JP2003282047A - Current shut-off element and battery pack having this current shut-off element built-in - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability and safety of a current shut-off element when it is surely made to actuate by being inserted into a resin molding part in an embedded state, and produce a large amount of inexpensive current shut- off elements by reducing failures in the case of inserting the element into the resin molding part. <P>SOLUTION: This current shut-off element is provided with a case 61, a pair of output terminals 62 comprised by being fixed to this case 61, and a current shut-off part 63 which is built-in in the case 61 and which shuts-off the current by separating a contact point 64 when the temperature becomes higher than a set temperature or over-current flows. The case 61 is composed of the main body case 61A and a cap case 61B made of a polyamide resin in which the filler is not substantially filled. The main body case 61A has a housing space to have the current shut-off part 63 built-in, and the opening part of this housing space 65 is occluded by the cap case 61B. In the main body case 61A, all the surroundings of the opening part is molded by the polyamide resin, and the cap case 61B made of the polyamide resin is adhered to all the surroundings of the opening part by a supersonic wave welding. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current cut-off device which is connected in series with a battery to protect the battery by cutting off the current when an overcurrent flows in the battery or when the battery temperature rises to an abnormal temperature. And a battery pack incorporating this current interruption element.

[0002]

2. Description of the Related Art Current breaking devices such as breakers and PTC devices are used to protect batteries from overcurrent and abnormal temperature rise. These current interrupting elements are connected in series with the battery. The breaker contains a bimetal which is heated and deformed by an electric current in a case. The bimetal moves the movable contact of the breaker. This bimetal deforms when an overcurrent flows and separates the movable contact from the fixed contact. When this happens, the breaker shuts off the current. The PTC element has a built-in PTC whose electric resistance increases when the temperature becomes higher than a set temperature. The PTC element is built in the case of the battery pack close to the battery. In this battery pack, when the PTC element is heated by the battery and rises to a set temperature, the electric resistance of the PTC element suddenly increases significantly, and the current flowing through the battery is substantially cut off.

[0003]

The conventional battery pack is
These current interrupting elements are built in the case and are connected in series with the battery. The battery pack having this structure can be safely used as a current interrupt device. However, if the current cut-off element cannot operate normally, the reliability of the battery pack is significantly reduced. It is difficult for the conventional current cut-off element to always operate normally depending on the state of being built in the battery pack. For example, instead of putting the battery pack in a preformed case to assemble it, a battery pack that is manufactured by insert molding a part or the whole of the battery into the resin molding part that forms the battery case is There is a drawback that it is difficult to operate the blocking element normally. This is because when the conventional current cutoff element is insert-molded in the resin molding portion and fixed in an embedded state, the resin molding the resin molding portion may enter the case of the current interruption element. The resin that enters the breaker case may interfere with the movement of the movable contact and may not operate normally. The breaker that intrudes the movable contact against the fixed contact by the invading resin cannot cut off the current,
On the other hand, the breaker that intrudes the movable contact in the direction of separating the movable contact from the fixed contact cannot energize. Also, P
The resin that has entered the case of the TC element has a drawback that it cannot be energized normally in a state where the PTC is overheated and tripped, and the electric resistance of the PTC is largely changed. The current cut-off element that does not operate normally when the resin enters the case does not operate normally when the battery pack is completed. For this reason, it is necessary to inspect all the manufactured battery packs, which requires time and labor, and if a defective product is generated in this process, the yield of the battery pack is deteriorated. Further, even if the battery operates normally when inspected, the resin that intrudes may cause the battery pack to not operate normally during use. This not only lowers the yield of mass-produced pack batteries, but also adversely affects the reliability. Further, when molding the resin molding portion that constitutes the case, it is necessary to set the molding pressure and the like to a low level, which also limits the manufacturing process.

The applicant of the present application has developed a current cutoff device in which a case is formed of a liquid crystal polymer for the purpose of eliminating this problem. This current cutoff element is manufactured by forming a case with two parts including a main body case and a lid case, and ultrasonically welding the lid case to the opening edge of the main body case. The current cut-off element having this structure can improve reliability because the inside has a sealed structure. Furthermore, in order to make the case more tough, glass fibers are filled and reinforced.

The current interrupting device having this structure has the advantage that the case can be hermetically sealed and therefore the reliability can be improved. However, glass fibers filled in the liquid crystal polymer for reinforcement may make ultrasonic welding difficult. For example, when glass fibers are exposed on the welding surface between the opening edge of the main body case and the lid case, this prevents complete adhesion between the main body case and the lid case, and a gap is created. When this current interruption element is inserted into the resin molding portion, the molten resin penetrates the gap and enters the inside of the case. The molten resin that has entered the case causes a failure. This resin prevents the contacts from moving normally. If the filling amount of the glass fiber is reduced to avoid this adverse effect, the strength of the main body case and the lid case is reduced. The current interrupting element whose strength of the case is reduced cannot withstand the pressure when it is inserted into the resin molding portion. Even if a low temperature molding resin such as a polyamide resin is used in the resin molding portion, the pressure is about 30 atm and the temperature is about 230 ° C. at the time of molding, resulting in a considerably high temperature and high pressure environment. As a result, the case of the current interrupt element that cannot withstand this severe environment will not operate normally due to deformation of the case. By the way, PTC as a current cutoff element
If you use a fuse, it may trip at the temperature when molding, and if you use a fuse, it will be blown by heat.

In order to prevent this harmful effect, the applicant of the present application provides a resin molding part with a resin intrusion prevention part for preventing the intrusion of molten resin, and arranges a current interruption element in this resin intrusion prevention part to provide a core pack. We have developed a battery pack that is manufactured by inserting the resin into the resin molding part (Japanese Patent Application No. 2001-329013). This battery pack is manufactured by inserting the core pack of the battery into the resin molding portion so that the current cutoff element is not embedded in the resin molding portion. The battery pack having this structure has a drawback in that it cannot be easily manufactured because the resin intrusion prevention portion is provided when the resin molding portion is molded, and the manufacturing cost increases. Further, there is a drawback that if the heated resin in a molten state enters the resin invasion preventing portion in the manufacturing process, the current interruption element is heated and fails.

The present invention was developed for the purpose of solving such a drawback of the present invention, and an important object of the present invention is to insert the resin molding portion in a buried state so that it can surely operate, thereby ensuring reliability and safety. It is an object of the present invention to provide a current interrupting element capable of remarkably improving the performance and a battery pack incorporating the current interrupting element. Further, another important object of the present invention is to reduce the failure rate in the manufacturing process, especially the failure at the time of inserting into the resin molding part, to significantly improve the reliability and to mass-produce the current cutoff device at low cost. And to provide a battery pack incorporating this current interruption element. Furthermore, another important object of the present invention is to provide a current interrupting element and a battery pack containing the current interrupting element, which can efficiently produce a large quantity of high quality products by reducing restrictions on the manufacturing process. is there.

[0008]

According to a first aspect of the present invention, there is provided a case 61 in which a current cutoff element is made of plastic.
And a pair of output terminals 6 fixed to the case 61
2 and a current cut-off portion 63 that is electrically connected to the output terminal 62 and is built in the case 61 to separate the contact point 64 to cut off the current when the temperature becomes higher than the set temperature or when an overcurrent flows. Equipped with. The case 61 is composed of a main body case 61A and a lid case 61B made of polyamide resin that are substantially not filled with a filler. Body case 61
A has a storage space 65 having an opening for incorporating the current cutoff portion 63, and the opening of the storage space 65 is closed by a lid case 61B. Further, in the step of molding the main body case 61A made of polyamide resin, the pair of output terminals 62 are insert-molded and fixed, and the main body case 61A has the entire circumference of the opening formed of polyamide resin. A lid case 61B made of polyamide resin is ultrasonically welded and adhered to the entire circumference of the opening of the body case 61A.

A battery pack according to a second aspect of the present invention is a resin molding part 1 in which a core pack 10 of the battery is insert-molded.
A current interrupting element 6 that is connected in series with the battery 2 and interrupts the current flowing through the battery 2 in the event of an abnormality is inserted in the resin molded portion 1. The current interruption element 6 is electrically connected to the output terminal 62, a case 61 formed of a polyamide resin that is not substantially filled with a filler, a pair of output terminals 62 fixed to the case 61. It is configured with a current cut-off portion 63 having a contact 64 which is built in the case 61 and cuts off the current. The current cutoff element 6 cuts off the current flowing to the battery 2 by separating the contact 64 when the temperature becomes higher than the set temperature or an overcurrent flows.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. However, the examples described below are examples of the current cutoff element 6 and the battery pack for embodying the technical idea of the present invention, and the present invention shows the current cutoff element 6
And the battery pack is not specified below.

Further, in this specification, in order to facilitate understanding of the claims, the numbers corresponding to the members shown in the embodiments are referred to as "the claims column" and "to solve the problems. It is added to the members shown in "Means column".
However, the members shown in the claims are not limited to the members of the embodiment.

In the battery pack of FIG. 1, a resin molding 1 is adhered and fixed to the battery end surface. The battery pack shown in FIG.
As shown in FIG. 3, the resin molded part 1 is fixed to the electrode end surface having the convex electrode 2B. However, the battery pack of the present invention has a battery end surface (not shown) opposite to the battery end surface having the convex electrode. The resin molding part 1 can also be fixed. Further, although not shown, in the battery pack of the present invention, the resin molding portion 1 can be fixed to both narrow side surfaces of the thin battery. In the above-described battery pack, the core pack 10 of the battery 2 is temporarily fixed in the molding chamber of the mold, the molten resin is injected into the molding chamber, and the resin molding unit 1
It is manufactured by inserting the core pack 10 into the. The core pack 10 is formed by connecting the circuit board 5 and the current interruption element 6 which is a protection element of the battery 2 to the battery 2. The core pack 10 is shown in an exploded perspective view in FIG. In the core pack 10 shown in this figure, the circuit board 5 and the current interruption element 6 are connected to the battery 2. The circuit board 5 is connected to the battery 2 via the lead plate 7 and the current interruption element 6.

In the core pack 10, as shown in FIGS. 3 and 4, the holder 4 may be arranged between the circuit board 5 and the battery 2. The holder 4 is manufactured by molding plastic that is harder than the resin molding portion 1. This holder 4
Is molded into a shape in which the circuit board 5 is fitted and arranged at a fixed position, and further, a position fitting part 14 for positioning the battery pack is provided, and the position fitting part 14 is exposed to the outside. In this way, the resin molding part 1 is inserted. In the battery pack of this structure, the positioning fitting portion 14 can be provided by the hard plastic holder 4. Therefore, the position fitting portion 14 has a solid structure, and the battery pack can be accurately positioned and attached to an electric device. The position fitting portion 14 in the figure is a concave portion, and the fitting convex portion provided in the electric device is inserted therein, and the battery pack is mounted in a fixed position. The position fitting portion may be a convex portion. The positioning fitting portion of the convex portion is fitted into the concave portion provided in the electric device. The core pack 10 having the holder 4 has a feature that the circuit board 5 can be connected to a fixed position of the battery 2 and temporarily fixed to a mold.

In the battery pack in which the circuit board 5 of the core pack 10 is inserted into the resin molding portion 1, the circuit board 5 can be fixed at the correct position by the resin molding portion 1. Therefore, the circuit board 5 can be fixed at an accurate position without necessarily using the holder. In addition, the core pack 10 without the holder also has advantages over the core pack 10 with the holder 4. It is a circuit board 5 with a lead plate 7 and a battery 2
This is because it is possible to temporarily fix the relative position between the battery 2 and the circuit board 5 to the molding chamber of the mold by temporarily adjusting the relative position. With the core pack 10 having this structure, the dimensional error of the battery 2 is corrected and the resin molding portion 1 is molded to form a battery pack having a small dimensional error. The battery 2 may have a dimensional error in length in the manufacturing process. The dimensional error in the lengthwise direction of the battery 2 can be absorbed by the distance between the circuit board 5 and the battery 2. For example, in a battery pack containing a long battery, bring the circuit board close to the battery,
For a battery pack containing a short battery, fix the circuit board away from the battery. In this way, the size of the entire battery pack can be set to the specified size. The gap between the circuit board 5 and the battery 2 is absorbed by deforming the lead plate 7 connecting the circuit board 5 to the battery 2. The mold has a molding chamber for temporarily fixing the battery 2 and the circuit board 5 at correct positions. Core pack 1
In No. 0, the lead plate 7 is slightly compressed and temporarily fixed in the molding chamber, and the circuit board 5 and the battery 2 are set at fixed positions. In this state, molten resin is injected into the molding chamber to fix the circuit board 5 at a correct position.

The battery 2 is a rechargeable secondary battery such as a lithium ion battery, a nickel-hydrogen battery or a nickel-cadmium battery. The battery 2 in the figure is a thin battery, and the outer can 2
Both sides of A are curved surfaces, and the four corners of the outer can 2A are chamfered. Using a lithium-ion battery as the thin battery has the feature that the charging capacity relative to the capacity of the entire battery pack can be increased. This battery 2 has a sealing plate 2C located on the electrode end surface provided with the convex electrode 2B.
The safety valve 16 is provided in the. In the battery 2 shown in FIGS. 2 and 4, the convex electrode 2B is provided in the central portion of the sealing plate 2C, and the safety valve 16 is provided at one end. The battery may have a safety valve built in the convex electrode. The safety valve 16 opens when the internal pressure of the battery 2 becomes higher than the set pressure. The opened safety valve 16 discharges the gas inside and stops the rise of the internal pressure of the outer can 2A.

The circuit board 5 is mounted with an electronic component 9 that realizes a protection circuit for the battery 2. The battery pack in this figure
Although the protection circuit is mounted on the circuit board 5, the protection circuit may be a small IC and may be inserted into the resin molded portion 1 in the same manner as the current cutoff element 6. In this battery pack, the circuit board 5 can be omitted. Further, in the battery packs shown in FIGS. 2 and 4, the output terminal 3 made of a metal plate is fixed to the circuit board 5. The output terminal 3 is exposed to the outside through the electrode window 12 provided in the resin molding portion 1. Further circuit board 5
Also fixes the test point terminal 17, which is a metal plate, to the surface. The test point terminal 17 is a terminal for testing whether the manufactured battery pack operates normally. The test point terminal 17 is also exposed to the outside through the terminal window 13 provided in the resin molding portion 1. Since the test point terminal 17 is not used in a normal use state, after the battery pack is manufactured and tested for normal operation, the test point terminal 17 is sealed with the sticker 18 attached.

The current interruption element 6 shown in the exploded perspective view of FIG. 5 and the sectional view of FIG. 6 is connected to the case 61, a pair of output terminals 62 fixed to the case 61, and the output terminal 62. In addition, the case 61 is provided with a current cutoff portion 63 having a contact 64 for cutting off the current when the temperature becomes higher than a set temperature or an overcurrent flows.

The case 61 is composed of a main body case 61A and a lid case 61B which are made of polyamide resin. Both the main body case 61A and the lid case 61B are made of polyamide resin because the current cut-off element 6 is made of resin.
This is to prevent deformation due to heat and pressure when inserting into. When the resin molding part 1 of the battery pack is molded with a polyamide resin which is a low-temperature molding resin or a polyamide resin to which an epoxy resin is added, the molding pressure is about 30 atm and the temperature is about 230 ° C. . The plastic for molding the case 61 of the current interruption element 6 is
It is a polyamide resin that is not deformed by the temperature and pressure when molding the resin molding part 1.

Further, the main body case 61 of the current interruption element 6
Polyamide resin molding A and lid case 61B is
Substantially no filler such as glass fiber is filled. This is because if a filler such as glass fiber is filled, when the lid case 61B is ultrasonically welded to the opening of the main body case 61A, the lid case 61B cannot be welded in a completely adhered state. Therefore, in the present specification, “substantially not filled with the filler” means that the filler is filled to such an extent that the ultrasonic welding between the main body case 61A and the lid case 61B is not hindered. From this fact, in the battery pack of the present invention, the polyamide resin used for molding the case 61 of the current interrupting element 6 ideally contains no filler, but contains a slight amount of filler. Even if it does, it may be below the extent that it does not hinder the ultrasonic welding between the main body case 61A and the lid case 61B.

The main body case 61A has a storage space 65 having an opening for accommodating the current interruption portion 63, and the opening of the storage space 65 is closed by a lid case 61B. The body case 61A shown in the figure has a peripheral wall 66 provided around the storage space 65. The peripheral wall 66 is the lid case 6
A recess 67 is provided to connect 1B in place.
The lid case 61B is provided with a convex portion (not shown) that can be fitted into the concave portion 67 so as to project from the lower surface. The case 61 having this structure can connect the lid case 61B to the main body case 61A at an accurate position.

In the main body case 61A, a pair of output terminals 62, that is, a first output terminal 62A and a second output terminal 62B are insert-molded and fixed in a plastic molding process. The output terminal 62 penetrates the bottom portion of the main body case 61A and protrudes from the storage space 65 to the outside so as not to be exposed on the welding surface 66A of the peripheral wall 66 provided around the storage space 65. First output terminal 62A
Is inserted into the main body case 61A and extended to the bottom surface to reinforce the bottom surface of the main body case 61A. In the body case 61A, the bottom of the storage space 65 is thin. The bottom made of a thin polyamide resin is easily deformed by heat and pressure when it is inserted into the resin molding portion 1. In particular, since the current cut-off element 6 inserted in the resin molded portion 1 of the battery pack needs to be extremely small, the bottom of the storage space 65 becomes extremely thin. For example, the total thickness is 1.1m
In the case of a small current interrupting device having a size of m, the thickness of the bottom of the storage space is about ⅓ of the total thickness, which is extremely thin. The current cut-off element 6 shown in the figure has the first output terminal 62A, which is a metal plate, exposed on the surface of the bottom in order to reinforce the thin bottom and prevent deformation when it is inserted into the resin molding portion 1. Inserted and fixed. Further, the first output terminal 6
2A has a size that covers almost the entire bottom of the resin molding portion 1 and reinforces the thin bottom.

The lid case 61B made of polyamide resin is also reinforced by inserting the metal plate 68. The metal plate 68 is also provided so as to close the opening of the storage space 65 provided in the main body case 61A. The illustrated metal plate 68 covers almost the entire opening of the storage space 65. Furthermore, this metal plate 6
No. 8 is fixed to the lid case 61B by inserting it so that one end is embedded in the lid case 61B.
In this way, the metal plate 68 is inserted into the body case 61A and the lid case 61B to reinforce the polyamide resin above and below the storage space 65. It has the feature that it is not deformed by pressure and heat when it is pressed.

The second output terminal 62B fixed to the body case 61A is exposed in the recess 67 of the body case 61A and is electrically connected to the movable arm 69 arranged therein. The first output terminal 62A and the second output terminal 62B are
The main body case 61A is inserted and fixed so as not to come into contact with it. The main body case 61A has a structure in which the output terminal 62 is not exposed on the welding surface 66A of the peripheral wall 66, and the entire circumference of the opening, in other words, the entire circumference of the welding surface 66A of the peripheral wall 66 is formed of polyamide resin. The body case 61A in the figure is
The opening is flat and is closed by a plate-like lid case 61B. The main body case 61A has a lid case 61B, which is a polyamide resin, adhered to the entire circumference of the opening by ultrasonic welding. In the case 61 having this structure, the lid case 61B is ultrasonically welded to the welding surface 66A of the peripheral wall 66 provided in the main body case 61A, and the lid case 61B is welded along the entire circumference of the opening of the storage space 65. , The storage space 65 is sealed. The lid case 61B is welded to the entire circumference of the opening of the main body case 61A to make the storage space 65 completely sealed. Therefore, when the current cutoff element 6 is inserted into the resin molded portion 1 of the battery pack, the heated and melted plastic does not enter the inside of the case 61.

The current breaking element 6 shown in the figure is a breaker, and the current breaking portion 63 has a contact 64 for breaking the current. Contact 64
Is provided at the end of the movable arm 69 electrically connected to the fixed contact 64A provided to the first output terminal 62A which is one output terminal 62 and the second output terminal 62B which is the other output terminal 62. And the movable contact 64B being opened. The movable arm 69 is a conductive metal plate that can be elastically deformed.
The movable arm 69 in the figure is provided with a movable contact 64B at one end,
The other end is electrically connected to the second output terminal 62B. A portion electrically connected to the output terminal 62 is branched into a T shape and fitted into a recess 67 provided in the main body case 61A.
Further, the T-shaped branch portion 69A is electrically connected so that the lid case 61B welded to the main body case 61A does not press the second output terminal 62B and cause poor contact.

The movable contact 64B is pressed by the fixed contact 64A by the elastic force of the movable arm 69 which is elastically deformed, so that the current interruption element 6 is energized. The movable contact 64B is the fixed contact 6
When separated from 4A, the current cutoff element 6 is in a state of cutting off the current. In the current interruption element 6 shown in the figure, a disk 70 that deforms by heat to deform the movable arm 69 is arranged between the fixed contact 64A and the movable contact 64B. This disk 70 is a differential thermal expansion laminated metal plate such as bimetal or trimetal. This breaker causes the movable arm 69 to elastically press the movable contact 64B against the fixed contact 64A to bring it into a conductive state when a current smaller than the set current flows or when the temperature of the battery is lower than the set temperature. When an overcurrent larger than the set current flows or becomes higher than the set temperature, the disk 70 is thermally deformed, and the deformed disk 70 deforms the movable arm 69 to move the movable contact 64B.
Is separated from the fixed contact 64A to cut off the current.

In the battery pack, the resin molding part 1 is molded by temporarily fixing the core pack 10 in the molding chamber. The synthetic resin that molds the resin molding part 1 is a low temperature molding resin. The low temperature molding resin is a polyamide resin or a polyurethane resin.
An epoxy resin may be added to the polyamide resin. The polyamide resin to which the epoxy resin is added can have a stronger adhesive force than the polyamide resin alone. Polyamide resins and polyurethane resins have a low softening temperature and a low viscosity when melted, so that they can be molded at a lower temperature and a lower pressure than other thermoplastic synthetic resins. It also has the feature that it can be quickly released from the mold forming chamber. low temperature,
The resin molding part 1 molded at low pressure has a feature that the time required for molding can be shortened and adverse effects on heat and injection pressure at the time of resin molding to electronic parts and the like can be reduced.

However, in the battery pack of the present invention, the resin for molding the resin molding portion 1 is not limited to polyamide resin and polyurethane resin. Any thermoplastic resin other than polyamide resin or polyurethane resin that does not adversely affect heat and pressure on the current cutoff element 6 and the electronic component 9 of the circuit board 5 can be used. Thermoplastic resins such as polyethylene, acryl and polypropylene resins can be used as long as the heat resistance of the electronic component that realizes the protective circuit or the like inserted in the resin molding portion 1 can be improved.

The core pack 10 connecting the circuit board 5 and the current interruption element 6 to the battery 2 is temporarily fixed in the molding chamber of the mold, and the resin molding portion 1 is molded so that the current interruption element 6 is inserted. To do. In the battery pack shown in the cross-sectional views of FIGS. 7 and 8, molten resin is injected between the circuit board 5 and the end surface of the battery, and the resin molding portion 1 is provided there to connect the current cut-off element 6 and the circuit board 5 to the battery. It is fixed at 2. Further, in the battery pack shown in the figure, the resin molding portion 1 is also molded on the upper surface of the circuit board 5 to firmly connect the circuit board 5 to the battery end surface.
In the battery pack of FIG. 7, the circuit board 5 is provided with a through hole 15,
Molten resin is injected into the through hole 15, and the resin molding portions 1 on the upper and lower surfaces of the circuit board 5 are connected by the resin in the through hole 15. This structure can be connected to the circuit board 5 so that the resin molded portion 1 is not peeled off more firmly. In particular, in a battery pack in which a plurality of through holes 15 are provided in the circuit board 5 and the resin molding portions 1 are connected to the upper and lower surfaces, the circuit is formed so that the thin resin molding portion 1 molded on the upper surface of the circuit board 5 is not peeled off firmly. It can be adhered to the substrate 5.

Further, as shown in FIGS. 7 and 8, the resin molding portion 1 has a thin lap portion 11 extending from the battery end face to the outer peripheral surface of the battery 2. This lap thin portion 11
Is molded integrally with the resin molding portion 1 and is bonded to the outer peripheral surface of the battery 2 when molding the resin molding portion 1. The molten resin injected into the molding chamber of the mold is injected from the battery end surface to the portion where the lap thin portion 11 is molded, and the lap thin portion 11 is integrally molded with the resin molding portion 1. The thin wrap portion 11 is preferably provided all around the outer peripheral surface of the battery. The resin molded portion 1 is connected to the battery 2 so that the thin resin wrap portion 11 provided on the entire circumference of the outer peripheral surface does not peel most. However, the thin wrap portion 11 may be provided only on the wide outer peripheral surface of the thin battery.

If the thin wrap portion 11 is thick, the outer shape of the battery pack is enlarged, and if it is thin, the lap thin portion 11 cannot have sufficient strength. Therefore, the wall thickness of the thin wrap portion 11 is preferably 0.1 to
The thickness is 0.3 mm, more preferably 0.1 to 0.2 mm. The thin wrap thin portion 11 does not substantially increase the overall thickness of the battery pack containing the thin battery. This is because it is absorbed by the "swelling amount" when the thin battery is used. The thin battery has a property that when the internal pressure rises, the central portion thereof expands to some extent and becomes thicker. The thin wrap portion 11 having the above-mentioned wall thickness is smaller than the "bulging amount" of the thin battery. Further, the thin wrap portion 11 is provided so as to extend from the battery end surface to the outer peripheral surface, but this portion does not swell. Therefore, when the center of the thin battery swells due to an increase in internal pressure, the thickness of the battery pack in the portion where the thin wrap portion 11 is provided becomes thinner than in the swelled central portion. Therefore, the provision of the thin wrap portion 11 does not substantially increase the thickness of the entire battery pack containing the thin battery.

The width (W1) of the thin wrap portion 11 can be widened to increase the bonding strength with the battery 2. Wrap thin part 1
In the case of 1, the resin molded portion 1 can be firmly adhered to the battery end face even if the width is considerably narrowed. In particular, as shown in the figure, in the battery pack whose surface is covered with the surface covering sheet 19, the surface covering sheet 19 can press the lap thin portion 11 against the surface of the battery so as not to peel it off. Therefore, the width (W1) of the thin wrap portion 11 is narrowed to 0.1 to 2 mm, preferably 0.2 to 1 mm, for example 0.5 mm, so that the resin molded portion 1 can be firmly connected to the battery 2. The narrow lap thin portion 11 can be surely injected with a molten synthetic resin to be molded into a prescribed shape.

The surface covering sheet 19 is a heat-shrinkable tube which can be shrunk by heating. This surface covering sheet 19 is
It is adhered to the surfaces of the resin molding portion 1 and the thin wrap portion 11,
The resin molding 1 is firmly connected to the battery 2. further,
In the battery pack covered with the surface-coating sheet 19, there is no intrusion of delamination between the thin wrap portion 11 and the battery 2, and this also prevents delamination of the thin wrap portion 11. However, the surface covering sheet may be a label or an adhesive tape. The surface covering sheet, which is a label or an adhesive tape, is attached to the surface of the resin molding and the thin portion of the wrap or the surface of the battery to firmly connect the resin molding to the battery.

The battery pack shown in FIGS. 7 and 8 has a resin molding portion 1
A step 20 is provided on the outer periphery of the above, and the low molding portion is covered with the surface covering sheet 19. This resin molding part 1
The surface-coated sheet 19 does not protrude from the resin-molded portion 1, and the surfaces of the resin-molded portion 1 and the surface-coated sheet 19 can be substantially flush with each other.

Further, in the battery pack shown in the drawing, the bottom surface of the battery 2 in the drawing is covered with the plastic molding 21 on the end surface of the battery opposite to the side where the resin molding portion 1 is molded. The plastic molded body 21 is molded from plastic that is harder than the resin molded portion 1. The plastic molded body 21 includes a bottom portion 22 that covers the front surface of the battery end surface.
And a second thin wrap portion 23 extending from the battery end surface to the outer peripheral surface of the battery 2 are integrally molded. The bottom portion 22 is formed thicker than the second thin wrap portion 23, and is provided with a hooking recess portion 24 into which a user puts in a toe when the battery pack is detached from an electric device. This battery pack can be smoothly removed from an electric device by inserting a hook into the hooking recess 24. Further, since the portion where the hooking concave portion 24 is provided is molded of hard plastic, this portion can have a strong structure.

The second thin portion 23 of the lap is the resin molding portion 1.
The thin wall portion 11 is formed to have the same thickness. However, the width (W2) of the second thin wrap portion 23 is wider than the width (W1) of the thin wrap portion 11 of the resin molding portion 1, and
It is 5 mm, preferably 1.5 to 3 mm, for example 2 mm. This is for covering with the surface covering sheet 19 and firmly connecting to the battery 2. This plastic molding 2
1 is bonded and fixed to the battery 2, and further connected by the surface coating sheet 19.

The above battery pack is manufactured as follows. (1) The circuit board 5 is connected to the battery 2 with the current interruption element 6 and the lead plate 7, and the current interruption element 6, the circuit board 5 and the holder 4 are arranged at fixed positions of the battery 2 to manufacture the core pack 10. To do. In the core pack 10 having the holder 4, the holder 4 is arranged between the circuit board 5 and the battery 2. The core pack 10 that connects the plastic molded body 21 to the bottom is fixed by adhering the plastic molded body 21.

(2) The core pack 10 is set in the molding chamber of the mold. After setting the core pack 10 in the molding chamber,
Clamp the mold. The mold that is clamped is the resin molding part 1
A molding chamber for molding the is formed. In this molding room,
The heated molten resin is injected to mold the resin molding part 1. The molten resin is injected from a liquid injection hole opened in the mold. The injected molten resin inserts and fixes the current cut-off element 6, and is also injected up to the portion where the thin lap portion 11 is formed, thereby forming the thin lap portion 11 integral with the resin molding portion 1. (3) After the resin molding part 1 is cured, the mold is opened and the battery pack in which a part of the core pack 10 is insert-molded in the resin molding part 1 is taken out.

(4) After that, the battery pack is put into the cylindrical surface covering sheet 19 which is a heat-shrink tube, and the heat-shrink tube is heated to be brought into close contact with the surface of the battery pack. The surface covering sheet 19 is closely adhered to the step 20 provided in the resin molding portion 1 and the plastic molding body 21 to firmly connect the resin molding portion 1 and the plastic molding body 21 to the battery 2.

(5) A needle electrode is inserted into the test point terminal 17 to test whether the battery pack operates normally. After confirming that the battery pack operates normally, the terminal window 13 of the test point terminal 17 is opened. The seal 18 is adhered so as to close it.

[0040]

The current cut-off element of the present invention and the battery pack incorporating this current cut-off element can be reliably operated by inserting the current cut-off element in the resin molding portion in an embedded state, and the reliability and safety are remarkably improved. There is a feature that can be done. The current cut-off element of the present invention fixes a pair of output terminals to a case molded of polyamide resin, and has a built-in current cut-off portion having a contact electrically cut off by being electrically connected to the output terminals. In addition, the battery pack of the present invention,
This is because the current interrupting element is used as the current interrupting element that is inserted into the resin molding part in which the core pack of the battery is insert-molded.

The current interrupting element of the present invention is characterized in that the case is molded of polyamide resin. As described above, the case molded with the polyamide resin can realize excellent strength and heat resistance as compared with the case molded with the liquid crystal polymer or the like. Therefore, the current interrupting element of the present invention effectively prevents the case from being deformed by the heat and pressure of the heated molten resin and the molten resin from entering the case even when it is inserted into the resin molding portion. Therefore, it is possible to surely prevent the failure of the current interruption element.

Further, in the current interruption element of the present invention, the case is composed of a main body case and a lid case made of polyamide resin which are substantially not filled with a filling material, and the current interruption part is built in the storage space of the main body case. The opening is closed with a lid case. In particular, the main body case is formed by molding the entire circumference of the opening with a polyamide resin, and a polyamide resin lid case is ultrasonically welded to the entire circumference of the opening to be in close contact therewith. For this reason, it is possible to surely prevent the formation of a gap in the welded portion by completely adhering the welded portion without causing a welding defect unlike a case made of a liquid crystal polymer reinforced by filling glass fibers.

Therefore, the current cut-off element and the battery pack of the present invention can significantly reduce the failure rate in the manufacturing process, especially the failure at the time of inserting into the resin molding portion, significantly improve the reliability and safety, and are inexpensive. Can be mass-produced. Furthermore, there is also a feature that it is possible to reduce restrictions in the manufacturing process of inserting the current cut-off element into the resin molding portion and to efficiently mass-produce high-quality ones.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a battery pack according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a core pack of the battery pack shown in FIG.

FIG. 3 is a perspective view of a core pack of a battery pack according to another embodiment of the present invention.

FIG. 4 is an exploded perspective view of the core pack shown in FIG.

FIG. 5 is an exploded perspective view of a current interruption element according to an embodiment of the present invention.

FIG. 6 is a cross-sectional view of a current interruption element according to an embodiment of the present invention.

7 is a cross-sectional view of a resin molding portion of the battery pack shown in FIG.

8 is a vertical cross-sectional view of the battery pack shown in FIG.

[Explanation of symbols]

1 ... Resin molding part 2 ... Battery 2A ... Exterior can 2
B ... Convex electrode 2C ... Sealing plate 3 ... Output terminal 4 ... Holder 5 ... Circuit board 6 ... Current blocking element 7 ... Lead plate 9 ... Electronic component 10 ... Core pack 11 ... Wrap thin portion 12 ... Electrode window 13 ... Terminal window 14 ... Position fitting part 15 ... Through hole 16 ... Safety valve 17 ... Test point terminal 18 ... Seal 19 ... Surface covering sheet 20 ... Step 21 ... Plastic molding 22 ... Bottom 23 ... Second lap thin part 24 ... Hooking recess 61 ... Case 61A ... Main body case 6
1B ... Lid case 62 ... Output terminal 62A ... 1st output terminal 6
2B ... 2nd output terminal 63 ... Current interruption part 64 ... Contact 64A ... Fixed contact 6
4B ... Movable contact 65 ... Storage space 66 ... Peripheral wall 66A ... Welding surface 67 ... Recess 68 ... Metal plate 69 ... Movable arm 69A ... Branch 70 ... Disk

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuhiko Kawabata             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Masatsugu Naka             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Kei Kubota             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Taiki Teraoka             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F term (reference) 5H022 AA19 BB03 CC02 KK01                 5H040 AA40 AS11 AY04 DD08

Claims (2)

[Claims] 1. A case (61) molded of plastic.
And a pair of output terminals (6
2) is electrically connected to this output terminal (62) and the case
A current interrupting device having a current interrupting part (63) which is built in (61) and separates the contact (64) to interrupt the current when the temperature becomes higher than the set temperature or an overcurrent flows, The case (61) is composed of a main body case (61A) and a lid case (61B) made of a polyamide resin that is not substantially filled with a filler, and the main body case (61A) is opened to incorporate the current cutoff part (63). It has a storage space (65) with a part, the opening of this storage space (65) is closed by a lid case (61B), further, in the step of molding the main body case (61A) made of polyamide resin, The pair of output terminals (62) are insert-molded and fixed, and the main body case (61A) is molded with polyamide resin over the entire circumference of the opening, and the entire circumference of the opening of the main body case (61A) is covered with polyamide. A current cutoff element in which a resin lid case (61B) is ultrasonically welded and adhered. 2. A resin molding part (1) for insert molding a core pack (10) of a battery is provided, and this resin molding part is provided.
(1) is connected in series with the battery (2) so that the battery (2)
A current interrupting element (6) for interrupting the current flowing through is inserted, and further, the current interrupting element (6) is molded with a polyamide resin that is not substantially filled with a filler (61), and A pair of output terminals (62) fixed to the case (61),
It is electrically connected to this output terminal (62) and is built into the case (61) and is composed of a current interrupting part (63) having a contact (64) for interrupting the current. Is higher than the set temperature, or when overcurrent flows, separate the contact (64) and remove the battery (2).
A battery pack including a current cutoff element configured to cut off a current flowing through the battery pack.