JP3283401B2 - Pressure protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure protection device used to secure the safety of a storage battery such as a Li-ion secondary battery even when the gas pressure inside the storage battery exceeds a certain pressure. .

[0002]

2. Description of the Related Art When a rechargeable battery such as a Li-ion secondary battery is charged after a predetermined charge is completed, or charged or discharged with a current larger than a specified current, the electrolyte in the rechargeable battery is decomposed. Then, gas is generated in the storage battery or the temperature of the storage battery is increased. When gas is generated in the battery, the pressure inside the battery increases, so that the battery expands and cracks, and the electrolyte in the battery exudes. Therefore, it is necessary to immediately stop using the storage battery in which the abnormality has occurred, so that the storage battery cannot be reused.

By the way, safety measures are taken for this type of storage battery, and a safety valve is opened due to a rise in atmospheric pressure in the storage battery to exhaust gas in the storage battery, or a rise in the temperature of the storage battery is detected to detect a rise in the temperature of the storage battery. A method of stopping charging or discharging from a storage battery, or providing them at the same time, has been used.

However, in these methods, there is a possibility that the gas will be reused after the gas is exhausted by the safety valve or after the temperature is lowered.
No. 79619 proposes a pressure protection device of the type housed in a storage battery. This is a type in which once the pressure inside the battery rises, the electric circuit of the pressure protection device is cut off, and power cannot be supplied inside and outside the battery. FIG. 10 shows a specific configuration, and FIG. 11 shows a schematic state of being housed in a storage battery. This pressure protection device 1 comprises a circuit board 4 having a conductive path 2 provided on a ceramic substrate 3, A housing 5 for holding the substrate 4 in an airtight manner, a holding member 6, a lid 7, and a projection 7 a formed on the lid 7 and facing the ceramic substrate 3.
Lead portions 2a, 2 provided at the end of the conductive path 2
b, and a pair of wiring members 8a, 8b connected to the drawers 2a, 2b by a method such as pressure contact and led out to the outside. The pair of wiring members 8a and 8b are connected to the conductive path 2
The housing 5 is made of thick aluminum and is not easily deformed, and the lid 7 is formed to be thin and easy to bend.

[0005] The pressure protection device 1 is incorporated in a storage battery 9 such as a lithium ion secondary battery or a nickel hydride secondary battery. FIG. 11 shows an outline of a storage battery 9 by taking a lithium ion secondary battery as an example. Reference numeral 10 denotes a bottomed hollow cylindrical body having an open upper end, which serves as an external negative electrode. Reference numeral 13a denotes an external positive electrode portion having conductivity, which is generally formed of stainless steel. Reference numeral 13b denotes a positive electrode cover serving as a positive electrode inside the battery, which is formed of aluminum and is electrically connected to the external positive electrode portion 13a. A gasket 12 is provided over the entire circumference between the cylindrical body 10 and the positive electrode lid 13b, and a caulking portion 10b provided at the top of the cylindrical body 10 is swaged over the entire circumference, thereby forming the cylindrical body 10 of the positive electrode lid 13b. , The insulation between the cylindrical body 10 and the positive electrode lid 13b, the airtightness in the storage battery, and the shielding between the stainless steel external positive electrode portion 13a and the electrolyte 17 described later.

A positive electrode 14 made of lithium cobalt oxide, a negative electrode 15 made of carbon, a separator 16 for preventing a short circuit between the positive electrode and the negative electrode, and a pressure protection device 1 are incorporated in the cylindrical body 10 as internal electrodes.
The pressure protection device 1 is connected to the positive electrode lid 13b by a wiring member 8a, and is connected to the positive electrode 14 by a wiring member 8b. The negative electrode 15 is provided so as to face the positive electrode 14 with the separator 16 interposed therebetween, and is connected to the cylindrical body 10. Further, the inside of the cylindrical body 10 is filled with the electrolytic solution 17.

[0007] The storage battery 9 configured as described above.
When charging and discharging are performed with a current larger than the specified current, the electrolytic solution 17 in the storage battery is decomposed to generate gas in the storage battery 9 and the pressure inside the storage battery increases. Then, the lid 7 bends and the projection 7a is
To break the ceramic substrate 3 and cut off the ends of the conductive paths 2 at the same time, so that electrical conduction between the pair of wiring members 8a and 8b is interrupted, and To stop charging or discharging the battery.

The conductive path 2 is formed by printing and firing a paste containing silver or the like, or by forming a metal material on a ceramic substrate by plating or the like.

[0009]

However, according to the prior art proposed by the present applicant, even if a load is applied to the ceramic substrate and the ceramic substrate is broken, the silver component or the metal material in the conductive path is stretched so that the conductive path is not expanded. There has been a problem that the conductive path is difficult to be interrupted because a part thereof remains connected.

Further, since the connection between the conductive path and the terminal is made by pressure welding, there is a problem that reliability is poor. In addition,
Although it is conceivable to secure the reliability of the contact by soldering the connection portion, it is difficult to control the amount of solder or the operation is complicated.

SUMMARY OF THE INVENTION In view of the above prior art, a first object of the present invention is to provide a pressure protection device in which a conductive path is reliably cut off and cannot be reused.

It is a second object of the present invention to provide a pressure protection device which can increase the reliability of connection between electrodes and terminals of a conductive path and can easily connect electrodes and terminals.

[0013]

In order to achieve the first object, the present invention provides a conductive path having a metal component, a conductive path provided on a surface of the conductive path, and an elongation rate higher than the conductive path. A circuit board having a small insulating substrate, a hard coat member integrally formed on the conductive path and having a smaller elongation than the conductive path, a housing for hermetically storing the circuit board, and A movable portion formed and facing the outside and facing the circuit board, and a pair of terminals which are electrically connected to the conductive path and exposed to the outside, wherein the movable portion is displaced by external pressure and cuts off the conductive path; This is achieved by the first means described above.

The second object is to provide an electrode at the end of the conductive path in the first means, to provide the coating member on the electrode, and to provide an opening in the coating member on the electrode. This is achieved by the second means connected to the electrode by placing the terminal in the opening and soldering the terminal.

[0015]

In the first means, a conductive path having a metal component and having a large elongation is sandwiched between a substrate having a smaller elongation than the conductive path and a hard coating material, and is integrally formed with the conductive path. Since it is formed, the extension of the conductive path is suppressed, and the conductive path is easily broken. Therefore, when the pressure outside the pressure protection device rises, the movable portion comes into pressure contact with the substrate to break the substrate, and at the same time, to reliably cut off between the ends of the conductive paths.

According to the second means, if an opening is formed in the coating member on the electrode and the terminal is soldered, the connection between the two is ensured and the solder does not easily flow out, so that the amount of solder can be easily managed. Also, the amount of protrusion of the soldering portion can be suppressed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a pressure protection device according to the present invention will be described in detail based on embodiments. 1 is an exploded perspective view of a pressure protection device according to a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the pressure protection device of FIG. 1, and FIG. 3 is a pressure protection device of FIG. FIG. FIG. 4 is a view showing the circuit board and the first terminal of FIG. 1, FIG. 5 is a view in which the first terminal is soldered to the circuit board of FIG. 1, and FIG. Here's how. FIG. 7 shows a modification of the opening. Figures 8 and 9
Shows a second embodiment of the present invention.

A pressure protection device 20 according to a first embodiment of the present invention.
Are a circuit board 21, a housing 22 for hermetically housing the circuit board 21, and a driving body 33 formed on the housing 22 and facing the outside.
And a pair of terminals 24a and 24b connected to the circuit board 21,
And

The circuit board 21 has a ceramic substrate 25 as a substrate, a pair of electrodes 26a and 26b provided at both ends on the ceramic substrate 25, and a conductive path 27 provided between the electrodes 26a and 26b. , The electrodes 26a, 26b
Coating member 2 made of an insulator having an opening 28a thereon
8 are provided on the electrodes 26 a and 26 b and the conductive path 27.

The housing 22 is made of epoxy resin and has a bottomed first housing 29 having an opening 29a. The housing 22 is made of butyl rubber and covers the opening 29a.
A first lid 30 having a plate-like shape forming a cavity therein, and a first housing 29, a first lid 30 having a side wall 31a on a peripheral edge.
The peripheral edge of the first lid 30 is pressed against the first housing 29 without any gap by caulking the tip of the side wall 31a.

The pair of terminals 24a and 24b are
Copper first terminals 24 c and 24 d connected to the conductive paths 27 by solder 34, respectively;
c, 24d external take-out terminal 2 connected to aluminum
4e, 24f.

The first housing 29 is made of epoxy resin and has an outer peripheral wall 29b and a flange 29c provided outside the outer peripheral wall 29b and having four cutouts 29h. Is provided with a first concave portion 29d, and a second concave portion 29d deeper than the first concave portion 29d is provided in the first concave portion 29d.
Recess 29e is provided. The first recess 29
d, a first convex portion 29f and a third concave portion 29g are provided, and the external extraction terminals 24e and 24f are formed by outsert molding so as to be exposed in the third concave portion 29g. The external extraction terminals 24e, 24f are connected to the first terminals 24c, 24d by ultrasonic welding or the like at the third recess 29g. Then, the third concave portion 2 covers the connection portion.
9g is filled with an adhesive 32. As shown in FIGS. 4 and 5, the first terminals 24c and 24d are formed of a thin metal plate and have split portions 24g and 24h at the tips. From the opening 28a of the member 28, the electrodes 26a, 26b
Are soldered by solder 34.

The first lid 30 is made of butyl rubber, has a movable portion 23 surrounded by a thin portion 30a at the center thereof, and has an outer peripheral edge 30c in contact with the outer peripheral wall 29b and the flange portion 29c at the outer peripheral edge. Having.

The circuit board 21 is housed in the first housing 29 such that the back surface side where the conductive path 27 is not formed is opposed to the movable portion 23, and a metal driving body 33 is provided between them. Can be At the center of the driving body 33, a protruding portion 33a protruding toward the circuit board 21 is formed, and upright walls 33b are provided at both side edges in the longitudinal direction. The standing wall 33b guides the driving body 33 to the circuit board 21 and has strength so that the driving body 33 is hardly deformed in the longitudinal direction. A gap 35 is provided between the center of the movable portion 23 and the driving body 33.

Next, a method of manufacturing the protection device will be described. A method of manufacturing a circuit board will be described with reference to FIG.
First, as shown in FIG. 6A, a green sheet having predetermined division grooves 50 formed on one surface is fired to form a ceramic substrate 5.
1 (corresponding to the ceramic substrate 25) is obtained. Next, FIG.
As shown in FIG. 6B, a conductive path 52 (corresponding to the conductive path 27) is formed by printing and baking on the entire surface of the ceramic substrate 51 on which the division grooves are not formed, and thereafter, as shown in FIG. Strip-shaped electrode 53 on the back surface so as to straddle the dividing groove 50
(Corresponding to 26a and 26b) is formed by printing and baking.
Thereafter, as shown in FIG. 6D, an insulating coating member 54 (corresponding to the coating member 28) is formed on the entire surface of the ceramic substrate 51 while leaving an opening 54a (corresponding to the opening 28a) in a part of the electrode 53. It is formed by printing and firing. Finally, the ceramic substrate 51 is divided by the dividing grooves to obtain a plurality of individual circuit boards 21.

The electrodes 26a and 26b contain palladium in addition to silver, and the electrodes 26a and 26b
When the first terminals 24c and 24d are soldered, the silver is melted into the solder, that is, the so-called silver erosion phenomenon is unlikely to occur, and the conductive path 27 is connected to the electrodes 26a and 24d. The resistance value is reduced by containing more silver as compared with 26b.

Further, the conductive path 27 and the electrodes 26a, 2
6b, the coating member 28 is formed by printing a paste using a binder of the same material as a glass component and then sintering the glass component, so that the glass components are bonded to each other, so that the ceramic substrate 25, the conductive path 27, Coat member 28
Are formed integrally with high adhesion. The coating member 28 is formed harder than the conductive path 27.

By the way, when manufacturing the circuit board 21,
As described above, the electrode 53 and the coating member 54 are integrally formed, and the electrode 53 is
When the ceramic substrate 51 is divided by the dividing groove 50, the elongation phenomenon peculiar to the metal of the silver component contained in the electrode 53 is suppressed by the hard ceramic on both surfaces and the coating member, and the ceramic substrate 51 is easily separated. I have.

Then, as shown in FIG.
The split portions 24g and 24h of the first terminals 24c and 24d are placed on the opening 28a of the eighth electrode 8, and the electrodes 26a and 26b and the first terminals 24c and 24d are soldered by the solder.
Therefore, since the solder 34 is accumulated in the opening 28a, the solder 34
Is difficult to flow out, and the terminal split portions 24g and 24h
The solder 34 can easily enter due to the surface tension between them, so that it is securely fixed to the electrodes 26a and 26b. Opening 2
Since 8a is formed in a concave shape, the height of the soldered portion can be suppressed.

As described above, the first terminal 2 is connected to the circuit board 21.
4c and 24d are fixed, and a first housing 29 is formed by integrally forming a plate-shaped aluminum material 24 punched into a predetermined shape by outsert molding.
g, the first terminal 24 attached to the circuit board 21
The circuit board 21 is housed in the first concave portion 29d so that c and 24d are arranged. And the plate-like aluminum material 2
The external take-out terminals 24e and 24f, which are part of the first terminal 4, and the first terminals 24c and 24d are fixed by ultrasonic welding. Then, the adhesive 32 is applied to the welded portion and dried, and the driver 33 is placed on the back surface of the circuit board 21 where the conductive path 27 is not formed. Thereafter, the outer peripheral wall 30c of the first lid 30 is attached to the flange portion. The first lid 30 is put on the first housing 29 so as to be in contact with the first housing 29c. When the adhesive 32 is applied, the adhesive 32 does not flow into the circuit board 21 due to the first protrusion 29f. After that, the cover 31 is fitted into the cover 31 and the front end of the side wall 31 a of the cover 31 is caulked to fix the first housing 29 and the first lid 30 so that no gap is formed between the peripheral edges. Finally, portions A and B shown in FIG. 1 of the plate-like aluminum material 24 are deleted, and the external take-out terminals 24 are provided on the upper and lower surfaces of the protection device 20 as in the conventional example.
Bending is performed so that e and 24f are positioned to form external extraction terminals 24e and 24f. In addition, the notch 29h of the first housing 29 corresponding to the bent portion is provided, and the width of the notch 29h is set to be narrower than the external extraction terminals 24e and 24f. However, the stress in the bent portion is dispersed, and the external extraction terminals 24e,
24f can be made hard to fall off. In addition, a part of the first housing 29 is connected to the external extraction terminals 24e and 24f.
A reinforcing tongue piece 29i embedded in the first housing 29 is provided so that both ends on one side in the longitudinal direction of the external extraction terminals 24e and 24f are embedded in the first housing 29. It is held in one housing 29.

Next, the operation when the pressure protection device 20 is housed in a storage battery will be described. Note that the configuration is the same as that of the conventional example shown in FIG.
When overcharge or overdischarge occurs in the storage battery and the pressure in the battery increases, the movable portion 23 bends inward due to the pressure difference because the inside of the pressure protection device 20 is airtight and almost at atmospheric pressure. Accordingly, the driver 33 applies a weight to the circuit board 21. Here, the first terminals 24c and 24d are formed of a thin plate material, and a second recess 29e is provided between the circuit board 21 and the first housing 29.
Is deformed and breaks when a predetermined pressure is exceeded. As a result, the electric circuit between the external extraction terminals 24e and 24f is cut off, and charging and discharging to and from the storage battery are stopped. Since the protective device that comes into contact with the electrolyte in the storage battery is made of epoxy resin, aluminum, and butyl rubber as described above, it has excellent chemical resistance and is less likely to be corroded. In addition, the protective device is formed as one element. Therefore, when the battery is used, it can be used if it is put in the storage battery and made an electrical connection, so that the reliability of the storage battery can be increased with a simple configuration by using the conventional method together with the conventional method.

As described above, since the back surface side where the conductive path 27 is not formed is provided so as to face the movable portion 23, if the circuit board 21 breaks, the broken conductive path moves away. To be shut off. In addition, since the movable portion 23 and the metal driving body 33 are provided, the movable body can react sensitively to the pressure inside the storage battery, and the hard driving body 33 can be reliably connected to the ceramic substrate 25.
Can be weighted. Also, as shown in FIG.
The adhesive 32 is formed by the protrusion 30 d provided on the first lid 30.
The upper portion is pressed to make the connection between the first terminals 24c and 24d and the external extraction terminals 24e and 24f more reliable.

In the first embodiment of the present invention, the conductive path is formed by printing. However, the conductive path may be formed by metal plating or the like. A system adhesive may be formed to ensure close contact with the plating surface, and the adhesive may be used as an insulating coating member. Further, in the first embodiment, the movable portion 23
And the metal driving body 33 is provided, but the driving body 33 may be omitted as in the conventional example as long as the movable portion 23 can have sufficient hardness. Further, instead of the ceramic substrate 25, a hard molding resin having a small elongation percentage such as PPS or epoxy resin may be used. Further, the external take-out terminals 24e and 24f do not necessarily have to be led out of the main body of the pressure protection device 21, but are simply exposed.
A wiring member that presses against this may be provided inside the storage battery.
The opening provided in the insulating coating member has a shape surrounded by four sides, but may have a shape without one side on the end side of the ceramic substrate as shown in FIG.

Next, a second embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 8 is a sectional view of a main part of a pressure protection device according to a second embodiment of the present invention, and FIG. 9 is an exploded perspective view of the pressure protection device shown in FIG. The difference from the first embodiment is that ceramic substrates 40a and 40b having aluminum foil 41 sandwiched from both sides are provided instead of the circuit board 21 and the first terminals 24c and 24d. The aluminum foil 41 has a thickness of about 0.2 mm and a width substantially equal to that of the ceramic substrates 40a and 40b, and is bonded between the aluminum foil 41 and the ceramic substrates 40a and 40b to integrate them. A member 42 is provided.
Both ends of the aluminum foil 41 are ceramic substrates 40a, 40b
Further extended portions 41a and 41b are provided, and the extended portions 41a and 41b are bent and connected to the external take-out terminal by a method such as ultrasonic welding as in the first embodiment. I have. Even when formed in this manner, the elongation of the metal foil sandwiched between the ceramic substrates is suppressed, and the metal foil is easily broken, and since the conductive path is a metal foil, the resistance value can be reduced. Since the reduction can be achieved, the reliability is improved, and the soldering work and the accompanying management are not required at all.

In the second embodiment of the present invention, the aluminum foil 41 is insert-molded by using a hard and low elongation resin such as PPS or epoxy resin instead of the ceramic substrates 40a and 40b. Is also good. Also,
Not only aluminum foil but also other metal foils may be used.

[0036]

According to the present invention, a conductive path having a metal component and having a high elongation is sandwiched between a substrate having a lower elongation than the conductive path and a hard coat member, and is formed integrally with the conductive path. It suppresses elongation and makes it easy to break the conductive path. Therefore, when the pressure outside the pressure protection device rises, the movable portion comes into pressure contact with the substrate, breaking the substrate and at the same time reliably shutting off the ends of the conductive paths. External charging or discharging can be stopped. Also, if an opening is provided in the coating member on the electrode and the terminal is soldered, the connection between the two is made securely, the solder does not easily flow out, the management of the amount of solder is easy, and the amount of protrusion of the soldering part is reduced. It is possible to suppress.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a pressure protection device according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the pressure protection device shown in FIG.

FIG. 3 is a cross-sectional view of the pressure protection device shown in FIG.

FIG. 4 is a diagram showing a circuit board and first terminals shown in FIG. 1;

FIG. 5 is a diagram in which first terminals are soldered to the circuit board of FIG. 1;

FIG. 6 is a view showing a manufacturing process of the circuit board shown in FIG. 1;

FIG. 7 is a view showing a modification of the opening of the pressure protection device according to the first embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a pressure protection device according to a second embodiment of the present invention.

9 is an exploded perspective view of the pressure protection device shown in FIG.

FIG. 10 is a diagram showing a conventional pressure protection device.

FIG. 11 is a diagram showing a circuit of a storage battery to which a conventional pressure protection device is attached.

[Explanation of symbols]

 Reference Signs List 20 pressure protection device 21 circuit board 22 housing 23 movable portion 24a terminal 24b terminal 25 ceramic substrate (substrate) 26a electrode 26b electrode 27 conductive path 28 coating member 28a opening

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 2 / 06,2 / 12,2 / 34 H02H 5 / 08,7 / 18

Claims (2)

(57) [Claims] A conductive path having a metal component, an insulating substrate provided on the surface of the conductive path and having a lower elongation rate than the conductive path, and an insulating substrate integrally formed on the conductive path and having an elongation rate higher than the conductive path. A circuit board having a small hard coat member, a housing for hermetically housing the circuit board, a movable portion formed on the housing and facing the outside and facing the circuit board; A pressure protection device having a pair of terminals that are conductive and exposed to the outside, wherein the movable portion is displaced by an external pressure to cut off the conductive path. 2. An electrode is provided at an end of the conductive path, the coating member is provided on the electrode, an opening is provided in the coating member on the electrode, and the terminal is placed in the opening. The pressure protection device according to claim 1, wherein the pressure protection device is connected to the electrode by soldering.