Description Title of Invention: CIRCUIT BREAKER
Technical Field
[0001] The present invention relates to a circuit breaker for bringing a movable contact element into contact with a stationary contact element or separating the movable contact element from the stationary contact element.
Background Art
[0002] There has hitherto been known a circuit breaker configured to connect a movable contact element to a stationary contact element by interlocking a plunger of an electromagnet and a movable contact element with each other through a link mechanism and moving the plunger through energization of a coil of a stator of the electromagnet. The above-mentioned related-art circuit breaker has a configuration in which a toggle mechanism is used as a link mechanism, and the toggle mechanism reaches a dead center when the movable contact element is connected to the stationary contact element. With this, a strong contact pressure with respect to the stationary contact element, which is required after connection of the movable contact element, is reduced to suppress electromagnetic force required for the electromagnet.
[0003] However, in the related-art circuit breaker, in terms of the structure of the electromagnet, a gap between the stator

and the plunger is large in an initial stage of a connection operation of the movable contact element, and the gap becomes smaller as the connection operation proceeds. Therefore, the electromagnetic force of the electromagnet increases as the connection operation of the movable contact element proceeds. Meanwhile, the toggle mechanism is brought close to the dead center as the movable contact element moves in a connection direction, and hence a load of the electromagnet required for the connection operation decreases as the connection operation of the movable contact element proceeds. In view of the foregoing, in the related-art circuit breaker, the characteristics of the electromagnetic force generated by the electromagnet and the characteristics of the load required for the electromagnet are opposite to each other with respect to the connection operation of the movable contact element. Therefore, in the related-art circuit breaker, there is a problem in that a large electromagnet having unsatisfactory efficiency is required with respect to the characteristics of the load required for the electromagnet. [0004] In view of the foregoing, in order to suppress an increase in size of the electromagnet, there has hitherto been proposed a circuit breaker having the following configuration. A lever that is interlocked with the movable contact element is rotatably provided to a lever shaft, and the lever is rotated by a roller while the roller is moved to the lever shaft with the electromagnetic force of the electromagnet, to thereby connect the

movable contact element to the stationary contact element. In such related-art circuit breaker, an action point of the roller with respect to the lever approaches the lever shaft as the movable contact element is brought close to the stationary contact element. Thus, the characteristics of the load required for the electromagnet are approximated to the characteristics of the electromagnetic force of the electromagnet, thereby suppressing the increase in size of the electromagnet (see, for example, Patent Literature 1) .
Citation List Patent Literature [0005] [PTL 1] JP 2010-44927 A
Summary of Invention Technical Problem
[0006] However, in the related-art circuit breaker disclosed in Patent Literature 1, the roller is moved while being held in contact with the lever, with the result that the roller is liable to wear. With this, the direction of a force line of the roller that acts on the lever changes, and there is a risk in that a defect may occur in the connection operation of the movable contact element Further, a variation in wear amount of the roller increases depending on, for example, the use condition of the circuit breaker. Therefore, an individual difference of the circuit breaker increases, with the result that it also becomes difficult to manage

durability of the circuit breaker. Further, it is difficult to increase the movement amount of the roller in a limited stroke of the electromagnet, with the result that the electromagnet cannot be further downsized.
[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a circuit breaker in which an electromagnet can be downsized and the stability of an operation can be improved.
Solution to Problem
[0008] According to one embodiment of the present invention, there is provided a circuit breaker, including : a stationary contact element; a movable contact element, which is brought into contact with the stationary contact element at a time of connection and is separated from the stationary contact element at a time of disconnection; a movable support member, which is connected to the movable contact element, and is displaceable among a non-connection position at which the movable contact element is separated from the stationary contact element at the time of disconnection, a connection start position at which the movable contact element starts being brought into contact with the stationary contact element in a connection operation process at the time of connection, and a connection completion position at which the movable support member is brought closer to the movable contact element as compared to the connection start position to press the movable contact

element against the stationary contact element; a lever, which is coupled to the movable support member; a lever shaft, which is configured to rotatably support the lever; a first coupling link, which is rotatably coupled to the lever; a second coupling link, which is coupled to the first coupling link; a plunger, which is rotatably coupled to the second coupling link; an electromagnet, which is configured to displace the plunger in the connection operation process, to thereby displace the movable support member from the non-connection position to the connection completion position through the connection start position; a holding body, which exerts a holding force so as to hold an angle of the second coupling link with respect to the first coupling link at a first set angle; and a restricting member, which is configured to restrict rotation of the first coupling link with respect to the lever in a direction in which an angle of the first coupling link with respect to the lever becomes smaller than a second set angle.
Advantageous Effects of Invention
[0009] With the circuit breaker according to the present invention, the restricting member restricts the rotation of the first coupling link with respect to the lever, and the angle of the second coupling link with respect to the first coupling link becomes smaller against the holding force of the holding body. Therefore, the action point of a force for connection of an electromagnetic actuator with respect to the lever can be brought

close to the lever shaft. With this, the moment action distance with respect to the lever can be reduced in accordance with the force of the electromagnetic actuator, which increases through displacement of the plunger from a retreat position to an advance position, and hence an electromagnet having a size according to a change in moment action distance required for a connection operation of the circuit breaker can be used. As a result, the electromagnet can be downsized. Further, wear is less liable to occur in a link mechanism, and hence the stability of an operation of the circuit breaker can be improved.
Brief Description of Drawings
[0010] FIG. 1 is a configuration view for illustrating a circuit breaker according to a first embodiment of the present invention.
FIG. 2 is a configuration view for schematically illustrating main portions of the circuit breaker of FIG. 1.
FIG. 3 is a configuration view for schematically illustrating the main portions of the circuit breaker at a time when a plunger of FIG. 2 is at a retreat position.
FIG. 4 is a configuration view for schematically illustrating the main portions of the circuit breaker at a time when a movable support member reaches a connection start position while the plunger of FIG 3 is displaced to an advance position.
FIG. 5 is a configuration view for schematically illustrating

the circuit breaker at a time when a first coupling link is brought into abutment against a restricting member while the plunger of FIG. 4 is displaced to the advance position.
FIG. 6 is a configuration view for schematically illustrating the circuit breaker at a time when the plunger of FIG. 5 reaches the advance position to press a movable body against a stationary contact element at a connection position.
FIG. 7 is a graph for showing a relationship between a load moment [N-mm] required for rotating the lever of FIG. 1 and a stroke [mm] from the retreat position to the advance position of the plunger.
FIG. 8 is a graph for showing a relationship between an electromagnetic attraction force [N] generated by the electromagnetic actuator of FIG. 1 and the stroke [mm] from the retreat position to the advance position of the plunger.
FIG. 9 is a graph for showing a relationship between a moment action distance required for rotating the lever of FIG. 1 and the stroke [mm] from the retreat position to the advance position of the plunger.
FIG. 10 is a graph for showing a comparison between a moment action distance [mm] with respect to the lever, which is caused during a connection operation of the circuit breaker of FIG. 1, and a moment action distance [mm] required for rotating the lever during the connection operation of the circuit breaker of FIG. 1.
FIG. 11 is a configuration view for illustrating a circuit

breaker according to a fourth embodiment of the present invention.
Description of Embodiments
[0011] Now, embodiments of the present invention are described with reference to the accompanying drawings. First Embodiment
FIG. 1 is a configuration view for illustrating a circuit breaker according to a first embodiment of the present invention. FIG. 2 is a configuration view for schematically illustrating main portions of the circuit breaker of FIG. 1. In FIG. 1, a circuit breaker 1 includes a housing 2 being a base, a stationary contact element 3 provided to the housing 2, a conductive movable body 4 that is brought into contact with the stationary contact element 3 and is separated from the stationary contact element 3, an electromagnetic actuator 5 configured to generate a drive force for displacing the movable body 4, and a link mechanism 6 configured to interlock the movable body 4 and the electromagnetic actuator 5 with each other. The stationary contact element 3, the movable body 4, the electromagnetic actuator 5, and the link mechanism 6 are arranged in the housing 2.
[0012] A power supply side terminal 7 and a load side terminal 8, which are respectively exposed to outside of the housing 2, are fixed to the housing 2 at a distance. In this example, the power supply side terminal 7 is arranged above the load side terminal 8. The power supply side terminal 7 is always electrically

connected to the stationary contact element 3.
[0013] The movable body 4 includes a movable piece 41 and a movable contact element 42 provided to the movable piece 41. The movable piece 41 is coupled to the link mechanism 6. With this, the movable body 4 is displaceable with respect to the housing 2 in accordance with the operation of the link mechanism 6.
[0014] The movable piece 41 is connected to the load side terminal 8 through intermediation of a flexible conductor 43 . With this, the movable contact element 42 is always electrically connected to the load side terminal 8 . The movable contact element 42 is opposed to the stationary contact element 3 . The movable body 4 is displaceable with respect to the stationary contact element 3 and the housing 2 while bending the flexible conductor 43 between a contact point contact position at which the movable contact element 42 is brought into contact with the stationary contact element 3 and a contact point separation position at which the movable contact element 42 is separated from the stationary contact element 3 . In the circuit breaker 1, when the movable body 4 reaches the contact point contact position, the power supply side terminal 7 is electrically connected to the load side terminal 8 . When the movable body 4 leaves the contact point contact position to be separated from the stationary contact element 3, the power supply side terminal 7 and the load side terminal 8 are electrically disconnected from each other. Thus, the movable contact element 42 is brought into contact with the stationary contact element 3

at a time of connection of the circuit breaker 1, and the movable contact element 42 is separated from the stationary contact element 3 at a time of disconnection of the circuit breaker 1. [0015] The electromagnetic actuator 5 includes a plunger 51 and an electromagnet 52. The electromagnet 52 is fixed to the housing 2, and is configured to displace the plunger 51 with respect to the housing 2.
[0016] The plunger 51 includes a movable core portion 53 accommodated in the electromagnet 52 and a protruding portion 54 protruding from the movable core portion 53 to outside of the electromagnet 52. Further, the plunger 51 is displaceable with respect to the housing 2 between an advance position at which the protruding portion 54 protrudes from the electromagnet 52 by a certain protrusion amount and a retreat position at which the protrusion amount of the protruding portion 54 from the electromagnet 52 is smaller than that in a case in which the plunger 51 is at the advance position. In this example, the plunger 51 is displaceable on a straight line extending along a vertical direction, and the advance position of the plunger 51 is set above the retreat position. Further, in this example, for example, a guide configured to guide displacement of the plunger 51 is arranged in the electromagnet 52 .
[0017] The electromagnet 52 includes a stationary core 55 fixed to the housing 2 and a coil 56 for connection provided to the stationary core 55.

[0018] The stationary core 55 includes a regulating portion 55a configured to regulate displacement of the plunger 51 by receiving the movable core portion 53 when the plunger 51 reaches the advance position. A gap between the regulating portion 55a of the stationary core 55 and the movable core portion 53 becomes largest when the plunger 51 is at the retreat position and becomes smaller as the plunger 51 is displaced from the retreat position toward the advance position.
[0019] The electromagnet 52 is configured to generate an electromagnetic attraction force for attracting the movable core portion 53 to the regulating portion 55a through energization of the coil 56 for connection. The plunger 51 is displaced from the retreat position to the advance position through generation of the electromagnetic attraction force of the electromagnet 52 . Further, the electromagnet 52 stops generating the electromagnetic attraction force when energization of the coil 56 for connection is stopped. The plunger 51 is displaced from the advance position to the retreat position due to, for example, its own weight when the electromagnetic attraction force of the electromagnet 52 is eliminated.
[0020] The link mechanism 6 includes a lever shaft 9 provided to the housing 2, a lever 61 that is supported by the lever shaft 9 and is rotatable about the lever shaft 9, a support shaft 10 provided to the housing 2, a movable support member 62 that is supported by the support shaft 10 and is rotatable about the support

shaft 10, an insulating rod 63 that is rotatably coupled to each of the lever 61 and the movable support member 62, a coupling body 64 that is rotatably coupled to each of the lever 61 and the plunger 51, and a restricting member 65 configured to restrict rotation of the coupling body 64 with respect to the lever 61. The lever shaft 9 and the support shaft 10 are provided to the housing 2, and hence respective positions of the lever shaft 9 and the support shaft 10 with respect to the stationary contact element 3 are fixed.
[0021] In the link mechanism 6 , the coupling body 64 , the lever 61, the insulating rod 63, and the movable support member 62 are displaced in accordance with displacement of the plunger 51. With this, the link mechanism 6 displaces the movable body 4 to the contact point contact position through displacement of the plunger 51 to the advance position and displaces the movable body 4 to the contact point separation position through displacement of the plunger 51 to the retreat position.
[0022] The lever shaft 9 is arranged at a position between the plunger 51 and the stationary contact element 3 in a horizontal direction. An intermediate portion of the lever 61 is mounted to the lever shaft 9. A first pin 11 is provided at one end portion of the lever 61, and a second pin 12 is provided at another end portion of the lever 61. In this example, a distance between the lever shaft 9 and the first pin 11 is longer a distance that between the lever shaft 9 and the second pin 12. The first pin 11 is positioned on the electromagnetic actuator 5 side of the lever shaft

9, and the second pin 12 is positioned on the stationary contact element 3 side of the lever shaft 9. The first pin 11 is positioned farther from the lever shaft 9 as compared to the plunger 51 in the horizontal direction. The coupling body 64 is rotatable about the first pin 11 with respect to the lever 61, and the insulating rod 63 is rotatable about the second pin 12 with respect to the lever 61.
[0023] The support shaft 10 is arranged at a position between the lever shaft 9 and the stationary contact element 3 in the horizontal direction. Further, the support shaft 10 is arranged in parallel to the lever shaft 9 . A lower end portion of the movable support member 62 is rotatably mounted to the support shaft 10.
[0024] A third pin 13 is provided at an intermediate portion of the movable support member 62 . The movable body 4 is rotatable about the third pin 13 with respect to the movable support member 62. A lower end portion of the movable piece 41 is mounted to the third pin 13. A pressure contact spring 66 being an elastic body is arranged between upper end portions of the movable support member 62 and the movable piece 41. The upper end portion of the movable piece 41 is connected to the upper end portion of the movable support member 62 through intermediation of the pressure contact spring 66. With this, the movable support member 62 is connected to the movable contact element 42 through intermediation of the pressure contact spring 66 and the movable piece 41. The magnitude of an elastic restoration force generated by the pressure contact spring

66 varies depending on rotation of the movable piece 41 with respect to the movable support member 62.
[0025] The movable body 4 is displaced between the contact point contact position and the contact point separation position through rotation of the movable support member 62 about the support shaft 10. Under a state in which the movable body 4 is separated from the stationary contact element 3, the movable body 4 is displaced integrally with the movable support member 62 with respect to the housing 2 . Under a state in which the movable body 4 reaches the contact point contact position, when the movable support member 62 is rotated in a direction of being brought close to the stationary contact element 3, the pressure contact spring 66 is compressed between the movable support member 62 and the movable body 4, and the movable contact element 42 of the movable body 4 is pressed against the stationary contact element 3 due to the elastic restoration force of the pressure contact spring 66.
[0026] Thus, through rotation about the support shaft 10, the movable support member 62 is displaceable among a non-connection position at which the movable contact element 42 is separated from the stationary contact element 3 at a time of disconnection, a connection start position at which the movable contact element 42 starts being brought into contact with the stationary contact element 3 in a connection operation process at a time of connection, and a connection completion position at which the movable support member 62 is brought closer to the movable piece 41 and the movable

contact element 42 as compared to the connection start position to press the movable contact element 42 against the stationary contact element 3. The movable support member 62 is brought close to the stationary contact element 3 by being displaced in the order of the non-connection position, the connection start position, and the connection completion position.
[0027] In this example, under a state in which the movable contact element 42 is separated from the stationary contact element 3, the pressure contact spring 66 is compressed in advance with a certain force between the movable support member 62 and the movable piece 41 so as to store energy. That is, in this example, a certain initial load for pressing the movable contact element 42 against the stationary contact element 3 is applied to the pressure contact spring 66 in advance. With this, in the circuit breaker 1, from a timing at which the movable contact element 42 is brought into contact with the stationary contact element 3 , that is, from a timing at which the movable support member 62 reaches the connection start position, a contact pressure of the movable contact element 42 with respect to the stationary contact element 3 is increased. In this example, the state in which the pressure contact spring 66 is compressed is kept by preventing the distance between the movable support member 62 and the movable piece 41 from increasing with a holding tool, and thus the initial load is applied to the pressure contact spring 66.
[0028] One end portion of the insulating rod 63 is coupled to

the lever 61 through intermediation of the second pin 12 , and another end portion of the insulating rod 63 is coupled to the movable support member 62 through intermediation of the third pin 13 . The insulating rod 63 is rotatable about the second pin 12 with respect to the lever 61, and is rotatable about the third pin 13 with respect to the movable support member 62. With this, the lever 61 is displaceably coupled to the movable support member 62 through intermediation of the insulating rod 63 . Further, the insulating rod 63 is made of a material having a high electric insulation property, for example, a resin. The lever 61 is electrically insulated from the movable body 4 by the insulating rod 63 . With this, a current flowing between the power supply side terminal 7 and the load side terminal 8 is prevented from leaking to the lever 61.
[0029] The coupling body 64 is configured to couple the lever 61 and the plunger 51 to each other. Further, the coupling body 64 includes a first coupling link 641 that is rotatably coupled to the lever 61, a second coupling link 642 that is coupled to the first coupling link 641 and rotatably coupled to the protruding portion 54 of the plunger 51, and a holding body 643 configured to hold an angle of the second coupling link 642 with respect to the first coupling link 641 at a first set angle.
[0030] One end portion of the first coupling link 641 is coupled to the lever 61 through intermediation of the first pin 11. The first coupling link 641 is rotatable about the first pin

11 with respect to the lever 61. A fourth pin 14 is provided to the protruding portion 54 of the plunger 51. One end portion of the second coupling link 642 is coupled to the plunger 51 through intermediation of the fourth pin 14. The second coupling link 642 is rotatable about the fourth pin 14 with respect to the plunger 51. Another end portion of the first coupling link 641 and another end portion of the second coupling link 642 are rotatably coupled to each other through intermediation of a fifth pin 15. [0031] The holding body 643 is connected to each of the first coupling link 641 and the second coupling link 642 . As the holding body 643, for example, an elastic body such as a spring or a rubber that stores energy in advance is used. The holding body 643 exerts a holding force so as to hold the angle of the second coupling link 642 with respect to the first coupling link 641 at the first set angle. That is, the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle with the holding force of the holding body 643 until a force acting on between the first coupling link 641 and the second coupling link 642 (hereinafter referred to as "action force between coupling links") caused by a moment acting on the periphery of the fifth pin 15 reaches a certain limit value. Meanwhile, when the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, exceeds the certain limit value, the second coupling link 642 is rotated against the holding force of the holding body 643 with respect to the first

coupling link 641, and the angle of the second coupling link 642 with respect to the first coupling link 641 changes due to elastic deformation of the holding body 643. In this example, the first set angle is set to an obtuse angle larger than 90°. It is only required that the first set angle be an angle other than 180°, and may be 90° or an acute angle smaller than 90°.
[0032] Under a state in which the movable contact element 42 is separated from the stationary contact element 3, that is, under a state in which the movable support member 62 is positioned on the non-connection position side from the connection start position, the action force between coupling links is smaller than the certain limit value, and the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle.
[0033] Meanwhile, in a process in which the movable support member 62 reaches the connection start position to bring the movable contact element 42 into contact with the stationary contact element 3 at the contact point contact position, and then the movable support member 62 reaches the connection completion position through displacement of the plunger 51 to the advance position, the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, exceeds the certain limit value, and the angle of the second coupling link 642 with respect to the first coupling link 641 is smaller than the first set angle against the holding force of the holding body 643 .

That is, under a state in which the movable body 4 is pressed against the stationary contact element 3 at the contact point contact position, and the movable support member 62 reaches the connection completion position, with the plunger 51 reaching the advance position, the angle of the second coupling link 642 with respect to the first coupling link 641 is smaller than the first set angle against the holding force of the holding body 643. [0034] The restricting member 65 is arranged between the lever 61 and the first coupling link 641. In this example, the restricting member 65 is fixed to the lever 61 under a state in which the restricting member 65 protrudes from a side surface of the lever 61 to the first coupling link 641. As the restricting member 65, for example, a protrusion or a pin fixed to the lever 61 is used. [0035] Further, in a process in which the movable support member 62 reaches the connection start position to bring the movable contact element 42 into contact with the stationary contact element 3 at the contact point contact position, and then the movable support member 62 reaches the connection completion position through displacement of the plunger 51 to the advance position, when the angle of the first coupling link 641 with respect to the lever 61 reaches a second set angle, the restricting member 65 receives the first coupling link 641. With this, the restricting member 65 restricts rotation of the first coupling link 641 with respect to the lever 61 in a direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second

set angle. In this example, the second set angle is set to an acute angle smaller than 90°. It is only required that the second set angle be an angle other than 180°, and may be 90° or an obtuse angle larger than 90°.
[0036] Specifically, when the angle of the first coupling link 641 with respect to the lever 61 is larger than the second set angle, the first coupling link 641 is freely rotated about the first pin 11 with respect to the lever 61. However, when the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the rotation of the first coupling link 641 in a direction of being brought close to the lever 61, that is, the rotation of the first coupling link 641 in a counterclockwise direction of FIG. 1 is restricted by the restricting member 65. With this, when an attempt is made to further rotate the first coupling link 641 with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second set angle, the first coupling link 641 is displaced integrally with the lever 61 while the angle of the first coupling link 641 with respect to the lever 61 is held at the second set angle.
[0037] Next, a connection operation of the circuit breaker 1 is described. FIG. 3 is a configuration view for schematically illustrating the main portions of the circuit breaker 1 at a time when the plunger 51 of FIG. 2 is at the retreat position. FIG. 4 is a configuration view for schematically illustrating the main

portions of the circuit breaker 1 at a time when the movable support member 62 reaches the connection start position while the plunger 51 of FIG. 3 is displaced to the advance position. FIG. 5 is a configuration view for schematically illustrating the circuit breaker 1 at a time when the first coupling link 641 is brought into abutment against the restricting member 65 while the plunger 51 of FIG. 4 is displaced to the advance position. FIG. 6 is a configuration view for schematically illustrating the circuit breaker 1 at a time when the plunger 51 of FIG. 5 reaches the advance position to press the movable body 4 against the stationary contact element 3 at the contact point contact position.
[0038] When the plunger 51 is at the retreat position, and the movable support member 62 is at the non-connection position, the movable body 4 is at the contact point separation position, and the movable contact element 42 is separated from the stationary contact element 3, as illustrated in FIG. 3. That is, when the plunger 51 is at the retreat position, the circuit breaker 1 is in an opened state.
[0039] When the circuit breaker 1 receives a connection instruction from outside, a current flows through the coil 56 for connection, and the coil 56 for connection is excited. When the coil 56 for connection is excited, the electromagnetic attraction force for attracting the movable core portion 53 of the plunger 51 to the regulating portion 55a of the stationary core 55 is generated in the electromagnet 52. With this, the force directed

from the retreat position to the advance position above the retreat position acts on the plunger 51, and the upward force acting on the plunger 51 is transmitted from the plunger 51 to the coupling body 64 . In this case, the load of the link mechanism 6 withstanding the displacement of the plunger 51 is only a friction force having a small magnitude of each of the elements 61 to 64 of the link mechanism 6, which occurs on the periphery of the lever shaft 9, the support shaft 10, and the first to fourth pins 11 to 14. Thus, in this case, the lever 61, the movable support member 62, the insulating rod 63, and the coupling body 64 are freely rotatable about the lever shaft 9, the support shaft 10, the second and third pins 12 and 13, and the first and fourth pins 11 and 14, respectively. That is, when the movable contact element 42 is separated from the stationary contact element 3, the force required for the electromagnetic actuator 5 to displace the coupling body 64 may be small, and the coupling body 64, the lever 61, the insulating rod 63, and the movable support member 62 are displaced in accordance with the displacement of the plunger 51.
[0040] Further, when the movable contact element 42 is separated from the stationary contact element 3, the action force between coupling links acting on between the first coupling link 641 and the second coupling link 642 is smaller than the certain limit value because the force required for the plunger 51 to displace the coupling body 64 is small. Thus, when the plunger 51 is displaced from the retreat position to the advance position, the

coupling body 64 is rotated integrally with each of the plunger 51 and the lever 61 while the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle. In this case, the coupling body 64 is rotated with respect to the lever 61 in a direction in which the first coupling link 641 is brought close to the lever 61, that is, in a counterclockwise direction of FIG. 3 about the first pin 11. With this, the lever 61 is rotated about the lever shaft 9 in a clockwise direction of FIG. 3. Further, the insulating rod 63 is rotated in the counterclockwise direction of FIG. 3 with respect to the lever 61, and the movable support member 62 is rotated about the support shaft 10 in the clockwise direction of FIG. 3. With this, the movable support member 62 is displaced from the non-connection position to the connection start position, and the movable body 4 is displaced integrally with the movable support member 62 in a direction of being brought close to the stationary contact element 3.
[0041] In this case, the direction of a force fl that acts on the lever 61 from the plunger 51 is a direction from the fourth pin 14 to the first pin 11, that is, an arrow direction of the force fl of FIG. 3. Further, in this case, a force line distance at which the force fl acts on the lever shaft 9 as a moment, that is, the moment action distance with respect to the lever 61 is a distance LI of FIG. 3, that is, the distance LI between the first pin 11 and the lever shaft 9.

[0042] After that, when the plunger 51 is further displaced to the advance position, the lever 61 is further rotated in the clockwise direction of FIG. 3 while the angle of the first coupling link 641 with respect to the lever 61 decreases. When the fourth pin 14 of the plunger 51 reaches a position separated from a reference line A by a distance xl, the movable support member 62 reaches the connection start position, and the movable body 4 reaches the contact point contact position as illustrated in FIG. 4, with the result that the movable contact element 42 is brought into contact with the stationary contact element 3. In this case, the direction of a force flr, which acts on the lever 61 from the plunger 51, is a direction from the fourth pin 14 to the first pin 11, that is, an arrow direction of the force f1' of FIG. 4. When the plunger 51 is further displaced to the advance position, the lever 61 is rotated about the lever shaft 9 in a clockwise direction of FIG. 4, and the movable support member 62 is displaced in a direction of being brought close to the movable body 4 from the connection start position to the connection position while the angle of the first coupling link 641 with respect to the lever 61 further decreases. With this, the pressure contact spring 66 is compressed between the movable body 4 and the movable support member 62 in accordance with rotation of the lever 61. In this case, a contact point resistance force according to the elastic restoration force of the pressure contact spring 66 acts on the movable contact element 42 . The action force between coupling links, which acts on between

the first coupling link 641 and the second coupling link 642, increases as a result of generation of the contact point resistance force with respect to the movable contact element 42 as a load. However, at this time, the contact point resistance force is smaller than the holding force of the holding body 643, and the angle of the first coupling link 641 with respect to the lever 61 is held at the first set angle.
[0043] After that, when the plunger 51 is displaced to the advance position, and the fourth pin 14 of the plunger 51 reaches a position separated from the reference line A by a distance x2, the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, and the first coupling link 641 is brought into abutment against the restricting member 65 as illustrated in FIG. 5. The reference line A is a straight line indicating the position of the fourth pin 14 at a time when the plunger 51 is at the retreat position. With this, the angle of the first coupling link 641 with respect to the lever 61 is prevented from becoming smaller than the second set angle, with the result that the first coupling link 641 is rotated integrally with the lever 61. Further, in this case, the action force between coupling links does not exceed the certain limit value, and the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle by the holding body 643. With this, the second coupling link 642 is also rotated integrally with the first coupling link 641. As a result, in this case, while

the angle of the first coupling link 641 with respect to the lever
61 is held at the second set angle, and the angle of the second
coupling link 642 with respect to the first coupling link 641 is
held at the first set angle, the lever 61, the first coupling link
641, and the second coupling link 642 are integrally rotated about
the lever shaft 9. Thus, when the fourth pin 14 of the plunger 51
reaches the position separated from the reference line A by the
distance x2, and the first coupling link 641 is brought into abutment
against the restricting member 65, the direction of the force acting
on the lever 61 from the plunger 51 changes from the arrow direction
of f1' of FIG. 4 to an arrow direction of f2 of FIG. 5, that is,
the direction in which the plunger 51 moves from the retreat position
to the advance position. With this, the action point of the force
from the plunger 51 to the lever 61 is brought close to the lever
shaft 9 from the position of the first pin 11, and a force line
distance at which the force f2 acts on the lever shaft 9 as a moment
changes to a distance L2 of FIG. 5 smaller than the distance LI
of FIG. 4.
[0044] After that, the plunger 51 is further displaced to reach the advance position at which the fourth pin 14 of the plunger 51 is separated from the reference line A by a distance x3 (x3>x2) as illustrated in FIG. 6. In this case, the movable support member
62 is rotated in a direction of being brought close to the movable
body 4 while compressing the pressure contact spring 6 6 to reach
the connection completion position. With this, the contact

pressure for pressing the movable contact element 42 against the stationary contact element 3 increases, and the contact pressure of the movable contact element 42 with respect to the stationary contact element 3 is ensured. Further, the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, increases as the plunger 51 is brought close to the advance position and exceeds the holding force of the holding body 643 by the time when the plunger 51 reaches the advance position. That is, the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642 increases as the movable support member 62 is brought close to the connection completion position from the connection start position and exceeds the holding force of the holding body 643 by the time when the movable support member 62 reaches the connection completion position. In this example, the displacement distance between the plunger 51 and the movable support member 62 from a time when the first coupling link 641 is brought into abutment against the restricting member 65 to a time when the action force between coupling links exceeds the holding force of the holding body 643 is small, and the action force between coupling links exceeds the holding force of the holding body 643 immediately after the first coupling link 641 is brought into abutment against the restricting member 65. When the action force between coupling links exceeds the holding force of the holding body 643 , the rotation of the second coupling link 642 with respect to the first coupling

link 641 is started against the holding force of the holding body 643, and the angle of the second coupling link 642 with respect to the first coupling link 641 decreases . In this case, the rotation of the first coupling link 641 with respect to the lever 61 is restricted by the restricting member 65, and the angle of the first coupling link 641 with respect to the lever 61 is held at the second set angle. Therefore, the lever 61 and the first coupling link 641 are integrally rotated about the lever shaft 9 . When the angle of the second coupling link 642 with respect to the first coupling link 641 decreases against the holding force of the holding body 643, the direction of the force acting on the lever 61 from the plunger 51 changes from the arrow direction of f2 of FIG. 5 to an arrow direction of f3 of FIG. 6, that is, a direction from the fourth pin 14 to the fifth pin 15 . With this, the action point of the force from the plunger 51 to the lever 61 is further brought close to the lever shaft 9, and a force line distance at which the force f3 acts on the lever shaft 9 as a moment changes to a distance L3 of FIG. 6 smaller than the distance L2 of FIG. 5. [0045] When the plunger 51 reaches the advance position, and the movable support member 62 reaches the connection completion position, the movable core portion 53 of the plunger 51 is brought into contact with the regulating portion 55a of the stationary core 55, to thereby complete the connection operation of the circuit breaker 1. When the plunger 51 reaches the advance position, and the movable support member 62 reaches the connection completion

position, the angle of the second coupling link 642 with respect to the first coupling link 641 is smaller than the first set angle against the holding force of the holding body 643 under a state in which the angle of the first coupling link 641 with respect to the lever 61 is held at the second set angle by the restricting member 65. Further, under a state in which the plunger 51 reaches the advance position, and the movable support member 62 reaches the connection completion position, the third pin 13 is positioned at a dead center positioned on a straight line passing through the lever shaft 9 and the second pin 12 or in the vicinity of the dead center.
[0046] Here, FIG. 7 is a graph for showing a relationship between a load moment [N-mm] required for rotating the lever 61 of FIG. 1 and a stroke [mm] from the retreat position to the advance position of the plunger 51. FIG. 8 is a graph for showing a relationship between an electromagnetic attraction force [N] generated by the electromagnetic actuator 5 of FIG. 1 and the stroke
[mm] from the retreat position to the advance position of the plunger 51. In FIG. 7 and FIG. 8, the state in which the plunger 51 is at the retreat position is shown as an opened state of the circuit breaker 1, and the state in which the plunger 51 is at the advance position is shown as a connected state of the circuit breaker 1.
[0047] When the plunger 51 is displaced from the retreat position to the advance position, the load moment required for rotating the lever 61 has a magnitude based on a small friction

force of each of the elements 61 to 64 on the periphery of each of the lever shaft 9, the support shaft 10, and the first to fourth pins 11 to 14 and hence is kept at a certain small value until the movable contact element 42 is brought into contact with the stationary contact element 3, that is, until the contact point contact as shown in FIG. 7. When the movable support member 6 2 reaches the connection start position, and the movable contact element 42 is brought into contact with the stationary contact element 3, the contact point resistance force according to the initial load stored in the pressure contact spring 66 is generated as a load, and the load moment required for rotating the lever 61 abruptly increases. The movable support member 62 is rotated about the support shaft 10 in accordance with the rotation of the lever 61 after the movable contact element 42 is brought into contact with the stationary contact element 3 until the plunger 51 reaches the advance position. Therefore, although the elastic restoration force stored in the pressure contact spring 66 increases, a toggle mechanism formed of the lever 61 and the insulating rod 63 is brought close to the dead center. As a result, by virtue of this effect of the toggle mechanism, the magnitude of the load moment required for rotating the lever 61 abruptly approaches 0. [0048] Meanwhile, the electromagnetic attraction force generated by the electromagnet 52 of the electromagnetic actuator 5 abruptly increases in inverse proportion to the distance between the movable core portion 53 of the plunger 51 and the regulating

portion 55a of the stationary core 55 as shown in FIG. 8 . Therefore, the magnitude of the electromagnetic attraction force of the electromagnet 52 becomes maximum at a time when the plunger 51 reaches the advance position.
[0049] The moment action distance required for rotating the lever 61 is roughly estimated based on the respective characteristics of the load moment required for rotating the lever 61 (FIG. 7) and the electromagnetic attraction force generated by the electromagnet 52 (FIG. 8) as shown in a graph of FIG. 9. FIG. 9 is a graph for showing a relationship between the moment action distance required for rotating the lever 61 of FIG. 1 and the stroke
[mm] from the retreat position (opened state) to the advance position (connected state) of the plunger 51.
[0050] As shown in FIG. 9, at a time when the displacement of the plunger 51 is started from the retreat position to the advance position, the electromagnetic attraction force of the electromagnet is small with respect to the load moment acting on the lever 61, and hence a moment action distance having a certain degree of magnitude is required for rotating the lever 61. Further, from a time when the displacement of the plunger 51 is started toward the advance position to a time when the movable contact element 42 is brought into contact with the stationary contact element 3, the load moment required for rotating the lever 61 is substantially constant as shown in FIG. 7, and the electromagnetic attraction force generated by the electromagnet 52 minutely increases as shown

in FIG. 8. Therefore, the moment action distance required for rotating the lever 61 is minutely reduced from the distance at a time of the displacement start of the plunger 51 as shown in FIG. 9. At a time when the movable support member 62 reaches the connection start position, and the movable contact element 42 is brought into contact with the stationary contact element 3, the load moment required for rotating the lever 61 abruptly increases as shown in FIG. 7, and hence the moment action distance required for rotating the lever 61 also abruptly increases. After the movable contact element 42 is brought into contact with the stationary contact element 3 until the plunger 51 reaches the advance position, the magnitude of the load moment required for rotating the lever 61 abruptly decreases, and the electromagnetic attraction force generated by the electromagnet 52 abruptly increases. Therefore, the moment action distance required for rotating the lever 61 also abruptly approaches 0 as the plunger 51 is brought close to the advance position.
[0051] FIG. 10 is a graph for showing a comparison between a moment action distance [mm] with respect to the lever 61, which is caused during the connection operation of the circuit breaker 1 of FIG. 1, and a moment action distance [mm] required for rotating the lever 61 during the connection operation of the circuit breaker 1 of FIG. 1. In FIG. 10, the moment action distance with respect to the lever 61, which is caused during the connection operation of the circuit breaker 1, is represented by the solid line, and

the moment action distance required for rotating the lever 61 during the connection operation of the circuit breaker 1 is represented by the broken line.
[0052] As shown in FIG. 10, the moment action distance with respect to the lever 61, which is caused during the connection operation of the circuit breaker 1, is a large distance LI from a time when the displacement of the plunger 51 is started until the contact point contact time, at which the movable support member 62 reaches the connection start position, and the movable contact element 42 is brought into contact with the stationary contact element 3, has elapsed. When the rotation of the first coupling link 641 with respect to the lever 61 is restricted by the restricting member 65 after the contact point contact time has elapsed, the moment action distance with respect to the lever 61 changes to a distance L2 smaller than LI. After that, when the plunger 51 is further displaced to the advance position, and the movable support member 62 is further displaced to the connection completion position, the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, exceeds the holding force of the holding body 643, and the second coupling link 642 is rotated with respect to the first coupling link 641, with the result that the angle of the second coupling link 642 with respect to the first coupling link 641 becomes smaller than the first set angle. With this, the moment action distance with respect to the lever 61 changes to a distance L3

further smaller than L2 . After that, until the plunger 51 reaches the advance position, and the movable support member 62 reaches the connection completion position to complete the connection operation of the circuit breaker 1, the moment action distance with respect to the lever 61 slightly changes through displacement of each element of the link mechanism 6 but remains at a value close to about L3 . Thus, when the characteristics of the moment action distance that are changed by the restricting member 65 and the holding body 643 are set in accordance with the characteristics of the moment action distance required for the circuit breaker 1, the ability of the electromagnet 52 can be effectively used with respect to the characteristics of the moment action distance required for the connection operation of the circuit breaker 1. [0053] In the circuit breaker 1, the restricting member 65 restricts the rotation of the first coupling link 641 with respect to the lever 61 so that the angle of the first coupling link 641 with respect to the lever 61 does not become smaller than the second set angle, and the holding body 643 holds the angle of the second coupling link 642 with respect to the first coupling link 641 at the first set angle. Therefore, when the plunger 51 is displaced from the retreat position to the advance position, the restricting member 65 restricts the rotation of the first coupling link 64 with respect to the lever 61, and the angle of the second coupling link 642 with respect to the first coupling link 641 decreases against the holding force of the holding body 643, with the result that

the action point of the force for connection of the electromagnetic actuator 5 with respect to the lever 61 can be brought close to the lever shaft 9. That is, through arrangement of each of the elements 61 to 65 of the link mechanism 6, the second set angle restricted by the restricting member 65, and design of the holding force of the holding body 643, the action point of the force for connection of the electromagnetic actuator 5 during the connection operation can be changed largely and freely without depending on the stroke of the plunger 51. With this, the moment action distance with respect to the lever 61 can be reduced in accordance with the force for connection of the electromagnetic actuator 5 that increases through displacement of the plunger 51 from the retreat position to the advance position, and the electromagnetic attraction force of the electromagnet 52 can be efficiently used for the connection operation of the circuit breaker 1. Thus, the electromagnet 52 having a size according to a change in moment action distance required for the connection operation of the circuit breaker 1 can be used, and the electromagnet 52 can be downsized and reduced in cost. Further, wear in association with friction is less liable to occur in the link mechanism 6. Therefore, stable load characteristics can be maintained irrespective of the number of connection operations of the circuit breaker 1, and stability of the operation of the circuit breaker 1 can be improved. In addition, durability of the circuit breaker 1 can be easily managed. [0054] Further, the first coupling link 641 and the second

coupling link 642 are rotatably coupled to each other through intermediation of the fifth pin 15, and the holding body 643 is connected to each of the first coupling link 641 and the second coupling link 642. Therefore, the first coupling link 641, the second coupling link 642, and the holding body 643 can be easily assembled, and the coupling body 64 can be easily manufactured.
[0055] In the above-mentioned example, during the connection operation of the circuit breaker 1, the first coupling link 641 is brought into abutment against the restricting member 65 after the movable contact element 42 is brought into contact with the stationary contact element 3, that is, after the movable support member 62 is brought closer to the connection completion position as compared to the connection start position. However, the first coupling link 641 may be brought into abutment against the restricting member 65 to restrict the rotation of the first coupling link 641 with respect to the lever 61 before the movable contact element 42 is brought into contact with the stationary contact element 3, that is, when the movable support member 62 is on the non-connection position side from the connection start position.
[0056] When the first coupling link 641 is brought into abutment against the restricting member 65 before the movable contact element 42 is brought into contact with the stationary contact element 3, that is, when the movable support member 62 is on the non-connection position side from the connection start position, the connection operation of the circuit breaker 1 is

performed as follows.
[0057] Specifically, when the plunger 51 is displaced from the retreat position to the advance position, the coupling body 64, the lever 61, the insulating rod 63, and the movable support member 62 are displaced in accordance with the displacement of the plunger 51, and the movable body 4 is displaced to the contact point contact position, while the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle in the same manner as in the above-mentioned example until the first coupling link 641 is brought into abutment against the restricting member 65 . In this case, the angle of the first coupling link 641 with respect to the lever 61 decreases in accordance with the displacement of the plunger 51. Further, in this case, the direction of the force acting on the lever 61 from the plunger 51 is a direction from the fourth pin 14 to the first pin 11, and the moment action distance with respect to the lever 61 is the distance LI between the first pin 11 and the lever shaft 9. [0058] After that, when the plunger 51 is further displaced to the advance position, and the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the first coupling link 641 is brought into abutment against the restricting member 65 before the movable support member 62 reaches the connection start position. With this, the angle of the first coupling link 641 with respect to the lever 61 is prevented from becoming smaller than the second set angle, with the result that

the first coupling link 641 is rotated integrally with the lever 61. Further, in this case, the action force between coupling links does not exceed the certain limit value, and the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle by the holding body 643. That is, when the first coupling link 641 is brought into abutment against the restricting member 65, the lever 61, the first coupling link 641, and the second coupling link 642 are integrally rotated about the lever shaft 9 while the angle of the first coupling link 641 with respect to the lever 61 is held at the second set angle, and the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle. Thus, in this case, the direction of the force acting on the lever 61 from the plunger 51 changes to a direction in which the plunger 51 moves from the retreat position to the advance position, and the moment action distance with respect to the lever 61 also changes to the distance L2 smaller than the distance LI.
[0059] After that, when the plunger 51 is further displaced to the advance position, the movable support member 62 reaches the connection start position, and the movable body 4 reaches the contact point contact position. With this, the movable contact element 42 is brought into contact with the stationary contact element 3. After that, the plunger 51 is further displaced to the advance position, and the movable support member 62 is displaced from the connection start position to the connection completion

position. With this, the contact point resistance force according to the initial load stored in the pressure contact spring 66 is generated as a load, and the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, increases. When the action force between coupling links exceeds the holding force of the holding body 643, the rotation of the second coupling link 642 with respect to the first coupling link 641 is started against the holding force of the holding body 643, and the angle of the second coupling link 642 with respect to the first coupling link 641 decreases. In this case, the lever 61 and the first coupling link 641 are integrally rotated about the lever shaft 9. When the angle of the second coupling link 642 with respect to the first coupling link 641 decreases against the holding force of the holding body 643, the direction of the force acting on the lever 61 from the plunger 51 changes to the direction from the fourth pin 14 to the fifth pin 15, and the moment action distance with respect to the lever 61 also changes to the distance L3 smaller than the distance L2. [0060] After that, the plunger 51 is displaced until the plunger 51 reaches the advance position. In this case, the lever 61 and the first coupling link 641 are integrally rotated about the lever shaft 9 while the second coupling link 642 is further rotated with respect to the first coupling link 641 against the holding force of the holding body 643, and the insulating rod 63 is displaced in accordance with the rotation of the lever 61. With

this, the movable support member 62 is rotated about the support shaft 10 in the direction of being brought close to the movable body 4 toward the connection completion position in accordance with the displacement of the insulating rod 63, and the pressure contact spring 6 6 is compressed between the movable body 4 and the movable support member 62. With this, the contact pressure for pressing the movable contact element 42 against the stationary contact element 3 increases, and the contact pressure of the movable contact element 42 with respect to the stationary contact element 3 is ensured.
[0061] As described above, even when the first coupling link 641 is brought into abutment against the restricting member 65 before the movable contact element 42 is brought into contact with the stationary contact element 3, that is, when the movable support member 62 is on the non-connection position side from the connection start position, the moment action distance with respect to the lever 61 can be reduced when the plunger 51 is displaced from the retreat position to the advance position. With this, the moment action distance with respect to the lever 61 can be reduced in accordance with the force for connection of the electromagnetic actuator 5, which increases through displacement of the plunger 51 from the retreat position to the advance position, and the electromagnetic attraction force of the electromagnet 52 can be efficiently used for the connection operation of the circuit breaker 1.
[0062] Second Embodiment

In the second embodiment, the restricting member 65 is formed of an elastic member. As the restricting member 65, for example, a spring or a rubber is used. The restricting member 65 is provided on the lever 61 under a state of being compressed to be elastically deformed with a holding tool (not shown) . With this, the restricting member 65 stores an initial load exceeding the holding force of the holding body 643 configured to hold the angle of the second coupling link 642 with respect to the first coupling link 641 at the first set angle. In the link mechanism 6, when the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the restricting member 65 receives the first coupling link 641 to restrict the rotation of the first coupling link 641 with respect to the lever 61. Other configurations and operations are the same as those of the first embodiment.
[0063] During the connection operation of this embodiment, when the plunger 51 is displaced to the advance position, the first coupling link 641 is freely rotated with respect to the lever 61 while the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle with the holding force of the holding body 643 until the first coupling link 641 is brought into abutment against the restricting member 65.
[0064] When the first coupling link 641 is brought into abutment against the restricting member 65, the lever 61 and the first coupling link 641 are integrally rotated about the lever shaft

9 while the angle of the first coupling link 641 with respect to the lever 61 is held at the second set angle. In this case, the restricting member 65 is formed of an elastic member, and hence the impact which the restricting member 65 receives from the first coupling link 641 is absorbed by elastic deformation of the restricting member 65. Further, in this case, the direction of the force acting on the lever 61 from the plunger 51 changes from the arrow direction of the force f1' of FIG. 4 to the arrow direction of the force f2 of FIG. 5 in the same manner as in the first embodiment. Further, in this case, the force line distance at which the force from the plunger 51 acts on the lever shaft 9 as a moment, that is, the moment action distance of the lever 61 also changes from the distance LI of FIG. 4 to the distance L2 of FIG. 5. [0065] After that, the movable support member 62 is rotated in the direction of being brought close to the movable body 4 as the plunger 51 is brought close to the advance position. With this, the contact point resistance force with respect to the movable contact element 42 increases as a load of the link mechanism 6. In this case, the rotation force of the first coupling link 641 with respect to the lever 61 does not exceed the initial load of the restricting member 65, and the action force between coupling links acting on between the first coupling link 641 and the second coupling link 642 exceeds the holding force of the holding body 643. With this, the lever 61 and the first coupling link 641 are rotated about the lever shaft 9 while the angle of the first coupling

link 641 with respect to the lever 61 is held at the second set angle by the restricting member 65 . Meanwhile, the second coupling link 642 is rotated about the first coupling link 641, and the angle of the second coupling link 642 with respect to the first coupling link 641 decreases against the holding force of the holding body 643. With this, the direction of the force acting on the lever 61 from the plunger 51 changes from the arrow direction of the force f2 of FIG. 5 to the arrow direction of the force f3 of FIG. 6 in the same manner as in the first embodiment. Further, in this case, the force line distance at which the force from the plunger 51 acts on the lever shaft 9 as a moment, that is, the moment action distance of the lever 61 also changes from the distance L2 of FIG. 5 to the distance L3 of FIG. 6.
[0066] In the circuit breaker 1 as described above, the restricting member 65 is formed of an elastic member, and the initial load exceeding the holding force of the holding body 643 configured to hold the first set angle is stored in the restricting member 65 . Therefore, the angle of the first coupling link 641 with respect to the lever 61 can be elastically restricted by the restricting member 65, and the impact force and noise caused when the first coupling link 641 is brought into abutment against the restricting member 65 can be alleviated. With this, the impact force with respect to the lever 61 and the first coupling link 641 during operation of the circuit breaker 1 can be alleviated, and the required strength of the lever 61 and the first coupling link 641

can be reduced. Thus, the circuit breaker 1 can be further downsized. [0067] Third Embodiment
In the first and second embodiments, the restricting member 65 is fixed to the lever 61, but the restricting member 65 may be provided on the lever 61 so as to be slidable in a longitudinal direction of the lever 61. In this embodiment, the restricting member 65 is slidable with respect to the lever 61 between a normal position and an operation position that is closer to the lever shaft 9 than the normal position. The material for the restricting member 65 in this embodiment is the same as that for the restricting member 65 in the first embodiment. Further, the restricting member 65 is held at the normal position with the elastic restoration force of an elastic body, for example, a spring (not shown) with respect to the lever 61. Further, the restricting member 65 is slidable with respect to the lever 61 from the normal position and the operation position when a force against the elastic restoration force of the elastic body is applied to the restricting member 65. [0068] When the restricting member 65 is held at the operation position with respect to the lever 61, the restricting member 65 restricts the rotation of the first coupling link 641 with respect to the lever 61 in a direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second set angle. Further, when the restricting member 65 is at the normal position, the first coupling link 641 is brought into abutment

against the restricting member 65 when the angle of the first coupling link 641 with respect to the lever 61 reaches a third set angle larger than the second set angle. Further, under a state in which the first coupling link 641 is held in abutment against the restricting member 65, the first coupling link 641 presses the restricting member 65 against the elastic restoration force of the elastic body to cause the restricting member 65 to slide with respect to the lever 61 from the normal position to the operation position, with the result that the first coupling link 641 is rotated with respect to the lever 61 in a direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the third set angle. Other configurations are the same as those of the first embodiment.
[0069] Next, an operation is described. When the circuit breaker 1 is in an opened state, the first coupling link 641 is separated from the restricting member 65, and the restricting member 65 is held at the normal position with the elastic restoration force of the elastic body. When the circuit breaker 1 performs the connection operation, the plunger 51 is displaced from the retreat position to the advance position, and with this, the movable support member 62 is displaced from the non-connection position to the connection start position. When the movable support member 62 reaches the connection start position, the movable body 4 reaches the contact point contact position, and the movable contact element 42 is brought into contact with the stationary contact element 3.

In this case, the angle of the first coupling link 641 with respect to the lever 61 is larger than the third set angle, and the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle by the holding body 643.
[0070] When the plunger 51 is further displaced to the advance position after the movable support member 62 reaches the connection start position, the movable support member 62 is displaced from the connection start position to the connection completion position, and the contact resistance force acts on the movable contact element 42 having the pressure contact spring 66 compressed thereon. With this, the angle of the first coupling link 641 with respect to the lever 61 reaches the third set angle to bring the first coupling link 641 into abutment against the restricting member 65, and the angle of the second coupling link 641 with respect to the first coupling link 641 becomes smaller than the first set angle against the holding force of the holding body 643.
[0071] After that, when an attempt is made to further rotate the first coupling link 641 with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the third set angle by further displacing the plunger 51 to the advance position, the restricting member 65 starts being displaced from the normal position to the operation position with a reaction force received from the first coupling link 641 against the elastic restoration force of the elastic body. In this case, when a load for pressing

the restricting member 65 with the first coupling link 641 reaches a load larger than the holding force of the holding body 643 for holding the first set angle, the displacement of the restricting member 65 from the normal position to the operation position is started.
[0072] When the restricting member 65 starts being displaced from the normal position to the operation position, the first coupling link 641 is rotated with respect to the lever 61 in accordance with the displacement of the restricting member 65 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the third set angle. When the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the restricting member 65 reaches the operation position. When the restricting member 65 reaches the operation position, the displacement of the restricting member 65 is stopped. With this, the first coupling link 641 is prevented from being rotated with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second set angle.
[0073] While the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle from the third set angle, the direction of the force acting on the lever 61 from the plunger 51 changes from the arrow direction of the force f1' of FIG. 4 to the arrow direction of the force f2 of FIG. 5 in the same manner as in the first embodiment. In this case, in this

embodiment, the restricting member 65 is displaced from the normal position to the operation position with the reaction force received from the first coupling link 641. Therefore, the direction and magnitude of the force f1' changes continuously and gently to the direction and magnitude of the force f2 without abruptly changing. [0074] After that, the movable support member 62 is displaced in the direction of the connection completion position as the plunger 51 is brought close to the advance position. With this, the contact point resistance force with respect to the movable contact element 42 increases as a load of the link mechanism 6. In this case, under a state in which the restricting member 65 is held at the operation position with respect to the lever 61, the restricting member 65 receives the first coupling link 641. Further, in this case, the reaction force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, is more than the holding force of the holding body 643. With this, the lever 61 and the first coupling link 641 are rotated integrally about the lever shaft 9 while the angle of the first coupling link 641 with respect to the lever 61 is held at the second set angle. Meanwhile, the second coupling link 642 is rotated about the first coupling link 641, and the angle of the second coupling link 642 with respect to the first coupling link 641 decreases against the holding force of the holding body 643. With this, the direction of the force acting on the lever 61 from the plunger 51 continuously changes from the arrow direction of

the force f2 of FIG. 5 to the arrow direction of the force f3 of FIG. 6. Further, in this case, the force line distance at which the force from the plunger 51 acts on the lever shaft 9 as a moment, that is, the moment action distance of the lever 61 also continuously changes from the distance L2 of FIG. 5 to the distance L3 of FIG. 6.
[0075] In the circuit breaker 1 as described above, the restricting member 65 is slidable with respect to the lever 61 between the normal position and the operation position that is closer to the lever shaft 9 than the normal position. Therefore, when the first coupling link 641 is rotated with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 decreases, the first coupling link 641 can be rotated with respect to the lever 61 while the restricting member 65 is pressed to slide with respect to the lever 61, and the direction and magnitude of the force acting on the lever 61 from the plunger 51 can be gently and continuously changed. With this, the energy required for the characteristics of the load required for the electromagnet 52 after the first coupling link 641 is brought into abutment against the restricting member 65 can be further reduced. Thus, the electromagnet 52 can be downsized, and the circuit breaker 1 can be further downsized.
[0076] In the above-mentioned example, the same restricting member as that of the first embodiment is used as the restricting member 65. However, the elastic member used as the restricting

member of the second embodiment may also be used as the restricting member 65 in this embodiment. [0077] Fourth Embodiment
FIG. 11 is a configuration view for illustrating the circuit breaker 1 according to a fourth embodiment of the present invention. The first coupling link 641 and the second coupling link 642 are not directly coupled to each other, but coupled to each other through intermediation of the holding body 643 bent in a U-shape. As the holding body 643, for example, a plate spring is used. In this example, the thickness of the holding body 643 is set to be smaller than that of each of the first coupling link 641 and the second coupling link 642, and the holding body 643 is elastically deformed more easily than the first coupling link 641 and the second coupling link 642. Further, in this example, the coupling body 64 is formed of a single material that is an integrated molded body. The angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle by the holding body 643. Other configurations and operations are the same as those of the first embodiment.
[0078] In the connection operation of this embodiment, when the plunger 51 is displaced to the advance position, the direction of the force acting on the lever 61 from the plunger 51 is a direction from the bent portion of the holding body 643 to the first pin 11 until the first coupling link 641 is brought into abutment against the restricting member 65.

[0079] When the first coupling link 641 is brought into abutment against the restricting member 65, the direction of the force acting on the lever 61 from the plunger 51 changes to the direction in which the plunger 51 moves from the retreat position to the advance position, and the moment action distance with respect to the lever 61 becomes short. After that, the lever 61 and the coupling body 64 are integrally rotated about the lever shaft 9 while the angle of the first coupling link 641 with respect to the lever 61 is kept at the second set angle, and the angle of the second coupling link 642 with respect to the first coupling link 641 is kept at the first set angle until the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, exceeds the holding force of the holding body 643.
[0080] When the action force between coupling links, which acts on between the first coupling link 641 and the second coupling link 642, exceeds the holding force of the holding body 643, the second coupling link 642 is rotated with respect to the first coupling link 641 while the holding body 643 is elastically deformed in a direction in which a bent angle of the holding body 643 decreases . With this, the angle of the second coupling link 642 with respect to the first coupling link 641 becomes smaller than the first set angle against the holding force of the holding body 643. In this case, the direction of the force acting on the lever 61 from the plunger 51 changes to the direction from the fourth pin 14 to the

bent portion of the holding body 643, and the moment action distance with respect to the lever 61 is further reduced.
[0081] In the circuit breaker 1, the first coupling link 641 and the second coupling link 642 are coupled to each other through intermediation of the holding body 643. Therefore, a pin for coupling the first coupling link 641 and the second coupling link 642 to each other can be omitted. With this, the number of components of the link mechanism 6 can be reduced, and the time and labor of an assembly operation of the link mechanism 6 can be reduced. Further, a loss caused by friction of the fifth pin 15 with respect to the first coupling link 641 and the second coupling link 642 can be eliminated, and hence the force from the plunger 51 can be efficiently transmitted to the movable body 4 by the link mechanism 6.
[0082] In the above-mentioned example, the coupling body 64 is formed of a single material, but the first coupling link 641, the second coupling link 642, and the holding body 643 may be formed of separate members. In this case, the holding body 643 is fixed to the first coupling link 641 and the second coupling link 642, for example, through welding or with a screw.
[0083] Further, in the above-mentioned example, the configuration in which the first coupling link 641 and the second coupling link 642 are coupled to each other through intermediation of the holding body 643 is applied to the coupling body 64 of the first embodiment. However, the configuration in which the first

coupling link 641 and the second coupling link 642 are coupled to each other through intermediation of the holding body 643 may be applied to the coupling body 64 of the second embodiment or the third embodiment.
[0084] Fifth Embodiment
In the fourth embodiment, the plate spring is used as the holding body 643 . However, a structure formed of a combination of a latch mechanism and an elastic body may be used as the holding body 643.
[0085] Specifically, the holding body 643 includes a latch mechanism and an auxiliary spring that is an elastic body. The latch mechanism includes a main body member arranged on the second coupling link 642, a cam member that is displaceably arranged on the first coupling link 641 and hung on the main body member, and a latch spring configured to hold the cam member on the first coupling link 641 under a state in which the cam member is hung on the main body member. The main body member and the cam member are each formed of a rigid body. The cam member protrudes from the first coupling link 641 to the restricting member 65 . When the angle of the first coupling link 641 with respect to the lever 61 is larger than the second set angle, the cam member is in a state of being hung on the main body member, and the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle. When the first coupling link 641 is rotated with respect to the lever 61 in the direction in which the angle

of the first coupling link 641 with respect to the lever 61 decreases, and the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the cam member is pressed against the restricting member 65 to come off the main body member in the latch mechanism. With this, the rotation of the first coupling link 641 with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second set angle is allowed. [0086] The auxiliary spring is arranged between the first coupling link 641 and the second coupling link 642. Further, the auxiliary spring generates an elastic restoration force against the rotation of the second coupling link 642 with respect to the first coupling link 641 in a direction in which the angle of the second coupling link 642 with respect to the first coupling link 641 becomes smaller than the first set angle. When the angle of the second coupling link 642 with respect to the first coupling link 641 becomes smaller than the first set angle against the elastic restoration force of the auxiliary spring, the force of the plunger 51 is transmitted from the second coupling link 642 to the first coupling link 641 through the auxiliary spring. That is, when the angle of the first coupling link 641 with respect to the lever 61 is larger than the second set angle, the holding force of the holding body 643 has a magnitude for strongly holding the angle of the second coupling link 642 with respect to the first coupling link 641 at the first set angle with the latch mechanism. However, when the

angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the holding force of the holding body 643 is weakened because holding by the latch mechanism is eliminated. Other configurations are the same as those of the first embodiment.
[0087] In the connection operation of the circuit breaker 1, as the plunger 51 is displaced from the retreat position to the advance position, the angle of the first coupling link 641 with respect to the lever 61 decreases. After that, when the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the first coupling link 641 is brought into abutment against the restricting member 65. In this case, the cam member of the latch mechanism is pressed against the restricting member 65 to come off the main body member. With this, the rotation of the first coupling link 641 with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second set angle is allowed. After that, when the plunger 51 is further displaced to the advance position, the second coupling link 642 is rotated with respect to the first coupling link 641 against the elastic restoration force of the auxiliary spring in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes smaller than the second set angle.
[0088] Meanwhile, in a disconnection operation of the circuit breaker 1, when the plunger 51 is displaced from the advance position to the retreat position, the second coupling link 642 is rotated

with respect to the first coupling link 641 in the direction in which the angle of the second coupling link 642 with respect to the first coupling link 641 increases, and the first coupling link 641 is rotated with respect to the lever 61 in the direction in which the angle of the first coupling link 641 with respect to the lever 61 becomes larger than the second set angle. With this, the cam member of the latch mechanism comes off the restricting member 65, and the state of the latch mechanism is returned to the state in which the cam member is hung on the main body member. When the state of the latch mechanism is returned to the state in which the cam member is hung on the main body member, the angle of the second coupling link 642 with respect to the first coupling link 641 is held at the first set angle again. The other operations are the same as those of the first embodiment.
[0089] In the circuit breaker 1, when the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the holding force of the holding body 643 is weakened. Therefore, when the angle of the first coupling link 641 with respect to the lever 61 is larger than the second set angle, the angle of the second coupling link 642 with respect to the first coupling link 641 can be held at the first set angle. When the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle, the angle of the second coupling link 642 with respect to the first coupling link 641 can be set to be smaller than the first set angle. With this, in the same manner as in the

first embodiment, the moment action distance with respect to the lever 61 can be reduced in accordance with the force for connection of the electromagnetic actuator 5 that increases through displacement of the plunger 51 from the retreat position to the advance position, and the electromagnetic attraction force of the electromagnet 52 can be efficiently used for the connection operation of the circuit breaker 1. Thus, the electromagnet 52 can be downsized and reduced in cost.
[0090] In the first, second, fourth, and fifth embodiments, the restricting member 65 is fixed to the lever 61, but the restricting member 65 may be provided in any other way as long as the rotation of the first coupling link 641 with respect to the lever 61 is restricted. For example, the restricting member 65 may be fixed to the first coupling link 641. Alternatively, the restricting member 65 may be rotatably arranged on the lever shaft 9 so that the restricting member 65 is caught between the lever 61 and the first coupling link 641 when the angle of the first coupling link 641 with respect to the lever 61 reaches the second set angle.
[0091] Further, in each of the above-mentioned embodiments, the electromagnet 52 includes the stationary core 55 and the coil 56 for connection, but the configuration of the electromagnet 52 is not limited thereto. For example, the electromagnet 52 may include, in addition to the stationary core 55 and the coil 56 for connection, a coil for disconnection configured to generate an

electromagnetic attraction force for displacing the plunger 51 in an opposite direction of the coil 56 for connection, that is, from the advance position to the retreat position. With this, the plunger 51 can be reliably displaced from the advance position to the retreat position, and the disconnection operation of the circuit breaker 1 can be reliably performed. Further, for example, the electromagnet 52 may include, in addition to the stationary core 55 and the coil 56 for connection, a permanent magnet for generating a magnetic force for holding the plunger 51 at the advance position after energization of the coil 56 for connection is stopped. With this, the plunger 51 can be held at the advance position under a state in which energization of the coil 56 for connection is stopped, with the result that the effect of energy saving can be improved. Further, the electromagnet 52 may be formed of a combination of the stationary core 55, the coil 56 for connection, the coil for disconnection, and the permanent magnet.
Reference Signs List
[0092] 1 circuit breaker, 2 housing (base), 3 stationary contact element, 4 movable body, 5 electromagnetic actuator, 6 link mechanism, 9 lever shaft, 10 support shaft, 15 fifth pin, 42 movable contact element, 51 plunger, 52 electromagnet, 61 lever, 64 coupling body, 65 restricting member, 641 first coupling link, 642 second coupling link, 643 holding body

Claims [Claim 1] A circuit breaker, comprising:
a stationary contact element;
a movable contact element, which is brought into contact with the stationary contact element at a time of connection and is separated from the stationary contact element at a time of disconnection;
a movable support member, which is connected to the movable contact element and is capable of being displaced among a non-connection position at which the movable contact element is separated from the stationary contact element at the time of disconnection, a connection start position at which the movable contact element starts being brought into contact with the stationary contact element in a connection operation process at the time of connection, and a connection completion position at which the movable support member is brought closer to the movable contact element as compared to the connection start position to press the movable contact element against the stationary contact element;
a lever, which is coupled to the movable support member;
a lever shaft, which is configured to rotatably support the lever;
a first coupling link, which is rotatably coupled to the lever;
a second coupling link, which is coupled to the first coupling

1 ink ;
a plunger, which is rotatably coupled to the second coupling 1 ink ;
an electromagnet, which is configured to displace the plunger in the connection operation process, to thereby displace the movable support member from the non-connection position to the connection completion position through the connection start position;
a holding body, which exerts a holding force so as to hold an angle of the second coupling link with respect to the first coupling link at a first set angle; and
a restricting member, which is configured to restrict rotation of the first coupling link with respect to the lever in a direction in which an angle of the first coupling link with respect to the lever becomes smaller than a second set angle.
[Claim 2] A circuit breaker according to claim 1, wherein the restricting member is configured to restrict the rotation of the first coupling link with respect to the lever in the direction in which the angle of the first coupling link with respect to the lever becomes smaller than the second set angle when the movable support member is brought closer to the connection completion position as compared to the connection start position.
[Claim 3] A circuit breaker according to claim 1,
wherein the first coupling link and the second coupling link

are rotatably coupled to each other through intermediation of a pin, and
wherein the holding body is connected to each of the first coupling link and the second coupling link.
[Claim 4] A circuit breaker according to claim 1, wherein the first coupling link and the second coupling link are coupled to each other through intermediation of the holding body.
[Claim 5] A circuit breaker according to claim 1, wherein the holding force of the holding body is weakened when the angle of the first coupling link with respect to the lever reaches the second set angle .
[Claim 6] A circuit breaker according to any one of claims 1 to
5, wherein, when the movable support member is at the connection
completion position, the angle of the first coupling link with
respect to the lever is the second set angle, and the angle of the
second coupling link with respect to the first coupling link is
smaller than the first set angle.
[Claim 7] A circuit breaker according to any one of claims 1 to
6, wherein the restricting member comprises an elastic member
storing an initial load higher than the holding force of the holding
body for holding the first set angle.