阅读说明：本技术 二次电池电路及其制造方法 (Secondary battery circuit and method for manufacturing same ) 是由 公文高博 于 2018-10-25 设计创作，主要内容包括：二次电池电路(500)包括：二次电池(501),其具有蓄电单元(510)、以及在蓄电单元(510)的外部露出的一对电极；负载(502),其由二次电池(501)驱动；以及断路器(1),其在二次电池(501)与负载(502)之间串联连接。断路器(1)具备：端子(22),其与二次电池(501)的正极(511)直接连接；固定触点(21)；可动片(4),其具有弹性变形的弹性部(44),以及在弹性部44的一端部具有可动触点(41),并将可动触点(41)向固定触点(21)按压而使其接触；热响应元件(5),其通过随着温度变化而发生变形,使可动片(4)的状态从可动触点(41)与固定触点(21)接触的导通状态转变为可动触点(41)从固定触点(21)分离的切断状态；以及壳体(10),其在使端子(22)露出的状态下,用于收容固定触点(21)、可动片(4)及热响应元件(5)。正极(511)和端子(22)被激光焊接。(A secondary battery circuit (500) comprises: a secondary battery (501) having a power storage cell (510), and a pair of electrodes exposed outside the power storage cell (510); a load (502) driven by the secondary battery (501); and a circuit breaker (1) connected in series between the secondary battery (501) and the load (502). A circuit breaker (1) is provided with: a terminal (22) directly connected to the positive electrode (511) of the secondary battery (501); a fixed contact (21); a movable piece (4) which has an elastic part (44) that elastically deforms, and a movable contact (41) that is provided at one end of the elastic part (44), and which presses the movable contact (41) against the fixed contact (21) to bring the movable contact into contact therewith; a thermally responsive element (5) which is deformed in accordance with a change in temperature, and which changes the state of the movable piece (4) from a conductive state in which the movable contact (41) is in contact with the fixed contact (21) to a disconnected state in which the movable contact (41) is separated from the fixed contact (21); and a housing (10) for housing the fixed contact (21), the movable piece (4), and the thermally responsive element (5) in a state in which the terminal (22) is exposed. The positive electrode (511) and the terminal (22) are laser-welded.)

1. A secondary battery circuit characterized in that,

the secondary battery circuit includes:

a secondary battery having an electric storage unit and a pair of electrodes exposed to the outside of the electric storage unit;

a load driven by the secondary battery; and

a circuit breaker connected in series between the secondary battery and a load,

the circuit breaker is provided with:

a first terminal directly connected to a positive electrode of the secondary battery;

a fixed contact;

a movable piece having an elastic portion that elastically deforms and a movable contact at one end of the elastic portion, the movable piece being configured to press the movable contact against the fixed contact and to bring the movable contact into contact with the fixed contact;

a thermally responsive element that changes its shape with a change in temperature, and changes the state of the movable piece from a conductive state in which the movable contact is in contact with the fixed contact to a disconnected state in which the movable contact is separated from the fixed contact; and

a housing for housing the fixed contact, the movable piece, and the thermally responsive element in a state where the first terminal is exposed,

the positive electrode and the first terminal are laser welded.

2. The secondary battery circuit according to claim 1,

a first plating layer that absorbs light used for the laser welding and melts is formed on a first surface of the first terminal, on which the light is irradiated.

3. The secondary battery circuit according to claim 2,

the first plating layer is locally formed on a part of the first surface.

4. The secondary battery circuit according to claim 2 or 3,

a second plating layer mainly composed of a metal having a higher ionization tendency than the first terminal and a lower ionization tendency than the positive electrode is formed on a second surface of the first terminal to be welded to the positive electrode.

5. The secondary battery circuit according to claim 4,

the second plating layer is locally formed on a part of the second surface.

6. The secondary battery circuit according to claim 4 or 5,

the first plating layer and the second plating layer are formed mainly of nickel, tin, or chromium.

7. The secondary battery circuit according to any one of claims 1 to 6,

the secondary battery circuit includes a metal plate connecting the circuit breaker with the load,

the circuit breaker is provided with a second terminal connected with the metal sheet,

the metal sheet and the second terminal are laser-welded.

8. The secondary battery circuit according to claim 7,

a third plating layer that absorbs the light and melts is formed on a third surface of the second terminal to which the light is irradiated.

9. The secondary battery circuit according to claim 8,

the third plating layer is locally formed on a part of the third surface.

10. The secondary battery circuit according to claim 8 or 9,

the third plating layer is composed mainly of nickel, tin, or chromium.

11. A method for manufacturing a secondary battery circuit, characterized in that,

the secondary battery circuit includes:

a secondary battery having an electric storage unit and a pair of electrodes exposed to the outside of the electric storage unit;

a load driven by the secondary battery;

and a circuit breaker having: a first terminal connected to a positive electrode of the secondary battery; a fixed contact; a movable piece having an elastic portion that elastically deforms and a movable contact at one end of the elastic portion; and a thermal response element that deforms with a change in temperature, the circuit breaker being connected in series between the secondary battery and a load,

the method for manufacturing the secondary battery circuit includes:

an assembling step of assembling the circuit breaker by housing the fixed contact, the movable piece, and the thermally responsive element in a case with the first terminal exposed; and

and a welding step of laser-welding the positive electrode and the first terminal.

12. The method for manufacturing a secondary battery circuit according to claim 11,

and a first plating step of forming a first plating layer that absorbs and melts light used for the laser welding on a first surface of the first terminal, on which the light is irradiated, before the welding step.

13. The method of manufacturing a secondary battery circuit according to claim 11 or 12,

and a second plating step of forming a second plating layer mainly composed of a metal having a higher ionization tendency than the first terminal and a lower ionization tendency than the positive electrode on a second surface of the first terminal to be welded to the positive electrode, before the welding step.

14. The method of manufacturing a secondary battery circuit according to any one of claims 11 to 13,

in the assembling step, the fixed contact, the movable piece, and the thermally responsive element are housed in the case with the second terminal connected to the metal piece provided between the fixed contact and the load exposed,

the welding step includes a step of laser welding the metal piece and the second terminal.

15. The method for manufacturing a secondary battery circuit according to claim 14,

and a third plating step of forming a third plating layer that absorbs the light and melts on a third surface of the second terminal to which the light is irradiated, before the soldering step.

Technical Field

The present invention relates to a secondary battery circuit including a circuit breaker suitable for a direct current circuit of an electrical apparatus.

Background

Conventionally, circuit breakers have been used as protection devices for secondary batteries, motors, and the like of various electrical devices. When an abnormality occurs such as an excessive temperature rise of the secondary battery during charging and discharging or when an overcurrent flows through a motor or the like provided in an apparatus such as an automobile or a home electric appliance, the breaker interrupts the current to protect the secondary battery, the motor, or the like. In order to ensure safety of equipment, a circuit breaker used as such a protection device is required to accurately operate (have good temperature characteristics) following a temperature change and to stabilize a resistance value at the time of energization.

The circuit breaker includes a thermally responsive element that operates in response to a temperature change to conduct or interrupt a current. A circuit breaker using a bimetal as a thermally responsive element is shown in patent document 1. The bimetal is an element that: and an element in which two kinds of plate-like metal materials having different thermal expansion coefficients are laminated, and the shape is changed according to a temperature change, thereby controlling the conduction state of the contact. The circuit breaker disclosed in this document is configured to house components such as a fixed piece, a movable piece, a thermally responsive element, and a PTC thermistor in a case, and terminals of the fixed piece and the movable piece protrude from the case and are connected to a secondary battery circuit of an electrical apparatus.

When the circuit breaker is used as a protection device for a secondary battery or the like provided in an electric device such as a thin multifunctional mobile phone called a notebook personal computer, a tablet-type portable information terminal device, or a smartphone, miniaturization is required in addition to the above-described safety protection. In particular, in recent portable information terminal devices, there is a strong desire for downsizing (thinning) of users, and in order to ensure design superiority, there is a remarkable tendency that devices newly distributed by companies are designed to be small-sized. Under such circumstances, further miniaturization is strongly demanded also for a circuit breaker mounted together with a secondary battery as one component constituting a portable information terminal device.

Documents of the prior art

Patent document

Patent document 1: WO2011/105175 publication

Disclosure of Invention

Problems to be solved by the invention

In recent electrical equipment, a circuit breaker having a small resistance and a large current capacity at the time of energization is desired for the purpose of improving performance and shortening the charging time of a secondary battery. Therefore, the fixed piece and the movable piece are made of a metal having excellent conductivity, for example, a metal containing copper as a main component.

The terminals provided on the fixed piece and the movable piece are usually joined to metal pieces (tabs) constituting a secondary battery circuit by welding. The metal sheet is composed mainly of nickel, for example.

However, since the resistance value of the nickel metal sheet having a lower conductivity than the fixed sheet and the movable sheet is large, the resistance value of the entire secondary battery circuit is increased.

The present invention has been made to solve the above problems, and a main object thereof is to provide a secondary battery circuit capable of easily reducing the resistance value of the entire circuit.

Means for solving the problems

A first aspect of the present invention is a secondary battery circuit, including: a secondary battery having an electric storage unit and a pair of electrodes exposed to the outside of the electric storage unit; a load driven by the secondary battery; and a circuit breaker connected in series between the secondary battery and a load, the circuit breaker including: a first terminal directly connected to a positive electrode of the secondary battery; a fixed contact; a movable piece having an elastic portion that elastically deforms and a movable contact at one end of the elastic portion, the movable piece being configured to press the movable contact against the fixed contact and to bring the movable contact into contact with the fixed contact; a thermally responsive element that changes its shape with a change in temperature, and changes the state of the movable piece from a conductive state in which the movable contact is in contact with the fixed contact to a disconnected state in which the movable contact is separated from the fixed contact; and a case for housing the fixed contact, the movable piece, and the thermally responsive element in a state in which the first terminal is exposed, wherein the positive electrode and the first terminal are laser-welded.

In the secondary battery circuit according to the present invention, it is preferable that a first plating layer that absorbs light used for the laser welding and melts is formed on a first surface of the first terminal to which the light is irradiated.

In the secondary battery circuit according to the present invention, it is preferable that the first plating layer is partially formed on a part of the first surface.

In the secondary battery circuit according to the present invention, it is preferable that a second plating layer containing a metal having a higher ionization tendency than the first terminal and a lower ionization tendency than the positive electrode as a main component is formed on a second surface of the first terminal welded to the positive electrode.

In the secondary battery circuit according to the present invention, it is preferable that the second plating layer is partially formed on a part of the second surface.

In the secondary battery circuit according to the present invention, it is preferable that the first plating layer and the second plating layer are formed using nickel, tin, or chromium as a main component.

In the secondary battery circuit according to the present invention, it is preferable that the secondary battery circuit includes a metal piece connecting the breaker and the load, the breaker includes a second terminal connected to the metal piece, and the metal piece and the second terminal are laser-welded.

In the secondary battery circuit according to the present invention, it is preferable that a third plating layer that absorbs the light and melts is formed on a third surface of the second terminal on which the light is irradiated.

In the secondary battery circuit according to the present invention, it is preferable that the third plating layer is partially formed on a part of the third surface.

In the secondary battery circuit according to the present invention, it is preferable that the third plating layer is composed mainly of nickel, tin, or chromium.

A second aspect of the present invention is a method for manufacturing a secondary battery circuit, the secondary battery circuit including: a secondary battery having an electric storage unit and a pair of electrodes exposed to the outside of the electric storage unit; a load driven by the secondary battery; and a circuit breaker having: a first terminal connected to a positive electrode of the secondary battery; a fixed contact; a movable piece having an elastic portion that elastically deforms and a movable contact at one end of the elastic portion; and a thermally responsive element that deforms with a change in temperature, the circuit breaker being connected in series between the secondary battery and a load, the method of manufacturing the secondary battery circuit including: an assembling step of assembling the circuit breaker by housing the fixed contact, the movable piece, and the thermally responsive element in a case with the first terminal exposed; and a welding step of laser-welding the positive electrode and the first terminal.

In the method for manufacturing a secondary battery circuit according to the present invention, it is preferable that a first plating step of forming a first plating layer that absorbs light used for the laser welding of the first terminal and melts the light is performed on a first surface of the first terminal to which the light is irradiated, be performed before the welding step.

In the method for manufacturing a secondary battery circuit according to the present invention, it is preferable that a second plating step of forming a second plating layer mainly containing a metal having a higher ionization tendency than the first terminal and a lower ionization tendency than the positive electrode on a second surface of the first terminal to be welded to the positive electrode is performed before the welding step.

In the method for manufacturing a secondary battery circuit according to the present invention, it is preferable that the assembling step includes a step of housing the fixed contact, the movable piece, and the thermally responsive element in the case in a state in which a second terminal connected to a metal piece provided between the metal piece and the load is exposed, and the welding step includes a step of laser-welding the metal piece and the second terminal.

In the method for manufacturing a secondary battery circuit according to the present invention, it is preferable that a third plating step of forming a third plating layer that absorbs the light and melts on a third surface of the second terminal on which the light is irradiated is performed before the soldering step.

Effects of the invention

A secondary battery circuit of a first invention includes an electric storage unit, a secondary battery, a load, and a breaker connected in series between the secondary battery and the load. The circuit breaker for the secondary battery circuit includes: a first terminal directly connected to a positive electrode of the secondary battery; a fixed contact; a movable piece having an elastic portion and a movable contact; a thermally responsive element that deforms with a change in temperature; and a housing for accommodating the fixed contact, the movable piece, and the thermally responsive element in a state where the first terminal is exposed. The positive electrode and the first terminal are laser welded. This eliminates the need for a nickel metal piece disposed between the positive electrode and the first terminal of the secondary battery in the conventional secondary battery circuit, and the resistance value of the entire secondary battery circuit can be easily reduced. In addition, the secondary battery circuit is simplified, and cost reduction can be easily achieved.

The second invention is a method of manufacturing a secondary battery circuit including an electric storage unit, a secondary battery, a load, and a breaker connected in series between the secondary battery and the load. The circuit breaker used for the manufacturing method comprises: a first terminal directly connected to a positive electrode of the secondary battery; a fixed contact; a movable piece having an elastic portion and a movable contact; a thermally responsive element that deforms with a change in temperature; and a housing for accommodating the fixed contact, the movable piece, and the thermally responsive element in a state where the first terminal is exposed. The positive electrode and the first terminal are laser welded. This eliminates the need for a nickel metal piece provided between the positive electrode and the first terminal of the secondary battery in the conventional secondary battery circuit, and the resistance value of the entire secondary battery circuit can be easily reduced. In addition, the secondary battery circuit is simplified, and cost reduction can be easily achieved.

Drawings

Fig. 1 is a circuit diagram of a secondary battery circuit according to a first invention.

Fig. 2 is a plan view illustrating a secondary battery pack.

Fig. 3 is a perspective view showing a schematic structure of a circuit breaker for a secondary battery pack before assembly.

Fig. 4 is a sectional view of the above-described circuit breaker showing a normal charged or discharged state.

Fig. 5 is a sectional view showing the above-described breaker in an overcharged state, an abnormal state, or the like.

Fig. 6 is a sectional view showing the structure of the breaker and its peripheral portion.

Fig. 7 is a sectional view showing a modification of the circuit breaker and a structure of a peripheral portion thereof.

Fig. 8 is a flowchart showing a method of manufacturing a secondary battery circuit according to a second aspect of the present invention.

Fig. 9 is a side view of the metal plate showing the plating process.

Detailed Description

Fig. 1 shows a secondary battery circuit 500 using a circuit breaker 1 according to an embodiment of the present invention. The secondary battery circuit 500 is a dc circuit including a breaker 1, a secondary battery 501, and a load 502. The load 502 is driven by the secondary battery 501. The breaker 1 is disposed between the secondary battery 501 and the load 502. The secondary battery 501, the breaker 1, and the load 502 are connected in series.

Fig. 2 shows a secondary battery pack 550 constituting at least a part of the secondary battery circuit 500. Secondary battery pack 550 includes secondary battery 501, breaker 1, and circuit board 503. The load 502 of the secondary battery circuit 500 is mounted on the circuit board 503 or outside the circuit board 503.

Secondary battery 501 includes a power storage cell 510 for storing electric charge, and a positive electrode 511 and a negative electrode 512 exposed to the outside of power storage cell 510. The positive electrode 511 is made of, for example, a metal sheet containing aluminum as a main component. The negative electrode 512 is made of, for example, a metal sheet containing copper as a main component. The positive electrode 511 and the negative electrode 512 constitute a pair of electrodes.

In addition to a general PCB (printed circuit board), an FPC (flexible printed circuit board) or the like is applied to the circuit board 503.

Between the positive electrode 511 of the secondary battery 501 and the circuit board 503, a breaker 1 is mounted. On the other hand, the negative electrode 512 of the secondary battery 501 is connected to the circuit board 503. Thus, the secondary battery circuit 500 including the positive electrode 511, the breaker 1, the circuit board 503, the load 502, and the negative electrode 512 is configured.

Fig. 3 to 5 show the structure of the circuit breaker 1. The circuit breaker 1 is mounted on an electrical device or the like, and protects the electrical device from an excessive temperature rise or an overcurrent.

The circuit breaker 1 includes a fixed plate 2 having a fixed contact 21, a movable plate 4 having a movable contact 41 at a distal end portion thereof, a thermally responsive element 5 that deforms in accordance with a Temperature change, a PTC (positive Temperature coefficient) thermistor 6, a case 10 that accommodates the fixed plate 2, the movable plate 4, the thermally responsive element 5, and the PTC thermistor 6, and the like. The casing 10 is composed of a casing main body (first casing) 7, a lid member (second casing) 8 attached to the upper surface of the casing main body 7, and the like.

The fixing piece 2 is formed with a terminal 22 exposed from the housing 10. The movable piece 4 exposed from the case 10 is formed with a terminal 42.

The fixing piece 2 is formed by, for example, pressing a plate-shaped metal material (in addition to a metal plate made of copper-titanium alloy, copper-nickel-zinc, brass, or the like) mainly composed of copper or the like. The fixing piece 2 is embedded in the housing body 7 by insert molding in a state where the terminals 22 are exposed to the outside of the housing body 7, and is accommodated in the housing body 7.

The fixed contact 21 is formed at a position facing the movable contact 41 by cladding, plating, coating, or the like of a material having good conductivity such as a copper-silver alloy, a gold-silver alloy, or the like, in addition to silver, nickel, or a nickel-silver alloy, and is exposed from a part of an opening 73a formed in the case main body 7.

The terminal 22 is formed at one end of the fixing piece 2. The terminals 22 protrude outward from the side walls of the end edges of the housing main body 7. The terminal 22 is electrically connected to the secondary battery 501. A support portion 23 for supporting the PTC thermistor 6 is formed on the other end side of the fixing piece 2. The support portion 23 is exposed to the internal space of the case main body 7 through an opening 73d formed in the case main body 7. The PTC thermistor 6 is placed on a protrusion (tenon) 24 protruding from the support portion 23 of the fixing piece 2 at the position 3, and is supported by the protrusion 24. The stationary plate 2 is bent in a step shape, and the stationary contact 21 and the support 23 are arranged at different heights, so that an internal space for accommodating the PTC thermistor 6 is easily secured.

In the present application, unless otherwise specified, the surface of stationary plate 2 on which fixed contacts 21 are formed (i.e., the upper surface in fig. 3) is referred to as "a" surface, and the opposite surface is referred to as "B" surface. When a direction from the fixed contact 21 toward the movable contact 41 is defined as a first direction and a direction opposite to the first direction is defined as a second direction, the a surface faces the first direction and the B surface faces the second direction. The same applies to other components such as the movable piece 4, the thermally responsive element 5, and the PTC thermistor 6.

The movable piece 4 is formed into an arm shape symmetrical with respect to a center line in the longitudinal direction by press working a plate-shaped metal material mainly composed of copper or the like.

A movable contact 41 is formed at the front end of the movable piece 4 in the longitudinal direction. The movable contact 41 is formed of a material similar to that of the fixed contact 21, for example, and is joined to the distal end of the movable piece 4 by a method such as cladding or caulking (crimping) in addition to welding.

At the other end in the longitudinal direction of the movable piece 4, a terminal 42 electrically connected to a secondary battery circuit 500 outside the circuit breaker 1 is formed. The terminals 42 protrude outward from the side walls of the end edges of the housing main body 7.

The movable piece 4 has a contact portion 43 and an elastic portion 44 between the movable contact 41 and the terminal 42. The contact portion 43 contacts the housing main body 7 and the lid member 8 between the terminal 42 and the elastic portion 44. The contact portion 43 has a projecting portion 43a projecting in a wing shape in the short side direction of the movable piece 4. By providing the protruding portion 43a, the abutting portion 43 is sandwiched between the case main body 7 and the cover member 8 over a wide area, and the movable piece 4 is firmly fixed to the case 10.

The elastic portion 44 extends from the contact portion 43 toward the movable contact 41. The contact portion 43 of the movable piece 4 on the proximal end side of the elastic portion 44 is supported by one side of the housing 10, and in this state, the elastic portion 44 is elastically deformed, and the movable contact 41 formed at the distal end portion of the elastic portion 44 is pressed toward the fixed contact 21 and brought into contact therewith, so that the fixed piece 2 and the movable piece 4 can be energized.

The movable piece 4 is bent or flexed by press working at the elastic portion 44. The degree of bending or buckling is not particularly limited as long as the thermally responsive element 5 can be accommodated, and may be appropriately set in consideration of the elastic force at the reverse rotation operation temperature and the normal rotation return temperature, the pressing force of the contact, and the like. Further, a pair of projections 44a and 44B are formed on the surface B of the elastic portion 44 so as to face the thermally responsive element 5. The projection 44a projects toward the thermally responsive element 5 on the proximal end side, and abuts against the thermally responsive element 5 in the cut state. The projection 44b projects toward the thermally responsive member 5 on the tip side (i.e., movable contact 41 side) of the projection 44a, and abuts against the thermally responsive member 5 in the cut-off state. When the thermally responsive element 5 is deformed due to overheating, the thermally responsive element 5 comes into contact with the projection 44a and the projection 44b, the deformation of the thermally responsive element 5 is transmitted to the elastic portion 44 via the projection 44a and the projection 44b, and the distal end portion of the movable piece 4 is pushed up (see fig. 5).

The thermally responsive element 5 changes the state of the movable piece 4 from a conductive state in which the movable contact 41 is in contact with the fixed contact 21 to a disconnected state in which the movable contact 41 is separated from the fixed contact 21. The thermally responsive element 5 has an initial shape in which the cross section is curved in an arc shape, and is formed in a plate shape by laminating thin plates having different thermal expansion coefficients. When the operating temperature is reached due to overheating, the curved shape of the thermally responsive element 5 is warped in the opposite direction as the snap movement, and is restored when it is lower than the recovery temperature due to cooling. The initial shape of the thermally responsive element 5 can be formed by press working. The material and shape of the thermally responsive element 5 are not particularly limited as long as the elastic portion 44 of the movable piece 4 is pushed up by the reverse buckling operation of the thermally responsive element 5 at a desired temperature and is restored to its original shape by the elastic force of the elastic portion 44, but a rectangular shape is preferable from the viewpoint of productivity and efficiency of the reverse buckling operation.

As the material of the thermally responsive element 5, a material in which two kinds of plate-like metal materials having different thermal expansion coefficients, which are made of various alloys such as copper-nickel-zinc, brass, and stainless steel, are laminated is used in combination according to a required combination of conditions. For example, as a material of the thermally responsive element 5 capable of obtaining a stable operating temperature and recovery temperature, a material in which a copper-nickel-manganese alloy is combined on the high expansion side and an iron-nickel alloy is combined on the low expansion side is preferable. From the viewpoint of chemical stability, a more preferable material is a material in which an iron-nickel-chromium alloy is combined on the high expansion side and an iron-nickel alloy is combined on the low expansion side. From the viewpoint of chemical stability and workability, a more preferable material is a material in which an iron-nickel-chromium alloy is combined on the high expansion side and an iron-nickel-cobalt alloy is combined on the low expansion side.

The PTC thermistor 6 conducts the fixed piece 2 and the movable piece 4 when the movable piece 4 is in the cut-off state. The PTC thermistor 6 is disposed between the stator 2 and the thermally responsive element 5. That is, the support portion 23 of the fixing piece 2 is located directly below the thermally responsive element 5 with the PTC thermistor 6 interposed therebetween. When the energization of the fixed piece 2 and the movable piece 4 is cut off due to the reverse warping operation of the thermally responsive element 5, the current flowing through the PTC thermistor 6 increases. The PTC thermistor 6 may be selected from various types as needed according to the operating current, operating voltage, operating temperature, recovery temperature, and the like, as long as the resistance value thereof increases with an increase in temperature to limit the current, and the material and shape thereof are not particularly limited as long as the above characteristics are not impaired. In the present embodiment, a ceramic sintered body containing barium titanate, strontium titanate, or calcium titanate is used. In addition to the ceramic sintered body, a so-called polymer PTC in which a polymer contains conductive particles such as carbon may be used.

The case body 7 and the lid member 8 constituting the case 10 are molded from a thermoplastic resin such as flame-retardant polyamide, polyphenylene sulfide (PPS) having excellent heat resistance, Liquid Crystal Polymer (LCP), and polybutylene terephthalate (PBT). Materials other than the resin may be used as long as the properties equivalent to or higher than those of the above-described resin can be obtained.

The case body 7 is formed with a recess 73 as an internal space for accommodating the movable piece 4, the thermally responsive element 5, the PTC thermistor 6, and the like. The recess 73 has: openings 73a and 73b for accommodating the movable piece 4; an opening 73c for accommodating the movable piece 4 and the thermally responsive element 5; and an opening 73d for accommodating the PTC thermistor 6. The movable piece 4 assembled to the case body 7 and the end edge of the thermally responsive element 5 are brought into contact with each other through a frame formed inside the concave portion 73, and are guided when the thermally responsive element 5 is warped in the reverse direction.

The lid member 8 may be embedded with a metal plate made of copper or the like as a main component or a metal plate made of stainless steel or the like by insert molding. The metal plate appropriately abuts on the a surface of the movable piece 4 to restrict the movement of the movable piece 4, and contributes to the miniaturization of the circuit breaker 1 while improving the rigidity and strength of the cover member 8 and the case 10 serving as a housing.

As shown in fig. 3, the lid member 8 is attached to the case main body 7 so as to close the openings 73a, 73b, 73c, etc. of the case main body 7 in which the fixed pieces 2 (fixed contacts 21), the movable pieces 4 (movable contacts 41, elastic portions 44), the thermally responsive element 5, the PTC thermistor 6, etc. are housed. The case body 7 and the lid member 8 are joined by, for example, ultrasonic welding. Thus, the circuit breaker 1 is assembled with the terminals 22 and 42 exposed.

Fig. 4 and 5 show an outline of the operation of the circuit breaker 1. Fig. 4 shows the operation of the circuit breaker 1 in a normal charging or discharging state. In a normal charged or discharged state, the thermally responsive element 5 maintains the original shape before reverse warping. When the movable contact 41 is pressed toward the fixed contact 21 by the elastic portion 44, the movable contact 41 comes into contact with the fixed contact 21, and the fixed piece 2 and the movable piece 4 of the circuit breaker 1 are brought into a conductive state.

As shown in fig. 4, the thermally responsive element 5 can be separated from the projections 44a and 44b of the movable piece 4 in the conductive state. This increases the contact pressure between the movable contact 41 and the fixed contact 21, and decreases the contact resistance therebetween.

Fig. 5 shows the operation of the circuit breaker 1 in an overcharged state, an abnormal state, or the like. When the temperature is high due to overcharge or abnormality, the thermally responsive element 5 having reached the operating temperature is reversely warped and brought into contact with the elastic portion 44 of the movable piece 4, and the elastic portion 44 is pushed up, so that the fixed contacts 21 are separated from the movable contacts 41. At this time, the current flowing between the fixed contact 21 and the movable contact 41 is interrupted. On the other hand, the thermally responsive element 5 is in contact with the movable piece 4, and a minute leakage current flows through the thermally responsive element 5 and the PTC thermistor 6. That is, the PTC thermistor 6 conducts the fixed piece 2 and the movable piece 4 through the thermally responsive element 5 that turns the movable piece 4 into the cut-off state. As long as such a leakage current flows, the PTC thermistor 6 continues to generate heat, and the resistance value is rapidly increased while the thermally responsive element 5 is maintained in the reverse warping state, so that the current does not flow through the path between the fixed contact 21 and the movable contact 41, and only the above-described slight leakage current (constituting a self-holding circuit) exists. This leakage current can be used for other functions of the security device.

When the overcharged state or abnormal state is eliminated, the heat generation of the PTC thermistor 6 is also suppressed, and the thermally responsive element 5 returns to the recovery temperature and returns to the original shape. Then, the movable contact 41 comes into contact with the fixed contact 21 again by the elastic force of the elastic portion 44 of the movable piece 4, and the circuit is released from the disconnected state and returns to the conductive state shown in fig. 4.

As shown in fig. 2, the terminal 22 of the circuit breaker 1 is directly connected to the positive electrode 511 of the secondary battery 501. The term "direct connection" refers to a state in which the terminal 22 is connected to the positive electrode 511 without a metal piece such as a tab.

In the present embodiment, the terminal 22 and the positive electrode 511 are connected by laser welding. The "laser welding" is a welding method in which a laser is irradiated to melt metals by energy of the laser to join the metals. For example, in the present embodiment, YAG laser light having a wavelength of 1064nm is used, and laser light is irradiated from the front toward the inside in fig. 2 (from the upper side toward the lower side in fig. 6 described later).

By laser welding the positive electrode 511 and the terminal 22, a nickel metal piece disposed between the positive electrode and the first terminal of the secondary battery in the conventional dc circuit is not required, and the resistance value of the entire secondary battery circuit 500 can be easily reduced. In addition, the secondary battery circuit 500 is simplified, and cost reduction can be easily achieved.

Fig. 6 shows the structure of the circuit breaker 1 and its peripheral portion. A plating layer 25 that absorbs the laser beam and melts is formed on the surface 22a (the surface a in the present embodiment) of the terminal 22 on which the laser beam is irradiated. In the present embodiment, the plating layer 25 is made of nickel, tin, or chromium, or an alloy containing these as a main component. As a result, when the plating layer 25 melts, the terminal 22 and the positive electrode 511 of the secondary battery 501 melt in sequence, and the terminal 22 and the positive electrode 511 are welded well. Therefore, the contact resistance between the positive electrode 511 and the terminal 22 can be easily reduced, and the resistance value of the entire secondary battery circuit 500 can be further reduced. The plating layer 25 may be formed on the surface 22B (the surface B) opposite to the surface 22 a. In this case, for example, the positive electrode 511 and the terminal 22 can be connected by turning the breaker 1 upside down with respect to the secondary battery 501.

A plating layer 26 is formed on a surface 22b of the terminal 22 to be welded to the positive electrode 511. The plating layer 26 contains, as a main component, a metal having a higher ionization tendency than the terminal 22 and a lower ionization tendency than the positive electrode 511. In the present embodiment, the plating layer 26 is made of nickel, tin, or chromium, or an alloy containing these as a main component. This suppresses corrosion from the terminal 22 to the positive electrode 511.

The plating layer 25 is preferably formed locally on a part of the face 22a of the terminal 22. In the present embodiment, the plating layer 25 is formed on the surface 22a except for the vicinity of the side wall of the case 10. As a result, stress applied to the plated layer 25 is reduced when the terminal 22 is deformed, and damage (e.g., cracks) to the plated layer 25 can be suppressed. In the embodiment in which the bent portion is formed in the terminal 22 by press working or the like, the plating layer 25 is preferably formed in a region excluding the bent portion and the vicinity thereof. This can suppress damage to the plating layer 25 when forming the bent portion. Similarly, the plating layer 26 is preferably formed partially on a part of the surface 22b of the terminal 22.

As shown in fig. 2, a metal piece 520 is provided between the circuit breaker 1 and the circuit board 503, that is, between the circuit breaker 1 and the load 502. The metal sheet 520 may be a part of a metal foil formed on the PCB or FPC described above. The metal sheet 520 is made of, for example, a metal containing copper as a main component, which has excellent conductivity. The terminal 42 of the circuit breaker 1 is connected to the metal plate 520 by laser welding.

A plating layer 45 that absorbs the laser beam and melts is formed on the surface 42a (the surface a in the present embodiment) of the terminal 42 on which the laser beam is irradiated. In the present embodiment, the plating layer 45 is made of nickel, tin, or chromium, or an alloy containing these as a main component. As a result, the terminal 42 and the metal piece 520 are sequentially melted when the plating layer 45 is melted, and the terminal 42 and the metal piece 520 are satisfactorily welded. Therefore, the contact resistance between the terminal 42 and the metal piece 520 can be easily reduced, and the resistance value of the entire secondary battery circuit 500 can be further reduced. The plating layer 45 may be formed on the surface 42B (the surface B) opposite to the surface 42 a. In this case, the breaker 1 is turned upside down with respect to the secondary battery 501, and the metal piece 520 and the terminal 42 can be connected.

The plating layer 45 is preferably formed locally on a part of the face 42a of the terminal 42. In the present embodiment, the plating layer 45 is formed on the surface 42a except for the vicinity of the side wall of the case 10. As a result, stress applied to the plating layer 45 when the terminal 42 is deformed is reduced, and damage to the plating layer 45 can be suppressed. Similarly, in the case of forming the plating layer on the surface 42b, it is preferable to form the plating layer partially on a part of the surface 42b of the terminal 42.

As in the circuit breaker 1 of the present embodiment, the bent portion 47 may be formed in the terminal 42 by press working or the like. In this case, the plating layer 45 is preferably formed in a region other than the bent portion 47 and the vicinity thereof. This can suppress damage to the plating layer 45 when the bent portion 47 is formed.

The terminals 22 and 42 extend and protrude from the side wall of the housing 10 in the longitudinal direction of the movable piece 4. The projection length L1 of the terminal 22 projecting from the housing 10 and the projection length L2 of the terminal 42 projecting from the housing 10 may be different. In the present embodiment, the projection length L1 of the terminal 22 is set to be greater than the projection length L2 of the terminal 42. This enlarges the contact area between the terminal 22 and the positive electrode 511, and can easily reduce the contact resistance therebetween. In the aspect in which the protrusion length L2 of the terminal 42 is set to be greater than the protrusion length L1 of the terminal 22, the contact area between the terminal 42 and the metal piece 520 is increased, and the contact resistance therebetween can be easily reduced.

The length L3 of the plating layer 25 may be different from the length L4 of the plating layer 45. The length L3 is the length of the plating 25 in the direction in which the terminal 22 protrudes from the housing 10 (the same applies to the length L4). In the present embodiment, the length L3 of the plating layer 25 is set to be greater than the length L4 of the plating layer 45. This allows the terminal 22 and the positive electrode 511 to be welded well in a large area. In the case where the length L4 of the plating layer 45 is set to be greater than the length L3 of the plating layer 25, the terminal 42 and the metal piece 520 are well soldered in a large area.

Thus, even in the embodiment in which a metal layer equivalent to the plating layer 26 is formed on the surface 22b of the terminal 22 by a cladding or the like, corrosion from the terminal 22 to the positive electrode 511 is suppressed. However, since the metal layer formed by the cladding or the like as described above has a large thickness, when a metal having low conductivity is used, the resistance value between the positive electrode 511 and the terminal 22 increases, and the voltage drop of the metal layer increases.

On the other hand, in the present embodiment, the thickness of the plating layer 26 formed on the surface 22b of the terminal 22 is smaller than that of a metal layer formed by a cladding or the like. Therefore, even when the plating layer 26 is made of a metal having a lower conductivity than the metal constituting the fixing piece 2, the resistance value between the positive electrode 511 and the terminal 22 is suppressed.

The secondary battery circuit 500 of the present invention has been described in detail above, but the present invention is not limited to the above-described specific embodiments and may be modified to various embodiments. That is, the present invention is a secondary battery circuit 500 including at least: a secondary battery 501 having a power storage cell 510 and a pair of electrodes exposed to the outside of the power storage cell 510; a load 502 driven by the secondary battery 501; and a circuit breaker 1 connected in series between the secondary battery 501 and the load 502, wherein the circuit breaker 1 has: a terminal 22 directly connected to the positive electrode 511 of the secondary battery 501; a fixed contact 21; a movable piece 4 having an elastic portion 44 that elastically deforms, and a movable contact 41 at one end of the elastic portion 44, and pressing and contacting the movable contact 41 against the fixed contact 21; a thermally responsive element 5 that changes its shape with a change in temperature, and that changes the state of the movable piece 4 from a conductive state in which the movable contact 41 is in contact with the fixed contact 21 to a disconnected state in which the movable contact 41 is separated from the fixed contact 21; and a case 10 for housing the fixed contact 21, the movable piece 4, and the thermally responsive element 5 in a state where the terminal 22 is exposed, the positive electrode 511 and the terminal 22 being laser-welded.

For example, the circuit breaker 1 used in the secondary battery circuit 500 of the present embodiment has a self-holding circuit by the PTC thermistor 6, but can be applied even if the configuration described above is omitted, and the resistance value of the entire dc circuit can be easily reduced.

Further, the movable piece 4 may be formed of a laminated metal such as bimetal or trimetal to integrally form the movable piece 4 and the thermally responsive element 5. In this case, the structure of the circuit breaker is simplified, and further miniaturization can be achieved.

Further, the movable piece 4 of the present embodiment is integrally formed from the elastic portion 44 to the terminal 42, but is not limited to the above-described embodiment, and for example, as shown in japanese patent application laid-open No. 2017-37757, the movable piece 4 of the embodiment of separating the movable piece into the movable arm on the movable contact 41 side and the terminal piece on the terminal 42 side may be applied to the present invention. The movable arm and the terminal piece may be fixed by welding or the like. In this case, the terminal piece on the terminal 42 side may be insert-molded with the fixing piece 2 or the like to the housing body 7.

Fig. 5 and 6 show the circuit breaker 1 in which the terminal 22 formed on the fixed piece 2 is a first terminal directly laser-welded to the positive electrode 511 of the secondary battery 501, and the terminal 42 formed on the movable piece 4 is a second terminal laser-welded to the metal piece 520. In addition, the plating layer 25 formed on the surface 22a is a first plating layer, the plating layer 26 formed on the surface 22b is a second plating layer, and the plating layer 45 formed on the surface 42a is a third plating layer.

In contrast, fig. 7 shows a circuit breaker 1A which is a modification of the circuit breaker 1 and a configuration of a peripheral portion thereof. As shown in the breaker 1A, in the secondary battery circuit 500 of the present invention, the terminal 42 formed on the movable piece 4 may be a first terminal laser-welded directly to the positive electrode 511 of the secondary battery 501. In this case, the terminal 22 formed on the fixing piece 2 may be a second terminal laser-welded to the metal piece 520. Accordingly, the plating layer 45 formed on the surface 42a is a first plating layer, the plating layer 46 formed on the surface 42b is a second plating layer, and the plating layer 25 formed on the surface 22a is a third plating layer. In the circuit breaker 1A, the other structures are equivalent to the circuit breaker 1.

Fig. 8 is a flowchart illustrating a method of manufacturing the secondary battery circuit 500. The method of manufacturing the secondary battery circuit 500 includes: an assembly step S10 of assembling the circuit breaker 1; and a welding step S20 of laser-welding the positive electrode 511 of the secondary battery 501 and the terminal 22 of the breaker 1.

As shown in fig. 3, in the assembling step S10, the fixed piece 2 including the fixed contacts 21, the movable piece 4, and the thermally responsive element 5 are housed in the case 10 with the terminals 22 exposed.

As shown in fig. 6, in the welding step S20, laser light is irradiated from the terminal 22 side in a state where the terminal 22 is overlapped with the positive electrode 511, and the positive electrode 511 and the terminal 22 are laser-welded. This eliminates the need for a nickel metal piece disposed between the positive electrode and the terminal of the secondary battery in the conventional secondary battery circuit, and the resistance value of the entire secondary battery circuit 500 can be easily reduced. In addition, the secondary battery circuit 500 is simplified, and cost reduction can be easily achieved.

As shown in fig. 8, in the method for manufacturing the circuit breaker 1, the plating step S5 is preferably performed before the soldering step S20. The plating step S5 includes a plating step S1 of forming a plating layer 25 on the surface 22a of the terminal 22.

Fig. 9 shows the plating process S5. In the plating step S1, the plating layer 25 is formed on one surface 200a of the sheet-like metal plate (blank) 200. Thereafter, in a pressing step (not shown), the metal plate 200 is punched out to form the fixing piece 2 including the terminal 22. After the metal plate 200 is punched out in the press step, the plating layer 25 may be formed on the surface 22a of the terminal 22, and the plating step S1 may be performed. In addition, the plating process S1 may be performed after the assembling process S10.

The plating step S5 may include a plating step S2 of forming a plating layer 26 on the surface 22b of the terminal 22. In the present embodiment, after the plating layer 26 is formed on the other surface 200b of the metal plate in the plating step S2, the metal plate 200 is punched out to form the fixing piece 2. The plating process S2 is performed after the plating process S1, for example. The plating step S2 may be performed simultaneously with the plating step S1. The plating process S2 may also be performed before the plating process S1. The plating process S2 may also be performed after the stamping process or after the assembling process S10.

The plating step S5 may include a plating step S3 of forming a plating layer 45 on the surface 42a of the terminal 42. In the present embodiment, after the plating layer 26 is formed on the one surface 400a of the metal plate 400 in the plating step S3, the metal plate 400 is punched out to form the movable piece 4. The plating step S3 is performed before or after the plating step S1, or simultaneously with the plating step S1, for example. The plating process S3 may also be performed after the stamping process or after the assembling process S10. In this case, the plating step S3 is preferably performed simultaneously with the plating step S1.

Although the method of manufacturing the secondary battery circuit 500 according to the present invention has been described in detail above, the present invention is not limited to the above-described specific embodiment, and may be modified to various embodiments. That is, the present invention is a method for manufacturing a secondary battery circuit 500, in which the secondary battery circuit 500 includes at least: a secondary battery 501 having a power storage cell 510 and a pair of electrodes exposed to the outside of the power storage cell 510; a load 502 driven by the secondary battery 501; and a circuit breaker 1 having a positive electrode 511 connection terminal 22 to the secondary battery 501, a fixed contact 21, a movable piece 4 having an elastic portion 44 elastically deformed and having a movable contact 41 at one end portion of the elastic portion 44, and a thermally responsive element 5 deformed with a temperature change, and connected in series between the secondary battery 501 and the load 502, the method comprising: an assembling step S10 of assembling the circuit breaker 1 by housing the fixed contacts 21, the movable piece 4, and the thermally responsive element 5 in the case 10 with the terminals 22 exposed; and a welding step S20 of laser-welding the positive electrode 511 and the terminal 22.

Description of the symbols

1 Circuit breaker

2 fixing sheet

4 Movable piece

5 thermally responsive element

10 casing

21 fixed contact

22 terminal

22a face

22b side

25 coating layer

26 coating layer

41 Movable contact

42 terminal

42a face

42b face

44 elastic part

45 coating layer

500 secondary battery circuit

501 Secondary battery

502 load

503 circuit board

510 electric storage unit

511 positive electrode

520 sheet metal

550 secondary battery pack

S10 Assembly Process

S20 welding procedure

S5 plating process.