JP7629181B2 - breaker - Google Patents

Description

The present invention relates to a breaker that cuts off current when the temperature exceeds a preset value.

Small breakers have been developed that can be built into devices such as battery packs and motors as protective elements. These breakers are used, for example, in lithium-ion battery packs, and cut off the current when the battery temperature becomes abnormally high. The temperature of motors can also become abnormally high, and in this state the breaker can cut off the current to safely protect the motor.

A small breaker for the above purpose has been developed (Patent Document 1).
A conventional breaker is shown in Fig. 17. In this breaker, a bimetal 108 that reverses at a set temperature is disposed between a fixed contact metal plate 104 and an elastic arm 106A of a movable contact metal plate 106. The bimetal 108 is in a non-reversed shape (see Fig. 17(a)) when the temperature is lower than the set temperature, and reverses and deforms to an inverted shape (see Fig. 17(b)) when the temperature exceeds the set temperature. The non-reversed bimetal 108 brings the movable contact 107 into contact with the fixed contact 105 without pressing the movable contact metal plate 106, turning the breaker on. When the temperature exceeds the set temperature, the bimetal 108 deforms to an inverted shape, and the movable contact 107 is separated from the fixed contact 105, switching the breaker to the off state.

JP 2011-198645 A

The breaker has a bimetal placed between a movable contact metal plate and a fixed contact metal plate, and an elastic arm on the movable contact metal plate. The movable contact is fixed to the tip of the elastic arm. When the bimetal is in a non-reversed shape, the elastic arm elastically presses the movable contact against the fixed contact to hold the contact in the ON state. When the bimetal reverses due to exceeding a set temperature, the reversed bimetal presses the elastic arm, separating the movable contact from the fixed contact and switching to the OFF state. The movable contact is pressed toward the fixed contact by the elastic force of the elastic arm, and the bimetal reverses and is separated from the fixed contact. In other words, the movable contact is pressed in opposite directions by the elastic force of the elastic arm and the reversed bimetal, switching the contact between the ON state and the OFF state. When the contact is in the ON state, the bimetal is in a non-reversed shape and does not press the elastic arm. Therefore, when the contact is in the ON state, the movable contact is pressed against the fixed contact by the elastic force of the elastic arm. In contrast, in the OFF state, the elastic arm biases the movable contact toward the fixed contact with its elastic force, and the bimetal is pushed by the inverted bimetal to separate the movable contact from the fixed contact. The bimetal is in a non-inverted shape when the temperature is lower than the set temperature, and inverts when the temperature exceeds the set temperature, but at the time of transformation from the non-inverted shape to the inverted shape, the elastic force of the elastic arm acts in a direction that suppresses the transformation of the bimetal into the inverted shape. The moment the contact is switched from the ON state to the OFF state is determined by the timing at which the deformation force that tries to reverse the bimetal becomes stronger than the elastic force of the elastic arm. As the bimetal is pressed by the elastic force of the elastic arm, a reversal force that overcomes this elastic force is generated, separating the movable contact from the fixed contact. The reversal force of the bimetal increases as the temperature rises from the set temperature, so the bimetal reverses at the temperature at which the reversal force exceeds the elastic force of the elastic arm, switching to the OFF state.

The bimetal overcomes the elastic force of the elastic arm, reverses, and switches the breaker to the OFF state, so any misalignment between the bimetal and the elastic arm relative to each other causes a large error in the reversal temperature at which the bimetal reverses. If the bimetal reverses while pressing against the tip of the elastic arm, the reversal temperature will be low, and conversely, if it reverses by moving away from the tip of the elastic arm and pressing against the base part that is fixed to the exterior case, the reversal temperature will be high. This is because the elastic force with which the elastic arm presses against the bimetal becomes weaker as it approaches the tip, making it easier for the bimetal to reverse. Furthermore, for the same reason, any misalignment between the bimetal and the elastic arm relative to each other also causes a large error in the return temperature at which a reversed bimetal returns to its original position.

The breaker has a movable contact metal plate fixed to an exterior case, and the bimetal is placed in a storage section of the exterior case. The storage section is placed so that the bimetal can be deformed between a non-reversed shape and a reversed shape, so the inner shape of the storage section is made slightly larger than the outer shape of the bimetal to provide a clearance between the storage section and the bimetal. The clearance causes the bimetal to shift out of position. By narrowing the clearance, the bimetal can be shifted out of position and the temperature error at which the bimetal reverses can be reduced, but a storage section with a narrow clearance makes it difficult to set the bimetal quickly and stably during the assembly process, and also causes the bimetal to be prevented from reversing reliably. This is because narrowing the clearance causes the outer edge of the bimetal to collide with the inner surface of the storage section. For this reason, reducing the bimetal's position shift and reducing the temperature and error at which it reverses and returns, and smoothly setting the bimetal in the storage section during the assembly process and reliably being able to reverse the bimetal in the storage section are mutually contradictory characteristics, and it is extremely difficult to satisfy both at the same time.

The present invention was developed with the aim of solving the above-mentioned shortcomings. An important object of the present invention is to provide a breaker that can specify the reversal temperature and return temperature of the bimetal with high accuracy, while smoothly setting the bimetal in its fixed position during the assembly process.

The breaker of the present invention comprises an outer case, a fixed contact metal plate having a fixed contact fixed to the outer case, a movable contact metal plate having a movable contact at a position opposite the fixed contact of the fixed contact metal plate and having a portion fixed to the outer case so that the movable contact can be moved, and a bimetal disposed between the movable contact metal plate and the fixed contact metal plate, which reverses from a non-reversed shape to an inverted shape when the temperature exceeds a set temperature, switching the movable contact metal plate from on to off. The outer case has a storage section in which the bimetal is arranged so that it can be freely deformed between a non-inverted shape and an inverted shape, and the storage section has a positioning guide on the surface facing the outer edge of the bimetal to position the bimetal in a fixed position, and the positioning guide has an inclined guide that is inclined in a direction in which the bimetal deforms from the non-inverted shape to the inverted shape and the gap with the outer edge increases , and the inclined guide is provided on the surface facing the outer edge of the bimetal, and the movable contact metal plate has an elastic arm that is pressed against the inverting bimetal and deforms to switch the contact from on to off, and the elastic arm has a protrusion that protrudes toward the surface of the bimetal at a position facing the end of the bimetal, and the end of the inverted shaped bimetal presses the protrusion to deform the elastic arm and switch from on to off.

The above breaker has the feature of being able to accurately determine the reversal temperature and return temperature of the bimetal, while reliably interrupting the current at the set temperature. This is because the exterior case of the above breaker is the inner surface of the storage section in which the bimetal is arranged so that it can be freely deformed between a non-reversed shape and an inverted shape, and is provided with a positioning guide on the surface facing the outer edge of the bimetal to place the bimetal in a fixed position, and this positioning guide has an inclined guide that is inclined in a direction that increases the gap with the outer edge of the bimetal that deforms from a non-reversed shape to an inverted shape. Furthermore, the above breaker has a positioning guide on the opposing surface of the storage section that faces the outer edge of the bimetal, so that in the assembly process, the bimetal can be set along the inclined guide of this positioning guide, allowing it to be smoothly and accurately placed in the fixed position of the storage section.

1 is a perspective view of a breaker according to an embodiment of the present invention; FIG. 2 is a partially enlarged vertical cross-sectional view showing the breaker shown in FIG. 1 in an on state. FIG. 2 is a partially enlarged vertical cross-sectional view showing the breaker shown in FIG. 1 in an OFF state. 4 is a partially enlarged cross-sectional view of the breaker shown in FIG. 2 taken along line IV-IV. FIG. 3 is a partially enlarged exploded sectional view of the breaker shown in FIG. 2 . FIG. 2 is a plan view of the breaker shown in FIG. 1 with a cover case removed. FIG. 7 is an exploded perspective view of the breaker shown in FIG. 6 . FIG. 4 is an enlarged perspective view of a main part of a storage section of a main body case. FIG. 11 is an enlarged perspective view of a main portion showing another example of a positioning guide. FIG. 11 is an exploded perspective view showing another example of the positioning guide. 11 is an enlarged sectional perspective view of a main portion of the positioning guide shown in FIG. 10. FIG. 11 is an enlarged cross-sectional view showing a main portion of another example of an inclined guide. 13 is a plan view showing another example of a main body case provided with a positioning guide. FIG. FIG. 3 is an enlarged cross-sectional view showing a contact structure of the breaker shown in FIG. 2 . 3 is a cross-sectional view showing an example of mounting the breaker shown in FIG. 2 on a circuit board. FIG. 11 is an enlarged cross-sectional view showing an inner structure of a housing portion of a breaker according to a comparative example. FIG. FIG. 1 is a cross-sectional view showing an example of a conventional breaker.

The present invention will be described in detail below with reference to the drawings. In the following description, terms indicating specific directions or positions (e.g., "upper", "lower", and other terms including these terms) are used as necessary, but the use of these terms is for the purpose of facilitating understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. In addition, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or members.
Furthermore, the embodiments shown below are specific examples of the technical ideas of the present invention, and do not limit the present invention to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative and not to limit the scope of the present invention. Furthermore, the contents described in one embodiment or example can be applied to other embodiments or examples. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated to clarify the explanation.

A breaker according to one embodiment of the present invention is a breaker comprising an outer case, a fixed contact metal plate having a fixed contact fixed to the outer case, a movable contact metal plate having a movable contact at a position opposite to the fixed contact of the fixed contact metal plate and a part of which is fixed to the outer case so that the movable contact can be moved, and a bimetal disposed between the movable contact metal plate and the fixed contact metal plate, which reverses from a non-reversed shape to a reversed shape when the temperature exceeds a set temperature, thereby switching the movable contact metal plate from on to off, the outer case having a storage section in which the bimetal is arranged so as to be freely deformed between a non-reversed shape and a reversed shape, the storage section being disposed on an outer periphery of the bimetal. The opposing surface has a positioning guide that positions the bimetal in a fixed position, and the positioning guide has an inclined guide that is inclined in the direction in which the bimetal deforms from a non-inverted shape to an inverted shape and the gap with the outer peripheral edge becomes larger , and the inclined guide is provided on the opposing surface to the outer peripheral edge of the bimetal, and the movable contact metal plate has an elastic arm that is pressed by the inverting bimetal and deforms to switch the contact from on to off, and the elastic arm has a protrusion that protrudes toward the surface of the bimetal at a position opposing the end of the bimetal, and the end of the inverted shaped bimetal presses the protrusion to deform the elastic arm and switch it from on to off.

In another embodiment of the breaker of the present invention, the inclined guide is provided in an area including the opening of the storage section.

In another embodiment of the breaker of the present invention, the positioning guide is a guide rib that protrudes inside the storage section, and the guide rib guides the surface facing the outer periphery of the bimetal at an angle.

In another embodiment of the breaker of the present invention, the inclined guide is an inclined plane.

In another embodiment of the breaker of the present invention, the bimetal and the storage section are rectangular in plan view, and the positioning guides are positioned at support positions on two opposing sides of the outer periphery of the rectangular bimetal.

In another embodiment of the breaker of the present invention, the bimetal and the storage section are rectangular in plan view, and the positioning guides are arranged at support positions on the four sides of the outer periphery of the rectangular bimetal.

In another embodiment of the breaker of the present invention, a positioning guide is provided around the entire circumference facing the outer edge of the bimetal, and an inclined guide is provided on the inner surface of the entire circumference of the positioning guide.

In another embodiment of the breaker of the present invention, the bimetal and the storage section are rectangular in plan view, the storage section has a corner wall section that is located outside the protruding corner section of the outer periphery of the bimetal, and a positioning guide is located on the corner wall section.

In another embodiment of the breaker of the present invention, positioning guides are placed at the support positions of two adjacent sides of the outer periphery of the bimetal in the corner wall.

In another embodiment of the breaker of the present invention, the positioning guide arranged on the corner wall is a guide rib that protrudes inside the storage section, and the surface of the guide rib facing the outer periphery of the bimetal is an inclined guide.

In another embodiment of the breaker of the present invention, the minimum gap (t) between the outer edge of the bimetal and the positioning guide is 100 μm or less when the bimetal is in a non-inverted shape.

In another embodiment of the breaker of the present invention, the inclination angle (α) of the inclined guide relative to the vertical plane is greater than 3 degrees.
In another embodiment of the breaker of the present invention, the outer case comprises a main case having a bimetal storage section and a lid case closing the upper surface of the bimetal storage section of the main case, the lid case having a deformation limiting convex portion protruding toward the surface of the elastic arm, and the deformation limiting convex portion can limit the amount of deformation of the elastic arm when pressed by the inverted shaped bimetal.

(Embodiment 1)
The breaker is built into the battery pack and breaks the current by deforming the built-in bimetal when the battery or ambient temperature becomes high or when the battery pack is used under abnormal conditions. However, the present invention does not specify the breaker and the application of the breaker, and can be used for all applications where the breaker detects a temperature rise and breaks the current, such as in a motor.

(Breaker 100)
The breaker 100 of Fig. 1 to Fig. 6 changes the bimetal 8 from a non-reversed shape to a reversed shape at the ambient temperature, and the reversing bimetal 8 changes the elastic arm 6A of the movable contact metal plate 6, so that the breaker 100 is switched from the on state to the off state. Furthermore, the breaker 100 of the figure has a built-in heater 9 for heating the bimetal 8. The breaker 100 with the built-in heater 9 can maintain the state in which the bimetal 8 is heated by the heater 9 and turned off to cut off the current. This is because the heater 9 is energized in the off state, and the energized heater 9 heats the bimetal 8 and can maintain the off state. This breaker 100 is built into a battery pack, and can further improve the safety of the battery pack. After the battery pack reaches an abnormal temperature and the breaker 100 cuts off the current, the battery can energize the heater 9 and maintain the off state, so that the breaker 100 can be maintained in the off state and the current flowing to the outside can be maintained in the cut off state as long as the battery can be discharged. When the battery is completely discharged, electricity cannot be passed through the heater 9 and the heater 9 is no longer able to heat the bimetal 8, so even if the on state is restored, the battery cannot be discharged in this state, ensuring safety. Furthermore, the breaker 100 incorporating the heater 9 can detect a battery abnormality and pass electricity through the heater 9, causing the heater 9 to heat the bimetal 8 and cut off the battery current. A battery pack incorporating a breaker connects the breaker in series with the unit cell, and the breaker cuts off the battery current.

The breaker 100 shown in the figure includes a fixed contact metal plate 4 having a fixed contact 5, a movable contact metal plate 6 having a movable contact 7 arranged at a position opposite the fixed contact 5, a bimetal 8 arranged between the fixed contact metal plate 4 and the movable contact metal plate 6, and an exterior case 1 fixing the fixed contact metal plate 4 and the movable contact metal plate 6. When the ambient temperature of this breaker 100 is lower than the set temperature, as shown in FIG. 2, the non-inverted bimetal 8 does not press the elastic arm 6A of the movable contact metal plate 6, and the movable contact 7 contacts the fixed contact 5 and is held in the ON state. When the ambient temperature rises and becomes higher than the set temperature, as shown in FIG. 3, the bimetal 8 is inverted and deformed into an inverted shape, and the inverted bimetal 8 presses the elastic arm 6A of the movable contact metal plate 6, moving the movable contact 7 away from the fixed contact 5 and switching the contact to the OFF state. When the ambient temperature drops to a specified temperature, the inverted bimetal 8 deforms to a non-inverted shape and no longer presses against the elastic arm 6A of the movable contact metal plate 6, causing the movable contact 7 to come into contact with the fixed contact 5 and switch to the on state.

(Outer case 1)
The exterior case 1 is made of a plastic main case 1A and a lid case 1B, and the lid case 1B is connected to the main case 1A by ultrasonic welding or by bonding. The exterior case 1 has a fixed contact metal plate 4 and a movable contact metal plate 6 fixed in fixed positions. In the exterior case 1 shown in the figure, the fixed contact metal plate 4 is fixed to the bottom of the main case 1A by insert molding, and the movable contact metal plate 6 is fixed between the main case 1A and the lid case 1B in a sandwiched state, and the lid case 1B is fixed to the top surface. The main case 1A has a first outer wall 11A and a second outer wall 11B protruding from both ends, and a storage section 20 in which a bimetal 8 and a heater 9 are arranged in fixed positions is provided between the first outer wall 11A and the second outer wall 11B. In the exterior case 1 shown in the figure, the bottom surface of the storage section 20 provided in the main case 1A is closed by the fixed contact metal plate 4, and the top surface of the storage section 20 is closed by the connected lid case 1B.

(Main body case 1A)
The main body case 1A has a storage section 20 in which the bimetal 8 is disposed inside the outer peripheral wall 10. The outer peripheral wall 10 is made up of 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, and the storage section 20 is provided inside the opposing walls 12 and the outer wall 11. The main body case 1A surrounds the periphery of the storage section 20 with the outer peripheral wall 10, and closes the bottom and top of the outer peripheral wall 10. The bottom of the storage section 20 is closed by the bottom part 13 and the fixed contact metal plate 4 that are integrally formed with the main body case 1A, and the top is closed by the lid case 1B that is connected to the main body case 1A, making the storage section 20 a closed hollow section.

The fixed contact metal plate 4 is fixed to the main case 1A by insert molding. In Figs. 2 and 3, the fixed contact metal plate 4 is fixed to the main case 1A by insert molding so that the middle portion 4B is embedded in the first outer wall 11A. This fixed contact metal plate 4 is fixed to the main case 1A in a state where it penetrates the first outer wall 11A, and the part exposed inside the outer case 1 is provided with a fixed contact 5, and the part drawn out to the outside is the connection terminal 4X.

(Bimetal 8)
The bimetal 8 is a laminate of metals with different thermal expansion coefficients so that it deforms when heated. The bimetal 8 is disposed between the heater 9 and the elastic arm 6A of the movable contact metal plate 6, and it reverses at a set temperature to separate the movable contact 7 from the fixed contact 5 and switch the breaker 100 to the OFF state. The bimetal 8 has a shape that is curved with a central convexity, and in a state where it is not thermally deformed, i.e., in a non-reversed shape, it is held in a position where the central protrusion protrudes toward the elastic arm 6A as shown in FIG. 2. When the bimetal 8 reaches a set temperature, it reverses and deforms into an inverted shape, but in the inverted shape, it is in a position where the central protrusion protrudes toward the heater 9 as shown in FIG. 3, and has a shape that presses the elastic arm 6A at both ends. In the inverted shape shown in FIG. 3, the bimetal 8 makes contact with the heater 9 with its central protrusion, and presses the elastic arm 6A at both ends, pushing up the elastic arm 6A to separate the movable contact 7 from the fixed contact 5 and switching it to the OFF state.

(Storage section 20)
The storage section 20 is provided with a positioning guide 30 on the inner surface of the outer peripheral wall 10 for positioning the bimetal 8 at a fixed position. The bimetal 8 shown in the plan view of FIG. 6 and the perspective view of FIG. 7 has a rectangular shape in plan view, and is set inside the storage section 20, which is substantially rectangular in plan view. The bimetal 8 is positioned at a fixed position in the storage section 20 by the positioning guide 30 provided on the outside of the outer peripheral edge 8a. The bimetal 8 is placed in the storage section 20 so that it can be deformed into a non-inverted shape and an inverted shape. Therefore, the positioning guide 30 of the bimetal 8 is provided with a clearance between the outer peripheral edge 8a of the bimetal 8 and the positioning guide 30. The positioning guide 30 reduces the clearance, reduces the positional deviation of the bimetal 8, and reduces the temperature error that causes inversion. However, as mentioned above, reducing the gap between the outer peripheral edge 8a of the bimetal 8 and the positioning guide 30, i.e., the clearance, makes it difficult to quickly set the bimetal 8 in the storage section 20 and also hinders the bimetal 8 from reversing reliably and stably inside the storage section 20, so it is difficult to reduce the clearance.

The positioning guide 30 in Figs. 6 to 8 is provided with an inclined guide 31 so that the bimetal 8 can be reversed and returned reliably and stably by reducing the positional deviation of the bimetal 8 and reducing the temperature error when it is reversed and assembled efficiently. As shown in Figs. 2 and 3, the inclined guide 31 is provided on the surface facing the outer periphery 8a of the bimetal 8, and is inclined in the direction in which the bimetal 8 reverses and the gap with the outer periphery 8a gradually increases. When the bimetal 8 is placed in the storage section 20 by the inclined guide 31 of the positioning guide 30, the clearance with the outer periphery 8a is reduced in the non-reversed shape, so that the bimetal 8 is placed in the exact position of the storage section 20. Furthermore, in the assembly process in which the bimetal 8 is set in the storage section 20, the opening area of the storage section 20 is increased, so that the bimetal 8 can be placed in the storage section 20 efficiently. Furthermore, when the bimetal 8 reverses, it can be reliably reversed without colliding with the positioning guide 30 and the breaker can be switched to the OFF state.

The breaker 100 shown in the plan view of FIG. 6 has a bimetal 8 and a storage section 20 in a rectangular shape when viewed from above, and positioning guides 30 are arranged at the support positions of the four opposing sides of the outer periphery 8a of the rectangular bimetal 8. The storage section 20 in this figure has two sets of positioning guides 30 arranged on one side of the outer periphery 8a of the rectangular bimetal 8, with each positioning guide 30 arranged at both ends of each side. In this structure, a pair of positioning guides 30 is arranged on the recessed corner wall portion 20A of the storage section 20, with the positioning guides 30 arranged at both ends of each side. The recessed corner wall portion 20A is arranged outside the protruding corner portion 8A of the outer periphery 8a of the bimetal 8, so the storage section 20, which has a pair of positioning guides 30 arranged on the recessed corner wall portion 20A at the four corners, holds the rectangular bimetal 8 in a fixed position at the four corners to prevent it from shifting out of position.

The positioning guide 30 shown in the perspective views of Figures 7 to 9 is a guide rib 32 that protrudes inward from the storage section 20, and the surface of this guide rib 32 facing the outer periphery 8a of the bimetal 8 shown in Figure 6 serves as a planar inclined guide 31 to position the bimetal 8 in a fixed position. Figure 8 is an enlarged perspective view of the main part of Figure 7, and the guide rib 32 shown in this figure has an overall shape of a roughly triangular prism with the inclined guide 31 being planar. As shown in the enlarged perspective view of Figure 9, the positioning guide 30 can be provided with an inclined guide 31 at the opening of the storage section 20 located at the top in the figure, and the lower part of the guide rib 32 in the figure can be a vertical guide 33. The breaker 100 shown in FIG. 6 uses the four opposing sides of the outer periphery 8a of the rectangular bimetal 8 as positioning guides 30, and provides multiple guide ribs 32 that protrude locally toward the inside of the storage section 20 on the positioning guide 30. Each guide rib 32 is provided with an inclined guide 31, and the bimetal 8 is guided to a fixed position by each inclined guide 31 provided on each guide rib 32.

Furthermore, as shown in Figures 10 and 11, the breaker can be configured such that the entire circumference facing the outer periphery 8a of the bimetal 8 serves as a positioning guide 30, and an inclined guide 31 is provided on the inner surface of the entire circumference of the positioning guide 30 to guide the bimetal 8 to a fixed position in the storage section 20. The positioning guide 30 shown in these figures is provided over the entire inner surface of the outer periphery wall 10, and the entire inner surface facing the outer periphery of the bimetal 8 serves as an inclined surface to serve as the inclined guide 31.

However, the positioning guide 30 may have a curved inclined guide 31 on the surface facing the outer periphery 8a of the bimetal 8. The positioning guide 30 shown in FIG. 12 has a curved inclined guide 31 on the surface facing the outer periphery 8a of the bimetal 8, the curved surface being concave at the center with a concave shape between the upper and lower ends. This positioning guide 30 has a curved inclined guide 31 that is curved along the trajectory of the outer periphery 8a along which the bimetal 8 moves in reverse, allowing the bimetal 8 to be smoothly reversed without being misaligned.

The positioning guide 30 can reduce the clearance between the inclined guide 31 and the bimetal 8 to reduce misalignment of the bimetal 8. Therefore, when the bimetal 8 is in a non-inverted shape, the minimum gap (t) between the outer periphery 8a of the bimetal 8 and the inclined guide 31 of the positioning guide 30 is set to, for example, 100 μm or less, preferably 80 μm or less, and more preferably 50 μm or less. The clearance is set to an optimal value taking into account the inclination angle of the inclined guide 31 so that the bimetal 8 can be set quickly in the storage section 20 and the bimetal 8 can be reliably inverted, but is preferably set to 10 μm or more so that the bimetal 8 can be set smoothly in the storage section 20 during the assembly process.

In this specification, the "minimum clearance gap" refers to the minimum gap (t) between the outer periphery 8a of the bimetal 8 and the positioning guide 30 when the non-inverted bimetal 8 is placed in the center of the storage section 20. In the case of a positioning guide 30 having a guide rib 32, the minimum clearance gap (t) refers to the minimum gap (t) between the outer periphery 8a of the bimetal 8 and the guide rib 32.

The positioning guide 30 has a large inclination angle (α) of the inclined guide 31 shown in FIG. 5, so that the bimetal 8 can be smoothly set in the storage section 20. Therefore, the inclination angle (α) of the inclined guide 31 is preferably set to be greater than 3 degrees. However, since a too large inclination angle can cause a large positional deviation of the bimetal 8 that is reversed, the inclination angle is preferably set to be less than 30 degrees, and more preferably less than 15 degrees. Here, the inclination angle (α) of the inclined guide 31 is the angle with respect to the vertical plane, and in FIG. 5 and FIG. 8, it means the angle of inclination of the inclined surface that protrudes inward from the upper end to the lower end of the inclined guide 31 with respect to the vertical plane that is the inner wall surface 20a of the outer peripheral wall 10 of the storage section 20.

The above-mentioned storage section 20 is provided with a pair of positioning guides 30 at the four corners of a rectangle, and the bimetal 8 is arranged in a fixed position in the storage section 20, but the storage section 20 can also be arranged at the support positions of two sides of the outer periphery 8a of the rectangular bimetal 8 as shown in FIG. 13. The breaker in FIG. 13 has positioning guides 30 at positions facing the outer periphery 8a of two sides of the bimetal 8 located at both ends of the elastic arm 6A. This storage section 20 uses the positioning guides 30 to prevent the bimetal 8 from shifting in position in the longitudinal direction of the elastic arm 6A. The width (W) of the bimetal 8 is larger than the width (d) of the elastic arm 6A, and the outer periphery of the two sides located at both ends of the elastic arm 6A becomes the pressing edge 8b of the inverted bimetal 8. Since the positional deviation between the pressing edge 8b and the elastic arm 6A causes an error in the reversal temperature, the positional deviation of the bimetal 8 in this direction can be suppressed to reduce the error in the reversal temperature. Therefore, as shown in Figure 13, positioning guides 30 are arranged only on both sides of the pressing edge 8b of the bimetal 8, thereby reducing the error in the reversal temperature of the bimetal 8. However, preferably, positioning guides 30 are arranged on the outside of the four sides of the outer periphery 8a of the bimetal 8, as shown in Figures 6 and 7. This is because this breaker 100 smoothly positions the bimetal 8 in the housing section 20 while reducing the error in the reversal temperature, and allows the bimetal 8 to smoothly reverse.

The above breaker 100 has a rectangular bimetal 8 and storage section 20, positioning guides 30 are provided at the corners of the rectangle, and multiple positioning guides 30 are arranged locally on the outer periphery 8a of the bimetal 8. This has the advantage that the bimetal 8 can be flipped more smoothly compared to a breaker (not shown) that has positioning guides arranged all around the outer periphery of the bimetal. This is because it is possible to reduce the probability that the outer periphery 8a of the flipping bimetal 8 will collide with the inner wall surface 20a of the storage section 20. In addition, the breaker 100 with this structure has the advantage that the bimetal 8 can be smoothly set in the storage section 20, which has a small clearance.

In the above breaker 100, the bimetal 8 and storage section 20 are rectangular in plan view, but the bimetal 8 and storage section 20 are not limited to a rectangle. For example, although not shown, the bimetal and storage section can be elliptical or circular, positioning guides can be placed at multiple points on the outer periphery of the bimetal, and an elastic arm can be placed in the center of the bimetal. A breaker with an elliptical or circular bimetal or storage section has an elastic arm placed in the center of the ellipse or circle, and the elliptical bimetal is placed in a position where the longitudinal direction of the elastic arm and the major axis direction of the ellipse are parallel, and the reversing bimetal can press the elastic arm to switch to the off state.

Furthermore, the main body case 1A shown in the cross-sectional views of Figures 2 to 5 has a storage recess 29 in which the heater 9 is placed in the storage section 20. The storage recess 29 is located in the center of the storage section 20, and its bottom surface is closed by the tip 4A of the fixed contact metal plate 4. The storage recess 29 has an inner shape slightly larger than the outer shape of the heater 9 so that the heater 9 can be inserted therein. The storage recess 29 also has a protruding portion 14 along its outer periphery. The heater 9 inserted into the storage recess 29 protrudes slightly from the upper surface of the protruding portion 14, and the bimetal 8 curved on the upper surface is placed in a thermally coupled state.

The bottom surface of the storage recess 29 of the storage section 20 is closed with a fixed contact metal plate 4, and the outer bottom surface of the storage recess 29 is closed with the plastic of the main body case 1A. The main body case 1A is fixed to the main body case 1A by insert molding the fixed contact metal plate 4 into the plastic bottom 13 that closes the bottom of the storage section 20 on the outside of the storage recess 29.

(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 outer case 1, and an elastic arm 6A having a movable contact 7 at its tip. As shown in Figures 2 and 3, the movable contact metal plate 6 has the fixed portion 6B fixed to the outer case 1, and the elastic arm 6A on the tip side disposed in a storage portion 20 provided in the outer case 1. The movable contact metal plate 6 has the fixed portion 6B fixed to the upper portion of a second outer wall 11B provided on the outer case 1. The movable contact metal plate 6 has the outer side of the fixed portion 6B protruding from the outer case 1, and this protruding piece serves as a connection terminal 6X.

The movable contact metal plate 6 is a metal plate that can elastically deform as a whole, or as an elastic arm 6A arranged in the storage section 20. In the breaker 100 shown in the figure, the movable contact metal plate 6 is made of a single metal plate, so the entire plate is made of a metal plate that can elastically deform. However, the movable contact metal plate can also be made of two metal plates connected to each other. Although not shown, this movable contact metal plate is made of a terminal plate fixed to the exterior case and an elastic arm that is connected and fixed to the terminal plate by welding or the like, and the elastic arm is made of a metal plate that can elastically deform. A breaker in which the movable contact metal plate is made of two metal plates consisting of an elastic arm and a terminal plate can be manufactured by fixing the terminal plate to the main case by insert molding, and fixing the elastic arm to the terminal plate exposed inside the exterior case by laser welding or the like.

Moveable contact metal plate 6 has movable contact 7 on the tip of elastic arm 6A, facing fixed contact 5. When bimetal 8 is in a non-inverted state, this movable contact metal plate 6 brings movable contact 7 into contact with fixed contact 5 to turn the breaker on, and when bimetal 8 is in an inverted state, elastic arm 6A pressed by bimetal 8 is elastically deformed, moving movable contact 7 away from fixed contact 5 to turn the breaker off.

(Elastic arm 6A)
The elastic arm 6A is disposed above the bimetal 8 disposed in the storage section 20 as shown in Fig. 2 and Fig. 3, and is an elastic metal plate capable of elastic deformation. The elastic arm 6A is a Cu-Zr alloy or a Cu-Cr-Ag-Si alloy. The Cu-Zr alloy contains preferably 0.05-0.15 wt% Zr in the base material Cu. The Cu-Cr-Ag-Si alloy contains 0.01-5 wt%, preferably 0.01-2.5 wt%, 0.01-5 wt%, preferably 0.01-2.5 wt%, 0.01-5 wt%, preferably 0.01-2.5 wt%, Ag in the base material Cu, and 0.01-5 wt%, preferably 0.01-2.5 wt%, Si in the base material Cu. Furthermore, the elastic arm may be an elastic metal plate (QMET 300, registered trademark of MATERION PERFORMANCE ALLOYS AND COMPOSITES USA) made of a copper alloy having a total content of 0.5 to 3% by weight of Cr, Ag, and Si and an IACS of 78% to 84%. Furthermore, the elastic arm may be made of an elastic metal plate such as a copper alloy containing Ni, P, Zn, and Fe, a copper alloy containing Fe, P, and Zn, a copper alloy containing Cr and Mg and having an IACS of 75% or more, a copper alloy containing Zr and having an IACS of 80% or more, or a copper alloy containing Sn and having an IACS of 80% or more.
However, IACS [international annealed copper standard] is a notation that specifies the electrical conductivity of internationally adopted annealed standard soft copper (volume resistivity is 1.7241×10−2 μΩm) as 100% as a standard for electrical resistance or electrical conductivity.

Furthermore, the elastic arm 6A has a movable contact 7 on the tip thereof facing the fixed contact 5. The movable contact 7 of the elastic arm 6A shown in FIG. 14 is provided by fixing a metal plate made of silver or a silver alloy to the area facing the fixed contact 5, thereby reducing the contact resistance with the fixed contact 5. The movable contact 7 is, for example, a seam-welded Ag-Ni alloy with a thickness of 100 μm to 150 μm. When the bimetal 8 is not thermally deformed, the movable contact 7 contacts the fixed contact 5 and is in the ON state, and when the bimetal 8 is thermally deformed, the elastic arm 6A is pressed by the bimetal 8 and elastically deforms, so that the movable contact 7 separates from the fixed contact 5 and is in the OFF state. In the non-energized type breaker 100 shown in FIG. 2 and FIG. 3, a pressing protrusion 25 that presses the rear end side of the elastic arm 6A downward is provided protruding from the inner surface of the cover case 1B so that the movable contact 7 can reliably contact the fixed contact 5 when the bimetal 8 is not thermally deformed. When the rear end of this elastic arm 6A is pressed downward by the pressing protrusion 25, the tip is urged downward, ensuring that the movable contact 7 at the tip comes into contact with the fixed contact 5.

Furthermore, the breaker 100 in Figs. 2 and 3 has a deformation limiting protrusion 26 on the cover case 1B. The deformation limiting protrusion 26 is located at a position to press the tip of the elastic arm 6A, i.e., the movable contact 7 side, downward and protrudes toward the elastic arm 6A side in order to limit the amount of deformation of the elastic arm 6A when it is pressed 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. This breaker 100 can limit the amount of deformation of the elastic arm 6A when it is pushed up by the inverted bimetal 8 by pressing the tip of the elastic arm 6A downward, i.e., toward the fixed contact 5, with the deformation limiting protrusion 26. Therefore, the breaker 100 with this structure has the feature that it can prevent the inverted bimetal 8 from pushing up the elastic arm 6A beyond its elastic limit and reducing its springiness, and can press the movable contact 7 against the fixed contact 5 with a predetermined contact pressure after recovery to keep the contact resistance small.

Furthermore, the elastic arm 6A in Figures 2 to 5 has a protrusion 6C on its underside, and both ends of the bimetal 8 come into contact with this protrusion 6C to press against each other. The protrusion 6C shown in the figures has an arc-shaped outer shape, allowing both ends of the bimetal 8 to reliably come into contact and press against each other without sliding laterally. The elastic arm 6A shown in the figures has multiple protrusions 6C on its underside that face both ends of the bimetal 8. This structure allows even wide bimetal 8s to reliably come into contact and press against each other.

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 elastic arm 6A is arranged in the storage section 20. The breaker 30 in Fig. 2 and Fig. 3 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, 3, and 5, the main body case 1A has a step recess 21 on the upper end surface of the second outer wall 11B that is one step lower than the upper surface of the outer peripheral wall 10, and the fixed portion 6B of the movable contact metal plate 6 is fitted into this step recess 21 to be arranged in a fixed position. The main body case 1A in Fig. 7 has a connecting protrusion 15 that protrudes from the center of this step recess 21 and penetrates the fixed portion 6B of the movable contact metal plate 6. The fixed portion 6B of the movable contact metal plate 6 has a through hole 6F that penetrates the connecting protrusion 15. The connecting protrusion 15 shown in the figure has an elliptical horizontal cross-sectional shape, so that the fixed portion 6B of the movable contact metal plate 6 can be positioned in the stepped recess 21 in an accurate position. Furthermore, the stepped recess 21 shown in Figures 6 and 7 forms a positioning rib 22 for positioning both sides of the movable contact metal plate 6 at the upper end of the second outer wall 11B. The second outer wall 11B shown in Figure 7 forms a stepped positioning rib 22 by lowering the portion other than the positioning rib 22 on its upper end surface below the upper surface of the outer peripheral wall 10 to provide the stepped recess 21. The movable contact metal plate 6 is provided with positioning recesses 6G on both sides of the fixed portion 6B for guiding the positioning rib 22. The connecting protrusion 15 is inserted into the through hole 6F opened in the fixed portion 6B, and the positioning rib 22 is guided by the positioning recesses 6G provided on both sides of the fixed portion 6B, so that the movable contact metal plate 6 is positioned at a fixed position in the stepped recess 21 of the second outer wall 11B. The movable contact metal plate 6, with the fixed portion 6B disposed in the stepped recess 21, is fixed to the second outer wall 11B by adhesion, or is sandwiched between the lid case 1B, which is fixed to the main body case 1A; that is, it is sandwiched from both above and below between the bottom surface of the stepped recess 21 of the second outer wall 11B and the opposing surface of the lid case 1B, and is fixed in a fixed position on the outer case 1.

The movable contact metal plate 6 has an extension portion that is pulled out from the outer case 1 to the outside, which serves as a connection terminal 6X. The connection terminal 6X shown in the figure has its rear end bent into a stepped shape so that it is positioned approximately on the same plane as the connection terminal 4X of the fixed contact metal plate 4 that is pulled out from the opposite end face of the outer case 1.

(Lid case 1B)
As shown in Figs. 2 to 5, the cover case 1B is disposed on the opening side of the main case 1A in a state where it covers the upper part of the elastic arm 6A. The cover case 1B shown in the figures includes a laminated metal plate 24 laminated on the outside of the movable contact metal plate 6 at the upper end opening side of the main case 1A, and a connecting plastic 23 that fixes the laminated metal plate 24. The cover case 1B is disposed on the opening side of the main case 1A in a state where the laminated metal plate 24 covers the upper part of the movable contact metal plate 6 with the laminated metal plate 24, with the laminated metal plate 24 exposed on the inner side, i.e., the main case 1A side. The cover case 1B shown in Figs. 2 to 5 is insulated by covering almost the entire surface of the laminated metal plate 24 with the connecting plastic 23 on the upper side. The laminated metal plate 24 is fixed to the connecting plastic 23 by insert molding. The insert molded laminated metal plate 24 is temporarily fixed in a molding chamber of a mold that molds the connecting plastic 23, and is fixed to the connecting plastic 23 by injecting molten plastic into the molding chamber. The laminated metal plate 24, which is insert molded into the connecting plastic 23, has a pressing protrusion 25 that presses the rear end of the elastic arm 6A downward and a deformation limiting protrusion 26 that protrudes from the inner surface and limits the amount of deformation of the elastic arm 6A when pressed by the bimetal 8.

The above-mentioned lid case 1B is fixed to the main 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 case 1A. As shown in FIG. 5, the connecting plastic 23 of the lid case 1B has an outer peripheral wall 27 that protrudes toward the main case 1A at the outer peripheral edge facing the outer peripheral wall 10 of the main case 1A, and the laminated metal plate 24 is exposed on the inside of this outer peripheral wall 27. As shown in FIG. 5, the inside of the outer peripheral wall 27 of the lid case 1B is a recessed shape with a downward opening, which serves as a space for accommodating the elastic arm 6A that is elastically deformed when pressed by the bimetal 8. The outer peripheral wall 27 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 case 1A, and is further fixed to the opposing wall 12.

The exterior case 1 shown in Figures 5 to 7 has connecting protrusions 15, 17 and connecting recesses 16, 18 that fit together to connect the lid case 1B and the main case 1A while accurately positioning them. As described above, the main case 1A has a protruding connecting protrusion 15 that penetrates the fixed portion 6B of the movable contact metal plate 6 and positions it on the upper surface of the second outer wall 11B. The lid case 1B has a connecting recess 16 that guides the connecting protrusion 15 at a position opposite the connecting protrusion 15 at the end of the second outer wall 11B side of the main case 1A. Furthermore, the lid case 1B shown in Figure 5 has connecting protrusions 17 that protrude from the lower surface of the outer wall 27 toward the main case 1A on both sides of the end of the first outer wall 11A side of the main case 1A. The main case 1A has connecting recesses 18 that guide the connecting protrusions 17 on the upper surface of the outer wall 10 that faces these connecting protrusions 17, as shown in Figures 6 and 7.

In the above exterior case 1, the connecting protrusions 17 on both sides of the lid case 1B are guided into the connecting recesses 18 of the main case 1A at the end on the first outer wall 11A side of the main case 1A, and the connecting protrusions 15 that penetrate the fixed portion 6B of the movable contact metal plate 6 are guided into the connecting recesses 16 of the lid case 1B at the end on the second outer wall 11B side of the main case 1A, so that the lid case 1B is connected to the main case 1A in an accurate position.

The lid case 1B and the main case 1A are connected in a fixed position via the connecting protrusions 15, 17 and the connecting recesses 16, 18, and the connecting plastic 23 is fixed to the main case 1A by ultrasonic welding. The lid case 1B shown in FIG. 5 has a melting protrusion 28 that is located on the underside of the outer wall 27 of the connecting plastic 23, which faces the outer wall 10 of the main case 1A and is melted by ultrasonic vibration. The lid case 1B in the figure has a melting protrusion 28 protruding along the underside of the outer wall 27. This lid case 1B has a melting protrusion 28 that is approximately U-shaped when viewed from the bottom, on the outer edge except for the part facing the fixed part 6B of the movable contact metal plate 6. This lid case 1B is connected in a fixed position to the main case 1A via the connecting protrusions 15, 17 and the connecting recesses 16, 18, and the outer periphery is ultrasonically vibrated to melt the melting protrusion 28 by frictional heat and weld it to the outer wall 10 of the main case 1A. Furthermore, the ultrasonically vibrated lid case 1B and main case 3 are welded together by the frictional heat of the contact areas of the connecting protrusions 15, 17 and connecting recesses 16, 18 that are connected to each other. However, the exterior case can also be fixed by gluing the connecting plastic of the lid case and the main case, or by connecting them with a fitting structure or a locking structure.

(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 is fixed to the main body case 1A by insert molding such that the tip portion 4A closes the opening of the bottom 13 of the storage section 20, and the middle portion 4B and a part of the tip portion 4A are embedded in the first outer wall 11A of the main body case 1A from the bottom 13 of the storage section 20. The fixed contact metal plate 4 in Figures 2 and 3 has a step portion 4D so that the portion embedded in the first outer wall 11A is higher than the portion closing the bottom of the storage recess 29, and the step portion 4D is embedded in the bottom 13 of the main body case 1A, and the rear end side of the step portion 4D is exposed to the upper surface of the bottom 13, and this exposed portion serves as the fixed contact 5.

As shown in FIG. 14, the fixed contact metal plate 4 has a silver-plated layer in the area facing the movable contact 7 to form the fixed contact 5. The silver-plated layer of the fixed contact 5 is, for example, 5 μm thick. However, the film thickness of the silver-plated layer of the fixed contact can be 3 μm to 20 μm, and preferably 4 μm to 10 μm. By making the silver-plated layer of the fixed contact 5 thinner, the manufacturing cost can be reduced.

The fixed contact metal plate 4 has an extension portion that is pulled out from the exterior case 1 to the outside as a connection terminal 4X. The fixed contact metal plate 4 shown in the figure has a portion that is pulled out from the exterior case 1 to the outside in a straight line from an intermediate portion 4B that is embedded in the exterior case 1 to form a connection terminal 4X.

In the above breaker 100, the bimetal 8 instantly reverses when the ambient temperature reaches the set temperature, and instantly returns to its original position when the ambient temperature drops to the reset temperature, deforming the elastic arm, but this makes it difficult to securely fix the elastic arm to the terminal board for a long period of time. In addition, in a microbreaker that is extremely small overall, even a slight deviation in the contact position of the contacts increases the contact resistance. This is because the contact pressure between the movable contact and the fixed contact is weak, and in the on state, the movable contact and the fixed contact are in contact in an extremely narrow local area. Furthermore, the surfaces of the breaker's movable contact and fixed contact are not always maintained in a uniform state over the entire surface, and compared to the positions where they are in constant contact, the surfaces of the non-contact positions where they are not in constant contact have higher contact resistance due to thin oxide films, etc.

Microbreakers use an activation process to reduce the contact resistance of the contacts. The contacts are activated by ultrasonically vibrating them while they are energized in the on state. Contacts activated in this way only have low contact resistance when the movable contact and fixed contact are in contact at a specific position, so if the contact position of the contacts shifts, the contact resistance increases.

(Contact activation process)
The contact resistance of the micro breaker with weak contact pressure can be reduced by activating the contacts in the assembled state. The activation process of the contacts is performed by ultrasonically vibrating the contacts of the assembled breaker 100 while current is flowing. The breaker 100 causes the movable contact 7 and the fixed contact 5 to collide with each other and ultrasonically vibrate in the direction of separation. That is, the breaker 100 ultrasonically vibrates the fixed contact 5 and the movable contact 7 so that they approach each other, collide with each other, and move relatively in the direction of separation. The current of the contacts in the ultrasonic vibration state is preferably 0.1 A to 100 A in the resistive load state. The contacts are more effectively activated by increasing the contact current during ultrasonic vibration. In the case of an inductive load in which a coil is connected in series with a resistor, the current energy stored in the coil when the current is interrupted is large, so the contact current can be reduced to activate the contacts. This is because the discharge current of the contacts is large to consume the energy of the current stored in the coil. Therefore, the contact current is set to an optimal value in consideration of the resistive load and the inductive load. Furthermore, the breaker 100 has the characteristic that when the current through the contacts is increased, it generates heat due to Joule heat and switches itself to the OFF state. To activate the contacts with ultrasonic vibration, it is necessary to hold the movable contact 7 in the ON state in contact with the fixed contact 5. Therefore, the method of passing a large current through the contacts to generate ultrasonic vibration shortens the time for which ultrasonic vibration is generated, and ultrasonic vibration is generated while the contacts are in the ON state. Therefore, the method of passing a large current through the contacts to generate ultrasonic vibration shortens the time for which ultrasonic vibration is generated.

The time for which the contacts are ultrasonically vibrated while current is flowing is set to 0.1 milliseconds to 1 second. The contacts can be activated more effectively by making the ultrasonic vibration time longer, but if the time is too long the silver plating layer of the contacts will be damaged, so the time is set to activate the contacts without damaging the silver plating layer. Contact activation by ultrasonic vibration is also affected by the contact current, type of load, and amplitude of ultrasonic vibration; if the contact current and amplitude are large, the contacts are activated more effectively in a short time. Therefore, the time for ultrasonic vibration is set to an optimal value within the above-mentioned range, taking into account the contact current and amplitude of ultrasonic vibration.

The frequency at which the contacts are ultrasonically vibrated is 20 KHz to 6 GHz, preferably 20 KHz to 1 GHz. By increasing the frequency of the ultrasonic vibration, the number of collisions and separations between the movable contact 7 and the fixed contact 5 per unit time can be increased. However, if the frequency of the ultrasonic vibration is too high, the distance between the movable contact 7 and the fixed contact 5 becomes narrower, reducing activation by discharge, and conversely, if the frequency is too low, the number of collisions decreases and activation decreases, so the frequency of the ultrasonic vibration is set to an optimal value taking into account the thickness and length of the elastic arm 6A, as well as the resonant frequency of the elastic arm 6A.

Furthermore, the amplitude of ultrasonic vibration of the breaker 100 is set to 0.01 μm to 100 μm. By increasing the amplitude of ultrasonic vibration, the kinetic energy of the movable contact 7 colliding with the fixed contact 5 can be increased, and the distance at which the movable contact 7 is separated from the fixed contact 5 can be increased. The amplitude of ultrasonic vibration of the breaker 100 affects the distance at which the movable contact 7 is separated from the fixed contact 5. However, the distance 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 resonating the elastic arm 6A. Therefore, by setting the frequency at which the ultrasonic vibration of the breaker 100 is performed to the resonant frequency of the elastic arm 6A or in the vicinity thereof, or to an integer multiple of the resonant frequency, or to an integer fraction of the resonant frequency, the movable contact 7 can be separated from the fixed contact 5 by a sufficient distance, and can be effectively activated.

To increase the amplitude of 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 exterior case 1 of the breaker 100 to cause ultrasonic vibration, there are problems such as deformation of the contact point with the ultrasonic vibrator due to heat generated by the ultrasonic vibration, so the amplitude of ultrasonic vibration of the breaker 100 is set small within the range in which 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 PTC heater with oval or rectangular opposing surfaces, and has electrodes on the top and bottom surfaces. However, it is not necessary to use a PTC heater, and any heater that can heat the bimetal 8 when energized can be used. The heater 9 with electrodes on the top and bottom surfaces is designed so that the bottom surface is in contact with the fixed contact metal plate 4, and the top surface is in contact with the elastic arm 6A via the bimetal 8. In the ON state where the movable contact 7 of the elastic arm 6A is in contact with the fixed contact 5, the elastic arm 6A and the bimetal 8 are not in contact with each other, and no current is passed through the heater 9. In the OFF state where the movable contact 7 of the elastic arm 6A is separated from the fixed contact 5, the heater 9 is energized through the bimetal 8 in contact with the elastic arm 6A and the fixed contact metal plate 4, generating heat and heating the bimetal 8. The heated bimetal 8 maintains the OFF state where the movable contact 7 is separated from the fixed contact 5, as shown in FIG. 3. This non-energized type breaker 100 can be used safely with battery packs because it keeps the movable contact 7 in the OFF state when it is switched to the OFF state. This is because, after the battery pack is used in an abnormal state and the temperature rises above the set temperature and the non-energized type breaker 100 is switched to the OFF state, electricity continues to flow from the battery of the battery pack to the heater 9, heating the bimetal 8, so that the breaker 100 does not return to the ON state and can maintain the current interrupting state until the battery is discharged.

However, the breaker is not necessarily limited to a structure with a built-in heater. In a breaker without a built-in heater, when the bimetal 8 becomes warmer than the set temperature and deforms, deforming the elastic arm and switching the contact to the OFF state, the bimetal and elastic arm are restored to their original state when the bimetal 8 drops to a specified temperature, without heating the bimetal to hold the breaker in the OFF state.

(Installation of breaker 100 in battery pack)
The above-described breaker 100 is built into a battery pack, for example, and cuts off current when the battery or ambient temperature becomes high or when the battery pack is used in an abnormal state. The breaker 100 built into the battery pack has a pair of connection terminals 6X, 4X drawn out from both ends of the exterior case 1, which are connected directly or via connection leads to a battery terminal or a circuit board. The connection terminals 6X, 4X are connected to the connection leads or battery terminals by, for example, laser welding. The breaker 100 is disposed with the exterior case 1 close to the battery surface or the circuit board, preferably in a thermally coupled state, and when the battery or ambient temperature becomes high, the built-in bimetal 8 is reversed to cut off current.

(Fixing of breaker 100 to circuit board)
The above breaker 100 can also be fixed by soldering to the circuit board 60 as the structure shown in Fig. 15. In the breaker 100 shown in Fig. 15, the connection terminal 6X of the movable contact metal plate 6 and the connection terminal 4X of the fixed contact metal plate 4, which are drawn out from the outer case 1, are bent so as to be positioned almost flush with the bottom surface of the outer case 1, i.e., the bottom surface of the main body case 1A. This breaker 100 is fixed by soldering the connection terminal 6X of the movable contact metal plate 6 and the connection terminal 4X of the fixed contact metal plate 4, which are drawn out from both ends of the outer case 1, to the circuit board 60. This breaker 100 is placed and soldered on the circuit board 60 with the bottom surface of the outer case 1, i.e., the bottom surface of the main body case 1A, facing the upper surface of the circuit board 60. This breaker 100 is heated and reflow soldered in a state in which the connection terminals 6X and 4X provided at both ends of the outer case 1 are placed on the solder surface 61 provided on the surface of the circuit board 60. The breaker 100 is connected to the solder surface 61 of the circuit board 60 via the connection terminals 6X and 4X, and is fixed in a fixed position on the circuit board 60.

[Example 1]
The bimetal 8 is a rectangle of 3.48 mm x 3.00 mm, has a thickness of 68 μm, a reversal temperature of 85° C., and a return temperature of 30° C.; as shown in FIGS. 6 to 8 , a pair of positioning guides 30 are provided on the corner wall portion 20A of the storage portion 20, the inclined guide 31 of the positioning guide 30 has a width of 0.3 mm, the length of the positioning guide 30 in the bimetal reversal direction is 0.41 mm, the clearance between the outer periphery 8a of the bimetal 8 and the inclined guide 31 in the non-reversed shape is 20 μm, and the clearance between the outer periphery 8a of the bimetal 8 and the inclined guide 31 in the reversed shape is 30 μm;
A prototype breaker 100 was manufactured in which the elastic arm 6A, which is formed from a part of the movable contact metal plate 6, is 100 μm thick, a Cu-Zr alloy is used for the elastic arm 6A, the length of the elastic arm 6A is 4.35 mm, the width is 1.5 mm, a movable contact 7 is provided at the tip of the elastic arm 6A, this movable contact 7 is made of a seam material (Ag-Ni) with a thickness of 120 μm, the fixed contact 5 is an Ag plating layer of 4.5 μm, and the external dimensions of the outer case 1 are 5.8 mm in length, 3.7 mm in width, and 1.05 mm in height. This breaker 100 was turned upside down with the longitudinal direction of the elastic arm 6A in a vertical position, and then switched from the OFF state to the ON state. When the temperature difference at the time of switching was detected, the temperature variation range of the recovery temperature was 5°C or less.

The Cu--Zr alloy used in this Example 1 had the following composition.
Cu……99.9wt%
Zr: 0.1 wt%

[Example 2]
The breaker of Example 2 has the same structure as Example 1, except that the clearance between the outer peripheral edge 8a of the non-inverted bimetal 8 and the inclined guide 31 of the positioning guide 30 is 25 μm, and the clearance between the outer peripheral edge 8a of the inverted bimetal 8 and the inclined guide 31 is 35 μm. The variation range of the recovery temperature is approximately 10° C.

[Comparative Example 1]
A breaker of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the inner wall surface 20a of the storage section 20 was not inclined but was perpendicular to the bottom surface as shown in Fig. 16, and the clearance between the outer periphery 8a of the bimetal 8 and the inner wall surface 20a of the storage section 20 was 60 µm in the non-inverted shape and the inverted shape. When the reversal temperature of this breaker was detected by inverting it upside down, the variation range of the return temperature was about 20°C, which was four times larger than that of Example 1.

The present invention can be suitably used as a breaker that requires high precision in the bimetal reversal temperature and can reliably cut off current at a set temperature.

100...breaker 1...outer case 1A...main body case 1B...lid case 4...fixed contact metal plate 4A...tip portion 4B...middle portion 4D...step portion 4X...connection terminal 5...fixed contact 6...movable contact metal plate 6A...elastic arm 6B...fixed portion 6C...projection portion 6F...through hole 6G...positioning recess 6X...connection terminal 7...movable contact 8...bimetal 8a...outer peripheral edge 8b...pressing edge 8A...corner portion 9...heater 10...outer peripheral wall 11...outer wall 11A...first outer wall 11B...second outer wall 12...opposing wall 13...bottom 14...projection portion 15...connecting protrusion 16...connecting Connection recess 17...connecting protrusion 18...connecting recess 20...storage section 20A...corner wall section 20a...inner wall surface 21...step recess 22...positioning rib 23...connecting plastic 24...laminated metal plate 25...pressing protrusion 26...deformation limiting protrusion 27...outer wall 28...melting protrusion 29...storage recess 30...positioning guide 31...inclined guide 32...guide rib 33...vertical guide 60...circuit board 61...solder surface 104...fixed contact metal plate 105...fixed contact 106...movable contact metal plate 106A...elastic arm 107...movable contact 108...bimetal

Claims (13)

An outer case,
a fixed contact metal plate having a fixed contact fixed to the exterior case;
a movable contact metal plate having a movable contact at a position opposite to the fixed contact of the fixed contact metal plate, the movable contact being partially fixed to the exterior case so that the movable contact can be moved;
a bimetal disposed between the movable contact metal plate and the fixed contact metal plate, which reverses from a non-reversed shape to a reversed shape when the temperature exceeds a set temperature, thereby switching the movable contact metal plate from on to off;
A breaker comprising:
the exterior case has a storage section in which the bimetal is arranged so as to be freely deformed between a non-inverted shape and an inverted shape,
the storage section has a positioning guide on an opposing surface of an outer periphery of the bimetal for positioning the bimetal in a fixed position;
the positioning guide has an inclined guide inclined in a direction in which the gap between the bimetal and an outer circumferential edge increases as the bimetal deforms from a non-inverted shape to an inverted shape,
the inclined guide is provided on a surface facing an outer circumferential edge of the bimetal,
The movable contact metal plate is
a resilient arm that is pressed by the reversing bimetal and deforms to switch a contact from on to off,
The elastic arm is
At a position facing the end of the bimetal,
a protrusion protruding toward a surface of the bimetal;
The end of the inverted bimetal presses against the protrusion,
The breaker is switched from on to off by deforming the elastic arm. 2. The breaker of claim 1,
The inclined guide is
A breaker provided in a region including an opening of the storage section. 3. The breaker according to claim 1 or 2,
The positioning guide is
A guide rib protruding inwardly from the storage portion,
The guide rib is
A breaker, wherein a surface facing an outer periphery of the bimetal is used as the inclined guide. 4. The breaker according to claim 2 or 3,
The inclined guide is
A breaker having an inclined plane. A breaker according to any one of claims 1 to 4,
The bimetal and the housing are rectangular in plan view,
The positioning guide is
A breaker characterized in that it is arranged at support positions on two opposing sides of the outer periphery of the rectangular bimetal. A breaker according to any one of claims 1 to 4,
The bimetal and the housing are rectangular in plan view,
The positioning guide is
A breaker characterized in that said breakers are arranged at support positions on four sides of the outer periphery of said rectangular bimetal. 3. The breaker according to claim 1 or 2,
The positioning guide is
The bimetal is provided on the entire circumference opposite to the outer periphery thereof.
A breaker comprising: said positioning guide provided on an inner surface of said positioning guide; said inclined guide provided on said inner surface of said positioning guide; 3. The breaker according to claim 1 or 2,
The bimetal and the housing are rectangular in plan view,
The storage section is
a recessed corner wall portion disposed outside a protruding corner portion of an outer circumferential edge of the bimetal;
The positioning guide is
A breaker disposed on the recessed corner wall. 9. The breaker of claim 8,
In the corner wall portion,
a positioning guide disposed at a support position on two adjacent sides of an outer periphery of the bimetal; 10. A breaker according to claim 8 or 9,
The positioning guide disposed on the recessed corner wall portion is
A guide rib protruding inwardly from the storage portion,
The guide rib is
A breaker, wherein a surface facing an outer periphery of the bimetal is used as the inclined guide. A breaker according to any one of claims 1 to 10,
In the non-inverted form of the bimetal,
A breaker characterized in that the minimum gap between the outer peripheral edge of the bimetal and the positioning guide is 100 μm or less. A breaker according to any one of claims 1 to 11,
A breaker characterized in that the inclination angle of said inclined guide with respect to a vertical plane is greater than 3 degrees. 2. The breaker of claim 1,
The outer case is
a main body case having the storage portion for the bimetal;
a cover case that closes an upper surface of the housing portion for housing the bimetal of the main body case,
The cover case is
a deformation limiting protrusion protruding toward a surface of the elastic arm,
The deformation limiting convex portion is
The breaker limits the amount of deformation of the elastic arm which is deformed by being pressed by the inverted bimetal.

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