JP3468421B2 - Battery pack - Google Patents

Description

Description: 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. 2. Description of the Related Art If a battery pack continues to be used after its life has expired, not only the capacity value is extremely reduced, but also overcharging and overdischarging are repeated. Lithium may precipitate in the form of dendrite and break through the separator, and if liquid enters the battery pack due to submersion or leakage of electrolyte, it may cause a short circuit inside the battery, resulting in smoke or ignition. Becomes larger. 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. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and aims to improve the safety of a battery pack when an abnormal state occurs, and to analyze the original cause of the failure of the battery pack. To provide useful information to [0005] Therefore, the present invention provides a battery pack having a protection function in the event of an abnormal state, which is used even when a current is flowing beyond the reference value of the charging time or when the charging switch element is turned off. An abnormality detecting means for detecting an abnormality when the charging current flows over a predetermined value for a predetermined period, a heat generation control means for causing the heating resistor to generate heat by detecting the abnormality by the abnormality detecting means, and a charge / discharge current A temperature fuse inserted into a path and blown by the heat generated by the heat generating resistor. When an abnormality is detected, the current path of the charge / discharge is cut by blowing the temperature fuse to control charging or charging / discharging. It is characterized by having comprised. 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. The present invention detects an abnormality when a charge current has flowed for a predetermined period or more for a predetermined period in spite of the fact that the current flows for more than a reference value of the charging time or the charging switch element is turned off. The abnormality detection means of the present embodiment,
Hereinafter, a description will be given of a liquid detection unit that detects an abnormality when water is immersed, the electrolyte leaks, and the like. The liquid detecting section and the thermal fuse 8 detect the liquid by the liquid detecting element when the liquid enters the battery pack due to submersion, leakage of the electrolytic solution, or the like.
The ET is controlled so that, for example, the heating element is heated 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, for example, 1 kΩ. 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. 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 occurrence of an abnormal state, comprising: an abnormality detecting means for detecting an abnormality; Heating control means for causing the heating resistor to generate heat when an abnormality is detected, and a temperature fuse inserted into the charging / discharging current path and being blown by the heat of the heating resistor. Discharge current path is cut to control charging or charging / discharging, so that intrusion of liquid including water or electrolyte, overcharging or overvoltage, abnormal charging time, multiple cell voltages connected in series Is controlled to disable charging or charging when an abnormal state occurs, such as when a charging current has flowed for a predetermined period or more for a predetermined period in spite of the unbalance of the charging switch element. Therefore, the safety of the battery pack can be improved. 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. [Description of Signs] 1 ... Battery 2 ... Battery voltage monitoring IC 3 ... Charging / discharging 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

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 2/10 H01M 10/44 H01M 10/48

Claims (1)

(57) [Claim 1] A battery pack having a protection function in the event of occurrence of an abnormal condition, wherein a current flows beyond the reference value of the charging time or the battery pack is charged.
Charging current even though the power switch element is off
Abnormality detection means for detecting an abnormality when a predetermined value or more flows for a predetermined period, heat generation control means for causing a heating resistor to generate heat upon detection of an abnormality by the abnormality detection means, inserted into a charge / discharge current path. A temperature fuse that is blown by the heat generated by the heat generating resistor, and when an abnormality is detected, the current path of the charge / discharge is cut by blowing the temperature fuse to control charging or discharging to be impossible. Characteristic battery pack.