JPH11306938A - Thermal protector and battery pack using thermal protector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal protector capable of resetting the contacts manually after it is once actuated. SOLUTION: The contacts of a thermal protector are contacted and separated by the axial direction motions of a plunger 3 installed in a vessel 1, and the first compression coil spring 4 and a leaf spring 5 in the form of a sideways facing angle are installed with a flange 2 interposed, and the flange 2 is equipped with a thermal sensitive element 6 which curves the leaf spring 5 by an inverting motion. The leaf spring 5 is furnished at the tip with an engaging part 7 which is engaged with the first part to be engaged 8 in recessed shape formed in the specified position on the inner surface of the vessel 1 so that a latch is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal protector for preventing burnout of electric equipment due to overheating and overcurrent, and to a secondary battery pack equipped with the same.

[0002]

2. Description of the Related Art A self-recovering type thermal protector includes a movable electrode having a thermally responsive element that performs an inversion operation by heat,
A fixed electrode is provided facing the movable electrode, and is provided so as to be able to contact and separate from the movable electrode. When it does, it reverses and opens the contact point between the movable electrode and the fixed electrode, shuts off the power supply and protects the device. Then, when the abnormality of the electric device is removed and the temperature of the thermal responsive element falls, the thermal responsive element performs an inverting operation again and restarts power supply. As described above, the self-recovering type thermal protector does not need to be replaced and can detect an abnormality in an electric device, and is used as one of safety elements having a great advantage different from a fuse.

The conventional thermal protector shown in FIG. 12 is provided in a container 27 at a fixed electrode support 29 and a thermally responsive element support 30 fixed to a resin block 28 and at one end of the fixed electrode support 29. Fixed electrode 31 and thermoresponsive element 3 provided at one end of thermoresponsive element support 30
2 and a movable electrode 3 installed at one end of the thermoresponsive element 32
3 are connected to the other end of the fixed electrode support 29 and the other end of the thermally responsive element support 30, respectively, and the lead 34 is led out of the container 27 to the outside. The resin block 28 is filled with the filler 13 in the container 27.
Is fixed inside.

[0004]

Such a conventional self-recovering type thermal protector is currently used in the field of secondary battery packs for relatively low current capacity devices such as mobile phones. On the other hand, in the case of equipment with a large current capacity represented by electric tools, etc., the self-recovery type is not suitable from the viewpoint of safety. Due to the fact that the rated current is excessive for the required dimensions, there has been no suitable thermal protector for secondary short circuits, and safety issues have been pointed out.

The present invention has been made to solve such a problem, and has as its object to provide a manual recovery type thermal protector.

[0006]

According to a first aspect of the present invention, there is provided a thermal protector including a fixed electrode, a movable electrode, and a movable electrode with respect to the fixed electrode in a container having a locked portion on an inner surface. A plunger for bringing the electrode into and out of contact, a first spring attached to the plunger, and a second spring attached to the plunger and having a locking portion locked to the locked portion. A thermally responsive element that releases the locking portion of the second spring from the locked portion by a reversing operation, and expands and contracts the first spring as the locking portion of the second spring releases. By moving the plunger in the axial direction by the action, the contact state between the fixed electrode and the movable electrode is released and separated, and the separated state is maintained.

As a result, the second spring bends due to the reversing operation of the thermoresponsive element accompanying the temperature rise of the device, and the second spring is bent.
Of the spring is disengaged from the locked portion. At this time the first
The extension of the spring causes the plunger to move, releasing the contact state between the fixed electrode and the movable electrode to separate them, thereby interrupting the circuit.

Next, after removing the abnormal state of the device, the plunger is pushed back to a position where the locking portion of the second spring and the locked portion are locked. The contact is closed and the power supply is resumed, so that a manual reset type thermal protector can be obtained.

According to a second aspect of the present invention, in the thermal protector according to the first aspect, the thermal responsive element is provided near a contact point between the fixed electrode and the movable electrode.

[0010] By arranging the thermally responsive element closer to the contact point between the fixed electrode and the movable electrode, that is, to the heat generating portion that is energized, the operational sensitivity to self-heating due to overcurrent of the device can be improved. .

According to a third aspect of the present invention, in the thermal protector according to the first or second aspect, another locked portion to which the locking portion of the second spring can be locked is provided on the inner surface of the container. It has a configuration that has been formed.

With this arrangement, in a state where the contact between the fixed electrode and the movable electrode is separated, the plunger is inadvertently disengaged from the contact because the locking portion of the second spring is locked by another locking portion. It can be prevented from moving in the closing direction.

According to a fourth aspect of the present invention, in the thermal protector according to any one of the first to third aspects, a third spring having a biasing force opposing the first spring is attached to the plunger. It has an attached configuration.

Thus, the contact pressure of the contact between the fixed electrode and the movable electrode can be stabilized and optimized.

According to a fifth aspect of the present invention, in the thermal protector according to any one of the first to fourth aspects, a configuration is provided in which a bent portion or a curved portion is formed in a part of the second spring. Have.

As a result, the second spring is bent by the urging force of the first spring in the extension direction. By receiving the bending force at the bent portion or the bent portion of the second spring, the locking portion of the second spring can be prevented from being accidentally detached from the locked portion.

[0017] The battery pack according to claim 6 of the present invention comprises:
2. The battery pack according to claim 1, wherein the battery pack contains a plurality of secondary batteries.
The thermal protector according to any one of claims 5 to 5 is connected in series to a battery circuit, and the separated state between the fixed electrode and the movable electrode of the thermal protector is set to a contact state, and the off state of the battery circuit is set. It has a configuration in which a reset button to be turned on is provided.

Thus, when an abnormality such as a secondary short circuit of the secondary battery occurs, the fixed electrode and the movable electrode are separated from each other, and the battery circuit can be cut off (off state). Thereafter, the reset button is pushed back to bring the fixed electrode and the movable electrode into contact with each other, whereby the battery circuit can be turned on (on), and power supply is resumed.

According to a seventh aspect of the present invention, in the battery pack according to the sixth aspect, a through hole is formed in a part of the battery pack, and the reset button is disposed in the through hole. ing.

Thus, the operation of the reset button can be performed from outside the battery pack.

According to an eighth aspect of the present invention, in the battery pack according to the sixth or seventh aspect, when the fixed electrode and the movable electrode are in contact with each other, the tip of the reset button is connected to the battery pack. It has a configuration that is located inside the outer surface.

Thus, when the battery pack is mounted on a predetermined device and used, the reset button of the thermal protector can be prevented from hindering the operation.

According to a ninth aspect of the present invention, there is provided the battery pack according to any one of the sixth to eighth aspects, wherein the battery pack has a cap which is attached to the through hole and allows the reset button to be operated. Have.

Thus, the battery pack can be protected from moisture, dust, etc., which may enter through the through-hole of the battery pack, which may adversely affect the secondary battery and the thermal protector inside the battery pack. .

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a thermal protector according to a first embodiment of the present invention has a circular shape having a disk-shaped flange 2 at a substantially central portion in an insulating container 1. A columnar plunger 3 is provided in the same direction as the central axis of the container 1. A first compression spring 4 in the form of a coil is arranged on one side of the plunger 3 via a flange 2, and a leaf spring 5 in the shape of a letter is arranged on the other side. On the side of the plunger 3 on which the U-shaped leaf spring 5 is provided, a heat responsive element 6 having one end fixed to the flange 2 and the other end bending the U-shaped leaf spring 5 by reversing operation is arranged. doing. At the end of the U-shaped leaf spring 5, an engaging portion 7 formed by bending this end is provided. The locking portion 7 is engaged with a concave first locked portion 8 formed at a predetermined position on the inner surface of the container 1 to form a latch. A movable electrode 9 is provided at the tip of the plunger 3 on the side where the first compression spring 4 is arranged. The movable electrode 9 is in contact with both the first fixed electrode 10a and the second fixed electrode 10b, and the movable electrode 9 and the first fixed electrode 10a and the second fixed electrode 10a A contact pressure is generated at the contact point with the fixed electrode 10b, and the contact point maintains the contact state, whereby the first and second fixed electrodes 10a, 10b are connected via the movable electrode 9.
A current path is formed therebetween.

When the temperature of the apparatus rises due to an overcurrent or an excessive rise in temperature, the inverted U-shaped plate spring 5 gradually moves the plunger 3 side as shown by an arrow in FIG. Pressed. When the operating temperature of the thermally responsive element 6 reaches a predetermined temperature and the pressing amount of the thermally responsive element 6 exceeds the groove depth of the concave first locked portion 8 forming the latch, the latch, that is, the latch Locking portion 7 of the V-shaped leaf spring 5 and the first
Is disengaged from the locked portion 8. At this moment, the coil-shaped first compression spring 4 urged in the extension direction expands, and the plunger 3 moves in the extension direction of the coil-shaped first compression spring 4, as shown in FIG. 2. As described above, the movable electrode 9 attached to the tip of the plunger 3 is separated from the first fixed electrode 10a and the second fixed electrode 10b to be in a separated state, and opens a contact to cut off a current path.

As a result, the reset button 11, that is, the end of the plunger 3, protrudes out of the container 1 by the extended distance of the coil-shaped first compression spring 4.

It should be noted that the flange 2 only needs to be a tray for the first compression spring 4 and does not have to be disk-shaped. Further, the shape of the concave first locked portion 8 may be a convex portion.

Next, after the thermal protector is operated, it is confirmed that the abnormal state of the device has been removed, and if the reset button 11 is pushed back to the position where the latch engages, the first fixed electrode 10a and the second Fixed electrode 10b
And the movable electrode 9 come into contact with each other, the contact is closed again, and power is supplied.

The container 1 is sealed with a resin block 12 and a filler 13. Further, in order to efficiently transmit the reversing operation of the thermoresponsive element 6 to the U-shaped leaf spring 5, a projection 14 is provided at a contact point between the U-shaped leaf spring 5 and the thermoresponsive element 6.
It is desirable to provide the U-shaped leaf spring 5.

As shown in FIG. 3, the configuration of the thermal protector according to the second embodiment of the present invention is the same as that of the thermal protector shown in FIG. 1 is different from the thermal protector shown in FIG. 1 in that a concave first locked portion 8 formed on the inner surface of the container 1 is separated from the movable electrode 9 by a predetermined distance in a direction away from the movable electrode 9. Locked part 1 of 2
5 was formed.

Thus, after the first fixed electrode 10a, the second fixed electrode 10b and the movable electrode 9 are separated from each other, the locking portion 7 at the distal end of the U-shaped leaf spring 5 has the concave second shape. The separated state is stabilized by being locked to the locked portion 15, and the plunger 3 does not inadvertently return in the closing direction of the contact.

As shown in FIG. 4, the configuration of the thermal protector according to the third embodiment of the present invention is the same as that of the thermal protector shown in FIG. The difference from the thermal protector shown in FIG. 1 is that the coil-shaped second compression spring 16 is disposed on the side of the plunger 3 on which the V-shaped leaf spring 5 is disposed.

Thus, the first compression spring 4 having a coil shape is formed.
Is received by the bending of the U-shaped leaf spring 5 and the biasing force of the coil-shaped second compression spring 16, so that the first fixed electrode 10 a and the second fixed The contact pressure of the contact point between the electrode 10b and the movable electrode 9 and the stability of the installation of the U-shaped leaf spring 5 can be improved.

As shown in FIG. 5, the configuration of a thermal protector according to a fourth embodiment of the present invention is the same as that of the thermal protector shown in FIG. The difference from the thermal protector shown in FIG. 1 is that a bent portion 17 formed by bending a part of the U-shaped leaf spring 5 is formed on a part of the U-shaped leaf spring 5. It is that you are.

Thus, when the bending portion 17 receives the urging force of the coil-shaped first compression spring 4 in the extension direction by the deflection of the U-shaped leaf spring 5, the bending portion 17 serves as a hinge. Thus, the contact pressure between the contact points between the first fixed electrode 10a and the second fixed electrode 10b and the movable electrode 9 and the stability of the placement of the U-shaped leaf spring 5 can be improved.

However, the curved portion 17 may be a bent portion formed by bending a part of the U-shaped leaf spring 5.

As shown in FIG. 6, the configuration of a thermal protector according to a fifth embodiment of the present invention is the same as that of the thermal protector shown in FIG. The difference from the thermal protector shown in FIG. 1 lies in that the U-shaped leaf spring 5 is arranged on the same side as the coil-shaped first compression spring 4 with respect to the flange 2, and the first compression A locking portion 18 for locking the locking portion 7 of the V-shaped leaf spring 5 formed at a predetermined position on the inner surface of the container 1 on the same side as the spring 4; That is, a stopper 19 is provided in a part. The locked portion 18 has the same function as the locked portion 8 shown in FIG. Further, the stopper 19 can prevent the reset button 11 at the end of the plunger 3 from protruding out of the container 1 too much when the plunger 3 moves in the direction to open the contact.

With this arrangement, the thermally responsive element 6 attached to the U-shaped leaf spring 5 is arranged at a position closer to the heat-generating portion due to the conduction between the movable electrode 9 and the first fixed electrode 10a and the second fixed electrode 10b. By doing so, the operational sensitivity to self-heating due to overcurrent of the device can be improved.

After the thermal protector is operated, as shown in FIG. 7, a stopper 19 formed on the plunger 3 is in contact with the inner surface of the container 1 to maintain a predetermined driving distance.

As shown in FIG. 8, the structure of the thermal protector according to the sixth embodiment of the present invention is the same as that of the thermal protector shown in FIG. The difference from the thermal protector of FIG.
That is, the movable electrode 21 having a spring action is disposed so as to be opposed to. One end of the movable electrode 21 is pressed against the tip of the plunger 3 on the side of the first compression coil, and comes into contact with one end of the fixed electrode 20 to maintain the contact state. Further, as shown in FIG. 9, the movable electrode 21 pressed by the plunger 3 due to the axial movement of the plunger 3 is separated from the fixed electrode 20 by a spring action to cut off the circuit.

Thereafter, when the reset button 11 is pressed, the plunger 3 moves, and the movable electrode 21 is pressed again by the plunger 3 and returned to the position where it comes into contact with the fixed electrode 20.

As shown in FIG. 10, a battery pack according to a seventh embodiment of the present invention has
The thermal protector 23 according to any of the first to sixth embodiments of the present invention is connected in series to a battery circuit in a space formed between the two battery packs, and a reset button 11 of the thermal protector is provided from outside the battery pack. It is provided so that it can be operated. A through hole 25 is formed in a part of the case 24 of the battery pack, and the reset button 11 is disposed in the through hole 25.

Thus, when an abnormality such as a secondary short circuit occurs in the battery pack, the contact between the fixed electrode and the movable electrode in the mounted thermal protector 23 is separated, and the circuit can be cut off. After confirming that the abnormal state has been eliminated, the reset button 11 protruding from the through hole 25 is pushed back to bring the contact between the fixed electrode and the movable electrode into a contact state, whereby the contact is closed again and power is supplied.

The tip of the reset button 11 may be always located inside the outer surface of the battery pack as shown in FIG. 10 when the contact between the fixed electrode and the movable electrode in the thermal protector 23 is in contact. .

As shown in FIG. 11, the configuration of the battery pack according to the eighth embodiment of the present invention is the same as that of the battery pack shown in FIG. 10 is different from FIG. 10 in that a cap 26 is attached to the through hole 25 and enables the reset button 11 to be operated.

As a result, the manual return operation by the reset button 11 is not hindered, and
5 has a function of protecting the battery pack from factors that adversely affect the secondary battery and the thermal protector 23 inside the secondary battery, such as moisture and dust that may enter from the battery pack 5.

Although the cap 26 is attached from the inside of the case 24, there is no problem if it is attached to the outer surface of the case 24.

[0049]

As described above, according to the present invention, a manual reset type thermal protector having a completely new structure can be obtained, and when used in a battery pack such as a power tool which is a device having a large current capacity, a secondary short-circuit can be obtained. Thus, a suitable thermal protector can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a thermal protector according to a first embodiment of the present invention, in which a fixed electrode and a movable electrode are in contact with each other.

FIG. 2 is a partially cutaway front view in which a fixed electrode and a movable electrode are separated from each other.

FIG. 3 is an enlarged partial cutaway front view of a main part of a thermal protector according to a second embodiment of the present invention.

FIG. 4 is a partially cutaway front view of a thermal protector according to a third embodiment of the present invention.

FIG. 5 is a partially cutaway front view of a thermal protector according to a fourth embodiment of the present invention.

FIG. 6 is a partially cutaway front view in which a fixed electrode and a movable electrode are in contact with each other in a thermal protector according to a fifth embodiment of the present invention.

FIG. 7 is a partially cutaway front view in which the fixed electrode and the movable electrode are separated from each other.

FIG. 8 is a partially cutaway front view in which a fixed electrode and a movable electrode are in contact with each other in a thermal protector according to a sixth embodiment of the present invention.

FIG. 9 is a partially cutaway front view in which the fixed electrode and the movable electrode are separated from each other.

FIG. 10 is a partially cutaway front view of a battery pack according to a seventh embodiment of the present invention.

FIG. 11 is a partially cutaway front view of a battery pack according to an eighth embodiment of the present invention.

FIG. 12 is a partially cutaway front view of a conventional thermal protector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Flange 3 Plunger 4 Coil-shaped 1st compression spring 5 Square-shaped leaf spring 6 Thermal response element 7 Locking part 8 First concave locked part 9 Movable electrode 10a, 10b Fixed electrode REFERENCE SIGNS LIST 11 reset button 15 concave second locked portion 16 coiled second compression spring 17 curved portion of leaf spring 22 battery 23 thermal protector 24 battery pack case 25 through hole 26 cap

Claims (9)

[Claims] 1. A fixed electrode, a movable electrode, a plunger for bringing the movable electrode into and out of contact with the fixed electrode in a container having a locked portion on an inner surface, and a first electrode attached to the plunger. A second spring having a spring attached to the plunger and locked by the locked portion.
The second portion from the locked portion by the reversing operation.
A thermally responsive element for detaching the locking portion of the spring, and moving the plunger in the axial direction by the expansion and contraction of the first spring with the detachment of the locking portion of the second spring. A thermal protector characterized in that a contact state between the fixed electrode and the movable electrode is released to separate the fixed electrode and the movable electrode, and the separated state is maintained. 2. The thermal protector according to claim 1, wherein said thermally responsive element is installed near a contact point between said fixed electrode and said movable electrode. 3. The thermal as claimed in claim 1, wherein another locked portion on which the locking portion of the second spring can be locked is formed on the inner surface of the container. Protector. 4. The thermal protector according to claim 1, wherein a third spring having a biasing force opposing the first spring is attached to the plunger. . 5. The thermal protector according to claim 1, wherein a bent portion or a curved portion is formed in a part of the second spring. 6. The thermal protector according to claim 1, wherein said thermal protector is connected in series to a battery circuit in a battery pack containing a plurality of secondary batteries, and said fixed electrode of said thermal protector is provided. A reset button for setting a state in which the battery electrode is separated from the movable electrode in a contact state, and a state in which an off state of the battery circuit is set to an on state. 7. The battery pack according to claim 6, wherein a through hole is formed in a part of the battery pack, and the reset button is disposed in the through hole. 8. The battery according to claim 6, wherein, when the fixed electrode and the movable electrode are in contact with each other, a tip of the reset button is located inside an outer surface of the battery pack. 8. The battery pack according to 7. 9. The battery pack according to claim 6, further comprising a cap attached to the through hole and operable to operate the reset button.