and temperature fuse, 9: LED display, 11: Liquid detection unit, 12: Temperature fuse, 14: Heating resistor, 15: Control microcomputer, Q
1, Q2 ... control FET

Claims (8)

[Claims] 1. A battery pack having a protection function in the event of occurrence of an abnormal state, comprising: an abnormality detecting means for detecting an abnormality; a heat generation control means for causing a heating resistor to generate heat by detecting the abnormality by the abnormality detecting means; A temperature fuse that is inserted into a discharge current path and is blown by the heat generated by the heat generating resistor. When an abnormality is detected, the charge / discharge current path is cut by blowing the temperature fuse to control charging or discharging to be impossible. A battery pack characterized in that: 2. A battery pack having a protection function in the event of occurrence of an abnormal state, comprising: an abnormality detecting means for detecting an abnormality; a non-volatile memory for storing the abnormality detected by the abnormality detecting means; A heating control means for causing the heating resistor to generate heat upon detection of an abnormality, a temperature fuse inserted into a charging / discharging current path to be blown by the heating of the heating resistor, and outputting information of the abnormality stored in the nonvolatile memory. Output means for disconnecting the charge / discharge current path by blowing the thermal fuse when an abnormality is detected, controlling charging or charging / discharging to be impossible, and outputting information on the abnormality stored in the nonvolatile memory. A battery pack characterized in that: 3. The output unit may be a communication unit that transmits information of the abnormality stored in the non-volatile memory by communication in response to a request from an external host device, or a display unit that displays the information of the abnormality. The battery pack according to claim 2, wherein: 4. The battery pack according to claim 1, wherein said abnormality detecting means is means for detecting intrusion of a liquid containing water or an electrolytic solution. 5. An apparatus according to claim 1, wherein said abnormality detecting means is means for detecting overcharge or overvoltage.
The battery pack as described. 6. The battery pack according to claim 1, wherein the abnormality detecting unit detects a charging time abnormality. 7. The battery pack according to claim 1, wherein the abnormality detecting means is means for detecting an imbalance of a plurality of cell voltages connected in series. 8. The abnormality detecting means according to claim 1, wherein the charging current is maintained for a predetermined period even though the charging switch element is off.
3. The battery pack according to claim 1, wherein the battery pack detects a flow of a predetermined value or more.