JPH076788A - Device for preventing over-discharge of secondary battery - Google Patents

Abstract

PURPOSE:To obtain an over-discharge preventing device for preventing the over-discharge of a secondary battery and for preventing the wrong use of discharged secondary battery. CONSTITUTION:A battery housing part 1 of an electronic equipment is provided in the side surface of a main body case 2, and houses a secondary battery 3. Springs 4 are fixed to the back surface of the battery housing part 1, and the tip of a coil core 5 is exposed inside of the back surface through a window 6. A permanent magnet 9 is fitted to a part of the side surface of the secondary battery 3, which abuts on the coil core 5 when the secondary battery 3 is inserted to the battery housing part 1. When the voltage of the secondary battery 3 is lowered gradually by using an electronic equipment and achieves the cut-off voltage, magnetization of the coil core 5, which attracts the permanent magnet 9 arranged in the secondary battery 3, is reversed, and the secondary battery 3 is discharged from the battery housing part 1 by the restoring force of the springs 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery overdischarge prevention device capable of discharging a secondary battery from a storage portion.

[0002]

2. Description of the Related Art Conventionally, in an electronic device using a rechargeable secondary battery, as a means for preventing a reduction in the life of the secondary battery due to over-discharge when the secondary battery is left attached to the device, for example, As disclosed in Japanese Patent Application Laid-Open No. 3-74135, it is provided with a voltage detecting means including a spring, an open / close switch, a switching coil and a circuit disconnecting means, and detects that the output voltage of the battery has dropped below a preset reference value. Then, the switching coil opens the open / close switch to electrically disconnect the battery from the load and prevent over-discharge of the secondary battery.

In another example, as shown in, for example, Japanese Patent Laid-Open No. 55-76578, a differentiation circuit, a switching circuit having a hold function, a circuit disconnecting means consisting of a relay and a voltage detecting means are provided, and a battery Detects a drop in the output voltage and disconnects the battery from the load, and once the current to the load has been interrupted, prevent the current from being re-supplied from the secondary battery to the load even if the voltage of the secondary battery returns to some extent. Was there.

[0004]

However, in the above structure, the voltage detecting means needs a circuit for comparing with the reference voltage for stopping the discharge, in addition to the monitoring circuit for the voltage of the secondary battery. Therefore, the cost and the equipment space are increased. In addition, in order to prevent current from being re-supplied from the secondary battery to the load even if the voltage of the secondary battery is restored to some extent after the current to the load is cut off, in addition to the voltage detection means and circuit disconnection means. A circuit having a hold function must also be provided in the device, which similarly leads to an increase in cost and an increase in device space.

The present invention has been made to solve the above-mentioned problems, and a secondary battery with a lowered voltage can be disconnected from a load with a simple structure without increasing cost and equipment space. It is also an object of the present invention to provide an over-discharge prevention device which can prevent re-supply of current from the secondary battery to the load even if the voltage of the secondary battery is restored to some extent.

[0006]

In order to achieve this object, a secondary battery over-discharge prevention device according to the present invention comprises a storage part for storing a secondary battery, and a secondary battery discharged from the storage part. Urging means, a permanent magnet arranged in the secondary battery, a coil mandrel arranged and fixed so as to face the permanent magnet when the secondary battery is housed in the housing, and a coil thereof. It has a solenoid coil arranged on the mandrel, and a coil driving means for driving the solenoid coil by the voltage of the secondary battery.

The coil mandrel may be made of a magnetic material having magnetic hysteresis.

Further, the solenoid coil, the coil mandrel and the permanent magnet may also serve as the biasing means.

[0009]

In the secondary battery over-discharge prevention device of the present invention having the above-mentioned structure, the battery housing portion houses the secondary battery, and the biasing means is arranged to discharge the secondary battery from the housing portion. The coil driving means supplies a current corresponding to the voltage of the secondary battery to the solenoid coil, and the solenoid coil and the coil mandrel are arranged in the secondary battery against the biasing means by the current generated by the coil driving means. Attracted permanent magnets.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the configuration of an embodiment embodying the present invention will be described with reference to FIGS. 1, 2 and 3.

A battery housing 1 of an electronic device using the over-discharge prevention device of this embodiment is provided on a side surface of a body case 2 so that a secondary battery 3 can be housed therein. A spring 4 as an urging means of the present invention is fixed to the inner surface of the battery housing portion 1. Inside the main body case 2, a columnar coil mandrel 5 is fixed at a position on the back side of the battery housing portion 1, and a tip of the coil mandrel 5 is passed through a window 6 opened in the inner surface of the battery housing portion 1 to store the battery. It is exposed inside the part 1. The coil mandrel 5 has magnetic hysteresis as shown in FIG.

A solenoid coil 7 is wound around the coil mandrel 5 and the tip of the solenoid coil 7 is a solenoid drive circuit 8.
Is electrically connected to. On the side surface of the secondary battery 3,
A permanent magnet 9 is attached to a portion that comes into contact with the coil mandrel 5 when the secondary battery 3 is inserted into the battery housing unit 1. A positive electrode terminal 10 and a negative electrode terminal (not shown) are exposed on the upper surface of the secondary battery 3. The electrode 1 is provided on the inner wall of the battery housing 1 at a position corresponding to the positive electrode terminal 10 and the negative electrode when the secondary battery 3 is housed in the battery housing 1.
One end of the electrode 11 is exposed, and the other end of the electrode 11 is electrically connected to the main circuit board including the solenoid drive circuit 8.

The solenoid drive circuit 8 includes a secondary battery 3
Is connected to the solenoid coil 7 to be supplied with electric power, and is connected to the solenoid coil 7 to control the energization operation of electricity to the solenoid coil 7.

Next, the operation of this embodiment will be described with reference to FIGS. 3, 4, and 5.

When the fully charged secondary battery 3 is set in the battery housing 1 against the elastic force of the spring 4, the main body electric circuit of the device is passed from the positive electrode terminal 10 and the negative electrode terminal (not shown) through the electrode 11. Electric power is supplied to the solenoid drive circuit 8 (not shown). The solenoid drive circuit 8 is shown in FIG.
As shown in, the current flowing through the solenoid 7 is controlled according to the voltage of the secondary battery 3. Therefore, when the fully charged secondary battery 3 is set, the current corresponding to the battery voltage v _A when fully charged. i _A is supplied to the solenoid coil 7.

Since the solenoid coil 7 generates a magnetic field inside the coil when an electric current is passed through it, the coil mandrel 5 is magnetized by the magnetic field, but the coil mandrel 5 has magnetic hysteresis as shown in FIG. , Current i
_{In the} magnetic field H _A generated by _A , it is magnetized to the value of M _A. When the direction of magnetization M _A is positive, the battery compartment 1 side is N
Since the permanent magnet 9 is disposed in the secondary battery 3 so that the S pole is exposed on the front side, the secondary battery 3 is attracted by the magnetic force, and the battery is exposed to the action of the spring 4. It is held inside the storage unit 1.

The voltage of the secondary battery 3 gradually decreases with the use of electronic equipment. When the battery voltage drops to v _B , the solenoid current i _B takes a negative value and the magnetic field H _B generated inside the solenoid coil 7 also becomes negative, but the magnetization of the coil mandrel 5 is B on the hysteresis in FIG. Since it passes through the point, it becomes a positive value M _B , and the coil mandrel 5 and the permanent magnet 9 still attract each other to hold the secondary battery 3 inside the battery housing portion 1.

Further, the voltage of the secondary battery 3 decreases,
When the preset cut-off voltage v _C is reached, the magnetization M _C of the coil mandrel 5 reverses to a negative value in the magnetic field H _C corresponding to the solenoid current i _C , and between the coil mandrel 5 and the permanent magnet 9. Since the suction force does not work, the secondary battery 3 is discharged from the battery housing portion 1 by the restoring force of the spring 4 as shown in FIG. Along with the discharge of the secondary battery 3, the positive electrode terminal 10
Since the connection between the negative electrode terminal and the electrode 11 is also disconnected, the secondary battery 3 is electrically disconnected from the load.

In this way, by reversing the magnetization of the coil mandrel 5 at the cut-off voltage of the secondary battery 3 to lose the attractive force, the secondary battery 3 is discharged from the battery housing 1 by the restoring force of the spring 4. Therefore, it is not necessary to separately provide a circuit for comparing the cutoff voltage of the battery and the battery voltage, and the battery discharging operation itself does not require electric power, and thus does not require a power supply for the notification means. In addition, since the discharged secondary battery 3 is disconnected from the load, over-discharge of the secondary battery 3 does not occur even if the user left it without noticing it, and the life of the secondary battery 3 is shortened. Can be reliably prevented.

In the secondary battery 3 which has been discharged and is once discharged, the load is released and the battery voltage is slightly recovered. When the secondary battery 3 that has recovered to the voltage v _D is set in the battery housing portion 1 again, the current i _D supplied to the solenoid coil 7 generates a magnetic field of H _D inside the solenoid coil 7, but once at point C Since the magnetization process of the coil mandrel 5 which has been magnetized up to this point returns through point D on the hysteresis of FIG. 3, the magnetization M _D still has a negative value, and the attractive force does not work between the coil mandrel 5 and the permanent magnet 9. The secondary battery 3 is immediately discharged from the battery storage unit 1.

When the secondary battery 3 is fully charged by the charger and then set in the battery storage unit 1, the battery voltage has recovered to v _A, so that the magnetic field H _A is applied to the solenoid coil 7.
Is applied, the magnetization of the coil mandrel 5 is inverted again and becomes a positive value. An attractive force acts between the positively magnetized coil mandrel 5 and the permanent magnet 9, and the secondary battery 3 is held in the battery housing portion 1 and the electronic device can be used.

As described above, by using the magnetic material having the magnetic hysteresis for the coil mandrel 5, even if the secondary battery which has been discharged is inserted into the battery housing portion 1, it is discharged from the battery housing portion 1. It is possible to prevent over-discharging of the discharge-terminated battery due to misuse, without specially providing a circuit for determining that the secondary battery 3 is sufficiently charged.

Next, a second embodiment will be described with reference to FIGS. 6, 3 and 4.

The present embodiment is almost the same as the first embodiment in its structure, but as shown in FIG.
There is no spring arranged on the inner surface of the battery, and the end surface of the coil mandrel 5 is passed through the window 6 opened on the inner surface of the battery housing portion 1,
It is aligned with the inner wall of the battery housing 1 and exposed.

When the fully charged secondary battery 3 is set in the battery storage portion 1, the secondary battery 3 is stored by the attraction force of the coil mandrel 5 and the permanent magnet 9 as in the first embodiment. Held in part 1. When the voltage of the secondary battery 3 decreases and reaches the cut-off voltage v _C with the use of the electronic device, the magnetization of the coil mandrel 5 reverses and becomes a negative value M _C , which appears on the battery accommodating portion 1 side of the coil mandrel 5. The pole becomes the S pole. Since the permanent magnet 9 is arranged on the surface of the secondary battery 3 so that the S pole is exposed, the magnetic force between the coil mandrel 5 and the permanent magnet 9 becomes a repulsive force, and the secondary battery 3 receives a repulsive force to store the battery. The positive electrode terminal 10 and the negative electrode terminal and the electrode 11 are discharged from the part 1.
Since the connection is also disconnected, the secondary battery 3 is electrically disconnected from the load and over-discharge is prevented. In this way, the coil mandrel 5
By utilizing the repulsive force of the permanent magnet 9, the secondary battery 3 can be separated from the load without using a spring, and overdischarge can be prevented.

[0027]

As is apparent from the above description, according to the secondary battery over-discharge prevention device of the present invention, the solenoid coil is driven by the voltage of the secondary battery, and the permanent magnet disposed in the secondary battery is removed. Since the secondary battery is sucked, and the secondary battery is discharged from the accommodating portion by the biasing means by bending the attractive force at the cutoff voltage, the voltage is lowered by the simple configuration without increasing the cost and the equipment space. The secondary battery can be disconnected from the load. Furthermore, if a magnetic material having magnetic hysteresis is used for the coil mandrel, it is possible to prevent the current from being re-supplied to the load even if the voltage of the secondary battery is restored to some extent. Even when the battery pack is set in the device, the battery is discharged without being discharged, so that it is possible to reliably prevent over-discharge of the secondary battery.

[Brief description of drawings]

FIG. 1 is a sectional view of a secondary battery over-discharge prevention device of the present invention.

FIG. 2 is a block diagram showing an electrical configuration.

FIG. 3 is a diagram showing magnetic hysteresis of a coil mandrel.

FIG. 4 is a diagram showing the relationship between the voltage of the secondary battery and the drive current of the solenoid coil.

FIG. 5 is a cross-sectional view showing an operation.

FIG. 6 is a sectional view of a second embodiment of the present invention.

[Explanation of symbols]

 1 Battery Storage 2 Body Case 3 Secondary Battery 4 Spring 5 Coil Mandrel 7 Solenoid Coil 8 Solenoid Drive Circuit 9 Permanent Magnet

Claims (3)

[Claims] 1. An accommodating portion for accommodating a secondary battery, an urging means for acting to eject the secondary battery from the accommodating portion, a permanent magnet arranged in the secondary battery, and the accommodating portion. When the secondary battery is housed in, the coil mandrel arranged and fixed so as to face the permanent magnet, the solenoid coil arranged on the coil mandrel, and the solenoid coil is driven by the voltage of the secondary battery. A secondary battery overdischarge prevention device comprising: a coil driving means. 2. The secondary battery over-discharge prevention device according to claim 1, wherein the coil mandrel is made of a magnetic material having magnetic hysteresis. 3. The secondary battery over-discharge prevention device according to claim 1, wherein the solenoid coil, the coil mandrel, and the permanent magnet also function as the biasing means.