JPH04117140A - Full-charge detector for battery pack - Google Patents

Abstract

PURPOSE:To realize a free circuit design in which sensor output voltage can be set freely, when the charging circuit for a battery pack is constituted, by providing the power supply input terminal of a latch circuit and the sensor output terminal in a battery pack individually. CONSTITUTION:A sensor output terminal 6 for introducing a full-charge detection signal to a charger 2 side and a power supply input electrode 7 for providing power supply to an internal latch circuit are provided individually. A charge control circuit 22 provides a power supply having predetermined level to a full-charge detecting circuit 20 through the power supply input electrode 7 and further pulls up the sensor output terminal 6 to a predetermined level. Furthermore, the detecting circuit 20 provides a full-charge detection output to the sensor output terminal 6 and full-charge is decided based on the variation of potential. An SCR 23 is then turned OFF to interrupt charging current supply or to switch to a minute current(trickle current).

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a battery pack that is detachably connected to a charger and has a storage battery internally charged, and in particular, a battery pack that is capable of detecting a temperature rise of the storage battery during charging. The present invention relates to a full charge detection device that outputs a detection result to a charger to perform charging control.

[Conventional technology]

Conventionally, various types of batteries have been proposed in which a heat-sensitive element such as a thermostat is disposed near the battery in order to detect a temperature rise during charging and control charging at full charge.

By the way, when the charger and the battery to be charged exist as an independent unit, such as in a battery pack in which the battery to be charged is housed integrally, the heat-sensitive element is not disposed inside the battery pack. There is.

In addition, after the battery temperature reaches a predetermined temperature and charging control is performed, a latch circuit is proposed to be connected to the temperature sensor so that recharging does not start when the temperature sensor returns due to a drop in battery temperature. (Unexamined Japanese Patent Publication No. 63-3
16641).

FIGS. 14 and 15 are diagrams showing the configuration of the temperature sensor and latch circuit portion in the conventional battery pack. In the figure, 60, 70, and 80 are a rectifier circuit, a switching element, and a charging control circuit on the charger side. Also, 90 is storage battery B
This is a sensor circuit that is provided on the side of the battery pack that has a built-in thermoswitch Th and a latch circuit.

In the above, the sensor output terminal S is pulled up to a predetermined voltage from the charging control circuit 80, and during charging, the thermostat Th is closed and the sensor output terminal S is set to a predetermined potential. When Q1. is opened, transistors Q1. Q2 are both turned on, changing the sensor output terminal S to a low potential. The charging control unit 80 detects this change in potential and performs charging control.

[Problem to be solved by invention C] However, as described above, if a predetermined voltage is pulled up to the sensor output terminal and a change in potential is detected, the latch state will not occur while the potential changes to a low level. It is necessary to supply the necessary voltage to maintain the output voltage, which makes it impossible to reduce the output to zero, and limits the output level range, which imposes restrictions on circuit design.

The present invention has been made in view of the above, and an object of the present invention is to provide a full charge detection device for a battery pack that allows for unlimited circuit design when configuring a charging circuit for a battery pack.

[Means to solve the problem]

A full charge detection device for a battery pack according to the present invention includes a temperature sensor and a battery pack whose internal storage battery is charged by being detachably connected to a charger. The battery is equipped with a latch circuit for latching, an output terminal for guiding the output of the latch circuit to the charger side, and a power supply terminal for the latch circuit.

Further, the latch circuit power supply terminal may be connected to the internal storage battery (Claim 2).

In the above, a reset switch for the latch may be provided between the internal storage battery and the latch circuit and closed when attached to the charger, or may be provided on the outer surface of the battery pack so as to be operable from the outside. Section 3.4).

Further, in claim 1, the latch circuit power supply terminal may have a terminal electrode on the outer surface of the battery pack, and may be supplied with power from a power supply section within the charger when attached to the charger. (Claim 5).

[Effect]

According to the present invention, the battery pack is detachably connected to the charger, and the storage battery in the battery pack is charged through the charger.

During charging, when the battery temperature exceeds a predetermined level, the latch circuit operates in response to the output signal from the temperature sensor at this time, and a full charge detection signal is sent to the output terminal to notify the charger that the battery is fully charged. Ru. The latch circuit is supplied with power from the latch circuit power supply terminal, thereby maintaining the sending of the full charge detection signal.

According to the second aspect of the invention, the latch circuit is supplied with power from the rechargeable battery.

According to the invention set forth in claim 3, the reset switch of the latch interposed between the internal storage battery and the latch circuit is opened when the battery pack is removed from the charger, thereby stopping the power supply to the reset circuit. and the latch operation is reset.

According to the invention set forth in claim 4, the latch reset switch interposed between the internal storage battery and the latch circuit can be operated even when the battery pack is attached to the charger, and when operated in such a state, the latch reset switch is opened. The power supply to the reset circuit is stopped.

According to the invention set forth in claim 5, the latch circuit is supplied with power from the power supply section inside the charger via the terminal electrode provided on the outer surface of the battery pack when the battery pack is attached to the charger. .

〔Example〕

FIG. 1 is a diagram showing a state in which a battery pack to which a full charge detection device for a battery pack according to the present invention is applied is attached to a charger.

In the figure, reference numeral 1 denotes a battery pack, which includes a battery, a temperature sensor, a latch circuit, etc. as described later. In this embodiment, a negative polarity thermistor whose resistance value decreases as the temperature rises is used as the temperature sensor, as shown in FIG.

Reference numeral 2 denotes a charger, which includes a plug 3 to be connected to a commercial power source, etc., and a mounting port 2a into which the battery pack 1 is mounted.

Inside this charger 2, there is a plug 3 as described below.
A rectifying circuit that rectifies alternating current from the battery, and a charging control circuit that performs charging or charging control based on battery temperature are provided.

In the state shown in the figure (assuming that the plug 3 is connected to an AC power source), the internal battery of the battery pack 1 is being charged, and when the battery temperature rises to a predetermined temperature by sensing the rise in battery temperature during charging, , charging control is performed by assuming that the battery is fully charged.

When the battery is fully charged, it is removed from the charger 2 and attached to a power tool (not shown), and operates as a battery for the power tool.

FIG. 2 shows connection terminals of the battery pack 1 with the charger 2 side, and 4.5 is a positive terminal and a negative terminal connected to both ends of the internal battery. 6 is a sensor output terminal for guiding a full charge detection signal to the charger 2 side, and 7 is a power input electrode for supplying power to the internal latch circuit.

Figure 3 shows the internal structure of the battery pack 1, in which six batteries B are housed, for example, electrically connected in series. 8 is a battery terminal block, 9 is a latch module housing a latch circuit, 10 is a tape for fixing the module, 11 is a lead wire for connecting a temperature sensor to be connected to a temperature sensor (not shown), and 12 is an insulating sheet. Although not shown in this figure, it is preferable that the temperature sensor be disposed at a central position surrounded by the batteries B so that it follows only the battery temperature and is not affected by the ambient temperature as much as possible.

FIG. 4 is a diagram showing the circuit configuration of the battery pack 1 and charger 2.

The chain line indicates the battery pack 1, B is the battery to be charged, and 20 is a full charge detection circuit consisting of a temperature sensor and a latch circuit.

21 is a rectifier circuit that converts AC input into DC voltage; 22 is a charging control circuit consisting of a switching element, a switching transformer, a rectifying and smoothing circuit, and a control unit that controls the switching operation of the switching element; A constant current or constant voltage output is supplied to the battery B via the battery B (as shown) 23. This charging control circuit 22 has a power supply section inside, and supplies power at a predetermined level to the full charge detection circuit 20 via the power input electrode 7, and also pulls up a potential at a predetermined level to the sensor output terminal 6. Then, upon receiving the full charge detection output to the sensor output terminal 6, the full charge is determined from the potential change and the 5CR is output.
23 is turned off, and the supply of charging current is stopped or switched to a minute current (trickle current).

FIG. 5 is a detailed circuit diagram showing an example of the full charge detection circuit 20.

R1 and R2 are voltage dividing resistors, and ZD is a constant voltage Zener diode. This resistor R□ is connected to the power supply input electrode 7, and a voltage at a predetermined level is applied to maintain the latch operation.

The thermistor Th and resistors R3 and R4 form a series circuit, and the transistor Q is connected in parallel to a thyristor.
1. Q2 is connected to perform a latch operation. The collector of the transistor Q and the base of the transistor Q2 are connected to the midpoint of the resistors R3 and R4 via a buffer circuit consisting of a resistor R5 and a capacitor C.

In addition, the constant voltage of the Zener diode ZD is resistor R6,
The voltage is applied to the base of the transistor Q3 via the reverse current prevention diode D□. The collector of the transistor Q3 is connected to the sensor output terminal 6 via a current limiting resistor R7.

Next, the operation will be explained using the time chart shown in FIG.

In FIG. 6, waveform a represents battery voltage, waveform a represents battery temperature, and waveform C represents sensor output terminal voltage. Further, it is designed in advance so that when the battery temperature reaches a predetermined temperature, it is determined that the battery is fully charged and charging control is performed.

Now, when the battery pack 1 is attached to the charger 2, power supply from the power input electrode 7 is started.

At the start of charging, the battery temperature is low and the resistance value of thermistor Th is large, so the voltage at the midpoint of resistors R3 and R4 is low, so that transistor Ql remains off and transistor Q2 also remains off. Become. Therefore, the transistor Q3 has a high base voltage (becomes high) and turns on. When the transistor Q3 turns on, the sensor output terminal 6 is pulled up to a predetermined level (the voltage V
2) decreases to voltage ■1. The charging control circuit 22 compares this voltage (1) with the reference voltage Vr, and if Vl<Vr, it determines that charging is in progress and continues the charging operation.

Thereafter, as charging continues, the battery temperature rises (that is, the resistance value of the thermistor Th1 decreases), and at the point in time when the battery temperature reaches a predetermined temperature, the thermistor Th
When the voltage at the midpoint of resistors R3 and R4 or the on-voltage of transistor Q2 is exceeded due to a decrease in the resistance value of the resistor, transistor Q2 is turned on and transistor Q1 is also turned on.

Therefore, the base voltage of the transistor Q3 decreases and turns off, and the voltage at the sensor output terminal 6 changes from V□ to V2. The charging control circuit 22 uses this voltage v2 and the reference voltage Vr.
If V r < V 2, it is determined that the battery is fully charged, and a control signal is output to the 5CR23 to perform charging control.

Note that, as described above, the transistor Q1. Since the transistor Q2 is connected to the thyristor, the transistor Q1.
If Q2 is turned on, even if the battery temperature drops and the partial pressure at the midpoint of resistors R3 and R4 becomes smaller after charging control, transistors Ql and Q2 will remain on (latched) and recharging will begin. It will not be done. Hereinafter, for convenience, the transistors Q1 and Q2 and the circuit section related to the latch operation will be referred to as a latch circuit. In this case, if the battery pack 1 is removed from the charger 2, the supply of power from the power input electrode 7 is stopped, so the latch circuit is reset.

In the above embodiment, power for the latch circuit was obtained from the power supply part of the charger 2 through the power supply input electrode, but the following
In this embodiment, the power is obtained from a battery to be charged.

FIG. 7 is a circuit diagram showing a second embodiment, in which the power input electrode 7 is removed from the circuit diagram of FIG. 5, and one end of the resistor R serving as the power input terminal is connected to the positive electrode of the battery B.

Components in the figure that are given the same numbers as in FIG. 5 have the same functions.

Resistors R to R4 have relatively large resistance values in order to minimize power consumption of battery B.

FIGS. 8 and 9 are a circuit diagram and a time chart showing the third embodiment.

In this embodiment, contrary to the second embodiment, charging control is performed when the sensor output terminal has a low voltage.

In the circuit diagram shown in FIG. 8, the same numbers as those in FIG. 7 are assigned the same functions. However, the resistor R7 is connected between the resistor R□ and the collector of the transistor Q3.

C2 is a buffer capacitor, Q4 is an output inversion transistor, and R8 is a current setting resistor.

Next, the operation will be briefly explained.

During charging up to the time point "to", the transistor Q3 is on as described above, so the base voltage of the transistor Q4 becomes low and the transistor Q4 is turned off. Therefore, the pulled-up voltage becomes a high voltage VIO determined by the current flowing through the resistor R8. The charging control circuit 22 uses this voltage Vlo and the base 211 voltage V
If Vr<VIO, it is determined that charging is in progress and the charging operation is continued.

On the other hand, after reaching the to point, since the transistor Q3 is off, the base voltage of the transistor Q4 becomes high and the transistor Q4 is turned on. Therefore, the pulled-up voltage is a low voltage V20 close to 0 (v) due to the on-resistance of the transistor Q4.
becomes. The charging control circuit 22 compares this voltage V20 with the reference voltage Vr, and since V2O<Vr, it determines that the battery is fully charged, outputs a control signal to the 5CR 23, and performs charging control.

In this way, the second. In the third embodiment, the power for the circuit is taken from a battery, so the sensor output voltage can be set freely, which facilitates circuit design. Further, since only three contact points are required between the battery pack 1 and the charger 2, there is no need to provide extra terminals.

By the way, the second. In the third embodiment, since the latch circuit is supplied with power from battery B, once the latch is engaged, battery B is sufficiently discharged using a power tool, and the battery voltage is increased by transistor Q1. We need to wait until the level in which it turns off in Q2. Alternatively, the resistance R□ may be adjusted by taking advantage of the fact that there is a difference in battery voltage between charging and discharging.

Although it is possible to set R2 and reset it at the start of discharge, it is not easy to set a resistance value that will reliably reset it.

Therefore, next, a configuration related to a method of resetting the latch circuit will be explained using FIG. 10 to FIG. 13.

10 to 12 are a circuit diagram and a configuration diagram illustrating the first reset method.

The circuit shown in FIG. 10 is the same as the circuit shown in FIG. 6, preferably with a switch SW1 interposed between the positive terminal 4 and the resistor R1.

FIG. 11 is a perspective view of the battery pack 1, in which a push-button switch is disposed on the top surface of the battery pack 1 as the switch SW1. This switch S front part is open in the normal state where it protrudes, and is closed when pressed.

FIG. 12 is a sectional view showing the switch state when the battery pack 1 is attached to and removed from the attachment port 2a of the charger 2, with (a) showing the attached state, and (b) showing the detached state. . In addition, 2
Reference numerals b and 2c designate resilient contact fittings that come into contact with the positive terminal 4, negative terminal 5, and other terminals when the battery pack 1 is attached.

In the state shown in Figure (a), the switch SW□ is pressed into contact with the inner bottom wall of the charger 2 and is in a closed state, so that power is being supplied from the battery B to the latch circuit. On the other hand, in Figure (b), the switch SW1 is separated from the inner bottom wall of the charger 2 and returns to the original protruding state, and becomes the open state. Therefore, the power supply from battery B to the latch circuit is stopped, and the latch circuit is reset.

As a result, even if the battery pack 1 is left plugged into the charger 2 after being fully charged, the latch will not be reset, and the latch will be reset only when the battery pack 1 is removed from the charger 2.

By the way, if the battery pack 1 is left in the charger 2 for a long period of time after being fully charged, the battery B will gradually discharge through the resistors R1 and R2. In this case, it is desirable to reset the battery pack 1 while it is plugged into the charger 2 to enable recharging.

FIG. 13 is a diagram illustrating the second reset method, showing the battery pack 1 attached to the charger 2.

In the figure, SW2 is, for example, a push button type switch disposed on the bottom surface of the battery pack 1.

In the circuit diagram of FIG. 10, this switch SW2 is connected in series with the previous switch S or alone, and is closed when it is in the normal state where it is protruded, and is opened when it is pressed. Therefore, with the battery pack 1 attached to the charger 2, pressing this switch SW2 performs a reset.

Note that the switch SW2 does not need to be located on the bottom surface of the battery pack, but may be disposed at a suitable location on the outside so that it can be operated from the outside during installation. Similarly, the switch SW1 does not need to be on the top surface of the battery pack 1 as long as it is closed when it is attached.

〔Effect of the invention〕

As explained above, according to the present invention, since the power input terminal and the sensor output terminal of the latch circuit in the battery pack are made separate, the voltage of the sensor output can be adjusted freely when configuring the charging circuit of the battery pack. This makes it possible to design a circuit without any restrictions, such as being able to set .

Further, since the latch circuit is configured to receive power from the battery to be charged, it is possible to operate the latch circuit with the existing number of terminals.

Furthermore, since the reset switch for the latch is opened and closed in accordance with attachment/detachment, the reset can be performed safely and reliably.

In addition, since a switch is provided that allows a reset operation even when the battery pack is attached, it is easy to recharge the battery pack that has been attached for a long time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which a battery pack to which the battery pack full charge detection device according to the present invention is applied is attached to a charger, and FIG. 2 is a diagram showing connection terminals of the battery pack with the charger side. , Figure 3 is a diagram showing the internal structure of the battery pack, Figure 4 is a diagram showing the circuit configuration of the battery pack and charger, Figure 5 is a detailed circuit diagram showing an example of the full charge detection circuit 20, and Figure 6 is a diagram showing the internal structure of the battery pack. The figure is a time chart for explaining the operation, Figure 7 is a circuit diagram showing the second embodiment, Figures 8 and 9 are circuit diagrams and time charts showing the third embodiment, and Figures 10 to 12. Figure (a) (
b) is a circuit diagram and configuration diagram explaining the first reset method, FIG. 13 is a diagram explaining the second reset method and shows the state in which the battery pack is attached to the charger, and FIGS. 14 and 15 are the above-mentioned diagrams. FIG. 2 is a diagram showing the configuration of a temperature sensor and a latch circuit portion in a conventional battery pack. DESCRIPTION OF SYMBOLS 1... Battery pack, 2... Charger, 2a... Mounting port, 4... Positive electrode terminal, 5... Negative electrode terminal, 6... Sensor output terminal, 7... Power input electrode , 20... Full charge detection circuit, B... Battery, R engineering ~ R8... Resistor, Q
□~Q4...Transistor, Th type...Thermistor, C1, C2...Capacitor, zD type...Zener diode, D type...Diode, SW□, SW2...
··switch. Patent applicant Matsushita Electric Works Co., Ltd. Agent
Patent Attorney Etsushi Kotani (a) (b)

Claims (1)

[Claims] 1. In a battery pack that is detachably connected to a charger to charge an internal storage battery, the battery pack includes a temperature sensor and a latch circuit that is connected to the temperature sensor and latches when the temperature exceeds a predetermined level. A full charge detection device for a battery pack, comprising: an output terminal for guiding the latch circuit output to a charger side; and the latch circuit power supply terminal. 2. The full charge detection device for a battery pack according to claim 1, wherein the latch circuit power supply terminal is connected to the internal storage battery. 3. The full charge detection device for a battery pack according to claim 2, further comprising a reset switch for the latch that is interposed between the internal storage battery and the latch circuit and is closed when the battery pack is attached to the charger. Full charge detection device for battery packs. 4. The battery pack full charge detection device according to claim 2, wherein the battery is interposed between the internal storage battery and the latch circuit, and is disposed on the outer surface of the battery pack so as to be operable from the outside. Pack full charge detection device. 5. The latch circuit power supply terminal has a terminal electrode on the outer surface of the battery pack, and is configured to receive power from a power supply section within the charger when attached to the charger. The full charge detection device for a battery pack according to claim 1.