JP6983642B2 - A breaker, a safety circuit equipped with it, and a secondary battery circuit. - Google Patents

Description

The present invention relates to a small breaker or the like built in a secondary battery pack or the like of an electric device.

Conventionally, a breaker has been used as a protective device (safety circuit) for a secondary battery, a motor, or the like of various electric devices. The circuit breaker is used when an abnormality occurs, such as when the temperature of the secondary battery during charging / discharging rises excessively, or when an overcurrent flows through the motor, etc. installed in equipment such as automobiles and home appliances. The current is cut off to protect the next battery and motor. The circuit breaker used as such a protective device operates accurately (has good temperature characteristics) following temperature changes and has a stable resistance value when energized in order to ensure the safety of the equipment. You are required to be there.

The breaker is equipped with a heat-responsive element that operates in response to a change in temperature and conducts or cuts off a current. Patent Document 1 discloses a circuit breaker to which a bimetal is applied as a heat-responsive element. Bimetal is an element that controls the conduction state of contacts by laminating two types of plate-shaped metal materials with different coefficients of thermal expansion and changing the shape according to a temperature change. In the circuit breaker shown in the same document, parts such as a fixed piece, a terminal piece, a movable piece, a heat-responsive element, and a PTC thermistor are housed in a case, and the terminal of the fixed piece and the terminal piece protrudes from the case, and electricity is supplied. It is used by being connected to the electric circuit of the device.

The case is molded of an insulating thermoplastic resin. The resin material constituting the case of an electronic component such as a breaker may be filled with a filler such as glass fiber. Such fillers increase the strength and rigidity of the case.

In the circuit breaker having the configuration disclosed in Patent Document 1, the case is composed of a case body and a lid member. A fixed piece is insert-molded into the case body, a movable piece, a heat-responsive element, etc. are housed in the case body, and then a lid member is attached to the case body, and both are ultrasonically welded (paragraph "" of the same document. 0037 ").

WO2011 / 105175 Gazette

However, when a resin filled with glass fiber is applied to the case body of the breaker described in Patent Document 1, for example, when the case body is released from the mold, the debris generated from the case body is movable with the fixed contact. If it penetrates between the contacts, it may affect the contact state between the fixed contacts and the movable contacts. Therefore, before shipping the breaker, an inspection process such as measuring the resistance value at the time of energization is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a breaker capable of simplifying an inspection process before shipment and improving productivity.

In order to achieve the above object, the present invention deforms with respect to a temperature change between a fixed piece having a fixed contact and a movable piece having a movable contact and pressing the movable contact against the fixed contact to bring them into contact with each other. Thereby, the heat-responsive element that shifts the movable piece from the conductive state in which the movable contact contacts the fixed contact to the cutoff state in which the movable contact is separated from the fixed contact, and the fixed piece, the movable piece, and the heat. In a breaker comprising a case accommodating a response element, the case includes a resin material and a filler filled in the resin material, and the surface roughness Rz conforming to JIS B 0601 of the fixed contact is determined. It is characterized in that it is larger than the length of the filler in the lateral direction.

In the breaker according to the present invention, it is desirable that the surface roughness Rz is 200% or more of the length of the filler in the lateral direction.

In the breaker according to the present invention, it is desirable that the surface roughness Rsm is smaller than the length of the filler in the longitudinal direction.

In the breaker according to the present invention, it is desirable that the surface roughness Rsm is 150% or more of the length in the longitudinal direction of the filler.

In the breaker according to the present invention, it is desirable that the fixed contact has a first surface and a second surface that spreads in a plane shape and has a surface roughness Rz larger than that of the first surface.

In the breaker according to the present invention, it is desirable that the filler is formed in the form of short fibers.

In the breaker according to the present invention, it is desirable that the ratio of the Vickers hardness of the filler to the Vickers hardness of the fixed contact according to JIS Z 2244 is 9 or less.

The safety circuit for an electric device of the present invention is characterized by including the breaker.

The secondary battery circuit of the present invention is characterized by including the breaker.

In the breaker of the present invention, the surface roughness Rz of the fixed contact according to JIS B 0601 is larger than the length of the filler in the lateral direction. Therefore, even if a piece of the case enters between the fixed contact and the movable contact, it is accommodated in the recess (valley) formed on the surface of the fixed contact and has an effect on the contact state between the fixed contact and the movable contact. Is suppressed. As a result, the inspection process before shipment can be simplified and the productivity can be improved.

The perspective view before assembly which shows the schematic structure of the breaker by one Embodiment of this invention. The cross-sectional view which shows the said breaker in a normal charge or discharge state. The cross-sectional view which shows the said breaker in the overcharge state or the time of abnormality. The side view which shows the filler contained in the case of the said breaker. The perspective view which shows the case body in the state which a lid member, a heat-reactive element, a movable piece, etc. are removed. A cross-sectional view showing an enlarged contact state between a fixed contact and a movable contact. A perspective view of the movable piece removed from the case body as viewed from the back side. The plan view of the secondary battery provided with the said breaker of this invention. The circuit diagram of the safety circuit provided with the said breaker of this invention.

A breaker according to an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show the configuration of the breaker 1. The breaker 1 is mounted on an electric device or the like and protects the electric device from an excessive temperature rise or an overcurrent.

The breaker 1 includes a fixed piece 2 having a fixed contact 21, a movable piece 4 having a movable contact 41 at the tip thereof, a heat-responsive element 5 that deforms with a temperature change, and a PTC (Positive Temperature Coefficient) thermistor 6. It is composed of a fixed piece 2, a movable piece 4, a heat-responsive element 5, a case 10 for accommodating a PTC thermistor 6, and the like. The case 10 is composed of a case body (first case) 7 and a lid member (second case) 8 mounted on the upper surface of the case body 7.

The fixed piece 2 is formed by, for example, pressing a metal plate containing copper or the like as a main component (in addition, a metal plate such as a copper-titanium alloy, nickel silver, brass, etc.), and is formed by insert molding into the case body 7. It is embedded. A terminal 22 electrically connected to an external circuit is formed at one end of the fixed piece 2, and a support portion 23 for supporting the PTC thermistor 6 is formed at the other end side. The PTC thermistor 6 is placed on a convex protrusion (dove) 24 formed at three points on the support portion 23 of the fixed piece 2 and supported by the protrusion 24. By bending the fixed piece 2 in a stepped manner, the fixed contact 21 and the support portion 23 are arranged in a stepped manner, and a space for accommodating the PTC thermistor 6 is easily secured.

The fixed contact 21 is formed at a position facing the movable contact 41 by clad, plating or coating of a highly conductive material such as silver, nickel, nickel-silver alloy, copper-silver alloy, gold-silver alloy and the like. , It is exposed from a part of the opening 73a formed inside the case body 7. The terminal 22 protrudes outward from the edge of the case body 7. The support portion 23 is exposed from the opening 73d formed inside the case body 7.

In the present application, unless otherwise specified, in the fixed piece 2, the surface on the side where the fixed contact 21 is formed (that is, the upper surface in FIG. 1) is the front surface, and the surface on the opposite side thereof. Is explained as the back side. When the direction from the fixed contact 21 to the movable contact 41 is defined as the first direction and the direction opposite to the first direction is defined as the second direction, the front surface faces the first direction and the back surface faces the second direction. The same applies to other parts such as the movable piece 4, the heat-responsive element 5, the PTC thermistor 6, and the like.

The movable piece 4 is formed in an arm shape symmetrical with respect to the center line in the longitudinal direction by pressing a plate-shaped metal material containing copper or the like as a main component.

A movable contact 41 is formed at the tip of the movable piece 4 in the longitudinal direction. The movable contact 41 is formed of, for example, a material equivalent to that of the fixed contact 21, and is joined to the tip of the movable piece 4 by a method such as welding, clad, or crimping.

A terminal 42 electrically connected to an external circuit is formed at the other end of the movable piece 4 in the longitudinal direction. The movable piece 4 has a contact portion 43 (corresponding to the base end of the arm-shaped movable piece 4 and a portion embedded in the case 10) and an elastic portion 44 between the movable contact 41 and the terminal 42. .. The abutting portion 43 has a protruding portion 43a that abuts between the terminal 42 and the elastic portion 44 with the case body 7 and the lid member 8 and projects like a wing in the lateral direction of the movable piece 4. Since the protrusion 43a is provided, the contact portion 43 is sandwiched by the contact portion 74 of the case body 7 and the contact portion 83 (see FIG. 2) of the lid member 8 in a wide and large area, and the movable piece 4 is formed. It is firmly fixed to the case 10.

The elastic portion 44 extends from the abutting portion 43 toward the movable contact 41. In the abutting portion 43, the movable piece 4 is fixed by being sandwiched between the case body 7 and the lid member 8 from both the front and back sides, and the elastic portion 44 is elastically deformed, so that the movable contact 41 formed at the tip thereof is a fixed contact. It is pressed against the side of 21 and comes into contact with it, so that the fixed piece 2 and the movable piece 4 can be energized.

The movable piece 4 is curved or bent by press working in the elastic portion 44. The degree of bending or bending is not particularly limited as long as the heat-responsive element 5 can be accommodated, and may be appropriately set in consideration of the elastic force at the reversing operation temperature and the normal rotation return temperature, the pressing force of the contact, and the like. Further, a pair of protrusions (contact portions) 44a and 44b are formed on the lower surface of the elastic portion 44 so as to face the heat-responsive element 5. The protrusions 44a and 44b come into contact with the heat-responsive element 5, and the deformation of the heat-responsive element 5 is transmitted to the elastic portion 44 via the protrusions 44a and 44b (see FIGS. 1, 2 and 3).

The heat-responsive element 5 shifts the movable piece 4 from a conductive state in which the movable contact 41 is in contact with the fixed contact 21 to a cutoff state in which the movable contact 41 is separated from the fixed contact 21. The heat-responsive element 5 has an initial shape with a curved cross section in an arc shape, and is formed by laminating thin plates having different coefficients of thermal expansion. When the operating temperature is reached due to overheating, the curved shape of the heat-responsive element 5 reversely warps with a snap motion, and is restored when the temperature drops below the return temperature due to cooling. The initial shape of the heat-responsive element 5 can be formed by press working. The material and shape of the heat-responsive element 5 are particularly limited as long as the elastic portion 44 of the movable piece 4 is pushed up by the reverse warp operation of the heat-responsive element 5 at the desired temperature and returns to its original state by the elastic force of the elastic portion 44. Although it is not, a rectangular shape is desirable from the viewpoint of productivity and efficiency of reverse warpage operation, and a rectangular shape close to a square is desirable in order to efficiently push up the elastic portion 44 while being small.

As the material of the heat-responsive element 5, two kinds of materials having different thermal expansion coefficients, which are made of various alloys such as nickel silver, brass, and stainless steel, are used in combination according to required conditions. For example, as a material of the heat-responsive element 5 that can obtain a stable operating temperature and a return temperature, a combination of a copper-nickel-manganese alloy on the high expansion side and an iron-nickel alloy on the low expansion side is desirable. Further, as a more desirable material from the viewpoint of chemical stability, a combination of an iron-nickel-chromium alloy on the high expansion side and an iron-nickel alloy on the low expansion side can be mentioned. Furthermore, as a more desirable material from the viewpoint of chemical stability and processability, a combination of an iron-nickel-chromium alloy on the high expansion side and an iron-nickel-cobalt alloy on the low expansion side can be mentioned.

The PTC thermistor 6 conducts the fixed piece 2 and the movable piece 4 when the movable piece 4 is in the cutoff state. The PTC thermistor 6 is arranged between the fixed piece 2 and the heat-responsive element 5. That is, the support portion 23 of the fixed piece 2 is located directly below the heat-responsive element 5 with the PTC thermistor 6 interposed therebetween. When the energization between the fixed piece 2 and the movable piece 4 is cut off by the reverse warp operation of the heat-responsive element 5, the current flowing through the PTC thermistor 6 increases. If the PTC thermistor 6 is a positive characteristic thermistor whose resistance value increases as the temperature rises and limits the current, the type can be selected according to the needs such as operating current, operating voltage, operating temperature, and recovery temperature. The material and shape are not particularly limited as long as these properties are not impaired. In this 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 conductive particles such as carbon are contained in the polymer 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, a liquid crystal polymer (LCP), and polybutylene terephthalate (PBT). Has been done. A material other than the resin may be applied as long as the characteristics equal to or higher than those of the above-mentioned resin can be obtained.

The case body 7 is formed with a storage recess 73, which is an internal space for housing a movable piece 4, a heat-responsive element 5, a PTC thermistor 6, and the like. The accommodating recess 73 has openings 73a and 73b for accommodating the movable piece 4, an opening 73c for accommodating the movable piece 4 and the heat-responsive element 5, an opening 73d for accommodating the PTC thermistor 6, and the like. is doing. The edges of the movable piece 4 and the heat-responsive element 5 incorporated in the case body 7 are brought into contact with each other by a frame formed inside the accommodating recess 73, and are guided when the heat-responsive element 5 is reversely warped. ..

A metal plate containing copper or the like as a main component or a metal plate such as stainless steel may be embedded in the lid member 8 by insert molding. The metal plate appropriately abuts on the surface of the movable piece 4, restricts the movement of the movable piece 4, and contributes to the miniaturization of the breaker 1 while increasing the rigidity and strength of the case 10 as the lid member 8 and thus the housing. ..

As shown in FIG. 1, the lid member 8 closes the openings 73a, 73b, 73c, etc. of the case body 7 accommodating the fixed piece 2, the movable piece 4, the heat-responsive element 5, the PTC thermistor 6, and the like. It is attached to the main body 7. The case body 7 and the lid member 8 are joined by, for example, ultrasonic welding.

2 and 3 show an outline of the operation of the breaker 1. FIG. 2 shows the operation of the circuit breaker 1 in a normal charging or discharging state. In a normal charging or discharging state, the heat-responsive element 5 maintains the initial shape before the reverse warp. Both terminals 22 and 42 of the breaker 1 are conducting with each other through the fixed contact 21, the movable contact 41, the elastic portion 44 of the movable piece 4, and the like. However, since the resistance of the PTC thermistor 6 is overwhelmingly larger than the resistance of the movable piece 4, the current flowing through the PTC thermistor 6 is substantially larger than the amount flowing through the fixed contact 21 and the movable contact 41. It can be ignored.

The heat-responsive element 5 may be separated from the movable piece 4 in the conductive state. As a result, the contact pressure between the movable contact 41 and the fixed contact 21 is increased, and the contact resistance between the two is reduced.

FIG. 3 shows the operation of the circuit breaker 1 in an overcharged state or an abnormal state. When the temperature becomes high due to overcharging or abnormality, the heat-responsive element 5 that has reached the operating temperature reversely warps and comes into contact with the elastic portion 44 of the movable piece 4, and the elastic portion 44 is pushed up to form the fixed contact 21 and the movable contact 41. Is separated. At this time, the current flowing between the fixed contact 21 and the movable contact 41 is cut off. On the other hand, the heat-responsive element 5 comes into contact with the movable piece 4, and a slight leakage current flows through the heat-responsive element 5 and the PTC thermistor 6. That is, the PTC thermistor 6 conducts the fixed piece 2 and the movable piece 4 via the heat-responsive element 5 that shifts the movable piece 4 to the cutoff state. The PTC thermistor 6 continues to generate heat as long as such a leakage current flows, and the resistance value is drastically increased while maintaining the heat-responsive element 5 in a reverse warp state. Therefore, the current is a path between the fixed contact 21 and the movable contact 41. There is only a small amount of leakage current as described above (which constitutes a self-holding circuit). This leakage current can be used for other functions of the safety device.

When the overcharged state is released or the abnormal state is resolved, the heat generated by the PTC thermistor 6 also subsides, and the heat-responsive element 5 returns to the return temperature and returns to the original initial shape. Then, the elastic contact force of the elastic portion 44 of the movable piece 4 causes the movable contact 41 and the fixed contact 21 to come into contact with each other again, the circuit is released from the cutoff state, and returns to the conduction state shown in FIG.

The case 10 includes the above-mentioned resin material and a filler filled in the resin material. The filler enhances the strength and rigidity of the case 10.

FIG. 4 shows the filler. The filler of the present embodiment is formed in a shape having a longitudinal direction and a lateral direction. The length L in the longitudinal direction is the maximum length of the filler, and the length D in the lateral direction is the maximum length of the filler in the lateral direction. When the cross section perpendicular to the longitudinal direction of the filler is circular, the length D in the lateral direction is represented by the maximum diameter of the filler. The tip shape of the filler may be sharp. Further, the shape may be such that the longitudinal direction and the lateral direction cannot be clearly distinguished (for example, a spherical shape). In this case, the length L and the length D are equal.

As the filler, a plurality of types of fillers having different combinations of shapes, that is, length L in the longitudinal direction and length D in the lateral direction may be mixed and used. Further, a plurality of types of fillers having different components (compositions) may be mixed and used.

FIG. 5 shows a case body 7 in a state where the lid member 8, the PTC thermistor 6, the heat-responsive element 5, and the movable piece 4 are removed. As described above, the fixing piece 2 is insert-molded in the case body 7. The fixed piece 2 is arranged so that the fixed contact 21 is exposed in the accommodating recess 73, which is the internal space of the case 10.

FIG. 6 shows an enlarged state of contact between the fixed contact 21 and the movable contact 41. The surface of the fixed contact 21 contains small irregularities as shown in FIG. That is, the fixed contact 21 has a concave portion (valley portion) 26 and a convex portion (mountain portion) 27 on its surface. Similarly, the surface of the movable contact 41 also contains small irregularities. That is, the movable contact 41 has a concave portion 46 and a convex portion 47 on its surface. Therefore, a large number of minute gaps G exist between the fixed contact 21 and the movable contact 41 even in a conductive state in which they are in contact with each other.

The surface roughness of the fixed contact 21 conforms to JIS B 0601 and can be measured by SURFCOM 3000A manufactured by Tokyo Seimitsu Co., Ltd. The measurement length is 0.25 mm, the cutoff wavelength is 0.25 mm, the measurement speed is 0.30 mm / s, the cutoff type is Gaussian, and the tilt correction is the minimum square straight line correction. , The λs cutoff ratio is 300. Of the surface roughness of the fixed contact 21 measured in this example, the arithmetic average roughness Ra is 0.7778 μm, the maximum height Rz is 5.2451 μm, and the average length Rsm of the elements is 33.9844 μm. Met.

In the present breaker 1, the surface roughness Rz of the fixed contact 21 is larger than the length D in the lateral direction of the filler. Therefore, even if debris generated from the material of the case body 7 or the lid member 8 in the manufacturing process enters between the fixed contact 21 and the movable contact 41, the recess 26 (microscopic) formed on the surface of the fixed contact 21 is formed. It is accommodated in the gap G), and the influence on the contact state between the fixed contact 21 and the movable contact 41 is suppressed. This makes it possible to suppress an increase in the contact resistance between the fixed contact 21 and the movable contact 41, that is, the resistance value of the breaker 1 when energized. Therefore, the inspection process before shipment can be simplified and the productivity can be improved.

It is desirable that the surface roughness Rz of the fixed contact 21 is, for example, 200% or more of the length D in the lateral direction of the filler. According to such a fixed contact 21, debris can be easily accommodated in the recess 26, and it is possible to further suppress an increase in contact resistance between the fixed contact 21 and the movable contact 41.

The surface roughness Rz of the fixed contact 21 is preferably 0.1 μm or more and 15 μm or less, for example. If the surface roughness Rz is less than 0.1 μm, it may be difficult for the debris to be contained in the recess 26. When the surface roughness Rz exceeds 15 μm, the contact area between the fixed contact 21 and the movable contact 41 may decrease.

It is desirable that the surface roughness Ra of the fixed contact 21 is, for example, 50% or more of the length D in the lateral direction of the filler. According to such a fixed contact 21, debris can be easily accommodated in the recess 26, and it is possible to further suppress an increase in contact resistance between the fixed contact 21 and the movable contact 41.

In the present embodiment, it is desirable that the surface roughness Rsm of the fixed contact 21 is larger than the length L in the longitudinal direction of the filler. According to such a fixed contact 21, debris is easily accommodated in the recess 26, and the influence on the contact state between the fixed contact 21 and the movable contact 41 is further suppressed.

It is desirable that the surface roughness Rsm of the fixed contact 21 is, for example, 150% or more of the length L in the longitudinal direction of the filler. According to such a fixed contact 21, debris is easily accommodated in the recess 26, and the influence on the contact state between the fixed contact 21 and the movable contact 41 is further suppressed.

In the present embodiment, the breaker 1 may be subjected to an activation treatment of the fixed contact 21 and the movable contact 41 before being shipped. In the activation process, in a state where the fixed contact 21 and the movable contact 41 are in contact with each other, high frequency vibration is applied to at least one of the fixed contact 21 and the movable contact 41, and the fixed contact 21 and the movable contact 41 are brought into contact with each other. This is a process for forming a new surface by removing the oxide film of the contact portion between the fixed contact 21 and the movable contact 41 and the peripheral portion thereof in a surface shape by being energized. The activation process stabilizes the conduction state between the fixed contact 21 and the movable contact 41.

The activated contact 21 has a first surface 21a and a second surface 21b, as shown in FIG. The second surface 21b is formed in the central portion of the fixed contact 21, and the first surface 21a is formed in the peripheral portion of the second surface 21b. The second surface 21b is a region in which the fixed contact 21 is exposed to the accommodating recess 73 and is in contact with the movable contact 41, and is a surface that has appeared by the activation treatment. The surface roughness Rz of the second surface 21b is larger than the surface roughness Rz of the first surface 21a. That is, the surface of the second surface 21b is formed coarser than that of the first surface 21a by the activation treatment. The surface roughness of the fixed contact 21 is measured on the second surface 21b.

The second surface 21b is not limited to the surface formed by the activation treatment, and may be formed by another surface roughening treatment. For example, the fixing piece 2 may be formed before being inserted into the mold for forming the case body 7. In this case, the entire surface of the fixed contact 21 may be roughened.

As shown in FIG. 4, the filler of the present embodiment is formed in the form of short fibers. Specific examples of the short fibrous filler include whiskers containing a boric acid compound (eg, potassium titanate) or a boric acid compound (eg, aluminum borate). Such whiskers have a smaller length D in the lateral direction and a length L in the longitudinal direction as compared with conventional glass fibers. Therefore, debris is less likely to be generated from the material of the case body 7 or the lid member 8 in the manufacturing process. Further, the debris is easily accommodated in the recess 26, and it is possible to further suppress the increase in the contact resistance between the fixed contact 21 and the movable contact 41.

The ratio L / D of the length L in the longitudinal direction to the length D in the lateral direction of the filler is preferably 20 or more. According to such a filler, the case 10 is strengthened and the generation of debris is suppressed, so that the influence on the contact state between the fixed contact 21 and the movable contact 41 is further suppressed. From the above viewpoint, the desirable range of the length D is 0.1 μm or more and 5 μm or less, and the more desirable range is 0.1 μm or more and 1 μm or less.

The Vickers hardness of the filler according to JIS Z 2244 is preferably 700 or less. In this case, the debris may affect the contact state between the fixed contact 21 and the movable contact 41.

The ratio of the Vickers hardness of the filler to the Vickers hardness of the fixed contact 21 is preferably 9 or less. If the above ratio exceeds 9, debris may affect the contact state between the fixed contact 21 and the movable contact 41. The ratio of the Vickers hardness of the filler to the Vickers hardness of the fixed contact 21 is preferably 0.25 or more. If the above ratio is less than 0.25, the strength and rigidity of the case 10 may be affected. From the above viewpoint, the more desirable range of the ratio of the Vickers hardness of the filler to the Vickers hardness of the fixed contact 21 is 0.35 or more and 7 or less, and the more desirable range is 0.5 or more and 4 or less. ..

The surface roughness of the movable contact 41 can be measured in the same manner as the surface roughness of the fixed contact 21. Of the surface roughness of the fixed contact 21 measured in this example, the arithmetic average roughness Ra is 1.8439 μm, the maximum height Rz is 8.4357 μm, and the average length Rsm of the elements is 70.6771 μm. Met.

In the present breaker 1, the surface roughness Rz of the movable contact 41 is larger than the length D in the lateral direction of the filler. Therefore, even if the debris peels off from the case body 7 and enters between the fixed contact 21 and the movable contact 41, it is accommodated and fixed in the recess 46 (small gap G) formed on the surface of the movable contact 41. The influence on the contact state between the contact 21 and the movable contact 41 is suppressed. This makes it possible to suppress an increase in the contact resistance between the fixed contact 21 and the movable contact 41, that is, the resistance value of the breaker 1 when energized. Therefore, the inspection process before shipment can be simplified and the productivity can be improved.

It is desirable that the surface roughness Rz of the movable contact 41 is, for example, 200% or more of the length D in the lateral direction of the filler. According to such a movable contact 41, debris can be easily accommodated in the recess 46, and it is possible to further suppress an increase in contact resistance between the fixed contact 21 and the movable contact 41.

The surface roughness Rz of the movable contact 41 is preferably, for example, 0.1 μm or more and 15 μm or less. If the surface roughness Rz is less than 0.1 μm, it may be difficult for the debris to be contained in the recess 46. When the surface roughness Rz exceeds 15 μm, the contact area between the fixed contact 21 and the movable contact 41 may decrease.

The surface roughness Ra of the movable contact 41 is preferably, for example, 50% or more of the length D in the lateral direction of the filler. According to such a movable contact 41, debris can be easily accommodated in the recess 46, and it is possible to further suppress an increase in contact resistance between the fixed contact 21 and the movable contact 41.

In the present embodiment, it is desirable that the surface roughness Rsm of the movable contact 41 is larger than the length L in the longitudinal direction of the filler. According to such a movable contact 41, debris is easily accommodated in the recess 46, and the influence on the contact state between the fixed contact 21 and the movable contact 41 is further suppressed.

It is desirable that the surface roughness Rsm of the movable contact 41 is, for example, 150% or more of the length L in the longitudinal direction of the filler. According to such a fixed contact 21, debris is easily accommodated in the recess 26, and the influence on the contact state between the fixed contact 21 and the movable contact 41 is further suppressed.

FIG. 7 shows the movable piece 4 after the activation treatment. The movable contact 41 has a first surface 41a and a second surface 41b. The second surface 41b is formed in the central portion of the movable contact 41, and the first surface 41a is formed in the peripheral portion of the second surface 41b. The second surface 41b is a region of the movable contact 41 that comes into contact with the fixed contact 21, and is a surface that has appeared by the activation treatment. The surface roughness Rz of the second surface 41b is larger than the surface roughness Rz of the first surface 41a. That is, the surface of the second surface 41b is roughly formed by the activation treatment. The surface roughness of the movable contact 41 is measured on the second surface 41b. In the breaker 1 after the activation treatment, the second surface 21b of the fixed contact 21 and the second surface 41b of the movable contact 41 come into contact with each other to conduct conduction.

The second surface 41b is not limited to the surface formed by the activation treatment, and may be formed by another surface roughening treatment. For example, the movable piece 4 may be formed before being loaded into the accommodating recess 73 of the case body 7. In this case, the entire surface of the movable contact 41 may be roughened.

The ratio of the Vickers hardness of the filler to the Vickers hardness of the movable contact 41 is preferably 6 or less. If the ratio exceeds 6, the debris may affect the contact state between the fixed contact 21 and the movable contact 41. The ratio of the Vickers hardness of the filler to the Vickers hardness of the movable contact 41 is preferably 0.25 or more. If the above ratio is less than 0.25, the strength and rigidity of the case 10 may be affected.

By the way, between the fixed contact 21 and the movable contact 41, spark (spark discharge) may occur from the negative electrode to the positive electrode when the contact is opened and closed. Therefore, the contact on the positive electrode side that receives the spark is preferably formed of a material having a Vickers hardness larger than that on the contact on the negative electrode side in order to suppress its wear (wear). In the present embodiment, as described above, since the movable piece 4 is formed only of a metal material and does not undergo insert molding, the movable contact 41 can be easily formed by caulking and welding or the like. Therefore, a material having a Vickers hardness larger than that of the fixed contact 21 can be easily applied to such a movable contact 41. Then, by mounting the breaker 1 on an electric device or the like so that the movable contact 41 becomes a contact on the positive electrode side, consumption of the contact on the positive electrode side can be suppressed.

It is desirable that the surface roughness Rz of the movable contact 41 is larger than the surface roughness Rz of the fixed contact 21. According to such a movable contact 41, it is possible to effectively suppress wear (deterioration of surface roughness) of the contact on the positive electrode side due to the above-mentioned spark.

The ratio of the surface roughness Ra of the movable contact 41 to the surface roughness Ra of the fixed contact 21 is preferably 0.5 or more and 3 or less. In such a fixed contact 21 and a movable contact 41, the contact area of both contacts is appropriately increased, the contact resistance and the resistance value of the breaker 1 at the time of energization are stable, and the current capacity of the breaker 1 can be easily secured. It will be possible.

The ratio of the surface roughness Rsm of the movable contact 41 to the surface roughness Rsm of the fixed contact 21 is preferably 0.5 or more and 3 or less. In such a fixed contact 21 and a movable contact 41, the contact area of both contacts is appropriately increased, the contact resistance and the resistance value of the breaker 1 at the time of energization are stable, and the current capacity of the breaker 1 can be easily secured. It will be possible.

The breaker 1 of the present invention is not limited to the configuration of the above embodiment, and may be modified into various embodiments. That is, the breaker 1 is deformed with temperature change, at least, a fixed piece 2 having a fixed contact 21 and a movable piece 4 having a movable contact 41 and pressing the movable contact 41 against the fixed contact 21 to make contact with the fixed contact 21. As a result, the heat-responsive element 5 that shifts the movable piece 4 from the conductive state in which the movable contact 41 contacts the fixed contact 21 to the cutoff state in which the movable contact 41 is separated from the fixed contact 21, the fixed piece 2, the movable piece 4, and heat. A case 10 for accommodating the response element 5 is provided, the case 10 includes a resin material and a filler filled with the resin material, and the surface roughness Rz of the fixed contact 21 according to JIS B 0601 is a filler. It suffices if it is larger than the length in the lateral direction of.

For example, the method of joining the case body 7 and the lid member 8 is not limited to ultrasonic welding, and can be appropriately applied as long as the method is such that the two are firmly joined. For example, both may be adhered by applying, filling, and curing a liquid or gel-like adhesive. Further, the case 10 is not limited to the form composed of the case main body 7, the lid member 8, and the like, and may be composed of two or more parts.

Further, the movable piece 4 may be integrally formed with the heat-responsive element 5 by forming the movable piece 4 with a laminated metal such as a bimetal or a trimetal. In this case, the circuit breaker configuration is simplified, and further miniaturization can be achieved.

Further, the present invention may be applied to a form in which the terminal piece and the movable piece are formed separately as shown in Japanese Patent Application Laid-Open No. 2017-37757. Furthermore, the present invention may be applied to a form in which movable pieces are formed in a stepped manner inside a case, as shown in Japanese Patent Application Laid-Open No. 2014-203787.

In the present embodiment, the self-holding circuit by the PTC thermistor 6 is provided, but even a form omitting such a configuration can be applied. With such a configuration, the height dimension of the breaker 1 becomes small, and it becomes possible to reduce the size.

Further, the activation process of the fixed contact 21 and the movable contact 41 is optional and may be omitted. In this case, the second surface 21b is not formed on the fixed contact 21, and the entire surface of the fixed contact 21 becomes the first surface 21a having the same surface roughness. Further, the second surface 41b is not formed on the movable contact 41, and the entire surface of the movable contact 41 becomes the first surface 41a having the same surface roughness.

Further, the breaker 1 of the present invention can be widely applied to a secondary battery pack, a safety circuit for an electric device, and the like. FIG. 8 shows the secondary battery pack 100. The secondary battery pack 100 includes a secondary battery 101 and a breaker 1 provided in the output end circuit of the secondary battery 101. FIG. 9 shows a safety circuit 502 for electrical equipment. The safety circuit 502 is provided with a breaker 1 in series in the output circuit of the secondary battery 501, and cuts off the current when the secondary battery abnormally generates heat. When the breaker 1 is mounted on a connector connected to various electric devices, the breaker 1 cuts off the current at the time of abnormal heat generation and enhances the safety of the electric device.

1: Breaker 2: Fixed piece 4: Movable piece 5: Heat-responsive element 10: Case 21: Fixed contact 21a: First surface 21b: Second surface 41: Movable contact 101: Secondary battery 502: Safety circuit

Claims (9)

A fixed piece with a fixed contact,
A movable piece having a movable contact and pressing the movable contact against the fixed contact to bring them into contact with each other.
A heat-responsive element that shifts the movable piece from a conductive state in which the movable contact contacts the fixed contact to a cutoff state in which the movable contact is separated from the fixed contact by deforming with a temperature change.
In a circuit breaker including the fixed piece, the movable piece, and the case for accommodating the heat-responsive element.
The case includes a resin material and a filler filled in the resin material.
A breaker characterized in that the surface roughness Rz of the fixed contact according to JIS B 0601 is larger than the length of the filler in the lateral direction. The breaker according to claim 1, wherein the surface roughness Rz is 200% or more of the length of the filler in the lateral direction. The breaker according to claim 1 or 2, wherein the surface roughness Rsm according to JIS B 0601 of the fixed contact is larger than the length in the longitudinal direction of the filler. The breaker according to claim 3, wherein the surface roughness Rsm is 150% or more of the length in the longitudinal direction of the filler. The breaker according to any one of claims 1 to 4, wherein the fixed contact has a first surface and a second surface that spreads in a plane shape and has a surface roughness Rz larger than that of the first surface. The breaker according to any one of claims 1 to 5, wherein the filler is formed in the form of short fibers. The breaker according to any one of claims 1 to 6, wherein the ratio of the Vickers hardness of the filler to the Vickers hardness of the fixed contact according to JIS Z 2244 is 9 or less. A safety circuit for electrical equipment, comprising the breaker according to any one of claims 1 to 7. A secondary battery circuit comprising the breaker according to any one of claims 1 to 7.

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