JPH06284591A - Charging apparatus - Google Patents

Abstract

PURPOSE:To provide a charging apparatus which controls detection of temperature in a system for charging a secondary battery with a quasi-constant current system. CONSTITUTION:Constitution is formed to realize control and charging for temperature detection by providing a temperature detecting element 7 within a battery cell 2 and also providing in a charger 1 a switching element 8 for stopping the charging when the temperature detecting element 7 has detected temperature rise of a battery cell 2. Thereby, a circuit in a simplified constitution for adequate charging by preventing over-charging and over-heating can be obtained easily. Moreover, good service life characteristic of a secondary battery can be realized and particular effect can also be indicated for a nickel-hydrogen battery which shows a high temperature rise during the charging operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device, and more particularly to an improved quasi-constant current type charging system mainly used for small portable devices and the like.

[0002]

2. Description of the Related Art FIG. 6 is a circuit diagram showing a conventional quasi-constant current type charging device used in, for example, a mobile phone.
In the figure, reference numeral 1 denotes a charger for charging a secondary battery 6, which is composed of a constant voltage power source 3, a resistor 4 and a diode 5. In this charger 1, 3 is a constant voltage power source for generating a constant voltage, 4 is a resistor having one end connected to the output of the constant voltage power source 3, and 5 is an anode connected to the other end of the resistor 4 and a cathode. It is a diode from which the output of the charger 1 is taken out. Further, 2 is a battery cell having a secondary battery 6 built therein.

Next, the operation will be described. A constant voltage power source 3 for converting a direct current voltage from an external power source such as a cigarette lighter of an automobile into a predetermined direct current voltage generates a predetermined constant voltage, and the constant voltage is used as a resistor 4 for increasing the impedance of the charging circuit. And by applying to the diode 5 which prevents discharge, a quasi-constant current, which is a substantially constant current on average, is supplied to the secondary battery 6 in the battery cell 2. The quasi-constant current makes it possible to charge the secondary battery.

The conventional quasi-constant current charging device is configured as described above, and the secondary battery can be charged with an extremely simple structure. However, since there is no charge control device, the secondary battery can be overcharged. there were.

This overcharging may decompose the electrolyte of the battery and shorten the life of the battery, and may cause the battery to heat up to a high temperature and become dangerous during use.

By the way, the demand for secondary batteries such as nickel-cadmium storage batteries is rapidly increasing with the expansion of the range of use of portable devices such as mobile phones. However, the capacity of these rechargeable secondary batteries should be further increased. Nickel-metal hydride storage batteries have come to the fore as a promising one. Since the battery voltage of this nickel-hydrogen storage battery is 1.2 V, which is almost equal to that of the nickel-cadmium storage battery, there is also an advantage that it can be compatible with this.

As described above, since the nickel-hydrogen storage battery has the same battery characteristics as the nickel-cadmium storage battery, it can be charged at the normal temperature by the same control method. However, when the battery is charged in a high temperature atmosphere of about 40 ° C. or higher, the temperature rise of only 15 to 20 ° C. occurs in the nickel-cadmium storage battery.
In the case of a nickel hydrogen storage battery, there is a temperature rise of 35 to 45 ° C. Therefore, in the case of a nickel-hydrogen storage battery, the life characteristics under an atmosphere of 40 ° C. are significantly inferior to those of the nickel-cadmium storage battery, and more than necessary temperature rise of the battery is likely to occur, which adversely affects the life characteristics and safe use. There is.

FIG. 1 of Japanese Patent Application Laid-Open No. 4-138029 discloses a charging device capable of preventing abnormal heating during charging of such a nickel-hydrogen storage battery in a high temperature atmosphere. It is a reproduction of FIG. 1 of the publication.

In the figure, 101 is a DC power source for supplying electric power for charging a nickel-hydrogen storage battery, 102 is a switching means for interrupting and supplying a charging current, and detects a decrease in voltage of the battery 103 during charging. -ΔV
The signal from the detection circuit 105 and the signal from the temperature detection circuit 106 that detects the temperature of the battery by detecting the resistance of the thermistor 104 are input to the charging control unit 107 and controlled by the output signal thereof. . When the battery temperature is lower than the set temperature value, the charging control unit 107 controls by the −ΔV detection circuit 105, and conversely, when the battery temperature is higher than the set temperature value, the temperature detection is performed at that time. The circuit 106 operates to generate a signal that terminates charging and controls the switching means 102 from on to off.

In the charging device having such a configuration, by setting the set temperature to 50 to 70 ° C. and controlling the charging current, it is possible to prevent abnormal heating of the storage battery during charging in a high temperature atmosphere. It is possible to maintain good battery life characteristics. The charging device can also charge nickel-cadmium storage batteries.

[0011]

However, in the device of FIG. 7, it is necessary to provide a −ΔV detection circuit and a temperature detection circuit for detecting a decrease in the voltage of the secondary battery during charging in order to detect the overcharge. Therefore, the circuit scale becomes large. Therefore, it is difficult to incorporate the charging function into the device itself that incorporates the secondary battery.

The present invention has been made in order to solve the above-mentioned problems, and is applicable to both a nickel-cadmium storage battery having a small temperature rise during charging and a nickel-hydrogen storage battery having a large temperature rise during charging. In addition to being able to charge the battery, overcharge prevention can be realized with a simple circuit configuration, and a simple charging function that simultaneously charges the battery-driven device while using it with an external power source can easily be built into the device. The purpose is to obtain a charging device.

[0013]

A charging device according to the present invention includes a temperature detecting element for detecting a temperature of a secondary battery in a battery cell, and a charger for charging the secondary battery by a quasi-constant current charging method. When the temperature detecting element detects the temperature rise of the secondary battery, the charging stop switching element built in the device stops the charging of the charging circuit.

Also, the charging device according to the present invention is provided with a second temperature detecting element for detecting the temperature of the charger on the side of the charger, and the switching element for charging stop is the second temperature detecting element. The charging of the charging circuit is stopped even when the temperature rise of the charger is detected.

The charging device according to the present invention uses a bimetal as the temperature detecting element.

Further, the charging device according to the present invention uses a nickel hydrogen storage battery as the secondary battery.

[0017]

In the charging device according to the present invention, the temperature detecting element is built in the battery cell, and when the temperature detecting element detects the temperature rise of the secondary battery, the charging stop switching element charges the charging circuit. It is possible to obtain a charging device with a simple configuration that can perform appropriate charging by temperature control of stopping the operation, prevent overcharging, and obtain the normal life characteristics of the secondary battery.

Further, in the charging device according to the present invention, a second temperature detecting element for detecting the temperature of the charger is also provided on the side of the charger, and the charging stop switching element is charged by the second temperature detecting element. Since the charging of the charging circuit is stopped even when the temperature rise of the charger is detected, it is possible to ensure the safety of the charging operation when the temperature of the charger side is high.

Further, in the charging device according to the present invention, since the bimetal is used as the temperature detecting element, the temperature detection can be realized at low cost, and the connection between the battery cell and the charger can be realized by the two-terminal connector. it can.

Furthermore, since the nickel-metal hydride storage battery is used as the secondary battery in the charging device according to the present invention, it is easy to charge the nickel-metal hydride storage battery having a larger capacity than the nickel-cadmium storage battery but a large temperature rise due to charging. It can be safely realized with a circuit.

[0021]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a charging device according to an embodiment of the present invention. In the figure, reference numeral 1 is a charger for charging a secondary battery 6, which is composed of a constant voltage power source 3, a resistor 4, a diode 5 and a switching element 8 for stopping charging. In this charger 1, 3 is a constant voltage power source for generating a constant voltage, for example, a voltage taken out from a cigarette lighter of an automobile is 8.5 V ± 1.
It is converted to 0% DC voltage and output. Reference numeral 4 denotes a resistor whose one end is connected to the output of the constant voltage power source 3, and has a value of 44Ω, for example. Reference numeral 5 is a diode whose anode is connected to the other end of the resistor 4, and constitutes a charging circuit together with the constant voltage power source 3 and the resistor 4. Reference numeral 8 is a switching element for stopping charging, the cathode of the diode 5 is connected to its input, the output of the temperature detecting element 7 is connected to its control input, and the output of the charger 1 is taken out from the output. . Reference numeral 2 is a battery cell having a secondary battery 6 and a temperature detecting element 7 for detecting the temperature thereof. The charger 1 and the battery cell 2 are connected to each other through a 3-terminal connector, and both are incorporated in a device in which a secondary battery is used.

FIG. 2 shows the structure of the circuit of the embodiment of FIG. 1 more concretely. In the figure, 7a is a thermistor as a temperature detecting element of the secondary battery 6, which is 25.degree.
Has a resistance value of 10 kΩ ± 1%, and 25 to 50
B constant of 3370K ± 1% at 25 ° C, 349 at 25 to 85 ° C
It has a B constant of 1K, and one end thereof is connected to the cathode side of the secondary battery 6. The B constant is generally called a thermistor constant and is defined by ΔE / 2k. This ΔE is the activation energy of the semiconductor forming the thermistor, and k is the Boltzmann constant. Also, 8a, 8
Reference numerals b and 8c are circuit elements forming the switching element 8. Reference numeral 8b is a PNP transistor whose emitter is connected to the other end of the resistor 4 and whose collector is connected to the anode of the diode 5, and 8a is a collector whose gate is the PNP transistor 8b. Is connected and the other end of the thermistor 7a is connected to the base, and 8c is a resistor connected between the cathode of the diode 5 and the base of the transistor 8a, and has a value of 12 kΩ, for example.

Next, the operation will be described. In FIG. 2, when the energy stored in the secondary battery is consumed and the voltage thereof is abnormally lowered, it is necessary to charge the battery. Before the start of charging, the transistor 8a is connected to the resistor 8
Since the voltage applied to the base of the transistor 8a is low due to the resistance division of the c and the thermistor 7a, the transistor 8a is turned off.
b is also off. Next, when charging is started, during normal charging, the potential of the secondary battery 6 is divided by the resistance division of the resistor 8c and the thermistor 7a, and the NPN transistor 8a is turned on. This allows PN
Since a current flows from the emitter of the P transistor 8b to the ground through the NPN transistor 8a, this PNP
The transistor 8b is also turned on, which causes the constant voltage power supply 3
When the battery and the secondary battery 6 are electrically connected to each other, charging can be performed with a quasi-constant current.

However, when the temperature of the battery cell 2 rises due to charging or the environmental temperature of the battery cell body exceeds a certain temperature of, for example, 60 ° C., the resistance value of the thermistor 7a lowers and is applied to the base of the transistor 8a. The voltage drops below the threshold value of the transistor 8a, which turns off the transistor 8a in the same manner as at the end of charging, so that PN
The P-transistor 8b is also turned off, and the quasi-constant current charging of the secondary battery 6 is stopped.

As described above, according to the above embodiment, the thermistor for detecting the temperature is built in the secondary battery, and the resistance value of the thermistor decreases when the temperature rises, so that the transistor for charging the secondary battery is provided. Since it is turned off, in the charging circuit that charges in the quasi-constant current charging system, by interposing a charge stop switch that operates at a constant temperature, temperature detection control charging can be performed, and the battery cell body is Since charging is not performed even at high temperatures, it is possible to avoid inappropriate charging, prevent overcharging and overheating, and prevent deterioration of characteristics such as shortening the life of the secondary battery. In addition, it is possible to prevent such overcharge and overheating of the secondary battery with a simple circuit. Therefore, while using the secondary battery connected to an external power source in a device using the secondary battery such as a mobile phone. The simple charging function of charging the secondary battery at the same time can be easily installed in the device to be used, and by connecting an external power source to the device to be used,
It becomes possible to charge the secondary battery while using the device.

Further, in this embodiment, not only a nickel-hydrogen storage battery but also a nickel-cadmium storage battery can be charged. In this case, the temperature detecting element built in the battery cell may be intentionally disconnected, or the one without the temperature detecting element may be used from the beginning.

Example 2. Although the thermistor is provided only in the battery cell in the first embodiment, as shown in FIG.
A thermistor may be provided on the charger side as well.

FIG. 3 shows a charging device according to a second embodiment of the present invention. In FIG. 2, 7b is a thermistor provided inside the charger 1, one end of which is a resistor 8c and an NPN.
The other end is connected to the connection point with the base of the transistor 8 a and the other end is connected to the other end of the thermistor 7 a provided in the battery cell 2.

As described above, the thermistor 7 is also provided in the charger 1.
By providing a, even if the environmental temperature of the main body of the charger 1 is high, the quasi-constant current charging can be stopped and the charging can be performed safely.

Example 3. Although the thermistor 7a is incorporated in the secondary battery as the temperature detecting element in the first embodiment, a bimetal may be used.

FIG. 4 shows a charging device according to a third embodiment of the present invention. In the figure, 7c is a bimetal provided inside the battery cell 2 so as to be connected in series with the secondary battery.

As shown in FIG. 4, by using the bimetal 7c, it is possible to detect the temperature rise of the secondary battery and control the charging thereof at low cost.

Further, in the above-mentioned first and second embodiments, 3
Although it was necessary to connect the charger and the battery cell with the connector of the terminal, in this embodiment using the bimetal, the charger and the battery cell can be connected with the connector of two terminals. Can be constructed at low cost.

Example 4. Further, in the third embodiment, the bimetal 7c is incorporated as a temperature detecting element in the secondary battery, but as shown in FIG. 5, the bimetal may be provided on the charger side as well.

FIG. 5 shows a charging device according to a fourth embodiment of the present invention. In FIG. 5, 7d is a bimetal provided inside the charger 1, one end of which is connected to the cathode of the diode 5 and the other end of which is connected to the other end of the bimetal 7c provided inside the battery cell 2.

In this way, the bimetal 7 is also provided in the charger 1.
By providing d, the quasi-constant current charging can be stopped even when the environmental temperature of the charger 1 main body is high.

Further, in the above-mentioned first and second embodiments, 3
Although it was necessary to connect the charger and the battery cell with the terminal connector, in this embodiment, the charger and the battery cell can be connected with the two-terminal connector as in the third embodiment. The device can be constructed at low cost.

[0038]

As described above, according to the charging device of the present invention, the temperature detecting element for detecting the temperature of the secondary battery is built in the battery cell, and the secondary battery is charged by the quasi-constant current charging method. When the temperature detection element detects the temperature rise of the secondary battery by the charging stop switching element built into the charger, it is configured to stop charging the charging circuit, so charging by the quasi-constant current charging method is overcharged. Therefore, there is an effect that the heating can be prevented and the heating can be appropriately performed, and that the overcharge and the heating of the secondary battery can be prevented by a simple circuit.

Also, the charging device according to the present invention is provided with a second temperature detecting element for detecting the temperature of the charger on the side of the charger, and the switching element for charging stop is the second temperature detecting element. Since the charging of the charging circuit is stopped even when the temperature rise of the charger is detected, the safety of the charging operation when the temperature on the charger side is high can be secured.

Further, since the charging device according to the present invention uses the bimetal as the temperature detecting element, the temperature detection can be realized at a low cost, and the connection between the battery cell and the charger is realized by the two-terminal connector. Therefore, there is an effect that the device can be configured at low cost.

Furthermore, since the charging device according to the present invention uses the nickel-hydrogen storage battery as the secondary battery, it has a larger capacity than the nickel-cadmium storage battery, but the temperature rise due to charging is large, and the electrolyte is decomposed by overcharging. If so, there is a section that a nickel-hydrogen storage battery that is also feared to be destroyed can be prevented from being destroyed and safely charged, and that the charging can be realized by a simple circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a quasi-constant current charging system having a temperature detection control function according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific quasi-constant current charging system having a temperature detection control function according to an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a more specific configuration of a quasi-constant current charging system having a temperature detection control function according to the second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a quasi-constant current charging system having a temperature detection control function according to a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a quasi-constant current charging system having a temperature detection control function according to a fourth embodiment of the present invention.

FIG. 6 is a circuit diagram showing a conventional quasi-constant current charging device.

FIG. 7 is a diagram showing a conventional charging device disclosed in Japanese Patent Laid-Open No. 4-138029.

[Explanation of symbols]

 1 Battery Charger 2 Battery Cell 3 Constant Voltage Power Supply 4 Resistor 5 Diode 6 Secondary Battery 7 Temperature Detection Element 7a Thermistor 7b Thermistor 7c Bimetal 8 Switching Element 8a NPN Transistor 8b PNP Transistor 8c Resistor

Claims (4)

[Claims] 1. A battery cell containing a secondary battery, a temperature detecting element for detecting the temperature of the secondary battery, a charging circuit for charging the secondary battery by a quasi-constant current method, and the temperature detecting element. And a charger having a switching element for stopping charging when the temperature rise of the secondary battery is detected, which stops charging of the charging circuit. 2. The charging device according to claim 1, wherein the charger is provided with a second temperature detecting element for detecting the temperature of the charger, and the charging stop switching element is the second temperature detecting element. A charging device, which stops the charging of the charging circuit even when a temperature rise of the charger is detected. 3. The charging device according to claim 1, wherein a bimetal is used as the temperature detecting element. 4. The charging device according to claim 1, wherein a nickel hydride storage battery is used as the secondary battery.