WO2023074752A1

WO2023074752A1 - Breaker

Info

Publication number: WO2023074752A1
Application number: PCT/JP2022/039976
Authority: WO
Inventors: 友則瀧口
Original assignee: 大塚テクノ株式会社
Priority date: 2021-10-27
Filing date: 2022-10-26
Publication date: 2023-05-04
Also published as: JP7558596B2; CN118120039A; JPWO2023074752A1

Abstract

The present invention reduces an error in the return temperature for returning to a state in which current is applied from a state in which current is cut off. Provided is a breaker in which a bi-metal that deforms between an inverted shape and a non-inverted shape with the ambient temperature deforms a movable contact metal plate and switches a contact on/off, wherein: the movable contact metal plate has an arm part at the tip of which is provided a movable contact and a fixed part which is fixed to a case; the arm part is provided with a deformable arm part which deforms with pressing by the bi-metal and a fixed arm part which is separated from the deformable arm part via a slit; and a contact part that determines the position of contact with the bi-metal is provided to the fixed arm part which does not move along with the deformable arm part.

Description

breaker

The present invention relates to a breaker that is built into an electric device such as a battery pack or a motor and cuts off the current when the temperature exceeds a preset temperature.

Equipment such as battery packs and motors can cut off the current when the temperature is abnormally high to improve safety. For this purpose, circuit breakers are used that switch off the contacts by detecting the ambient temperature with a bimetal. For example, a battery pack containing a lithium-ion battery will become hot if it is charged or discharged under abnormal usage conditions. can be safely used by blocking In addition, since the temperature of motors, etc., can become abnormally high when overloaded or when an abnormal current flows, they can be safely used with a breaker that cuts off the current when the set temperature is exceeded.

As a breaker used for such applications, a breaker has been developed in which the bimetal reverses when the ambient temperature rises above the set temperature, and the reversed bimetal pulls the movable contact away from the fixed contact to cut off the current. (See Patent Document 1)

This breaker is shown in the cross-sectional views of FIGS. 13 and 14. 13 shows an ON state in which the bimetal 108 is not reversed and the movable contact 107 is in contact with the fixed contact 105, and FIG. 14 shows an OFF state in which the bimetal 108 is reversed and the movable contact 107 is separated from the fixed contact 105. ing.

WO2017/154891

In the breakers shown in FIGS. 13 and 14, when the temperature exceeds the set temperature, the bimetal 108 is reversed to switch the contact from ON to OFF. In this state, the bimetal 108 is reversed and deformed so as to push up the movable contact metal plate 101 from below, thereby separating the movable contact 107 from the fixed contact 105 . When the temperature drops and the inverted bimetal 108 returns to its original shape, the elasticity of the movable contact metal plate 101 brings the movable contact 107 into contact with the fixed contact 105 and switches it to the ON state. The movable contact metal plate 101 elastically pushes the movable contact 107 against the fixed contact 105 in a state in which the bimetal 108 does not push up the movable contact metal plate 101, that is, in a non-inverted shape in which the bimetal 108 is not inverted. In this state, the movable contact 107 contacts the fixed contact 105 and the breaker is kept on.

In the breaker described above, when the ambient temperature exceeds the threshold value, the bimetal 108 is reversed to separate the movable contact 107 from the fixed contact 107 to switch to the OFF state. When the ambient temperature rises and exceeds the preset set temperature, that is, the current cut-off temperature, the breaker with this structure switches the contact from on to off to cut off the current, cuts off the current, and gradually increases the ambient temperature. When it cools down to the energization temperature at which it is energized, it returns the off-state contacts to the on-state. The breaker is set to have a reset temperature lower than the temperature at which the current is interrupted, but it is required to have characteristics to reduce variations in the interrupt temperature and to start energization at an accurate temperature.

In the breaker described above, when the ambient temperature drops to the return temperature, the bimetal 108 returns to its non-inverted shape, but the bimetal is pushed in the return direction by the movable contact metal plate 101 until just before the return. That is, the reverse bimetal returns while being pressed by the movable contact metal plate. Since the reversing bimetal returns from the reversal shape to the non-reversing shape while being pushed by the movable contact metal plate, the temperature at which the bimetal returns from the reversing state to the non-reversing shape does not affect the force with which the movable contact metal plate pushes the bimetal. receive. The force by which the movable contact metal plate pushes the bimetal pushes the reversing bimetal in the non-reversing direction, so when the force of the moving contact metal plate pushing the bimetal increases, the reversing bimetal easily returns to the non-reversing shape. Conversely, when the force of the movable contact metal plate pushing the reversing bimetal becomes small, the reversing bimetal becomes difficult to return. A bimetal that easily recovers from an inverted state to a non-inverted shape will recover with a small temperature drop, so the recovery temperature will be high. Lower recovery temperature.

The movable contact metal plate has a protrusion for specifying the contact position with the bimetal. In the breaker of this structure, the reversing bimetal pushes up the projection to separate the movable contact from the fixed contact and cut off the current. This structure can specify the position where the bimetal pushes the movable contact metal plate, and can reduce the error of the return temperature for switching the contact from off to on. However, in the breaker of this structure, the displacement of the projections, especially the displacement of the projections in the vertical direction, increases the error of the return temperature. This is because the displacement of the projection in the vertical direction changes the force with which the inverted bimetal pushes the projection.

The present invention has been developed with the object of solving the above drawbacks, and an important object of the present invention is to restore the reversed bimetal to its original shape so that the contact that was in the off state is in the on state. To provide a breaker capable of reducing the error of the return temperature switched to .

The breaker of the present invention comprises a fixed contact metal plate having a fixed contact, a movable contact metal plate having a movable contact arranged at a position facing the fixed contact, and a position facing the movable contact metal plate. It has a bimetal that switches the movable contact from on to off due to temperature, a fixed contact metal plate, a movable contact metal plate, and a case that houses the bimetal in a fixed position. The movable contact metal plate has an arm portion that is pushed by the reversing bimetal to separate the movable contact from the fixed contact, and a fixed portion that is fixed to the case. The arm portion is elastically deformed by being pushed by the reversing bimetal and separates the movable contact from the fixed contact, and is separated from the deformable arm portion through a slit and connects the root portion to the fixed portion. It is divided into a fixed arm section. The fixed arm portion has a contact portion that contacts the bimetal, and the contact portion is pushed by the reversing bimetal to switch the movable contact from on to off.

The above breaker has the feature that the reversed bimetal returns to its original shape and the contact that was in the OFF state is switched to the ON state, reducing the return temperature error.

1 is a perspective view of a breaker according to Embodiment 1 of the present invention; FIG. FIG. 2 is an exploded perspective view of the breaker shown in FIG. 1; FIG. 2 is an exploded perspective view of the breaker shown in FIG. 1; FIG. 2 is a cross-sectional view taken along line AA of the breaker shown in FIG. 1, showing a contact ON state; FIG. 2 is a cross-sectional view taken along line AA of the breaker shown in FIG. 1, showing a contact OFF state; FIG. 2 is a cross-sectional perspective view taken along the line AA of the breaker shown in FIG. 1, showing a contact ON state; FIG. 2 is a cross-sectional perspective view taken along line AA of the breaker shown in FIG. 1, showing a contact OFF state; FIG. 2 is a side cross-sectional view taken along the line BB of the breaker shown in FIG. 1, showing a contact ON state; FIG. 2 is a side cross-sectional view taken along the line BB of the breaker shown in FIG. 1, showing a contact OFF state; 5 is an enlarged sectional view of a movable contact and a fixed contact of the breaker shown in FIG. 4; FIG. FIG. 8 is an exploded perspective view of a breaker according to Embodiment 2; FIG. 12 is a cross-sectional view showing a contact ON state of the breaker shown in FIG. 11; FIG. 10 is a cross-sectional view showing an example of a conventional breaker in an ON state; FIG. 10 is a cross-sectional view showing an example of a conventional breaker in an off state;

The present invention will be described in detail below based on the drawings. In the following description, terms indicating specific directions and positions (e.g., "upper", "lower", and other terms including those terms) are used as necessary, but the use of these terms is These terms are used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the invention is not limited by the meaning of these terms. Also, parts with the same reference numerals appearing in a plurality of drawings indicate the same or equivalent parts or members.

Furthermore, the embodiments shown below are specific examples of the technical idea of the present invention, and the present invention is not limited to the following. In addition, unless there is a specific description, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are not intended to limit the scope of the present invention, but are intended to be examples. It is intended. In addition, the contents described in one embodiment and example can also be applied to other embodiments and examples. Also, the sizes and positional relationships of members shown in the drawings may be exaggerated for clarity of explanation.

A breaker according to an embodiment of the present invention houses a fixed contact metal plate, a movable contact metal plate, and a bimetal at fixed positions in a case. The fixed contact metal plate has a fixed contact, and the movable contact metal plate has a movable contact at a position facing the fixed contact. The bimetal is placed opposite the movable contact metal plate and reverses at a set temperature to switch the movable contact from on to off. The movable contact metal plate has an arm portion that is pushed by the reversing bimetal to separate the movable contact from the fixed contact, and a fixed portion that is fixed to the case. The arm portion is elastically deformed by being pushed by the reversing bimetal and separates the movable contact from the fixed contact, and is separated from the deformable arm portion through a slit and connects the root portion to the fixed portion. It is divided into a fixed arm section. The fixed arm portion has a contact portion that contacts the bimetal, and the contact portion is pushed by the reversing bimetal to switch the movable contact from on to off.

The above breaker can reduce the error in the return temperature that returns the contact to ON. For this reason, this breaker has the advantage of being able to turn on the contact at an accurate temperature when the ambient temperature rises and the current is interrupted and then the temperature drops. This excellent characteristic is achieved by separating the arm portion of the movable contact metal plate into a deformable arm portion having a movable contact at the tip and a fixed arm portion that does not deform. This is because the contact portion that is pushed by the reversed bimetal is provided and the contact portion is arranged at an accurate position, thereby preventing relative displacement between the bimetal and the contact portion.

The fixed arm section is separated from the deformable arm section through a slit, and the root section is connected to the fixed section. In the breaker of this structure, since the contact portion is provided on the fixed arm portion that does not deform together with the deformable arm portion, the contact portion can be prevented from being displaced in the vertical direction, and the error in the return temperature can be reduced.

The vertical positional deviation of the contact part provided on the arm changes the balance of the pressing force between the contact part and the bimetal, affecting the return temperature error. This is because the vertical displacement of the contact portion changes the pressing force for the contact portion to push down the reversing bimetal and return it to the non-reversing shape. Since the inverted bimetal is pressed by the elastic restoring force of the arm through the contact portion, it deforms from the inverted shape to the restored posture. As the force increases, the bimetal easily returns, and conversely, when the force with which the contact portion presses the bimetal weakens, it becomes difficult for the bimetal to return. Bimetals that are easy to reset are reset with a small drop in the ambient temperature, so the reset temperature is high, and bimetals that are difficult to reset are reset when the ambient temperature drops sufficiently, so the reset temperature is low. For example, when the contact portion shifts downward, the inverted bimetal is deformed to approach a non-inverted shape and the return temperature decreases.

Due to various factors in the assembly process, the contact part of the breaker is displaced in the vertical direction. In particular, breakers with this structure are often used as protective elements built into electronic devices such as battery packs, so miniaturization is required. is. With ultra-compact breakers, even a slight displacement of the contact portion in the vertical direction causes an error in the return temperature. A breaker that separates the arm portion into the deformable arm portion and the fixed arm portion and provides the contact portion on the fixed arm portion that is not deformed together with the deformable arm portion prevents the contact portion from being displaced in the vertical direction. Realize the feature that the return temperature can be set accurately.

A breaker according to another embodiment of the present invention can be provided with a convex portion on the deformed arm portion of the arm portion. The convex portion is provided between the movable contact and the contact portion so as to protrude toward the bimetal. In this breaker, the contact portion is provided on the fixed arm portion, the convex portion is provided on the deformable arm portion, the convex portion is provided between the movable contact and the contact portion, and the contact portion and the convex portion are provided at both ends of the bimetal. can be contacted.

This breaker has a structure in which the contact part and the convex part are in contact with both ends of the bimetal. can be switched.

A breaker according to another embodiment of the present invention can be provided with a fixed arm portion extending in the longitudinal direction at the center portion in the width direction of the arm portion. With this breaker, the contact portion that contacts the bimetal can be arranged at the optimum position, and the contact position between the contact portion and the bimetal can be arranged at the optimum position.

In a breaker according to another embodiment of the present invention, the length (L2) of the fixed arm portion can be set to 10% to 90% of the length (L1) of the arm portion. It can be arranged at the optimum position with the edge.

A breaker according to another embodiment of the present invention can be provided with a stopper convex portion on the inner surface of the case for limiting deformation of the fixed arm portion due to the pressing force of the bimetal. This breaker has the feature that the deformation of the fixed arm portion can be more reliably prevented by the stopper convex portion, the displacement of the contact portion in the vertical direction can be further reduced, and the return temperature can be accurately set.

A breaker according to another embodiment of the present invention comprises a main body case to which a fixed contact metal plate is fixed, and a lid case having a closing plate that closes an opening of the main body case. A stopper projection can be provided on the inner surface.

In a breaker according to another embodiment of the present invention, the contact portion can be a projection projecting from the fixed arm portion toward the bimetal.
[Embodiment 1]

1 to 3 mainly show a breaker 100 built in a battery pack. A breaker 100 incorporated in the battery pack detects a temperature rise of a battery or the like with a bimetal and cuts off current. Since the temperature of the battery pack rises due to thermal runaway caused by being used in an abnormal state or caused by an internal short circuit of the battery, the breaker 100 is incorporated as a protective element to prevent the temperature rise of the battery. It can be used safely by detecting and cutting off the current. The breaker 100 is often used as a protection element for battery packs, but the present invention does not specify the application of the breaker 100, but all applications, such as motors, that detect a temperature rise and cut off current. can be used for the breaker 100 used for
(Breaker 100)

The breaker 100 shown in FIGS. 1 to 9 includes a case 1, a fixed contact metal plate 4 having a fixed contact 5 fixed to the case 1, and a movable contact at a position of the fixed contact metal plate 4 facing the fixed contact 5. 7 and is arranged between the movable contact metal plate 6 and the movable contact metal plate 6 and the fixed contact metal plate 4, which is partly fixed to the case 1 so that the movable contact 7 can move, A bimetal 8 is provided for switching the movable contact metal plate 6 from ON to OFF by reversing from a non-reversed shape to a reversed shape when the temperature rises above a set temperature.

When the ambient temperature is lower than the set temperature, as shown in FIGS. 4, 6 and 8, the breaker 100 is in a state in which the bimetal 8 is not deformed, i. When the ambient temperature exceeds the set temperature, the bimetal 8 separates the movable contact 7 from the fixed contact 5 and switches to the OFF state, as shown in FIGS. When the temperature drops to the return temperature, it switches from off to on. The breaker 100 deforms the bimetal 8 from a non-reversed shape to a reversal shape at ambient temperature, and the reversing bimetal 8 deforms the movable contact metal plate 6 to move the movable contact 7 of the movable contact metal plate 6 from the fixed contact 5. Release to switch to OFF state. When the ambient temperature drops to a predetermined temperature, the inverted bimetal 8 is deformed into a non-inverted shape and does not press the arm portion 6A of the movable contact metal plate 6, thereby bringing the movable contact 7 into contact with the fixed contact 5. to return to the ON state.

Furthermore, the breaker 100 shown in FIGS. 4 to 9 incorporates a heater 9 for heating the bimetal 8. As shown in FIG. The heater 9 is preferably a plate-shaped PTC heater, and is arranged between the bimetal 8 and the fixed contact metal plate 4 to heat the bimetal 8 from the rear surface. A breaker 100 incorporating a heater 9 can heat the bimetal 8 with the heater 9 to keep the breaker 100 off. This breaker 100 is provided with a circuit (not shown) that energizes the heater 9 in the off state, and the heater 9 heats the bimetal 8 to maintain the off state. This breaker 100 is incorporated in a battery pack to further improve the safety of the battery pack. After the battery pack reaches an abnormal temperature and the current is cut off by the breaker 100, the heater 9 is energized by the battery and can be kept in the OFF state. This is because the flowing current can be maintained in a cut-off state. When the battery is completely discharged, the heater 9 cannot be energized and the heater 9 cannot heat the bimetal 8. Even if the heater 9 returns to the ON state, the battery cannot be discharged in this state, so safety is not ensured. Secured. Furthermore, the breaker 100 incorporating the heater 9 can detect an abnormality in the battery, turn on the heater 9, heat the bimetal 8 with the heater 9, and cut off the current of the battery. In a battery pack incorporating a breaker 100, the breaker 100 is connected in series with the unit cell, and the breaker 100 cuts off the current of the battery. The breaker 100, which heats the bimetal 8 with the heater 9 and keeps it on, restores the bimetal 8 to its non-inverted shape when the battery is completely discharged, the battery stops supplying power to the heater 9, and the temperature drops below the restoration temperature. to switch the contact to the ON state.
(Case 1)

The case 1 is composed of a main body case 1A and a lid case 1B made of plastic, and the lid case 1B is connected to the main body case 1A by ultrasonic welding or by bonding. The case 1 fixes the fixed contact metal plate 4 and the movable contact metal plate 6 at fixed positions. In the case 1 shown in the figure, a fixed contact metal plate 4 is insert-molded and fixed to the bottom of the main body case 1A, and a movable contact metal plate 6 is sandwiched and fixed between the main body case 1A and the cover case 1B. , the opening of the main body case 1A is closed by the lid case 1B. The main body case 1A is provided with a first outer wall 11A and a second outer wall 11B at both ends so as to protrude, and a bimetal 8 and a heater 9 are provided between the first outer wall 11A and the second outer wall 11B. is provided at a fixed position. In the illustrated case 1, the bottom surface of a storage portion 20 provided in a main body case 1A is closed with a fixed contact metal plate 4, and the top surface of the storage portion 20 is closed with a lid case 1B connected thereto.
(Main body case 1A)

The main body case 1A is provided with a storage portion 20 in which the bimetal 8 is arranged inside the outer peripheral wall 10. The outer peripheral wall 10 includes a pair of outer walls 11 consisting of a first outer wall 11A and a second outer wall 11B, and a pair of opposing walls 12 connecting both ends of the pair of outer walls 11. The opposing walls 12 and the outer walls 11 A storage portion 20 is provided inside the . The main body case 1A surrounds the storage portion 20 with the outer peripheral wall 10 and closes the bottom surface and the upper surface of the outer peripheral wall 10 . The bottom surface of the housing portion 20 is closed by the bottom portion 13 and the fixed contact metal plate 4 integrally formed with the main body case 1A, and the top surface is closed by the cover case 1B connected to the main body case 1A. 20 is closed and hollow.

A fixed contact metal plate 4 is fixed to the body case 1A by insert molding. 3 to 9, the fixed contact metal plate 4 is fixed to the main body case 1A by insert molding so that the intermediate portion 4B is embedded in the first outer wall 11A. This fixed contact metal plate 4 is fixed to the main body case 1A in a state of penetrating the first outer wall 11A. 4X.
(Bimetal 8)

The bimetal 8 is a laminate of metals having different coefficients of thermal expansion so as to deform and reverse when heated. The bimetal 8 is arranged between the heater 9 and the arm portion 6A of the movable contact metal plate 6, reverses at a set temperature, separates the movable contact 7 from the fixed contact 5, and switches the breaker 100 to the OFF state. The thickness (t) of the bimetal 8 is preferably set to 0.05 mm or more and 0.1 mm or less because the thickness of the bimetal 8 can be reduced to make the breaker 100 as a whole thinner. Further, the bimetal 8 has a shape that curves convexly at the center, and in a non-inverted state, that is, in a non-inverted shape, the central projecting portion is directed toward the arm portion 6A as shown in FIGS. It is held in a protruding posture. When the temperature reaches the set temperature, the bimetal 8 is reversed and deformed into a reversed shape. In the reversed shape, as shown in FIGS. It becomes the shape which presses the arm part 6A at both ends. In the reversed shape, the bimetal 8 contacts the heater 9 with its center projection and presses the arm 6A with both ends to push up the arm 6A and separate the movable contact 7 from the fixed contact 5 to turn it off.
(Movable contact metal plate 6)

The movable contact metal plate 6 is an elastically deformable metal plate, and has a fixed portion 6B fixed to the case 1 and an arm portion 6A having a movable contact 7 at its tip. As shown in FIGS. 4 to 9, the movable contact metal plate 6 has a fixing portion 6B fixed to the case 1 and an arm portion 6A disposed in a storage portion 20 provided in the case 1. FIG. The movable contact metal plate 6 has a fixed portion 6B fixed to the upper portion of the second outer wall 11B provided on the case 1 . In the movable contact metal plate 6, the outer end of the fixed portion 6B protrudes from the case 1 to form a connection terminal 6X.

The arm portion 6A has a movable contact 7 on the surface facing the fixed contact 5. In the non-inverted shape of the bimetal 8, the movable contact metal plate 6 brings the movable contact 7 at the tip into contact with the fixed contact 5 to turn on the breaker 100. In the inverted shape of the bimetal 8, the movable contact metal plate 6 is pushed by the bimetal 8. , the movable contact 7 is separated from the fixed contact 5 to turn off the breaker 100 .

The movable contact metal plate 6 has the arm portion 6A arranged above the bimetal 8 arranged in the storage portion 20, as shown in FIGS. The movable contact metal plate 6 shown in the figure consists of one elastic metal plate that can be elastically deformed. The thickness (d) of the movable contact metal plate 6 is specified in consideration of the current capacity. and Furthermore, the thickness (d) of the movable contact metal plate 6 is set to an optimum value in consideration of the maximum current capacity of the breaker 100, so it is preferably set to 0.1 mm or more and 0.5 mm or less.

The material of the movable contact metal plate 6 is specified in consideration of its elasticity and conductivity. For example, a Cu--Zr alloy or a Cu--Cr--Ag--Si alloy can be used. The Cu--Zr alloy preferably contains 0.05 to 0.15 wt % of Zr in Cu as a base. Cu--Cr--Ag--Si based alloy contains 0.01 to 5 wt%, preferably 0.01 to 2.5 wt% Cr and 0.01 to 5 wt%, preferably 0.01 It contains ˜2.5 wt % Ag and 0.01-5 wt %, preferably 0.01-2.5 wt % Si. Further, the movable contact metal plate 6 is an elastic metal plate made of a copper alloy with a total content of Cr, Ag and Si of 0.5 to 3% by weight and an IACS of 78% to 84% (Material Performance Alloy and Composite (MATERION PERFORMANCE ALLOYS AND COMPOSITES USA) QMET 300 registered trademark). Furthermore, the elastic metal plate 6 is composed of a copper alloy containing Ni, P, Zn and Fe, a copper alloy containing Fe, P and Zn, a copper containing Cr and Mg and having an IACS of 75% or more. An elastic metal plate such as an alloy, a copper alloy containing 80% or more of IACS containing Zr, or a copper alloy containing 80% or more of IACS containing Sn can also be used.

However, in this specification, IACS [international annealed copper standard] refers to the conductivity of annealed standard annealed copper (volume resistivity of 1.7241 × 10 ^-2 μΩm) internationally adopted as a standard of electrical resistance or electrical conductivity. It is a notation that defines the rate as 100%.

The movable contact metal plate 6 has a movable contact 7 on a surface facing the fixed contact 5 at the tip of the arm portion 6A. The movable contact 7 of the arm portion 6A shown in FIG. 10 is fixedly provided with a metal plate made of silver or a silver alloy in a region facing the fixed contact 5, thereby reducing the contact resistance with the fixed contact 5. . The movable contact 7 is, for example, seam-welded to join an Ag—Ni alloy having a thickness of 100 μm to 150 μm. When the bimetal 8 is not thermally deformed, the movable contact 7 comes into contact with the fixed contact 5 to turn on the arm 6A. The movable contact 7 is separated from the fixed contact 5 and turned off.

The arm portion 6A of the movable contact metal plate 6 shown in the exploded perspective views of FIGS. 2 and 3 is separated into a deformable arm portion 6b and a fixed arm portion 6a via a slit 6c. 6d is provided on the fixed arm portion 6a as a form of a contact portion, and a protrusion 6e protruding from the fixed arm portion 6a is provided. The projections 6e and the projections 6d protrude toward both ends of the bimetal 8. As shown in FIG. The arm portion 6A has a projection 6e on the root portion 6f side and a projection 6d between the movable contact 7 and the projection 6e. The projection 6e and the projection 6d are arranged at contact positions on both ends of the bimetal 8. As shown in FIG. The arm portion 6A is elastically deformed by being pushed up by the reversing bimetal 8 through the projection 6e and the convex portion 6d, thereby switching the movable contact 7 to the OFF state. The arm portion 6A is pushed up by both end portions of the bimetal 8 via the projection 6e and the convex portion 6d. In this breaker 100, the reverse bimetal 8 pushes up a specific position of the arm portion 6A via the projection 6e and the convex portion 6d to reliably switch the contact on and off.

In the movable contact metal plate 6, the arm portion 6A is separated into a deformed arm portion 6b and a fixed arm portion 6a in order to reduce variations in the return temperature, that is, errors in the return temperature. The fixed arm portion 6a is separated from the deformable arm portion 6b by a slit 6c so as not to be deformed together with the deformable arm portion 6b, and the root portion 6f is connected to the fixed portion 6B. The fixed arm portion 6a has a protrusion 6e protruding toward the bimetal 8 at its tip. The deformable arm portion 6b has a movable contact 7 arranged at a position facing the fixed contact 5, and a convex portion 6d provided between the movable contact 7 and the fixed portion 6B. It is arranged at a position in contact with the right end of the bimetal 8 in the drawing.

The arm portion 6A in FIGS. 2 and 3 has a fixed arm portion 6a extending in the longitudinal direction at the central portion in the width direction, and deformable arm portions 6b are arranged on both sides of the fixed arm portion 6a. This arm portion 6A is provided with a projection 6e in the central portion so that the left and right deformation arm portions 6b can be elastically deformed into the same shape in good balance. The fixed arm portion 6a has a length that allows the projection 6e to be arranged at the optimum position. The length (L2) of the fixed arm portion 6a is, for example, 10% to 90%, preferably 20% to 80%, more preferably 25% to 75% of the total length (L1) of the arm portion 6A. can be arranged at the end of the bimetal 8 (left end in the figure).

The slit 6c of the arm portion 6A is provided between the fixed arm portion 6a and the deformable arm portion 6b to separate the fixed arm portion 6a from the deformable arm portion 6b so that they are not elastically deformed together. The arm portion 6A is provided with slits 6c along the outer periphery of both side edges and the tip edge of the fixed arm portion 6a, and connects the base portion 6f to the fixed portion 6B. The slit 6c separates the fixed arm portion 6a from the deformable arm portion 6b and has a gap of, for example, 0.1 to 0.3 mm that allows only the deformable arm portion 6b to be elastically deformed without deforming the fixed arm portion 6a.

Since the arm portion 6A of the breaker 100 becomes a current-carrying portion when the contact is in the ON state, the electric resistance can be reduced and heat generation due to Joule heat can be reduced. The bimetal 8, which generates heat by Joule heat, heats the arm portion 6A, causing the adverse effect of reversing and interrupting the current before the ambient temperature rises to the set temperature. The arm portion 6A can be made of a thick metal plate to reduce electrical resistance. However, the breaker 100 having the arm portion 6A made of a thick metal plate requires the bimetal 8 to push up the arm portion 6A with a strong force to switch the contact to the OFF state, and the bimetal 8 needs to be thick.

As shown in FIG. 2, deformation arm portions 6b are provided on both sides of a fixed arm portion 6a, and an arm portion 6A that deforms only the deformation arm portions 6b on both sides is deformed with a small upward force on both sides of the fixed arm portion 6a. Two rows of narrow deformation regions 6g are arranged. Therefore, the movable contact metal plate 6 of this structure is made thicker to reduce the electric resistance of the arm portion 6A, while deforming the deformation region 6g by a small push-up of the bimetal 8 to turn the contact off. There is a feature that can be switched to By providing the fixed arm portion 6a, the arm portion 6A locally increases the electrical resistance in this region, but by thickening the metal plate, the electrical resistance in other regions can be reduced. While reducing the substantial electric resistance of the whole, it is also possible to realize the feature that the contact can be switched to the OFF state with a thin bimetal without increasing the pushing force of the bimetal 8 . In the arm portion 6A of this structure, while using a thick metal plate, the lateral width (W4) of the deformation region 6g can be narrowed to reduce the push-up force of the bimetal 8, and the lateral width (W4) of the deformation region 6g can be widened. Overall electrical resistance can be reduced.

The width of the fixed arm portion 6a is an optimum value in consideration of the thickness of the metal plate used for the movable contact metal plate 6, the electrical resistance required of the arm portion 6A, and the pushing force required to switch the bimetal 8 to the ON state. However, the width (W2) of the fixed arm portion 6a is preferably 20% to 70%, more preferably 30% to 50% of the width (W5) of the area where the fixed arm portion 6a is provided. set.
(Lid case 1B)

As shown in FIGS. 4 to 9, the lid case 1B includes a closing plate 27a that closes the opening of the main body case 1A while covering the upper side of the arm portion 6A. The closing plate 27a shown in the figure is fixed by insert-molding the laminated metal plate 24 into the connecting plastic 23. As shown in FIG. The lid case 1B has a stopper projection 25 on the closing plate 27a. The closing plate 27 a exposes the laminated metal plate 24 to the lower surface, and provides the stopper projection 25 on the surface of the laminated metal plate 24 . The stopper convex portion 25 is arranged above the fixed arm portion 6a, and restricts or prevents deformation of the fixed arm portion 6a by being pushed by the bimetal 8. don't stop. The stopper convex portion 25 is locally arranged above the fixed arm portion 6a so as not to restrict deformation of the deformation area 6g of the deformation arm portion 6b by being pushed upward by the bimetal 8. is not placed above the

The above-described lid case 1B closes the opening of the main body case 1A by fixing the outer peripheral edge of the connecting plastic 23 to the upper surface of the outer peripheral wall 10 of the main body case 1A. As shown in FIGS. 2 and 3, the connecting plastic 23 of the lid case 1B is provided with an outer peripheral wall 27b protruding toward the main case 1A on the outer peripheral edge facing the outer peripheral wall 10 of the main case 1A. The outer peripheral wall 27b of the connecting plastic 23 is fixed to the first outer wall 11A and the second outer wall 11B provided at both ends of the main body case 1A, and further fixed to the opposing wall 12. As shown in FIG.

The case 1 shown in FIGS. 5 to 9 includes connecting

projections

15 and 17 and connecting

recesses

16 and 18 that are fitted to each other in order to connect the lid case 1B and the main body case 1A while accurately positioning them. there is As described above, the main body case 1A is provided with the connecting protrusion 15 that protrudes from the upper surface of the second outer wall 11B and penetrates through the fixed portion 6B of the movable contact metal plate 6 for positioning. The lid case 1B is provided with a connecting concave portion 16 for guiding the connecting convex portion 15 at a position facing the connecting convex portion 15 at the end portion of the main body case 1A on the side of the second outer wall 11B. Furthermore, the lid case 1B shown in FIGS. 2 and 3 has connecting protrusions 17 projecting from the lower surface of the outer peripheral wall 27b toward the main body case 1A on both sides of the end portion of the main body case 1A on the side of the first outer wall 11A. are provided. As shown in FIGS. 2 and 3, the main body case 1A has connecting recesses 18 for guiding the connecting protrusions 17 on the upper surface of the outer peripheral wall 10 facing the connecting protrusions 17 .

In the case 1 described above, at the end of the main body case 1A on the side of the first outer wall 11A, the connection protrusions 17 on both sides of the lid case 1B are guided by the connection recesses 18 of the main body case 1A, 2, a connecting projection 15 penetrating through the fixed portion 6B of the movable contact metal plate 6 is guided by a connecting recess 16 of the lid case 1B, so that the lid case 1B can be accurately positioned with respect to the main body case 1A. connected to

The lid case 1B and the main body case 1A, which are connected in fixed positions via the connecting

protrusions

15, 17 and the connecting

recesses

16, 18, are ultrasonically welded to fix the connecting plastic 23 to the main body case 1A. The lid case 1B shown in FIGS. 2 to 9 is located on the lower surface of the outer peripheral wall 27b of the connecting plastic 23 and on the surface facing the outer peripheral wall 10 of the main body case 1A, and is melted by ultrasonic vibration. Article 28 is provided. The illustrated lid case 1B is provided with a melting protrusion 28 protruding along the lower surface of the outer peripheral wall 27b. The cover case 1B has a melting ridge 28 having a substantially U-shape when viewed from the bottom on the outer peripheral edge portion of the movable contact metal plate 6 except for the portion facing the fixed portion 6B. The cover case 1B is connected to the main body case 1A at a fixed position via the

connection protrusions

15 and 17 and the connection recesses 16 and 18, and the outer peripheral portion is ultrasonically vibrated to melt the protrusions 28. It is melted by frictional heat and welded to the outer peripheral wall 10 of the main body case 1A. Further, in the ultrasonically vibrated lid case 1B and main body case 13, the contact portions of the connecting

projections

15, 17 and the connecting

recesses

16, 18 connected to each other are also melted by frictional heat and welded to each other. However, the case 1 can also be fixed by bonding the connecting plastic of the lid case 1 and the main body case 1, or by connecting them with a fitting structure or locking structure.

Furthermore, the breaker 100 of FIGS. 2 and 3 has a deformation limiting projection 26 on the lid case 1B. The deformation limiting convex portion 26 is provided in order to limit the amount of deformation of the arm portion 6A when the bimetal 8 is pushed by the bimetal 8 in the OFF state in which the bimetal 8 is thermally deformed and the movable contact 7 is separated from the fixed contact 5. , ie, the movable contact 7 side, and protrudes toward the arm portion 6A. The breaker 100 presses the distal end portion of the arm portion 6A downward, that is, toward the fixed contact 5 side with the deformation limiting protrusion 26, and can limit the deformation amount of the arm portion 6A pushed up by the inverted bimetal 8. For this reason, the breaker 100 having this structure prevents the reversed bimetal 8 from pushing up the arm portion 6A beyond the elastic limit and lowering the spring property. It has the advantage of being able to keep the contact resistance small by pressing with a contact pressure of .

The movable contact metal plate 6 has the fixed portion 6B fixed to the second outer wall 11B of the main body case 1A and the arm portion 6A arranged in the storage portion 20. The breaker 100 shown in FIGS. 4 to 9 has the fixed portion 6B of the movable contact metal plate 6 fixed to the upper end surface of the second outer wall 11B. As shown in FIGS. 2 and 3, the main body case 1A is provided with a step recess 21 on the upper end surface of the second outer wall 11B, which is one step lower than the upper surface of the outer peripheral wall 10. 6 is fitted with a fixed portion 6B and arranged at a fixed position. The main body case 1A shown in FIGS. 6 and 7 is provided with a connecting projection 15 that protrudes from the central portion of the step recess 21 and penetrates the fixed portion 6B of the movable contact metal plate 6. As shown in FIG. A fixed portion 6B of the movable contact metal plate 6 is provided with a through hole 6F through which the connecting convex portion 15 is passed. The connecting projection 15 shown in the figure has an oval horizontal cross-sectional shape so that the fixing portion 6B of the movable contact metal plate 6 can be arranged in the stepped recess 21 in an accurate posture. 2 and 3, positioning ribs 22 for positioning both sides of the movable contact metal plate 6 are formed at the upper end of the second outer wall 11B. The second outer wall 11B shown in FIG. forming The movable contact metal plate 6 is provided with positioning recesses 6G for guiding the positioning ribs 22 on both sides of the fixed portion 6B. In the movable contact metal plate 6, the connecting projections 15 are inserted into the through holes 6F opened in the fixed portion 6B, and the positioning ribs 22 are guided by the positioning recesses 6G provided on both sides of the fixed portion 6B. It is arranged at a fixed position of the step recess 21 of the second outer wall 11B. The movable contact metal plate 6 with the fixed portion 6B arranged in the stepped recess 21 is fixed to the second outer wall 11B by bonding, or sandwiched between the cover case 1B fixed to the main body case 1A, that is, the second The bottom surface of the step recess 21 of the outer wall 11B and the facing surface of the lid case 1B are sandwiched from both upper and lower sides, and fixed to the fixed position of the case 1. As shown in FIG.

The movable contact metal plate 6 has a connection terminal 6X in an extended portion that is pulled out from the case 1 . The connecting terminal 6X shown in the figure has its rear end portion bent in a stepped shape so as to be positioned substantially on the same plane as the connecting terminal 4X of the fixed contact metal plate 4 pulled out from the opposite end face of the case 1. As shown in FIG.
(Fixed contact metal plate 4)

The fixed contact metal plate 4 is fixed to the main body case 1A by insert molding. The fixed contact metal plate 4 closes the opening of the bottom portion 13 of the storage portion 20 with the tip portion 4A, and extends the intermediate portion 4B and part of the tip portion 4A from the bottom portion 13 of the storage portion 20 to the first outer wall of the main body case 1A. It is fixed to the body case 1A by insert molding so as to be embedded in the body case 11A. The fixed contact metal plate 4 shown in FIG. 3 is provided with a stepped portion 4D so that the portion embedded in the first outer wall 11A is higher than the portion that closes the bottom of the housing portion 20, and the stepped portion 4D is provided with the main body case. It is embedded in the bottom portion 13 of 1A, the rear end side of the step portion 4D is exposed on the upper surface of the bottom portion 13, and this exposed portion serves as the fixed contact 5. As shown in FIG.

As shown in FIG. 10, the fixed contact metal plate 4 can be used as a fixed contact 5 by providing a silver plating layer in the area facing the movable contact 7 to reduce the contact resistance. The silver plating layer of fixed contact 5 is, for example, 5 μm. However, the film thickness of the silver plating layer of the fixed contact 5 can be 3 μm to 20 μm, preferably 4 μm to 10 μm. By thinning the silver plating layer of the fixed contact 5, the manufacturing cost can be reduced.

The fixed contact metal plate 4 has a connection terminal 4X that extends from the case 1 to the outside. The fixed contact metal plate 4 shown in the figure has a portion extending from the case 1 to the outside, which is linearly pulled out from an intermediate portion 4B embedded in the case 1 to form a connection terminal 4X.

The contact resistance of the micro-breaker 100, which is extremely small as a whole, increases even if the contact positions of the contacts are slightly displaced. This is because the contact pressure between the movable contact 7 and the fixed contact 5 is weak, and the movable contact 7 and the fixed contact 5 are in contact with each other in an extremely narrow area in the ON state. Furthermore, the surfaces of the movable contact 7 and the fixed contact 5 of the breaker 100 are not always kept in a uniform state over the entire surfaces, and the surfaces at the non-contact position where they are not in constant contact are Contact resistance increases due to thin oxide films and the like.

The micro-breaker 100 employs an activation process for the purpose of reducing the contact resistance of the contacts. The contact is activated by ultrasonic vibration while energized in the ON state. The contact activated by this method reduces the contact resistance only when the movable contact 7 and the fixed contact 5 are in contact with each other at a specific position. .
(Contact activation processing)

The micro-breaker 100 with weak contact pressure can reduce the contact resistance by activating the contacts in the assembled state. The contact activation process is performed by ultrasonically vibrating the contacts of the assembled breaker 100 while energizing them. The breaker 100 causes the movable contact 7 and the fixed contact 5 to collide with each other and ultrasonically vibrate in the separating direction. That is, the breaker 100 ultrasonically vibrates the fixed contact 5 and the movable contact 7 so that the fixed contact 5 and the movable contact 7 approach and collide with each other and relatively move away from each other. The current of the contact under ultrasonic vibration is preferably 0.1 A to 100 A under resistive load. By increasing the contact current during ultrasonic vibration, the contacts are activated more effectively. A load with an inductance that connects a coil in series with a resistor increases the current energy stored in the coil when the current is interrupted, so the contact current can be reduced to activate the contact. This is because the current energy stored in the coil is consumed, so that the contact discharge current becomes large. Therefore, the contact current is set to an optimum value considering the resistive load and the inductive load. Further, the breaker 100 has a characteristic that when the current of the contact is increased, it generates heat by Joule heat and switches itself to the off state. In order to activate the contacts with ultrasonic vibration, it is necessary to keep the movable contact 7 in an ON state in contact with the fixed contact 5 . Therefore, in the method of applying a large current to the contact to apply ultrasonic vibration, the time for ultrasonic vibration is shortened, and ultrasonic vibration is performed while the contact is in the ON state. Therefore, the method of applying a large current to the contact and subjecting it to ultrasonic vibration shortens the ultrasonic vibration time.

The time for ultrasonically vibrating the contact in the energized state shall be 0.1 milliseconds to 1 second. The time of ultrasonic vibration can be increased to activate the contacts more effectively, but if it is too long, the silver plating layer of the contacts will be damaged. set. In addition, contact activation by ultrasonic vibration is also affected by contact current, type of load, and amplitude of ultrasonic vibration. If the contact current and amplitude are large, the contact is activated more effectively in a short time. . Therefore, the ultrasonic vibration time is set to an optimum value within the above-described range, taking into consideration the contact current and the amplitude of the ultrasonic vibration.

Also, the frequency for ultrasonically vibrating the contact is 20 KHz to 6 GHz, preferably 20 KHz to 1 GHz. By increasing the frequency of the ultrasonic vibration, it is possible to increase the number of collisions and separations between the movable contact 7 and the fixed contact 5 per unit time. However, if the frequency of the ultrasonic vibration is too high, the distance between the movable contact 7 and the fixed contact 5 will become narrower, and the activation due to discharge will decrease. Therefore, the frequency of the ultrasonic vibration is set to an optimum value in consideration of the thickness and length of the arm portion 6A and the resonance frequency of the arm portion 6A.

Furthermore, the amplitude for ultrasonically vibrating the breaker 100 is set to 0.01 μm to 100 μm. By increasing the amplitude of the ultrasonic vibration, the energy of the motion of the movable contact 7 colliding with the fixed contact 5 can be increased, and the distance between the movable contact 7 and the fixed contact 5 can be increased. The amplitude with which the breaker 100 is ultrasonically vibrated affects the gap separating the movable contact 7 from the fixed contact 5 . However, the interval at which the movable contact 7 is separated from the fixed contact 5 can be made larger than the amplitude of ultrasonic vibration of the breaker 100 by causing the arm portion 6A to resonate. Therefore, the movable contact 7 is fixed by setting the frequency for ultrasonically vibrating the breaker 100 to the resonance frequency of the arm portion 6A, the vicinity thereof, an integral multiple of the resonance frequency, or an integer fraction of the resonance frequency. A sufficient distance from the contact 5 allows effective activation.

In order to increase the amplitude of the ultrasonic vibration of the breaker 100, it is necessary to increase the output of the ultrasonic vibrator or ultrasonic horn that contacts the breaker 100 and ultrasonically vibrates it. If a high-output ultrasonic vibrator or ultrasonic horn is pressed against the case 1 of the breaker 100 and ultrasonically vibrated, there is an adverse effect such as deformation of the contact point with the ultrasonic vibrator due to heat generated by the ultrasonic vibration. , the amplitude for ultrasonically vibrating the breaker 100 is set to a small value within a range where the contact can be activated.
(Heater 9)

The heater 9 generates heat when energized and heats the bimetal 8 . The heater 9 is a thick heater having an elliptical or rectangular facing surface, and electrodes are provided on the upper surface and the lower surface. For the heater, for example, all heaters that can be energized to heat the bimetal 8 can be used. A heater 9 having electrodes on its upper and lower surfaces has its lower surface in contact with the fixed contact metal plate 4 and its upper surface in contact with the arm portion 6A via the bimetal 8. As shown in FIG. In this heater 9, when the movable contact 7 of the arm portion 6A is in contact with the fixed contact 5, the arm portion 6A and the bimetal 8 are not in contact with each other, and electricity is not supplied, and the movable contact 7 of the arm portion 6A is fixed. In the OFF state away from the contact 5 , electricity is generated through the bimetal 8 in contact with the arm portion 6 A and the fixed contact metal plate 4 to heat the bimetal 8 . A heated bimetal 8 holds the movable contact 7 in an off state away from the fixed contact 5 . Since this non-energized type breaker 100 keeps the movable contact 7 in the OFF state when switched to the OFF state, it can be safely used in a battery pack. This is because the battery pack is used in an abnormal state and the temperature becomes higher than the set temperature, and after the non-energized type breaker 100 is switched off, the battery in the battery pack continues to energize the heater 9 and the bimetal 8 heats up. Therefore, the circuit breaker 100 does not return to the ON state, and the current interrupting state can be maintained until the battery is discharged.

However, the breaker 100 is not necessarily limited to a structure with a built-in heater. In the breaker 100 without a built-in heater, when the bimetal 8 becomes higher than the set temperature and deforms, deforming the arm portion 6A and switching the contact to the OFF state, the bimetal 8 is heated and the breaker 100 is kept in the OFF state. When the temperature of the bimetal 8 drops to a predetermined temperature, the bimetal 8 and the arm portion 6A are restored to switch the breaker 100 to the ON state.
[Embodiment 2]

In the breaker described above, the fixed arm portion 6a is provided with the protrusion 6e as one form of the contact portion. However, the present invention is not limited to the form in which the contact portion is provided with such protrusions, and may be configured without protrusions. That is, the contact portion does not necessarily have to be a protrusion projecting from the fixed arm portion, and for example, the flat surface of the fixed arm portion can be used as the contact portion. Such an example is shown in FIGS. 11 and 12 as a breaker according to the second embodiment. In these figures, the same reference numerals are assigned to the same members as in the first embodiment, and detailed description thereof will be omitted as appropriate. In the breaker shown in these figures, the fixed arm portion 6a' has a flat surface 6e' as the contact portion instead of the protrusion. The inventors have confirmed that similar characteristics can be obtained with this configuration as well.
(Built in the battery pack of the breaker 100)

The breaker 100 described above is incorporated in a battery pack, for example, and cuts off the current when the battery or the ambient temperature becomes high, or when the battery pack is used in an abnormal state. In the breaker 100 built in the battery pack, a pair of

connection terminals

6X and 4X drawn out from both ends of the case 1 are connected directly or via connection leads to battery terminals or a circuit board. The

connection terminals

6X and 4X are connected to connection leads and battery terminals by laser welding, for example. In addition, the breaker 100 is arranged in a state where the case 1 is close to the surface of the battery or the circuit board, preferably in a thermally coupled state, and when the temperature of the battery or the ambient temperature rises, the built-in bimetal 8 is reversed to cut off the current. .
(fixing the breaker to the circuit board)

The breaker described above can also be fixed by soldering to a circuit board or lead plate. For a breaker that is directly soldered to a circuit board, the connection terminals of the movable contact metal plate and the connection terminals of the fixed contact metal plate, which are pulled out from the case, should be positioned on the bottom surface of the case, that is, on the same plane as the bottom surface of the main body case. fold into This breaker can be fixed by soldering connection terminals drawn out from both ends of the case to the circuit board. This breaker can be soldered to a circuit board by placing the bottom of the case, that is, the bottom of the body case, on the circuit board.
[Example 1]

The bimetal 8 is a rectangle of 2.2 mm × 2.4 mm, the thickness (t) is 0.05 mm, the inversion temperature is 85 ° C., and the return temperature is 30 ° C.,
A Cu—Zr alloy is used for the movable contact metal plate 6, and the thickness (d) of the movable contact metal plate 6 is 0.15 mm.
The length (L1) of the arm portion 6A is 4.5 mm, the maximum width (W1) is 2.1 mm,
The length (L2) of the fixed arm portion 6a is 1.8 mm, the width (W2) is 0.5 mm,
The gap (W3) of the slit 6c is 0.2 mm,
Further, a movable contact 7 is provided at the tip of the arm portion 6A, the movable contact 7 is made of a seam material (Ag-Ni) with a thickness of 120 μm, the fixed contact 5 is made of a 4.5 μm Ag plating layer, and the case 1 is 5.8 mm long, 2.8 mm wide, and 1.15 mm high. The error of the return temperature of the breaker 100 is extremely small, 1/5 or less, and the contact can be returned to the ON state with extremely small variation in the return temperature.
Furthermore, this breaker 100 uses a metal plate with a thickness of 0.15 mm for the movable contact metal plate 6, and can reduce the maximum current capacity to 13 A and the on-resistance to 1.5 mΩ at an ambient temperature of 60°C.

The Cu—Zr alloy used in Example 1 had the following composition.
Cu: 99.9 wt%
Zr…………0.1wt%
[Example 2]

The breaker 100 having the same structure as that of the first embodiment except that the stopper protrusions 25 are provided on the closing plate 27a and provided with the stopper protrusions 25 on the closing plate 27a has a return temperature error of 1/6 or less of that of the conventional breaker 100. and more accurate.
[Comparative Example 1]

Example 1 was repeated except that the movable contact metal plate 6 with a thickness of 0.1 mm was used without separating the arm portion 6A of the movable contact metal plate 6 into the fixed arm portion 6a and the deformable arm portion 6b. A breaker 100 of Comparative Example 1 was manufactured. This breaker 100 has a return temperature error of 10° C. to 15° C., a maximum current capacity of 9 A at 60° C., and an ON resistance of 3 mΩ.

From the above, the breaker 100 of the first and second embodiments has the movable contact metal plate 6 separated into the fixed arm portion 6a and the deformed arm portion 6b, and the fixed arm portion 6a is provided with the protrusion 6e. The error of the return temperature can be significantly reduced, and the maximum current capacity of the breaker 100 can be increased from 9A of the breaker 100 of the comparative example to 13A and 4A. In the breakers 100 of the first and second embodiments, the movable contact metal plate 6 is made thicker, the arm portion 6A is used as the fixed arm portion 6a and the deformed arm portion 6b, the fixed arm portion 6a is provided with the protrusion 6e, and the reversible bimetal 8 is deformed. Since only the arm portion 6b is deformed, the same bimetal 8 as in the comparative example can be used to accurately set the return temperature, increase the maximum current capacity, and reduce the on-resistance.

The present invention can be suitably employed as a breaker that can control with high accuracy the return temperature at which current is cut off when the ambient temperature rises and then when the ambient temperature drops and the current is turned on.

DESCRIPTION OF SYMBOLS 100... Breaker 1... Case 1A... Main body case 1B... Lid case 4... Fixed contact metal plate 4A... Tip part 4B... Intermediate part 4D... Stepped part 4X... Connection terminal 5... Fixed contact 6... Movable contact metal plate 6A...

Arm part

6a, 6a' -- fixed arm portion 6b -- deformable arm portion 6c -- slit 6d -- convex portion 6e -- projection 6e' -- flat surface 6f -- root portion 6g -- deformable region 6B -- fixed portion 6F -- through hole 6G -- positioning recess 6X Connection terminal 7 Movable contact 8 Bimetal 9 Heater 10 Outer wall 11 Outer wall 11A First outer wall 11B Second outer wall 12 Opposite wall 13 Bottom 15 Connecting protrusion 16 Connecting recess 17 Connecting convex portion 18 Connecting concave portion 20 Receiving portion 21 Step concave portion 22 Positioning rib 23 Connecting plastic 24 Laminated metal plate 25 Stopper convex portion 26 Deformation limiting convex portion 27a Closing plate 27b Peripheral wall 28 Molten ridge 101 Movable contact metal plate 105 Fixed contact 106 Fixed contact metal plate 107 Movable contact 108 Bimetal

Claims

a fixed contact metal plate having a fixed contact;
a movable contact metal plate having a movable contact arranged at a position facing the fixed contact;
a bimetal arranged at a position facing the movable contact metal plate for switching the movable contact from on to off by reversing at a set temperature;
The fixed contact metal plate, the movable contact metal plate, and a case formed by arranging the bimetal at a fixed position,
The movable contact metal plate is
an arm portion that is pushed by the reversing bimetal to separate the movable contact from the fixed contact;
and a fixing portion fixed to the case,
The arm portion
a deformable arm portion elastically deformed by being pushed by the reversing bimetal to separate the movable contact from the fixed contact;
a fixed arm section separated from the deformable arm section through a slit and having a root section connected to the fixed section;
The fixed arm portion has a contact portion that contacts the bimetal,
A breaker in which the contact portion is pushed by the reversing bimetal to switch the movable contact from on to off.
A breaker according to claim 1,
In the breaker, the movable contact metal plate has a convex portion projecting toward the bimetal between the contact portion and the movable contact on the deformed arm portion of the arm portion.
The breaker according to claim 1 or 2,
A breaker in which the arm portion has the fixed arm portion extending in the longitudinal direction at the center portion in the width direction.
A breaker according to any one of claims 1 to 3,
A breaker in which the length of the fixed arm portion is 10% to 90% of the arm portion.
A breaker according to any one of claims 1 to 4,
A breaker in which the case has a stopper convex portion on an inner surface that limits deformation of the fixed arm portion due to the pressing force of the bimetal and does not limit deformation of the deformable arm portion.
A breaker according to claim 5,
the case is
a body case to which the fixed contact metal plate is fixed;
a lid case comprising a closing plate that closes the opening of the main body case;
A breaker in which the closing plate has the stopper projection on the inner surface thereof.
A breaker according to any one of claims 1 to 6,
A breaker in which a heater for heating the bimetal is incorporated in the case.
A breaker according to claim 7,
A breaker in which the heater is a PTC and is arranged between the bimetal and the case.
A breaker according to any one of claims 1 to 8,
The breaker, wherein the contact portion is a projection projecting from the fixed arm portion toward the bimetal.