CN109314013B

CN109314013B - Miniature circuit breaker for portable equipment and manufacturing method thereof

Info

Publication number: CN109314013B
Application number: CN201780036429.8A
Authority: CN
Inventors: 中西义博; 高桥知之
Original assignee: Otsuka Techno Corp
Current assignee: Otsuka Techno Corp
Priority date: 2016-06-14
Filing date: 2017-02-03
Publication date: 2020-04-14
Anticipated expiration: 2037-02-03
Also published as: JP6918298B2; JPWO2017217003A1; CN109314013A; WO2017217003A1

Abstract

Instantaneous disconnection due to strong impact is reliably prevented. The parts can be mass-produced at low cost without requiring high precision in machining and assembling the parts, and instantaneous disconnection can be reliably prevented. The miniature circuit breaker is a miniature circuit breaker for a portable device connected in series with a battery, and is provided with: a movable contact plate (1) having a movable contact (3) provided at the tip of the elastic arm (5); a fixed contact plate (2) having a fixed contact (4) disposed at a position opposite to the movable contact (3); a bimetal (6) which separates the movable contact (3) from the fixed contact (4) at a set temperature to be in an open state; and a PTC (7Y) for preventing instantaneous disconnection of the connection between the fixed contact plate (2) and the movable contact plate (1).

Description

Miniature circuit breaker for portable equipment and manufacturing method thereof

Technical Field

The present invention relates to a miniature circuit breaker for a portable device used as a protection element in a portable device such as a smart phone or a tablet computer, and a method for manufacturing the miniature circuit breaker.

In the present specification, the "miniature circuit breaker" refers to a subminiature circuit breaker having a thickness of 2mm or less.

Background

The portable device incorporates a PTC, a fuse, and a micro breaker as a battery protection element. When the PTC is higher than the set temperature, the PTC trips to rapidly increase the impedance value and cut off the current, when the PTC reaches the set temperature, the fuse melts and cuts off the current, and when the PTC reaches the set temperature, the micro circuit breaker separates the movable contact from the fixed contact and cuts off the current. PTC has the following disadvantages: the low impedance value of the resistor in the non-tripped state is larger than the contact impedance of the contact, and the power loss is large in a large-current portable device. The fuse has the following disadvantages: if fused, it cannot be reused after that. The micro circuit breaker cannot prevent instantaneous disconnection in which the movable contact is separated from the fixed contact due to an impact such as dropping of the portable device, and the power supply is instantaneously switched off. In the on state of the miniature circuit breaker, the contact resistance value of the contact is small, and the power loss in the case of large current can be reduced, so that the miniature circuit breaker can prevent the characteristic defect, namely instantaneous disconnection, and realize the excellent characteristics as the protection element of the portable equipment.

In the present specification, the "low resistance value" as the resistance in the state where the PTC is not tripped represents the resistance of the PTC at 20 ℃.

A micro circuit breaker is being developed to prevent instantaneous disconnection caused by instantaneous disconnection of contacts due to impact such as dropping. (see patent document 1)

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-110034

Disclosure of Invention

In the circuit breaker disclosed in patent document 1, in order to prevent instantaneous disconnection caused by separation of the movable contact from the fixed contact due to vibration generated by impact, a spacer is provided in the case. The spacer prevents the PTC, bimetal from being vibrated by impact, thereby preventing instantaneous disconnection. The micro circuit breaker has a bimetal and a PTC incorporated between a movable contact and a fixed contact, and when the bimetal reaches a set temperature, it reverses, thereby separating the movable contact from the fixed contact and switching the contacts to open. The PTC is energized in the off state of the contact to heat the bimetal. The heated bimetal is maintained in the inverted state, thereby maintaining the contact in the open state. When the breaker having this structure receives an impact, the bimetal and the PTC vibrate. The spacer is disposed to prevent vibration of the bimetal and the PTC. The spacer blocks the gap to prevent vibration.

In the structure in which the gap is reduced by the spacer to prevent instantaneous disconnection due to vibration, it is extremely difficult to adjust the gap with extremely high accuracy and assemble the structure. In particular, in a micro circuit breaker having an overall thickness of about 1mm and an open contact interval of about 100 μm, it is extremely difficult to prevent vibration by stacking a fixed contact plate, a PTC element, a bimetal, and a movable contact plate in a case and reducing a gap by a spacer. The reason for this is that extremely high precision is required for component processing and assembly. Further, since the micro circuit breaker deforms the elastic arm having the movable contact fixed to the tip end thereof to switch the contact on or off and inverts the bimetal to switch the contact off, a space for the elastic arm to deform is required and a space for the bimetal to invert is also required, and it is extremely difficult to arrange the bimetal to be inverted between the movable contact plate and the fixed contact plate without a gap with respect to the PTC. Even if the gap between the bimetal and the PTC element can be completely eliminated, the vibration caused by the impact of the elastic arm cannot be prevented. In particular, in a micro breaker in which an extremely thin metal plate having a thickness of about 100 μm is used as an elastic arm and a contact interval at the time of breaking is about 100 μm, a contact pressure of a contact is weak and instantaneous breaking due to vibration caused by an impact such as dropping cannot be prevented. Therefore, even if the instantaneous interruption due to an impact such as dropping can be reduced by providing the spacer, the instantaneous interruption due to a strong impact cannot be stably prevented.

The present invention has been made to further solve the above-mentioned drawbacks. An important object of the present invention is to provide a miniature circuit breaker capable of reliably preventing instantaneous disconnection due to strong impact and a method of manufacturing the same.

Another important object of the present invention is to provide a miniature circuit breaker and a method for manufacturing the same, which do not require high precision in processing and assembling of parts, can be mass-produced at low cost, and can reliably prevent instantaneous disconnection.

The miniature circuit breaker of the invention is a miniature circuit breaker for portable equipment connected with a battery in series, and comprises: a movable contact plate 1 having a movable contact 3 provided at the tip of an elastic arm 5; a fixed contact plate 2 having a fixed contact 4 provided at a position opposed to the movable contact 3; a bimetal 6 which is formed in an open state by separating the movable contact 3 from the fixed contact 4 at a set temperature; and a PTC7Y for preventing instantaneous disconnection, which is connected to the fixed contact plate 2 and the movable contact plate 1.

The above-described micro circuit breaker connects the PTC for instantaneous disconnection prevention to the fixed contact plate and the movable contact plate, and therefore, at the moment when the movable contact is separated from the fixed contact, the PTC for instantaneous disconnection prevention is brought into conduction with the movable contact and the fixed contact, and instantaneous disconnection caused by separation of the movable contact from the fixed contact due to a strong impact can be prevented. The PTC for preventing instantaneous disconnection is energized to keep the contact points connected when the contact points are disconnected by an impact, and in a state where the contact points are continuously disconnected, the PTC is tripped by heat generated by the current applied to increase the resistance and cut off the current. Therefore, in a state where the contact is temporarily opened by an impact, the PTC for instantaneous disconnection is brought into a state of connecting the contact to prevent instantaneous disconnection, but when the contact is continuously disconnected, the PTC for instantaneous disconnection is tripped to bring the circuit breaker into a disconnected state.

Further, since the above-described micro circuit breaker prevents instantaneous opening due to instantaneous opening of the contact by using the PTC for preventing instantaneous opening connected in parallel to the contact, unlike a conventional circuit breaker in which a spacer is provided in a case to adjust a gap to prevent instantaneous opening, it is necessary to perform component processing or assembly with high accuracy, and mass production at low cost is possible.

In the micro circuit breaker of the present invention, one electrode of the PTC7Y for preventing instantaneous disconnection can be connected to the fixed contact plate 1 by any of soldering, welding, and adhesion, and the other electrode of the PTC7Y for preventing instantaneous disconnection can be connected to the movable contact plate 2 by any of soldering, welding, and adhesion.

The above-described micro circuit breaker is characterized in that the PTC element for preventing instantaneous disconnection is fixed to the fixed contact plate and the movable contact plate by any one of soldering, welding and adhesion, and thus instantaneous disconnection under a strong impact can be reliably prevented. This is because the PTC for preventing instantaneous disconnection is stably connected to the movable contact plate and the fixed contact plate even when a strong impact is applied.

Further, the micro circuit breaker according to the present invention incorporates, between the movable contact plate 1 and the fixed contact plate 2: a bimetal 6 which reverses when a set temperature is reached and separates the movable contact 3 from the fixed contact 4; and a self-holding PTC4X, which is capable of holding the self-holding PTC4X in a reversed state by heating the bimetal 6 between the bimetal 6 and the fixed contact plate 2, and also of using the self-holding PTC7X as the PTC7Y for preventing instantaneous disconnection.

The above-described micro circuit breaker uses the PTC for instantaneous interruption prevention as the PTC for instantaneous interruption prevention, and therefore has a feature that instantaneous interruption can be prevented without adding a dedicated PTC for instantaneous interruption prevention.

Further, the miniature circuit breaker of the present invention comprises: a housing 8 to which the movable contact plate 1 and the fixed contact plate 2 are fixed; and a lead wire 14 connected to the surface of the PTC7, having an end portion led out of the case 8 to form an external connection terminal 19, and having an insulating sheet 17 between the external connection terminal 19 and the movable contact point plate 1 to connect the external connection terminal 19 and the movable contact point plate 1.

In the above-described micro circuit breaker, the external connection terminal led out to the outside of the case is provided on the lead wire, and the insulating sheet is disposed between the external connection terminal and the movable contact plate, whereby the external connection terminal and the movable contact plate are connected, and therefore, the micro circuit breaker can be assembled in a state where the lead wire is insulated from the movable contact plate by the insulating sheet. Therefore, the contact can be activated in a state where the lead wire is not connected to the movable contact plate, and the lead wire can be connected to the movable contact plate after the activation of the contact, whereby the PTC device can prevent instantaneous disconnection of the connection. Namely, the following features are provided: the contact can be brought into a low impedance state by the activation processing, and instantaneous disconnection can be prevented.

In the micro circuit breaker of the present invention, the insulating sheet 17 may be a thermoplastic plastic film of 5 μm to 50 μm, which is bonded to the surface of the lead 14.

Since the insulating sheet is a thin plastic film, the miniature circuit breaker can activate the contact point and prevent instantaneous disconnection, and can be made thin as a whole.

In the micro circuit breaker of the present invention, the lead wire 14 is arranged between the bimetal 6 and the PTC7, and the insulating sheet 17 can be provided on the surface facing the bimetal 6.

In the above-described micro circuit breaker, the insulating sheet is disposed on the surface of the bimetal facing the movable contact plate, and the bimetal and the movable contact plate are insulated from each other, so that the upper electrode of the PTC and the movable contact plate can be reliably maintained in an insulated state in the step of activating the contact. Therefore, the activation process can be performed stably while reliably achieving insulation.

In the micro circuit breaker of the present invention, the lead wire 14 can be laminated on the movable contact plate 1 via the insulating sheet 17 and fixed to the case 8.

The above miniature circuit breaker can easily fix the lead and the movable contact plate to the case in the assembly process of the case. In addition, since the lead wire and the movable contact plate can be insulated from each other in a state of being fixed to the housing, the contact can be activated to reduce contact resistance. Further, since the lead wire can be connected to the movable contact plate after assembly, the PTC element can be used to prevent instantaneous disconnection of the contact.

Also, the micro circuit breaker of the present invention can connect the lead 14 to the surface of the PTC7 by reflow soldering.

The above miniature circuit breaker has the following features: the lead wire and the PTC can be stably connected, and instantaneous disconnection can be reliably prevented by the PTC.

The micro circuit breaker of the present invention can connect the PTC7 to the fixed contact plate 2 by reflow soldering.

The PTC of the above miniature circuit breaker is also connected to the fixed contact plate by reflow soldering, and therefore the PTC can be stably connected to both the fixed contact plate and the movable contact plate. Therefore, the following features are provided: the PTC can more reliably prevent instantaneous disconnection of the contact.

In the micro circuit breaker of the present invention, the lead wire 14 can be arranged at a predetermined position of the case 8 by the positioning structure 18.

The above miniature circuit breaker can be provided by the positioning structure so as not to shift the predetermined position of the conductor relative to the housing, and therefore has the following features: the wire using a small and thin metal plate can be efficiently mass-produced.

In addition, the positioning structure 18 in the miniature circuit breaker of the present invention includes: a positioning hole 18A provided in the wire 14; and a positioning projection 18B provided in the housing 8 and inserted into the positioning hole 18A, and the lead 14 can be arranged at a predetermined position of the housing 8 by inserting the positioning projection 18B into the positioning hole 18A.

The above miniature circuit breaker can be provided so as not to displace the predetermined position of the conductor with respect to the case by inserting the positioning projection into the positioning hole, and therefore has the following features: the wire using a small and thin metal plate can be efficiently mass-produced.

The miniature circuit breaker of the present invention includes a case 8 to which the movable contact plate 1 and the fixed contact plate 2 are fixed, and the PTC7Y for preventing instantaneous disconnection can be disposed outside the case 8.

The above miniature circuit breaker has the following features because the PTC for self-holding is disposed outside the case: the instantaneous disconnection can be prevented without changing the conventional micro circuit breaker.

In the micro circuit breaker of the present invention, the fixed contact plate 2 is fixed along the bottom surface of the case 8, the connection terminal 13 is provided outside the case 8 by protruding from the bottom surface of the case 8 in the longitudinal direction, and the PTC7Y for preventing instantaneous disconnection is fixed to the upper surface of the connection terminal 13 in a stacked state.

The above-described micro-breaker can prevent instantaneous disconnection without changing the overall thickness, and therefore can be disposed at a position facing a step (terrace) portion of the stacked battery and a sealing plate of the rectangular battery cell. Therefore, the following features are provided: instantaneous disconnection can be prevented without changing the thickness of a battery pack including stacked batteries and prismatic battery cells.

Further, the miniature circuit breaker of the present invention may include: PTC7Y for preventing instantaneous disconnection, which is disposed outside case 8; and a PTC7X for self-holding, which is provided between movable contact plate 1 and fixed contact plate 2, and is provided in case 8, and which holds movable contact 3 in an off state at a set temperature.

The above miniature circuit breaker includes a PTC for self-holding and a PTC for preventing instantaneous disconnection, and therefore has the following features: the trip temperature of each PTC and the resistance in a low impedance state can be made to be the optimum resistance value.

The micro circuit breaker of the present invention includes the lead wire 14 connecting the PTC7Y for preventing instantaneous disconnection to the movable contact plate 1 and the fixed contact plate 2, and both ends of the lead wire 14 can be connected to the PTC7Y for preventing instantaneous disconnection, the movable contact plate 1, and the fixed contact plate 2 by any of soldering, welding, and adhesion.

The above-described micro circuit breaker has the following features because the PTC for self-holding is connected to the movable contact plate and the fixed contact plate by soldering or welding both ends of the lead wire: the PTC element for self-holding can be more reliably connected to the movable contact plate and the fixed contact plate.

In the micro circuit breaker of the present invention, the low resistance value in the energized state of PTC7Y for preventing instantaneous opening can be set to a resistance value in the state where movable contact 3 is in contact with fixed contact 4, that is, 10 times or more the contact resistance value.

The above-described miniature circuit breaker can reduce the shunt current flowing through the PTC for self-holding in the state where the contacts are connected, and can make almost all the current flowing through the circuit breaker flow to the contacts. Therefore, the following features are provided: the temperature rise due to the shunt current of the self-holding PTC can be reduced, and the trip due to the shunt current can be reliably prevented.

In addition, the micro circuit breaker of the present invention can set the contact resistance value to 5m Ω or less and set the low resistance value of the PTC7Y for preventing instantaneous opening to 4 Ω or less.

The above miniature circuit breaker has the following features: the contact resistance value is small, and the shunt current of the self-holding PTC can be reduced.

The miniature circuit breaker of the invention can set the low impedance value of the PTC7Y for preventing instantaneous disconnection to be more than 20m omega.

The method for manufacturing a miniature circuit breaker according to the present invention is a method for manufacturing a miniature circuit breaker for a portable device, the miniature circuit breaker including: a movable contact plate 1 having a movable contact 3 provided at the tip of an arm; a fixed contact plate 2 having a fixed contact 4 provided at a position opposed to the movable contact 3; a bimetal 6 which separates the movable contact 3 from the fixed contact 4 at a set temperature to open the bimetal 6; and an instantaneous disconnection preventing PTC7Y connected to the fixed contact plate 2 and the movable contact plate 1, wherein the instantaneous disconnection preventing PTC7Y is activated in a state of being connected to either or both of the movable contact plate 1 and the fixed contact plate 2, and after the activation, the instantaneous disconnection preventing PTC7Y is connected to the fixed contact plate 2 and the movable contact plate 1.

The above manufacturing method has the following advantages: a miniature circuit breaker can be manufactured, wherein contact resistance is reduced by activating a contact, and instantaneous opening of the contact due to impact can be prevented by using PTC. The overall thickness of the miniature circuit breaker is extremely small, about 1mm, and a thin metal plate is required for the movable contact plate, and the contact pressure of the contact cannot be increased. Therefore, it is extremely difficult to reduce and stabilize the contact resistance of the contact. However, in the above manufacturing method, the PTC element for preventing instantaneous disconnection is connected to either one of the movable contact plate and the fixed contact plate, or is not connected to both of them, and the movable contact and the fixed contact are subjected to activation processing. Therefore, the contact point is activated in this state, and the contact resistance can be reduced. Further, since the PTC for instantaneous disconnection prevention is connected between the fixed contact plate and the movable contact plate after the contact is activated to reduce the contact resistance, the PTC can prevent instantaneous disconnection of the contact, and can be used as a protection element for a mobile phone or the like.

Further, a method for manufacturing a miniature circuit breaker according to the present invention is a method for manufacturing a miniature circuit breaker for a portable device, the miniature circuit breaker including: a housing 8 to which the movable contact plate 1 and the fixed contact plate 2 are fixed; and a lead wire 14 connected to the surface of the PTC7Y for preventing instantaneous disconnection and having an end portion led out of the case 8 to form an external connection terminal 19, wherein the lead wire can be manufactured by the following steps: an insulation step of disposing the insulation sheet 17 between the external connection terminals 19 and the movable contact point plate 1 to insulate the lead wires 14 from the movable contact point plate 1; an activation step of activating movable contact 3 and fixed contact 4 while keeping wire 14 insulated from movable contact plate 1 by an insulation step; and a connecting step of connecting the external connection terminals 19 to the movable contact plate 1 outside the housing 8 after the contacts 10 are activated in the activating step.

In the above manufacturing method, the lead wire is assembled while being insulated from the movable contact plate, and therefore, the PTC element for preventing instantaneous disconnection can be assembled without being connected to the movable contact plate. Therefore, the contact point can be activated in the state where the lead wire and the movable contact plate are insulated, and the contact resistance can be reduced. After the contact point is activated to reduce the contact resistance, the lead is connected to the movable contact plate, and thus, in a completed state, the PTC for preventing instantaneous disconnection is connected between the fixed contact plate and the movable contact plate. Therefore, the PTC device for preventing instantaneous disconnection can reliably prevent instantaneous disconnection of the contact in the completed state.

In addition, according to the method of manufacturing the miniature circuit breaker of the present invention, the fixed contact plate 2 is disposed at a predetermined position of the case 8, the PTC7Y for instantaneous disconnection prevention is placed on the fixed contact plate 2, and the lead wire 14 is placed on the PTC7Y for instantaneous disconnection prevention, and in this state, the lower surface of the PTC7Y for instantaneous disconnection prevention is connected to the fixed contact plate 2 and the upper surface thereof is connected to the lead wire 14 by reflow soldering.

Further, according to the method of manufacturing a micro circuit breaker of the present invention, the non-insulating portion 19a having no insulating sheet 17 interposed between the non-insulating portion 19a and the movable contact plate 1 is provided at the tip end portion of the external connection terminal 19, the non-insulating portion 19a is separated from the movable contact plate 1 in the insulating step to form the lead 14 and the movable contact plate 1 in an insulated state, the contact 10 is activated in the activating step, and then the non-insulating portion 19 is connected to the movable contact plate 1 and the lead 14 is connected to the movable contact plate 1 in the connecting step.

In the above manufacturing method, the non-insulating portion, which is not interposed with the insulating sheet, is provided at the tip end portion of the external connection terminal of the lead wire led out to the outside of the housing, and the non-insulating portion and the movable contact plate are separated from each other, so that the lead wire and the movable contact plate are reliably insulated from each other and the contact is activated. Further, after the contact is activated, the non-insulating portion is connected to the movable contact plate and the lead wire is connected to the movable contact plate, and therefore, the following features are provided: the lead wire can be easily and stably connected to the movable contact plate.

Drawings

Fig. 1 is a schematic configuration diagram of a conventional micro circuit breaker.

Fig. 2 is a schematic configuration diagram of a micro circuit breaker according to the present invention.

Fig. 3 is a schematic cross-sectional view of a micro circuit breaker according to an embodiment of the present invention.

Fig. 4 is a schematic sectional view of a micro circuit breaker according to another embodiment of the present invention.

Fig. 5 is a schematic sectional view showing a process of activating contacts of the micro circuit breaker shown in fig. 4.

Fig. 6 is a sectional view of the micro circuit breaker shown in fig. 4.

Fig. 7 is a process diagram illustrating a manufacturing process of the micro circuit breaker shown in fig. 6.

Fig. 8 is a schematic sectional view of a micro circuit breaker according to another embodiment of the present invention.

Fig. 9 is a schematic sectional view of a micro circuit breaker according to another embodiment of the present invention.

Fig. 10 is a schematic sectional view of a micro circuit breaker according to another embodiment of the present invention.

Fig. 11 is a schematic sectional view of a micro circuit breaker according to another embodiment of the present invention.

Fig. 12 is a schematic sectional view of a micro circuit breaker according to another embodiment of the present invention.

Fig. 13 is a diagram showing a state in which the contact of the micro circuit breaker is switched to an open (open) state, and the resistance of the PTC is changed.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below exemplify a miniature circuit breaker for a portable device for embodying the technical idea of the present invention, and the present invention is not limited to the miniature circuit breaker for a portable device below. In addition, the components shown in the technical solutions are by no means limited to the components in the embodiments in the present specification.

The miniature circuit breaker of the invention is mainly used as a protection element in portable equipment such as mobile phones, tablet computers, notebook computers and the like. The micro circuit breaker is connected in series with a secondary battery for a power supply, and functions as a protection element that cuts off current when an abnormal temperature rises. The miniature circuit breaker is built in a battery pack of a portable device as a protection element. Since the portable device is thinned, it is required to thin the battery pack as much as possible. The entire thin battery pack is made thin by incorporating the laminated battery or the thin rectangular battery, and the entire thin battery pack is made thin by disposing a micro breaker at a position facing the step portion of the laminated battery or the sealing plate of the thin rectangular battery. The miniature circuit breaker is formed in an outer shape not protruding from the surface of the laminated battery. Thus, the thickness of the miniature circuit breaker built in the battery pack of the portable device is limited, and the thickness of the miniature circuit breaker generally used is reduced to about 1mm, which is extremely thin. In this micro circuit breaker, the movable contact plate, the bimetal, the PTC, and the fixed contact plate are placed in the case at a predetermined interval, and the entire thickness is reduced to about 1mm, which is extremely thin, and therefore, the structure and the manufacturing process are variously restricted, and for example, the contact pressure of the contact cannot be maintained high by using an extremely thin metal plate for the movable contact plate whose tip is fixed with the movable contact. The movable contact plate has a movable contact fixed to a tip end of the elastic arm, and is switched on when the movable contact is in contact with the fixed contact, and is switched off when the movable contact is separated from the fixed contact. The movable contact fixed to the tip of the elastic arm of the thin metal plate has a low contact pressure, and is separated from the fixed contact by a strong impact and instantaneously switched to be opened, thereby causing instantaneous opening.

Fig. 1 and 2 are schematic diagrams showing the operation principle of a conventional micro breaker (fig. 1) and a micro breaker (fig. 2) according to the present invention.

In the conventional micro circuit breaker shown in fig. 1,

(1) indicating the energized state of the circuit breaker in a state where the ambient temperature is lower than the set temperature.

Bimetal 96 is in this state in a non-inverted state such that contact 90 is closed.

(2) This indicates a state in which the ambient temperature is higher than the set temperature, and the circuit breaker interrupts the current.

The bimetal 96 is inverted in this state so that the contact 90 is opened.

(3) Indicating a state in which the contact 90 is opened due to vibration.

In this state, the bimetal 96 is in a non-inverted state so that the contact 90 is opened.

When a conventional micro circuit breaker receives an impact in a state where the ambient temperature is lower than the set temperature, the contact 90 is opened as shown in (3) to interrupt the current. In this state, the bimetal 96 is not inverted, and the contact 90 is not connected via the PTC 97. This state is a cause of instantaneous interruption due to current interruption in a state where the ambient temperature is lower than the set temperature.

In the miniature circuit breaker of the present invention shown in figure 2,

The bimetal 6 is in a non-inverted state in this state so that the contact 10 is closed.

PTC7 is connected in parallel with contact 10 and energized.

Therefore, although the current of the circuit breaker is shunted to the contact 10 and the PTC7 in this state, the contact resistance of the contact 10 is smaller than the low resistance value of the PTC7, and almost all of the current of the circuit breaker flows to the contact 10.

(2) This indicates a state in which the ambient temperature is higher than the set temperature and the contact 10 is opened.

In this state, the bimetal 6 is reversed to open the contact 10, and the PTC7 is energized because the PTC7 is connected in parallel with the contact 10, and the PTC7 is heated by the current to trip, and the resistance sharply increases to substantially cut off the current.

(3) This shows a state in which the contact 10 is opened by vibration.

This state is a state in which the bimetal 6 is in a non-inverted state so that the contact 10 is opened.

Although the PTC7 is connected in parallel with the junction 10, the resistance of the untripped PTC7 is small, so that the current flowing to the junction 10 flows to the PTC 7. Therefore, even if the contact 10 is opened in a moment, the current of the circuit breaker is not cut off. If the contact 10 is continuously in the open state, the PTC7 trips, which causes the resistance of the PTC7 to sharply increase and cut off the current, so that the time for which the contact 10 is opened by the impact is extremely short, and the PTC7 does not trip in this state. Therefore, even if the contact 10 is opened by vibration, current flows to the PTC7 to prevent instantaneous disconnection.

The miniature circuit breaker of fig. 2 may be a circuit breaker in which a built-in self-holding PTC7X is used as the PTC7Y for preventing instantaneous interruption, and the PTC7Y for preventing instantaneous interruption is connected to the outside of the conventional circuit breaker as shown by a broken line in fig. 1 to prevent instantaneous interruption.

Fig. 3 to 12 are schematic sectional views of a micro circuit breaker according to an embodiment of the present invention.

The micro circuit breaker comprises: a movable contact plate 1 having a movable contact 3 provided at the tip of an elastic arm 5; a fixed contact plate 2 having a fixed contact 4 provided at a position opposed to the movable contact 3; a bimetal 6, which is turned upside down when the ambient temperature rises to a set temperature, and which separates the movable contact 3 from the fixed contact 4 to be opened; and a PTC7 connected to the fixed contact plate 2 and the movable contact plate 1. The miniature circuit breaker of fig. 3 to 10 uses PTC7 built in case 8 as both PTC7X for self-holding and PTC7Y for preventing instantaneous interruption, and the miniature circuit breaker of fig. 11 and 12 uses PTC7 built in case 8 as PTC7X for self-holding and PTC7Y for preventing instantaneous interruption is arranged outside case 8.

In the micro circuit breaker shown in the above-mentioned drawings and the like, the movable contact plate 1 and the fixed contact plate 2 are fixed to the plastic case 8 in a posture facing each other, and the bimetal 6 and the PTC7X for self-holding are arranged between the movable contact plate 1 and the fixed contact plate 2. The housing 8 is provided with a hollow 9 therein. The elastic arm 5 of the movable contact plate 1, the bimetal 6, the PTC7, and the fixed contact plate 2 are disposed in the hollow portion 9.

In movable contact plate 1, elastic arm 5 provided at the front end portion is disposed in hollow portion 9 of case 8, the middle portion is fixed to peripheral wall 8A of case 8, and the rear end portion protrudes outside case 8 to form connection terminal 11.

Fixed contact plate 2 is disposed in hollow 9 provided in case 8, fixed contact 4 is disposed at a position facing movable contact 3 of elastic arm 5, and the front end portion is disposed at the bottom of case 8, and the rear end portion protrudes outside case 8 to form connection terminal 12. In the circuit breaker of fig. 11 and 12, both ends of the fixed contact plate 2 are protruded to the outside of the case 8, one protruded portion (right side in the drawing) is formed as a connection terminal 12, and the other protruded portion (left side in the drawing) is formed as a connection terminal 13, thereby connecting the PTC7Y for instantaneous disconnection prevention.

The breaker is provided with: a PTC7X for self-holding that heats the bimetal 6 to hold the contact 10 in an open state; and an instantaneous-disconnection-preventing PTC7Y for preventing instantaneous disconnection due to instantaneous disconnection of the contact 10 caused by an open state instantaneously, the circuit breaker of fig. 3 to 10 has a self-holding PTC7X incorporated in the case 8 serving as an instantaneous-disconnection-preventing PTC7Y, and the circuit breaker of fig. 11 and 12 has a self-holding PTC7X incorporated in the case 8 and has an instantaneous-disconnection-preventing PTC7Y connected to the outside of the case 8.

The PTC7 built in the case 8 and the PTC7 connected to the outside of the case 8 have low resistance values with low resistance in a state lower than the set temperature, and trip to rapidly increase the resistance above the set temperature, thereby having current cutoff resistance values to prevent the flow of current. Thus, the tripped PTC7 is essentially in an open state cutting off current. When the contact 10 is in the open state, the self-holding PTC7X is energized to heat the bimetal 6, thereby holding the contact 10 in the open state. The PTC7 is energized to cut off the current when it reaches the trip temperature, and is again set to a low impedance value when it falls to the trip temperature, and therefore, is kept at the trip temperature in the open state of the contact 10. The PTC7 kept at the trip temperature is kept in the reversed state by heating the bimetal 6, thereby keeping the contact 10 in the open state.

PTC7Y for preventing instantaneous disconnection connected in parallel with contact 10 is in a low impedance state when contact 10 is instantaneously opened. This is because the temperature of the PTC7 is lower than the trip temperature in the momentarily open state of the contact 10. When the contact 10 is continuously closed, the PTC7Y for instantaneous opening prevention has a low impedance value of low impedance, and therefore the current of the circuit breaker flows to both the PTC7Y for instantaneous opening prevention and the contact 10 having low impedance. The current ratio between the contact 10 and the PTC7Y for preventing instantaneous opening is determined by the ratio of the contact resistance of the contact 10 to the low resistance value of the PTC7Y for preventing instantaneous opening, and when the low resistance value of the PTC7Y for preventing instantaneous opening is increased, the current of the PTC7 is decreased and the current of the contact is increased. The PTC7Y for preventing momentary interruption can reduce the current and reduce the temperature rise. The reason for this is that the heat generation amount of the PTC7 is the product of the square of the current and the low resistance value. In the closed state of the contact 10, the PTC7Y for preventing instantaneous opening is required to reduce the magnitude of temperature rise due to current. Since the current of the PTC7Y for preventing instantaneous disconnection is determined by the ratio of the low resistance value of the PTC7 to the contact resistance of the contact 10, the low resistance value of the PTC7Y for preventing instantaneous disconnection is set to the optimum resistance value in consideration of the contact resistance of the contact 10.

The contact resistance of the contact 10 in the closed state is relatively small, and is 5m Ω or less. In particular, the activation process reduces the contact resistance of the contact 10. In a state where the PTC7 is connected in parallel with the contact 10, the resistance of the PTC7 can be made larger than the contact resistance of the contact 10, whereby the current of the PTC7 can be reduced to weaken the heat generation of the PTC7 caused by the current. In order to reduce heat generation by the current of the PTC7, the low resistance value of the PTC7 is, for example, 20m Ω or more, preferably 30m Ω or more, and more preferably 50m Ω or more. By setting the low resistance value of the PTC7 to 20m Ω or more and the contact resistance in the closed state of the contact 10 to 5m Ω or less, the current of the PTC7 can be set to 1/4 or less of the contact current in the closed state of the contact 10. Since the current of the PTC7 in the closed state of the contact 10 can be reduced by increasing the low resistance value of the PTC7 with respect to the contact resistance of the contact 10, the low resistance value of the PTC7 is preferably set to be 10 times or more the contact resistance of the contact 10 and to be 1/10 or less the current of the contact 10. The low resistance value of the PTC7 becomes the internal resistance of the circuit breaker in a state where the contact 10 is temporarily opened by the impact. The reason for this is that all of the current of the circuit breaker flows to the PTC 7. If the low impedance value of the PTC7 is too large, the internal impedance of the circuit breaker in the open state of the contact 10 becomes large, and it becomes difficult to reliably and stably prevent momentary disconnection. Therefore, the low resistance value of the PTC7 is set to 4 Ω or less, preferably 500m Ω or less, and more preferably 300m Ω or less.

The trip temperature of the PTC7Y for preventing instantaneous opening is set higher than the set temperature of the miniature circuit breaker, which is the temperature at which the built-in bimetal 6 is reversed to switch the contact 10 to the open state and interrupt the current. This is because, if the PTC7 trips in the instantaneously opened state of the contact 10, in which the contact 10 instantaneously opens due to an impact, the resistance of the PTC7 increases, and thus it is impossible to prevent the instantaneous opening of the micro breaker.

Fig. 13 shows a state in which the contact of the micro circuit breaker is switched to the open state, and the resistance of the PTC element changes. In the figure, the horizontal axis represents a time axis, and the vertical axis represents on/off of the contact (solid line a) and the resistance of the PTC element (broken line B). The solid line a indicates a state in which the ambient temperature is higher than the set temperature and the contact is continuously switched to the open state. As shown in this figure, the PTC exhibits a low resistance value that does not trip when the ambient temperature is higher than the set temperature and the bimetal is reversed to switch the contact to the open state. The reason for this is that the trip temperature of the PTC is higher than the set temperature of the micro breaker. In this state, the current of the micro breaker flows to the PTC. The current of the PTC heats the PTC to increase the temperature. When the PTC whose temperature rises exceeds the trip temperature, the resistance rapidly increases and a state of high resistance is obtained. The high resistance PTC limits the current of the micro circuit breaker to be significantly reduced.

A chain line C in fig. 13 indicates a state where the contact is instantaneously switched to the open state by the impact. Since the movable contact of the micro circuit breaker vibrates and the contact is momentarily opened, the micro circuit breaker may be momentarily opened a plurality of times. Even in the case of multiple instantaneous disconnections, the total time (T) (T1 + T2) obtained by adding the instantaneous disconnection time (T1, T2) is about several msec or less. The trip time (Tp) of the PTC is preferably set to be longer than the total time (T) during which the contact is instantaneously opened, for example, longer than 10msec, preferably longer than 100msec, and more preferably longer than 1000 msec. This is because, if the trip time (Tp) of the PTC is shorter than the instantaneous disconnection time (T1, T2), the PTC trips in a state where the contact is instantaneously disconnected, and instantaneous disconnection cannot be prevented.

The trip time (Tp) of the PTC varies according to the heat generation amount of the PTC. When the amount of heat generation increases, the temperature rapidly increases, and the trip time (Tp) is shortened. The resistance of the PTC affects the amount of heat generation, which increases in proportion to the resistance. When the contact is momentarily opened, the PTC is brought to a low resistance value, so that the low resistance value of the PTC is reduced to extend the trip time (Tp). The low resistance value of the PTC is set to 4 Ω or less, preferably 500m Ω or less, and more preferably 300m Ω or less, and the trip time (Tp) can be made longer than the total time (T) of instantaneous disconnection.

The amount of heat generation of the PTC7, i.e., the temperature increase width, is determined according to the current flowing to the PTC7 in the open state of the contact 10 and the low resistance value. The trip time is determined according to the temperature rise of the PTC7, and if the temperature rises rapidly due to an increase in the amount of heat generation, the trip time is shortened. Therefore, the heat generation amount is determined from the low resistance value of the PTC7, and the trip time is determined from the heat generation amount. Therefore, the low resistance value of the PTC7Y for preventing instantaneous disconnection was set to: a resistance value such that the time until PTC7 trips in the open state of contact 10 is longer than the instantaneous open time of contact 10.

The time for which the micro-breaker is subjected to an impact and the contact 10 is instantaneously opened varies depending on the length of the elastic arm 5, the material and thickness of the movable contact plate 1, the magnitude of the impact, and the like, but is usually several msec or less. The trip time of the PTC7Y for preventing instantaneous opening is shorter than the time during which the contact 10 is opened instantaneously by an impact. Therefore, even if the contact 10 is in the momentarily opened state, the PTC7 does not trip in the opened state of the contact 10, and the PTC7 with low resistance is connected to the momentarily opened contact 10 to prevent momentary disconnection.

The bimetal 6 is disposed between the PTC7 and the movable contact plate 1. The bimetal 6 is formed by laminating different metal plates having different thermal expansion coefficients, and is in a non-inverted state when the ambient temperature is lower than the set temperature, and is inverted when the ambient temperature is higher than the set temperature, thereby pushing up the elastic arm 5 and opening the contact 10. The bimetal 6 in the non-inverted state does not lift up the elastic arm 5 but makes the contact 10 in the closed state. As shown in fig. 3 to 12, the bimetal 6 is bent in such a shape that the center portion thereof protrudes toward the elastic arm 5. When the ambient temperature is higher than the set temperature and the contact point 10 is opened, the elastic arm 5 is pushed up. As shown in fig. 2 (2), the reversed bimetal 6 is deformed into a shape in which the center portion protrudes downward, and the elastic arm 5 is pushed up to open the contact 10.

The micro circuit breaker of fig. 3 to 12 differs in the connection structure of the PTC7Y for preventing instantaneous interruption. PTC7Y for preventing momentary interruption is provided with electrodes on the upper and lower sides in the drawing, one electrode being connected to movable contact plate 1 and the other electrode being connected to fixed contact plate 2. PTC7 connects the electrodes to movable contact plate 1 and fixed contact plate 2 directly or via lead wires 14. The lead 14 is a conductive metal wire or a metal plate. For connection of the electrode of PTC7 to movable contact plate 1 and fixed contact plate 2, soldering, welding, adhesion with a conductive adhesive, fixation with a caulking structure, or the like can be used. The bonding may be performed by a conductive adhesive, or the bonding may be performed by a non-conductive adhesive in a state where the lead and the metal plate are stacked in contact with each other and electrically connected to each other.

In the micro circuit breaker of fig. 3 to 6, PTC7 built in case 8 is used as both PTC7Y for preventing instantaneous disconnection and PTC7X for self-holding, lower electrode 7a of PTC7 is connected to fixed contact plate 2, and upper electrode 7b is connected to movable contact plate 1 via lead 14. Fig. 4 and 5 are schematic sectional views of the micro circuit breaker shown in fig. 6. Lower electrode 7a of PTC7 is connected to the upper surface of fixed contact plate 2 by soldering, welding, adhesion, or the like. Upper electrode 7b of PTC7 is connected to movable contact plate 1 via lead wire 14. Upper electrode 7b is connected to lead wire 14 by soldering, welding, bonding, or the like, and lead wire 14 and movable contact plate 1 are connected by soldering, welding, bonding, caulking, or the like. The micro circuit breaker of fig. 3 connects the lead wire 14 to the movable contact plate 1 at the peripheral wall 8A of the case 8, and the micro circuit breaker of fig. 4 connects the lead wire 14 to the movable contact plate 1 outside the case 8 after assembly. In the micro circuit breaker of fig. 4 to 6, the end of the lead wire 14 is drawn out of the case 8 to form the external connection terminal 19, the contact 10 is activated in a state where the external connection terminal 19 is not connected to the movable contact plate 1, and then the external connection terminal 19 is connected to the movable contact plate 1 to connect the lead wire 14 to the movable contact plate 1.

As shown in fig. 5, the contact 10 is activated by applying ultrasonic vibration to the micro breaker to discharge the electric current between the contacts in a state where the movable contact plate 1 and the fixed contact plate 2 are connected to the power supply 30. Although a dc power supply is suitable for the power supply 30, a low-frequency ac power supply may be used. The power supply 30 supplies current energy to the circuit by passing current through the contact 10 in the closed state, and vibrates the contact 10 by ultrasonic vibration. The vibrating contact 10 repeatedly achieves the closed state and the open state in a short cycle. At the moment when the contact 10 is opened, a high voltage is induced between the contacts by the energy of the current, and discharge is performed. A discharge is generated on the opposite surface of the contact 10, thereby activating the contact surface of the contact 10. The energy of the current accumulated in the circuit due to the discharge is consumed. Since the contact 10 is activated by inducing a high voltage to the contact 10 and discharging the high voltage, it is necessary to insulate the contacts. When the PTC7Y for preventing instantaneous disconnection is connected in parallel between the contacts, current flows to the PTC7, and therefore, discharge is not caused by high voltage, and the contacts 10 cannot be activated.

In the micro circuit breaker of fig. 4 to 6, since the lead wire 14 is connected to the movable contact plate 1 outside the case 8, the PTC7Y for preventing instantaneous disconnection is connected to the movable contact plate 1 after the contact 10 is activated. The micro circuit breaker of fig. 4 and 6 has a lead wire 14 and a movable contact plate 1 fixed to a case 8 in a stacked manner. The lead wire 14 is arranged at a predetermined position of the case 8 via a positioning structure 18. The positioning structure 18 shown in fig. 4 and 6 is composed of a positioning hole 18A provided in the lead 14 and a positioning projection 18B provided in the lower case 8Y and inserted into the positioning hole 18A. The positioning projection 18B is inserted into the positioning hole 18A so that the lead 14 is arranged at a predetermined position of the housing 8.

The miniature circuit breaker can clamp and fix the lead wire 14 and the movable contact plate 1 by the peripheral walls 8A of the upper case 8X and the lower case 8Y. In order to insulate the lead wire 14 from the movable contact plate 1 in the assembled state, the insulating sheet 17 is interposed between the lead wire 14 and the movable contact plate 1 and fixed to the peripheral wall 8A. The insulating sheet 17 is bonded to the surface of the lead 14 via a thermoplastic plastic sheet. The insulating sheet 17 is made of a material and has a thickness capable of withstanding a high-voltage insulation voltage generated between the movable contact plate 1 and the lead wire 14 during the activation process of the contact 10. For example, the insulating sheet 17 is a plastic sheet such as polyamide-imide having a thickness of 5 μm to 50 μm.

In the micro circuit breaker of fig. 4 to 6, a non-insulating portion 19a in which the insulating sheet 17 is not interposed between the movable contact plate 1 and the end portion of the lead wire 14 and the tip portion of the external connection terminal 19 drawn out from the case 8 is provided. In this micro circuit breaker, as shown in fig. 5, the lead wire 14 and the movable contact plate 1 can be insulated from each other by bending the distal end portion of the external connection terminal 19 to separate the non-insulated portion 19a from the movable contact plate 1. In this state, as shown in fig. 5, the movable contact plate 1 and the fixed contact plate 2 are connected to the power supply 30, and the micro-breaker is subjected to ultrasonic vibration to discharge electricity between the contacts 10 and activate the contacts. After the contact 10 is activated, as shown in fig. 4, the non-insulating portion 19a is connected to the movable contact plate 1, and the lead 14 is connected to the movable contact plate 1, whereby the PTC7Y for preventing momentary disconnection is connected to the fixed contact plate 2 and the movable contact plate 1.

The miniature circuit breaker of fig. 4 and 6 is preferably assembled by the process shown in fig. 7.

(1) Flux is supplied to the upper surface of fixed contact plate 2 which is insert molded and fixed to lower case 8Y.

(2) PTC7 is placed on fixed contact plate 2 to which flux is attached, and the flux is brought into close contact with contact plate 2 and lower electrode 7a of PTC 7.

(3) Flux is supplied to the upper electrode 7b of the PTC 7.

(4) The lead 14 is placed on the PTC 7. In order to provide the lead wire 14 at a predetermined position of the lower case 8Y, a through hole of the positioning hole 18A is provided for the lead wire 14, and a positioning projection 18B is provided at an insertion position of the positioning hole 18A for the lower case 8Y. The positioning protrusion 18B is inserted into the positioning hole 18A, and the lead 14 is set at a predetermined position of the lower case 8Y. The flux supplied to the upper electrode 7b of the PTC7 is brought into close contact with the upper electrode 7b and the lead wire 14.

In the above state, the assembled component 20 in which the PTC7 and the lead wire 14 are provided is formed in the lower case 8Y to which the fixed contact plate 2 is fixed.

(5) The assembly component 20 without the upper case is placed in the reflow furnace 31 and heated to melt the flux, the lower electrode 7a of the PTC7 is reflow-soldered and fixed to the fixed contact plate 2, and the upper electrode 7b of the PTC7 is reflow-soldered and fixed to the lead wire 14.

(6) Movable contact plate 1 is provided on lead wire 14 which is fixed by reflow soldering. At this time, the insulating sheet 17 is laminated between the lead wire 14 and the movable contact plate 1. The insulating sheet 17 is disposed in a portion where the lead wires 14 and the movable contact plate 1 are laminated, and is disposed in a region other than the non-insulating portion 19a of the distal end portion of the external connection terminal 19. Further, the bimetal 6 is disposed between the PTC7 and the movable contact plate 1. Thereafter, the upper case 8X is set and the upper case 8X is fixed to the lower case 8Y. The peripheral wall is melted by ultrasonic vibration or the upper case 8X and the lower case 8Y are fixed by adhesion via an adhesive.

(7) The front end of the external connection terminal 19 of the lead wire 14 drawn out from the housing 8 is bent to separate the non-insulating portion 19a from the movable contact plate 1, whereby the lead wire 14 and the movable contact plate 1 are brought into an insulated state without being connected to each other, and the contact 10 is activated.

(8) After the activation process is performed on the contact 10, the lead 14 is irradiated with a laser beam in a state where the non-insulating portion 19a of the external connection terminal 19 is laminated on the movable contact plate 1, and the lead 14 is connected to the movable contact plate 1.

In the above embodiment, the non-insulating portion 19a in which the insulating sheet 17 is not interposed between the lead wire 14 and the movable contact plate 1 is provided at the tip end portion of the lead wire 14, and the non-insulating portion 19a is separated from the movable contact plate 1, whereby the lead wire 14 is insulated from the movable contact plate 1 and the contact 10 is activated. However, the micro circuit breaker may be arranged not in a region where the insulating sheet is not interposed between the lead and the movable contact plate, and the lead may be connected to the movable contact plate by insulating the lead and the movable contact plate with the insulating sheet arranged therebetween, and heating the activated contact to remove the insulating state.

As such a method, for example, the insulating sheet is made of a thermoplastic plastic sheet, the lead wire is irradiated with a laser beam, and the insulating sheet is heated by the energy of the laser beam to remove the insulating state, and the lead wire is connected to the movable contact plate at the portion where the insulating sheet is removed. The laser beam irradiated to the lead wire heats and extinguishes the insulating sheet, and the lead wire is melted and fixed to the movable contact plate by welding. In the above method, the lead wire is irradiated with the laser beam, and the energy of the laser beam is used to eliminate the insulating state and weld the lead wire to the movable contact plate, so that the lead wire can be easily and stably connected to the movable contact plate.

Further, although not shown, the miniature circuit breaker may be configured such that the laminated portion of the lead and the movable contact plate is caulked to connect them to each other, or the lead and the movable contact plate may be electrically connected to each other via a coupling member that penetrates the lead and the movable contact plate.

In the miniature circuit breaker of fig. 8, lower electrode 7a of PTC7 is insulated from fixed contact plate 2 in the assembled state, and lower electrode 7a is connected to fixed contact plate 2 after assembly. The micro circuit breaker activates the contact 10 in a state where the lower electrode 7a is insulated from the fixed contact plate 2, and then connects the lower electrode 7a to the fixed contact plate 2. In the micro circuit breaker, the contact 10 can be activated by applying ultrasonic vibration in a state where the movable contact plate 1 and the fixed contact plate 2 are connected to a power supply. The power supply causes a current to flow in the contact 10 in the closed state. The contact 10 is vibrated by ultrasonic vibration. The vibrating contact 10 repeatedly achieves the closed state and the open state in a short period. The contact 10 discharges at the moment of opening. The energy of the current flowing to the contact 10 in the closed state due to the discharge is consumed. The surface of the contact 10 is activated by the discharge energy. In order to discharge the contacts 10 in the open state, it is necessary to insulate the contacts from each other. If the PTC7Y for preventing instantaneous disconnection is connected in parallel between the contacts, the current flows to the PTC7, and thus the discharge due to the high voltage is not caused, and the contacts 10 cannot be activated.

In the micro circuit breaker of fig. 8, lower electrode 7a of PTC7Y for preventing momentary interruption is assembled to fixed contact plate 2 in an insulated manner, and contact 10 is activated in this state. After the contact 10 is activated, the lower electrode 7a of the PTC7 is connected to the fixed contact plate 2, and the PTC7 is connected in parallel to the contact 10. In the miniature circuit breaker of fig. 8, the insulating member 15 is disposed between the lower electrode 7a and the fixed contact plate 2 in order to insulate the lower electrode 7a from the fixed contact plate 2 in an assembled state. The insulating member 15 is formed of a housing 8 molded from plastic, or an insulating sheet that is a separate member from the housing 8. An insulating member 15 formed of a part of the case 8 is provided on the upper surface of the fixed contact plate 2 in the step of insert-molding the fixed contact plate 2 so that the fixed contact plate 2 is insulated from the lower electrode 7a of the PTC 7. In a miniature circuit breaker using an insulating sheet separately from a case, the insulating sheet is disposed between the PTC element and the fixed contact plate in an assembly process. The insulating member 15 is required to have a structure capable of connecting the fixed contact plate 2 to the lower electrode 7a of the PTC7 after the contact 10 is activated. The micro circuit breaker of fig. 8 is provided with a connection hole 16 at the bottom surface of the case 8 and the insulating member 15. The housing 8 and the connection hole 16 of the insulating member 15 are provided at positions facing each other. The micro-breaker irradiates a laser beam from a connection hole 16 of a case 8, thereby melting a fixed contact plate 2 and welding and connecting a lower electrode 7a of a PTC 7. The micro-breaker of fig. 8 can also connect the fixed contact plate 2 to the PTC7 by injecting molten solder or a conductive adhesive into the connection hole 16.

The micro circuit breaker of fig. 9 and 10 has a lead wire 14 connected to the electrodes on both sides of the PTC 7. Lead 14 connected to lower electrode 7a is connected to fixed contact plate 2, and lead 14 connected to upper electrode 7b is connected to movable contact plate 1. The miniature circuit breaker has the following characteristics: since the lead 14 connects the both-side electrode of the PTC7 to the fixed contact plate 2 and the movable contact plate 1, the PTC7 can be reliably connected between the contacts. The micro circuit breaker of fig. 9 is assembled by connecting the lead 14 connected to the upper electrode 7b of the PTC7 to the movable contact plate 1. The miniature circuit breaker is assembled by being embedded in the peripheral wall 8A of the housing 8 in a state where the lead wire 14 is connected to the movable contact plate 1. The micro circuit breaker of fig. 10 is assembled in a state where the lead 14 is not connected to the movable contact plate 1, and after the contact 10 is activated, the lead 14 is connected to the movable contact plate 1 outside the case 8.

The miniature circuit breaker shown in fig. 11 and 12 has the self-holding PTC7X built in the case 8 and the momentary interruption preventing PTC7Y disposed outside the case 8. In this micro circuit breaker, the fixed contact plates 2 are projected to both ends of the case 8 in order to connect the PTC7Y for instantaneous interruption prevention to the outside of the case 8. PTC7 is disposed at one end in the longitudinal direction of rectangular case 8 and between fixed contact plate 2 and movable contact plate 1. The micro circuit breaker of fig. 11 directly connects the movable contact plate 1 and the fixed contact plate 2 to the electrodes on both sides of the PTC7Y for preventing instantaneous disconnection. The micro circuit breaker of fig. 12 is connected to electrodes on both sides of PTC7Y for preventing instantaneous opening by lead wires 14, and is connected to movable contact plate 1 and fixed contact plate 2 via lead wires 14.

The miniature circuit breaker of fig. 11 and 12 has the following features because the PTC7Y for preventing instantaneous opening is disposed outside the case 8: the PTC7Y for preventing instantaneous disconnection can be arranged without changing the structure and shape of the conventional micro circuit breaker and without changing the thickness and width of the circuit breaker. The battery pack is mainly disposed in the battery pack as a battery protection element, and the battery pack is disposed with the micro breaker at a position facing the step portion of the stacked batteries and the sealing plate of the rectangular battery cell. The position facing the step portion and the sealing plate is a narrow gap and has a space margin in the longitudinal direction. Therefore, the miniature circuit breaker in which the PTC7Y for preventing instantaneous disconnection can be disposed by merely changing the length without changing the thickness and width realizes a feature of preventing instantaneous disconnection without increasing the thickness of the battery pack. In addition, the micro circuit breaker of fig. 11 and 12 also realizes features capable of preventing instantaneous opening and activating the contact 10 to reduce internal impedance in a closed state.

Industrial applicability of the invention

The micro circuit breaker of the present invention can be used as a protection element for a portable device such as a smart phone or a tablet pc, as a circuit breaker capable of preventing instantaneous disconnection due to instantaneous disconnection of a contact caused by an impact such as dropping.

Description of the reference numerals

1 … movable contact board

2 … fixed contact board

3 … movable contact

4 … fixed contact

5 … elastic arm

6 … bimetal

7…PTC

7a … lower electrode

7b … upper electrode

PTC for 7X … self-holding

PTC for preventing 7Y … instantaneous cut

8 … casing

8X … Upper Shell

8Y … lower casing

8A … peripheral wall

9 … hollow part

10 … contact

11 … connection terminal

12 … connection terminal

13 … projection

14 … conducting wire

15 … insulating member

16 … connecting hole

17 … insulating sheet

18 … positioning structure

18A … location hole

18B … convex part

19 … external connection terminal

19a … non-insulating part

20 … Assembly parts

30 … power supply

31 … reflow oven

90 … contact point

96 … bimetal

97…PTC

Claims

1. A miniature circuit breaker for a portable device connected in series with a battery,

the miniature circuit breaker is characterized by comprising:

a movable contact plate formed by providing a movable contact at a tip of the elastic arm;

a fixed contact plate in which a fixed contact is provided at a position opposed to the movable contact;

a bimetal which is separated from the movable contact and the fixed contact at a set temperature to be in an open state; and

a PTC for preventing instantaneous disconnection, which is connected to the fixed contact plate and the movable contact plate,

the miniature circuit breaker is provided with:

a housing to which the movable contact plate and the fixed contact plate are fixed; and

a lead wire connected to a surface of the PTC and having an end portion led out of the case to form an external connection terminal,

an insulating sheet is provided between the external connection terminal and the movable contact point plate, and the external connection terminal is connected to the movable contact point plate.

2. The miniature circuit breaker of claim 1 wherein said miniature circuit breaker further comprises a first and a second switch,

one electrode of the PTC for preventing instantaneous disconnection is connected to the fixed contact plate by welding or bonding,

the other electrode of the PTC for preventing instantaneous disconnection is connected to the movable contact plate by welding or adhesion.

3. The miniature circuit breaker for portable equipment according to claim 1 or 2,

the movable contact plate and the fixed contact plate have built-in therebetween: a bimetal which reverses when a set temperature is reached and separates the movable contact from the fixed contact; and a PTC for self-holding which heats the bimetal between the bimetal and the fixed contact plate and holds the bimetal in a reverse state,

the PTC for self-holding also serves as the PTC for preventing the momentary interruption.

4. The miniature circuit breaker of claim 1 wherein said miniature circuit breaker further comprises a first and a second switch,

the insulating sheet is a thermoplastic plastic film having a thickness of 5 [ mu ] m to 50 [ mu ] m, which is bonded to the surface of the lead.

5. The miniature circuit breaker of claim 1 wherein said miniature circuit breaker further comprises a first and a second switch,

the lead is arranged between the bimetal and the PTC, and an insulating sheet is arranged on the surface opposite to the bimetal.

6. The miniature circuit breaker of claim 4 wherein said miniature circuit breaker further comprises a first and a second switch,

7. The miniature circuit breaker for portable equipment according to any one of claims 1 and 4 to 6,

the lead wire is laminated on the movable contact plate via the insulating sheet and fixed to the housing.

8. The miniature circuit breaker for portable equipment according to any one of claims 1 and 4 to 6,

the lead is connected to the surface of the PTC by reflow soldering.

9. The miniature circuit breaker of claim 8 wherein said circuit breaker further comprises a first switch,

the PTC is connected to the fixed contact plate by reflow soldering.

10. The miniature circuit breaker for portable equipment according to any one of claims 1 and 4 to 6,

the lead is disposed at a predetermined position of the housing via a positioning structure.

11. The miniature circuit breaker of claim 10 wherein said circuit breaker further comprises a first switch,

the positioning structure is constituted to include: the positioning hole is arranged on the lead; and a positioning protrusion provided in the housing and inserted into the positioning hole, the positioning protrusion being inserted into the positioning hole so that the lead is disposed at a predetermined position of the housing.

12. The miniature circuit breaker for portable equipment according to claim 1 or 2,

the miniature circuit breaker is provided with a shell fixed with the movable contact plate and the fixed contact plate,

the PTC for preventing instantaneous disconnection is disposed outside the case.

13. The miniature circuit breaker of claim 12 wherein said circuit breaker further comprises a first and a second switch,

the fixed contact plate is fixed along the bottom surface of the housing and protrudes from the bottom surface of the housing in the longitudinal direction to dispose the connection terminal outside the housing,

the PTC for preventing instantaneous disconnection is fixed to the upper surface of the connection terminal in a laminated state.

14. The miniature circuit breaker of claim 13 wherein said circuit breaker further comprises a first switch,

the miniature circuit breaker is provided with:

a PTC for preventing instantaneous disconnection, which is disposed outside the case; and

and a self-holding PTC which is provided between the movable contact plate and the fixed contact plate, is provided in the housing, and holds the movable contact in an off state at a set temperature.

15. The miniature circuit breaker for portable equipment according to claim 1 or 2,

the miniature circuit breaker is provided with a lead for connecting the PTC for preventing instantaneous disconnection with the movable contact plate and the fixed contact plate,

the lead wire is connected at both ends to the PTC for preventing momentary disconnection, the movable contact plate, and the fixed contact plate by welding or bonding.

16. The miniature circuit breaker for portable equipment according to claim 1 or 2,

the PTC device for preventing instantaneous disconnection has a low resistance value in a current-carrying state which is 10 times or more a contact resistance value which is a resistance value in a state where the movable contact is in contact with the fixed contact.

17. The miniature circuit breaker of claim 16 wherein said circuit breaker further comprises a first switch,

the contact resistance value is 5m omega or less, and the low resistance value of the PTC for instantaneous disconnection prevention is 4 omega or less.

18. The miniature circuit breaker of claim 16 wherein said circuit breaker further comprises a first switch,

the PTC for preventing instantaneous disconnection has a low resistance value of 20m Ω or more.

19. A method for manufacturing a miniature circuit breaker for a portable device, the miniature circuit breaker comprising:

a bimetal which separates the movable contact from the fixed contact at a set temperature to be in an off state; and

the method for manufacturing a miniature circuit breaker for a portable device is characterized in that,

the PTC for preventing momentary interruption is connected to either or both of the movable contact plate and the fixed contact plate, and is activated, and after the activation, the PTC for preventing momentary interruption is connected to the fixed contact plate and the movable contact plate.

20. The method for manufacturing a miniature circuit breaker for portable equipment as claimed in claim 19,

the miniature circuit breaker is provided with:

a lead wire connected to a surface of the PTC for preventing instantaneous disconnection and having an end portion led out of the case to form an external connection terminal,

the micro circuit breaker is manufactured by the following steps:

an insulating step of disposing an insulating sheet between the external connection terminal and the movable contact point plate to insulate the lead wire from the movable contact point plate;

an activation step of activating the movable contact and the fixed contact while keeping the lead wire and the movable contact plate in an insulated state by the insulation step; and

and a connecting step of connecting the external connection terminals and the movable contact plate outside the housing after the contacts are activated in the activating step.

21. The method for manufacturing a miniature circuit breaker for portable equipment as claimed in claim 20,

the PTC device is characterized in that the fixed contact plate is provided at a predetermined position of the case, the PTC for instantaneous disconnection prevention is placed on the fixed contact plate, and the lead is placed on the PTC for instantaneous disconnection prevention, and in this state, the lower surface of the PTC for instantaneous disconnection prevention is connected to the fixed contact plate and the upper surface of the PTC for instantaneous disconnection prevention is connected to the lead by reflow soldering.

22. The method for manufacturing a miniature circuit breaker for portable equipment as claimed in claim 20 or 21,

a non-insulating section provided at a distal end portion of the external connection terminal and having no insulating sheet interposed therebetween,

in the insulating step, the non-insulating portion is separated from the movable contact plate so that the lead wire and the movable contact plate are insulated from each other,

in the connection step, the non-insulating portion is connected to the movable contact plate and the lead wire is connected to the movable contact plate after the contact is activated in the activation step.