FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION [See section 10, Rule 13]
CIRCUIT BREAKER
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

DESCRIPTION
Field
[0001] The present invention relates to a structure of a circuit breaker in which a movable contact is brought into contact with and separated from a fixed contact.
Background
[0002] In related art, among circuit breakers in which an electromagnetic solenoid is used as a closing mechanism, such a type of circuit breakers that hold a closing state by application of current to the electromagnetic solenoid even after completion of closing, have been mainly developed. A circuit breaker that applies current to an electromagnetic solenoid even in the closing state is, however, problematic in that energy saving is difficult and in that a closing coil included in an electromagnetic solenoid is likely to be deteriorated owing to currents continuously flow in the closing coil.
[0003] Thus, Patent Literature 1 teaches development of a type of circuit breaker that holds, after completion of closing, the closing state by a tripping mechanism, and operates, for disconnection, the tripping mechanism to open the circuit breaker and terminates the closing state.
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Patent Application
Laid-open No. H06-84433
Summary

Technical Problem
[0005] In the circuit breaker described in Patent Literature 1, however, the number of components that constitute a link mechanism that operates when the circuit breaker opens is large. Thus, operations of such components in association with each other exhibit complicated behaviors, and moreover, long use of the components causes damage on the components and deterioration of mechanical characteristics over time, which may lower the reliability of the circuit breaker.
[000 6] In addition, the circuit breaker described in Patent Literature 1 exhibits characteristics of a soaring rise in mechanical load from the disconnected state to the closing state, and has largest mechanical load in the closing state. It is therefore necessary to provide a plurality of links to increase the reduction ratio, to reduce the tripping load, and in addition, to accommodate a complicated mechanism for increasing the reduction ratio within a limited arrangement area, which also deteriorates the assembling performance.
[0007] The present invention has been made in view of the above, and an object thereof is to provide a circuit breaker capable of reducing the load on the tripping mechanism, reducing the size of the tripping mechanism, and improving the assembling performance of the tripping mechanism.
Solution to Problem
[0008] To solve the aforementioned problems and achieve the object, a circuit breaker according to the present invention includes: a housing; a fixed terminal fixed to the housing, a fixed contact being attached to the fixed terminal; a mover holder connected with the housing in a

manner turnable about a first shaft center fixed to the housing; a mover turnably connected with the mover holder, a movable contact being attached to the mover; a contact pressure spring that applies pressure to the fixed contact and the movable contact when the fixed contact and the movable contact are in contact with each other; an electromagnetic solenoid including a plunger that moves linearly; a transfer mechanism that moves the mover with movement of the plunger to change from a disconnected state in which the movable contact is separated from the fixed contact to a closing state in which the movable contact is in contact with and electrically connected with the fixed contact; and a tripping mechanism that holds the closing state by engaging with the transfer mechanism and terminate the holding of the closing state by disengaging from the transfer mechanism. The transfer mechanism includes: a lever that turns about a second shaft center fixed to the housing with the movement of the plunger; and an insulating bar having one end turnably connected with one end of the lever, and an opposite end turnably connected with the mover. The plunger of the electromagnetic solenoid reaches, before a toggle mechanism constituted by the lever and the insulating bar reaches a dead center, a first position at which movement of the plunger is limited. The tripping mechanism engages with the transfer mechanism in a state in which the plunger is at a second position after having reached the first position and then having retracted, to hold the closing state.
Advantageous Effects of Invention
[0009] According to the present invention, advantageous effects of reducing the load on the tripping mechanism, reducing the size of the tripping mechanism, and improving

the assembling performance of the tripping mechanism are produced.
Brief Description of Drawings
[0010] FIG. 1 is a cross-sectional view illustrating an example of a configuration of a circuit breaker according to a first embodiment.
FIG. 2 is an enlarged view of a tripping mechanism illustrated in FIG. 1.
FIG. 3 is a configuration diagram illustrating a disconnected state of the circuit breaker according to the first embodiment.
FIG. 4 is an enlarged view of the tripping mechanism illustrated in FIG. 3.
FIG. 5 is a configuration diagram illustrating a state at a moment when contacts of the circuit breaker according to the first embodiment are started to be in contact with each other.
FIG. 6 is an enlarged view of the tripping mechanism illustrated in FIG. 5.
FIG. 7 is a configuration diagram illustrating a state of the circuit breaker according to the first embodiment in which a maximum closing position is reached.
FIG. 8 is an enlarged view of the tripping mechanism illustrated in FIG. 7.
FIG. 9 is an enlarged view of the tripping mechanism resulting from turning of a trip lever from the state illustrated in FIG. 7.
FIG. 10 is a configuration diagram illustrating a state of the circuit breaker according to the first embodiment in which a closing completion position is reached.
FIG. 11 is an enlarged view of the tripping mechanism

illustrated in FIG. 10.
FIG. 12 is a graph illustrating the relation between the position of movement of a core plunger and the amount of load applied to an electromagnetic solenoid according to the first embodiment.
FIG. 13 is a configuration diagram illustrating a disconnected state of a circuit breaker according to a second embodiment.
FIG. 14 is an enlarged view of a tripping mechanism illustrated in FIG. 13.
FIG. 15 is a configuration diagram illustrating a state of the tripping mechanism at a moment when contacts of the circuit breaker according to the second embodiment are started to be in contact with each other.
FIG. 16 is a configuration diagram illustrating a state of the tripping mechanism in a state in which a maximum closing position of the circuit breaker according to the second embodiment is reached.
FIG. 17 is a configuration diagram illustrating a state of the tripping mechanism in a state in which the maximum closing position of the circuit breaker according to the second embodiment is reached.
FIG. 18 is a configuration diagram illustrating a state of the tripping mechanism in a state in which a closing completion position of the circuit breaker according to the second embodiment is reached.
Description of Embodiments
[0011] A circuit breaker according to certain embodiments of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the embodiments.
[0012] First Embodiment.

A circuit breaker according to a first embodiment is an air circuit breaker for opening and closing a cable run such as a low-voltage power distribution line, and is configured to detect at least one of overcurrent and an electric leak and then disconnect the cable run. Hereinafter, for convenience of explanation, Z-axis positive direction is referred to as the upward direction, Z-axis negative direction is referred to as the downward direction, X-axis positive direction is referred to as the rightward direction, X-axis negative direction is referred to as the leftward direction, Y-axis positive direction is referred to as the frontward direction, and Y-axis negative direction is referred as to the rearward direction. In addition, hereinafter, clockwise and counterclockwise corresponding1y refer to c1ockwi se direction and counterclockwise direction on the drawings, which will be described later.
[0013] FIG. 1 is a diagram illustrating an example of a configuration of a circuit breaker according to the first embodiment of the present invention. As illustrated in FIG. 1, a circuit breaker 1 according to the first embodiment includes a housing 2 formed of an insulating member, a power supply terminal 3 and a load side terminal 4 each mounted on the housing 2 through a wall 2a of the housing 2, and a flexible conductor 5 having one end 5a connected with the load side terminal 4 inside the housing 2. The circuit breaker 1 also includes a mover 6 having one end 6a connected with the opposite end 5b of the flexible conductor 5, a mover holder 7 having one end 7a turnably mounted on the housing 2 inside the housing 2, and a contact pressure spring 8 having one end and the opposite end each of which is attached to corresponding one of an opposite end 7b of the mover holder 7 and the opposite end

6b of the mover 6.
[ 0014] The power supply terminal 3 is connected with a power supply side conductor, which is not illustrated, outside of the housing 2, and the load side terminal 4 is connected with a load side conductor, which is not illustrated, outside of the housing 2. A fixed contact 10 is electrically connected with the power supply terminal 3 inside the housing 2, and a movable contact 11 is electrically connected with the opposite end 6b of the mover 6. The power supply terminal 3 and the load side terminal 4 are fixed with a distance from each other. While the power supply terminal 3 is located above the load side terminal 4 in the example illustrated in FIG. 1, the load side terminal 4 may alternatively be located above the power supply terminal 3.
[0015] The flexible conductor 5 is a conductor having flexibility, with the one end 5a connected with the load side terminal 4 and the opposite end 5b connected with the mover 6. The flexible conductor 5 electrically connects the load side terminal 4 and the mover 6 with each other. As described above, the movable contact 11 is electrically connected with the mover 6. When the movable contact 11 comes into contact with the fixed contact 10, the circuit breaker 1 gets into a closing state in which the power supply terminal 3 and the load side terminal 4 are electrically connected with each other into a conducting state. When the movable contact 11 is separated from the fixed contact 10, the circuit breaker 1 gets into a disconnected state in which the power supply terminal 3 and the load side terminal 4 are electrically disconnected from each other.
[ 0016] The one end 7a of the mover holder 7 is attached to the housing 2 in such a manner that the mover holder 7

is turnable about a holder shaft center 12a by a holder shaft 12 . In addition, a middle portion 7c of the mover holder 7 is turnably attached to the one end 6a of the mover 6 with a connecting pin 13. The mover holder 7 is provided with a mover stopper 9.
[0017] The mover stopper 9 limits the angle at which the mover 6 turns about the connecting pin 13 relative to the mover holder 7. In the state illustrated in FIG. 1, the one end 6a of the mover 6 is in contact with the mover stopper 9. Thus, turning of the opposite end 6b of the mover 6 in the direction away from the opposite end 7b of the mover holder 7 is restricted by the mover stopper 9, but turning of the opposite end 6b of the mover 6 in the direction toward the opposite end 7b of the mover holder 7 is allowed.
[ 0018] The contact pressure spring 8 is a spring for pressing the movable contact 11 against the fixed contact 10. In the state illustrated in FIG. 1, the contact pressure spring 8 is in an energized state with a length shorter than its equilibrium length, which is a state with a predetermined initial contact pressure. Thus, when the opposite end 6b of the mover 6 turns in the direction toward the opposite end 7b of the mover holder 7, the distance between the opposite end 6b of the mover 6 and the opposite end 7b of the mover holder 7 becomes smaller, and the contact pressure spring 8 is further energized.
[0019] The circuit breaker 1 also includes an electromagnetic solenoid 2 0 located inside the housing 2 and serving as a closing actuator of the circuit breaker 1, a transfer mechanism 30 that transmits the driving force from the electromagnetic solenoid 2 0 to the mover 6 to make the movable contact 11 touch and leave the fixed contact 10, an opening spring 4 0 having one end and the opposite end

each of which is attached to corresponding one of the transfer mechanism 30 and the housing 2, and a tripping mechanism 50 that maintains the closing state and terminates the closing state.
[0020] The electromagnetic solenoid 20 includes a yoke 21 formed of a magnetic material, a closing coil 22 wound around a bobbin, which is not illustrated, and fixed to the inside of the yoke 21, a core plunger 23 capable of linearly reciprocating in the vertical direction (up-down direction), and a protruding portion 24 formed on a top of the core plunger 23. A guide, which is not illustrated, for guiding the moving direction of the core plunger 23 along the vertical direction is provided on at least one of the electromagnetic solenoid 2 0 and the housing 2, which allows the core plunger 2 3 to move only in the vertical direction. Note that the method of fixing the core plunger 2 3 and the protruding portion 2 4 is not limited as long as the core plunger 2 3 and the protruding portion 2 4 are fixed.
[ 0021] When power is supplied to the closing coil 22, electromagnetic attraction force is generated at the electromagnetic solenoid 20. The generated electromagnetic attraction force moves the core plunger 23 upward, the movement of the core plunger 2 3 is then limited at a point where a gap 25 between the core plunger 2 3 and the closing coil 22 is eliminated, and the core plunger 2 3 physically stops. Thus, the position where the core plunger 23 stops is the uppermost position of the core plunger 23, which will hereinafter be referred to as a maximum closing position or a maximum movement position. Note that the structure for stopping the core plunger 2 3 is not limited to the example described above. For example, a protruding portion may be provided on a bottom of the core plunger 23, so that the core plunger 2 3 physically stops by being

stopped by the bobbin of the closing coil 22 or the yoke 21.
[ 0022] After a lapse of a predetermined time from when the position of the core plunger 2 3 reached the maximum closing position, the power supply to the closing coil 22 is stopped and the electromagnetic solenoid 2 0 thus stops generation of the electromagnetic attraction force. When the electromagnetic attraction force of the electromagnetic solenoid 2 0 is eliminated, a downward force from the maximum closing position is applied to the core plunger 2 3 by the own weight of the core plunger 23 and the opening force of the opening spring 40, for example.
[0023] The transfer mechanism 30 includes a connecting link 31 having one end 31a turnably connected with the protruding portion 2 4 of the electromagnetic solenoid 20, a lever 32 turnably connected with the opposite end 31b of the connecting link 31, and an insulating bar 33 turnably connected with one end 32a of the lever 32.
[002 4] The one end 31a of the connecting link 31 is turnably connected with the protruding portion 2 4 of the electromagnetic solenoid 2 0 with a connecting pin 34, and the opposite end 31b of the connecting link 31 is turnably connected with the lever 32 with a connecting pin 35.
[002 5] The lever 32 is attached to a lever shaft 37 in such a manner as to be turnable about a lever shaft center 3 6 whose absolute position relative to the housing 2 is fixed. A region of the lever 32 closer to the tripping mechanism 50 with respect to the lever shaft 37 is connected with the opposite end 31b of the connecting link 31 with the connecting pin 35. The transfer mechanism 30 of the circuit breaker 1 also includes an engaging pin 51 that is fixed to the opposite end 32b of the lever 32.
[ 002 6] The insulating bar 33 has one end 33a that is turnably connected with the one end 32a of the lever 32

with a connecting pin 38, and the opposite end 33b that is turnably attached to the one end 6a of the mover 6 with the connecting pin 13. The insulating bar 33 is made of a materia], with high electric insulation SJCI as resin. Thus, current flowing between the power supply terminal 3 and the load side terminal 4 while the circuit breaker 1 is in the conducting state does not leak via the lever 32. Note that the insulating bar 33 need not be entirely made of an insulating material, but may be partially made of a conductor as long as insulation is provided between the connecting pin 13 and the connecting pin 38.
[002 7] The lever 32 and the insulating bar 33 constitute a toggle mechanism of four links in which the lever shaft center 3 6 and the holder shaft center 12a are fixed turning centers. Thus, as the arrangement of the lever shaft center 36, the connecting pin 38, and the connecting pin 13 is closer to a dead center at which the lever shaft center 3 6, the connecting pin 38, and the connecting pin 13 are arranged linearly, the transfer mechanism 30 can be driven with a smaller force. The protruding portion 24, the connecting link 31, the lever 32, the insulating bar 33, the mover 6, and the mover holder 7 constitute a link structure.
[ 002 8] As described above, the opening spring 4 0 has the one end and the opposite end each of which is attached to correspondi ng one of the .1 ever 32 and the housing 2, and the elastic restoring force of the opening spring 4 0 biases the transfer mechanism 30 to shift toward a disconnected state position, which will be described later.
[002 9] The tripping mechanism 50 has the functions of maintaining the closing state and terminating the closing state as described above. FIG. 2 is an enlarged view of the tripping mechanism illustrated in FIG. 1. In FIG. 2,

the housing 2 of the circuit breaker 1 is illustrated by a broken line.
[0030] As illustrated in FIG. 2, the tripping mechanism 50 includes a trip lever 52 that engages with the engaging pin 51 fixed to the opposite end 32b of the lever 32, and a first reset spring 53 having one end and the opposite end each of which is attached to corresponding one of the trip lever 52 and the housing 2. The tripping mechanism 50 also includes a trip bar 54 that is turned by a driving force of an actuator, which is not illustrated, and a second reset spring 55 having one end and the opposite end attached to the trip bar 54 and the housing 2, respectively. [ 0031] The engaging pin 51 protrudes from the lever 32 rightward in the direction perpendicular to the extending direction of the lever 32. The trip lever 52 has one end 52a attached in such a manner as to be turnable around a trip lever shaft center 60 fixed to the housing 2, and the opposite end 52b to which an are-like portion 5 6 having an arc face coming in contact with the engaging pin 51 during a closing process is provided. In addition, a recess 52c that is recessed rearward is formed at a middle portion of the trip lever 52. The recess 52c has an engaging face 57 that engages with the engaging pin 51 in the closing state. Furthermore, the trip lever 52 has an engaging portion 59 that engages with the trip bar 54 in a region in a front side of the opposite end 52b.
[ 0032] One end 54a of the trip bar 54 is attached to the housing 2 in such a manner as to be turnable about a trip bar shaft center 61, and has a semicircular portion 58 having a semicircular shape with its center at the trip bar shaft center 61. The semicircular portion 58 is constituted by an are-like portion 58a having an arc face and a flat portion 58b having a flat face.

[0033] The driving force of an actuator, which is not illustrated, turns the semicircular portion 58 about the trip bar shaft center 61, causing the are-like portion 58a of the semicircular portion 58 to be engaged with the engaging portion 59 formed at the one end 52a of the trip lever 52, which restricts turning of the opposite end 52b of the trip lever 52 frontward.
[0034 ] The second reset spring 55 biases the trip bar 54 in a direction causing the opposite end 54b of the trip bar 54 facing upward to turn frontward about the trip bar shaft center 61. In other words, the second reset spring 55 biases the trip bar 54 in the clockwise direction.
[0035] Operation of the circuit breaker 1 having the configuration as described above will be explained in detail. FIG. 3 is a configuration diagram illustrating a disconnected state of the circuit breaker according to the first embodiment, and FIG. 4 is an enlarged view of the tripping mechanism illustrated in FIG. 3. FIG. 5 is a configuration diagram illustrating a state at the moment when contacts of the circuit breaker according to the first embodiment are started to be in contact with each other, and FIG. 6 is an enlarged view of the tripping mechanism illustrated in FIG. 5. FIG. 7 is a configuration diagram illustrating a state of the circuit breaker according to the first embodiment in which the maximum closing position is reached, FIG. 8 is an enlarged view of the tripping mechanism illustrated in FIG. 7, and FIG. 9 is an enlarged view of the tripping mechanism resulting from turning of the trip lever from the state illustrated in FIG. 7. FIG. 10 is a configuration diagram illustrating a state of the circuit breaker according to the first embodiment in which a closing completion position is reached, and FIG. 11 is an enlarged view of the tripping mechanism illustrated in FIG.

10. In FIGS. 3 to 11, the housing 2 is illustrated by a broken line.
[0036] As illustrated in FIG. 3, when the circuit breaker 1 is in the disconnected state, the core plunger 23 of the electromagnetic solenoid 20 reaches its lowermost position due to the opening spring 40, comes into physical contact with the housing 2, and cannot move downward any further. At this point, the size of the gap 25 is largest.
[ 0037] In addition, when the core plunger 23 is at the lowermost position, the opposite end 32b of the lever 32 is located below the one end 32a thereof, and faces the one end 52a of the trip lever 52 in the horizontal direction
(right-left direction). In addition, rearward tension is applied to the one end 52a of the trip lever 52 by the elastic restoring force of the first reset spring 53. Thus, the engaging pin 51 attached to the opposite end 32b of the lever 32 is in contact with the are-like portion 5 6 formed at the one end 52a of the trip lever 52.
[ 0038] When the circuit breaker 1 is in the disconnected state, the mover stopper 9 of the mover holder 7 restricts turning of the mover 6 in a direction in which the opposite end 6b of the mover 6 moves away from the opposite end 7b of the mover holder 7, that is, clockwise turning of the mover 6. In addition, because the contact pressure spring 8 is in a state having a predetermined initial contact pressure as described above, the one end 6a of the mover 6 does not leave the mover stopper 9 as long as a reaction force against pressing from the fixed contact 10 against the movable contact 11 does not exceed the initial contact pressure.
[0039] As illustrated in FIG. 3, when the circuit breaker 1 is in the disconnected state, an opening distance, which is the shortest physical distance between the movable

contact 11 of the mover 6 and the fixed contact 10 is largest. As illustrated in FIG. 4, in the state illustrated in FIG. 3, the flat portion 58b of the semicircular portion 58 of the trip bar 54 is brought in contact with a corner portion of the engaging portion 59 formed at the one end 52a of the trip lever 52 by the elastic restoring force of the second reset spring 55 acting to turn the trip bar 54 in the clockwise direction. Thus, turning of the trip lever 52 is restricted, and the state illustrated in FIG. 4 is maintained.
[004 0] In addition, the one end 52a of the trip lever 52 is brought in contact with the engaging pin 51 of the lever 32 at the are-like portion 56 by the elastic restoring force of the first reset spring 53 acting to turn the trip lever 52 in the clockwise direction so that the one end 52a of the trip lever 52 moves rearward. Thus, turning of the trip lever 52 in the clockwise direction is restricted, and the sate illustrated in FIG. 4 is maintained.
[ 0041] When power is supplied to the closing coil 22 of the electromagnetic solenoid 2 0 while the circuit breaker 1 is in the disconnected state, the core plunger 2 3 moves upward as illustrated in FIG. 5. As the core plunger 2 3 moves upward, the lever 32 turns about the lever shaft center 36, which makes a connection angle between the lever 32 and the insulating bar 33 smaller. The connection angle refers to an angle between the extending direction of the lever 32 and the extending direction of the insulating bar 33. The connection angle becomes smaller as the circuit breaker 1 changes from the state illustrated in FIG. 3 to the state illustrated in FIG. 5.
[0042] As the connection angle becomes smaller, the mover 6 moves frontward, and the fixed contact 10 and the movable contact 11 come in contact with each other. The

state at the moment when the movable contact 11 and the fixed contact 10 starts being in contact with each other is referred to as a contact starting state. At this point, the power supply terminal 3 and the load side terminal 4 are electrically connected with each other via the fixed contact 10, the movable contact 11, and the flexible conductor 5.
[0043] In addition, as illustrated in FIGS. 4 and 6, as the connection angle becomes smaller, the engaging pin 51 attached to the distal end of the lever 32 turnable about the lever shaft center 36 slides along the are-like portion 5 6 formed at the opposite end 52b of the trip lever 52 while maintaining the contact with the trip lever 52 to which the elastic restoring force is applied by the second reset spring 55.
[ 004 4] The are-like portion 5 6 of the trip lever 52 is an arc with its center at the lever shaft center 36 of the lever 32. Thus, from the state illustrated in FIG. 4 to the state illustrated in FIG. 6, the position of the trip lever 52 does not change with the movement of the engaging pin 51 .
[0045] When the circuit breaker 1 reaches the contact starting state, the mover 6 is restricted from turning in the clockwise direction by the mover stopper 9 formed at the mover holder 7 but is allowed to turn in the counterclockwise direction. As the core plunger 2 3 further advances from the contact starting state illustrated in FIG. 6, contact reaction force from the fixed contact 10 against the movable contact 11 attached to the opposite end 6b of the mover 6 increases, which causes the opposite end 6b of the mover 6 to turn in the counterclockwise direction about the connecting pin 13 and come closer to the opposite end 7b of the mover holder 7. Thus, the contact pressure

spring 8 is further energized than in the state illustrated in FIG. 5.
[0046] As illustrated in FIG. 7, when the position of the core plunger 2 3 reaches the maximum closing position as a result of upward movement of the core plunger 23, the angle of turning of the mover 6 relative to the mover holder 7 by the contact reaction force from the fixed contact 10 against the movable contact 11 is largest, and the energized amount of the contact pressure spring 8 is also largest.
[ 004 7] In addition, when the position of the core plunger 2 3 reaches the maximum closing position, the engaging pin 51 having slid along the arc-like portion 5 6 of the trip lever 52 passes along the are-like portion 5 6 of the trip lever 52 and reaches an upper portion of the engaging face 57 of the trip lever 52, as illustrated in FIG. 8. Thus, the engaging pin 51 becomes in no contact with the trip lever 52 for an instant.
[004 8] When the relation between the trip lever 52, the clockwise turning of which has been restricted by the engaging pin 51, and the engaging pin 51 is changed to the non-contact state, the restriction of the clockwise turning is cancelled. Thus, as illustrated in FIG. 9, the recess 52c of the trip lever 52 is turned in the clockwise direction by the elastic restoring force of the first reset spring 53 and brought into contact with the engaging pin 51. The contact of the engaging pin 51 with the recess 52c of the trip lever 52 restricts clockwise turning of the trip lever 52.
[0049] In addition, when the engaging pin 51 reaches the upper portion of the engaging face 57 of the trip lever 52 and the trip lever 52 turns, the trip bar 54, the clockwise turning of which has been restricted by trip lever 52, is

turned in the clockwise direction by the elastic restoring force of the second reset spring 55, and as illustrated in FIGS. 8 and 9, the are-like portion 58a of the semicircular portion 58 moves above the engaging portion 59 and stops. Note that the circuit breaker 1 is provided with a stopper, which is not illustrated, for restricting the turning of the trip bar 54, which restricts the turning of the trip bar 54 in the state illustrated in FIGS. 8 and 9.
[0050] After the position of the core plunger 2 3 reaches the maximum closing position, power supply to the electromagnetic solenoid 2 0 is completed. When power supply to the electromagnetic solenoid 2 0 is completed, the driving of the transfer mechanism 30 by the electromagnetic solenoid 2 0 is terminated.
[ 0051] Thus, the reaction force of the energized contact pressure spring 8 acts between the fixed contact 10 and the movable contact 11, which generates, via the transfer mechanism 30, a force pressing back the core plunger 2 3 of the electromagnetic solenoid 2 0 to move from the maximum closing position to the disconnected state position. In addition, a force in the direction moving the core plunger 23 from the maximum closing position to the disconnected state position is applied at the same time by the weight of the core plunger 2 3 and the opening force of the opening spring 4 0. As a result, the core plunger 2 3 starts moving downward from the maximum closing position illustrated in FIG. 7.
[0052] As the core plunger 23 moves downward from the maximum closing position, the lever 32 turns in the counterclockwise direction about the lever shaft center 36. As the lever 32 turns in the counterclockwise direction, the engaging pin 51 turns in the counterclockwise direction about the lever shaft center 36, and comes into contact

with the engaging face 57 of the trip lever 52 as illustrated in FIGS. 10 and 11. The core plunger 23 thus reaches the closing completion position, and the closing operation of the circuit breaker 1 is thus completed. [0053] When the core plunger 23 reaches the closing completion position, the are-like portion 58a of the semicircular portion 58 is in engagement with a flat portion of the engaging portion 59 formed at the one end 52a of the trip lever 52, which restricts frontward turning of the opposite end 52b of the trip lever 52. [0054] Thus, even though a force based on the reaction force of the contact pressure spring 8 acts on the trip lever 52 via the engaging pin 51 to turn the trip lever 52 in the counterclockwise direction about the trip lever shaft center 60, the trip lever 52 does not turn owing to the restriction on turning by the are-like portion 58a of the semicircular portion 58 as illustrated in FIG. 11. [0055] As described above, when the circuit breaker 1 is in the disconnected state, the predetermined initial contact pressure is applied to the contact pressure spring 8, and the contact pressure of the movable contact 11 against the fixed contact 10 is set to become greater from the moment when the movable contact 11 starts being in contact with the fixed contact 10. Thus, while the circuit breaker 1 is in the conducting state, occurrence of separation between the contacts owing to electromagnetic repulsive force generated between the movable contact 11 and the fixed contact 10 is prevented, and the velocity of separation between the movable contact 11 and the fixed contact 10 after a tripping command, which will be described later, is issued, that is, the opening velocity is increased. [005 6] Next, tripping operation of the circuit breaker 1

will be explained. When a tripping command is given to the circuit breaker 1 from the outside while the circuit breaker 1 is in the state at the closing completion position illustrated in FIG. 10, the trip bar 54 is driven to turn in the counterclockwise direction by the actuator, which is not illustrated, provided in the circuit breaker 1. [ 0057] The counterclockwise turning of the trip bar 54 causes the are-like portion 58a of the semicircular portion 58 of the trip bar 54 to move away from the engaging portion 59 of the trip lever 52, and the are-like portion 58a and the engaging portion 59 are disengaged from each other. As a result, the trip lever 52 turns in the counterclockwise direction about the trip lever shaft center 60 by a force based on the reaction force of the contact pressure spring 8, and the core plunger 23 returns to the disconnected state position of FIG. 3 via the state illustrated in FIG. 5. The tripping of the circuit breaker
1 is thus completed.
[ 0058] Here, the relation between the position of movement of the core plunger 2 3 and the amount of load applied to the electromagnetic solenoid 2 0 will be explained. FIG. 12 is a graph illustrating the relation between the position of movement of the core plunger and the amount of load applied to the electromagnetic solenoid according to the first embodiment. The core plunger 2 3 moves within a range from the position illustrated in FIG. 3 to the maximum closing position illustrated in FIG. 7 .
[0059] Hereinafter, upward movement of the core plunger
2 3 will be referred to as advancement, and downward
movement of the core plunger 2 3 will be referred to as
retraction. In addition, the movement position of the core
plunger 2 3 resulting from advancement will be referred to
as an advancement position, and the movement position of

the core plunger 2 3 resulting from retraction will be referred to as a retraction position. In addition, the load on the electromagnetic solenoid 20 while the core plunger 2 3 advances will be referred to as an advancement load, and the load on the electromagnetic solenoid 20 while the core plunger 2 3 retracts will be referred to as a retraction load.
[00 60] As illustrated in FIG. 12, when the advancement position of the core plunger 2 3 is the disconnected state position, that is, from the disconnected state position before reaching a contact starting position, the transfer mechanism 30 is driven in a state in which the fixed contact 10 and the movable contact 11 are not in contact with each other. Thus, when the advancement position of the core plunger 2 3 is the disconnected state position, the load applied to the electromagnetic solenoid 20 is relatively small. When the advancement position of the core plunger 23 then reaches the contact starting position, the contact of the movable contact 11 with the fixed contact 10 is started. Thus, the lever 32 receives a reaction force from the contact pressure spring 8 as load torque in the counterclockwise direction about the lever shaft center 36 via the connecting pins 13 and 38, and the closing load applied to the electromagnetic solenoid 20 increases sharply.
[00 61 ] As the core plunger 2 3 further advances, however, the component, in the direction perpendicular to a line connecting the lever shaft center 36 with the connecting pin 38, of the reaction force from the contact pressure spring 8 acting on the connecting pin 38, which serves as the point of action, decreases sharply. Thus, the load torque in the counterclockwise direction about the lever shaft center 36 starts decreasing. In response to the

decrease in the load torque, the closing load of the electromagnetic solenoid 2 0 required to turn the lever 32 also changes to a decrease.
[ 00 62] In a mechanism state of the circuit breaker 1 when the advancement position reaches the maximum closing position for the first time after the closing operation started as a result of further advancement of the core plunger 23, the arrangement of the lever 32 and the insulating bar 33 becomes close to a line, and the toggle mechanism constituted by the lever 32 and the insulating bar 33 comes closest to the dead center. Thus, the component, in the direction perpendicular to the line connecting the lever shaft center 36 with the connecting pin 38, of the reaction force from the contact pressure spring 8 acting on the connecting pin 38 becomes close to zero, and the closing load of the electromagnetic solenoid 2 0 required to turn the lever 32 also rapidly becomes closer to zero. In other words, a load force acting distance, which is a distance the core plunger 2 3 of the electromagnetic solenoid 20 advances to apply load torque to the lever 32, is decreased with the closing force of the electromagnetic solenoid 2 0 increasing with transition from the disconnected state position to a closing state position. This not only enables the electromagnetic attraction force of the electromagnetic solenoid 20 to be efficiently used in the closing operation of the circuit breaker 1, but also enables use of the electromagnetic solenoid 2 0 having a size depending on a change in the load force acting distance required for the closing operation of the circuit breaker 1 and reduces the size and the cost of the electromagnetic solenoid 20. In addition, in the circuit breaker 1 according to the first embodiment, the core plunger 2 3 is configured to stop advancing before the

toggle mechanism described above exceeds the dead center. Because the dead center is not exceeded during transition from the closing state to the disconnected state, complication of the configuration of the tripping mechanism 50 can thus be avoided.
[00 63] In the state of the circuit breaker 1 after the contacts are brought into contact with each other, the contact between the movable contact 11 and the fixed contact 10 generates a contact pressure due to the reaction force from the contact pressure spring 8, which causes a pressing force in the front-rear direction against the lever shaft 37 via the insulating bar 33 and the lever 32. The pressing force against the lever shaft 37 causes friction torque on the lever shaft 37, which is combined with sliding friction load in the vertical direction of the electromagnetic solenoid 20 due to the component in the front-rear direction of the load transmitted to the electromagnetic solenoid 2 0 via the connecting link 31, resulting in a non-negligible frictional force that increases the closing load of the electromagnetic solenoid 20.
[0064] When the moving direction of the core plunger 23 changes to retraction after the core plunger 23 has reached the maximum closing position, the direction of the frictional force applied to the entire transfer mechanism 30 also changes. Thus, due to the effect of reducing the tripping load caused by the frictional force, the load on the tripping mechanism 50 in the closing state reduces. [00 65] As described above, because the load on the tripping mechanism 50 in the closing state is reduced, the configuration of the tripping mechanism 50 can be simplified. This enables reduction in the size of the tripping mechanism 50, and reduction in the size of the

circuit breaker 1, and also increase the reliability of the durability of the tripping mechanism 50 by reducing the number of components of the tripping mechanism 50.
[0066] Before the movable contact 11 is brought into contact with the fixed contact 10, frictional force associated with turning of turning portionsof the connecting pins 13 and 38, the lever shaft 37, and the connecting pins 34 and 35, is mainly generated. Thus, before the movable contact 11 is brought into contact with the fixed contact 10, the friction torque on the lever shaft 37 and the sliding friction load in the vertical direction of the electromagnetic solenoid 20, are smaller than those in the state after the contact pressure is caused by the reaction force from the contact pressure spring 8 after the movable contact 11 is brought into contact with the fixed contact 10. Thus, as illustrated in FIG. 12, the difference between the closing loads during advancement and during retraction caused by the frictional force before the contacts are brought into contact with each other, is smaller than the difference between the closing loads after the contacts are brought into contact with each other.
[ 00 67] Load characteristics of the electromagnetic solenoid 2 0 necessary for closing in the circuit breaker 1 can be formulated with respect to the series of closing operation and the closing load of the circuit breaker 1. For example, formulation of the load characteristics of the electromagnetic solenoid 2 0 necessary for closing in each of the states of FIGS. 3, 5, 7, and 10 enables significant reduction in the mechanical load during tripping by using mechanical friction, and enables design of the circuit breaker 1 having hysteresis in the closing load characteristics of the electromagnetic solenoid 2 0.

[00 68] As described above, the circuit breaker 1 according to the first embodiment includes the housing 2, the power supply terminal 3, the mover holder 7, the mover 6, the contact pressure spring 8, the electromagnetic solenoid 20, the transfer mechanism 30, and the tripping mechanism 50. The power supply terminal 3 is an example of a fixed terminal, to which the fixed contact 10 is attached and which is fixed to the housing 2. The mover holder 7 is connected with the housing 2 in such a manner as to be turnable about the holder shaft center 12a fixed to the housing 2. The holder shaft center 12a is an example of a first shaft center. The mover 6 is turnably connected with the mover holder 7, and the movable contact 11 is attached to the mover 6. The contact pressure spring 8 applies pressure to the fixed contact 10 and the movable contact 11 when the fixed contact 10 and the movable contact 11 are in contact with each other. The electromagnetic solenoid 20 includes the core plunger 23 that moves linearly. The core plunger 2 3 is an example of a plunger. The transfer mechanism 30 moves the mover 6 with the movement of the core plunger 23, to change from the disconnected state in which the movable contact 11 is separated from the fixed contact 10 to the closing state in which the movable contact 11 is in contact with and electrically connected with the fixed contact 10. The tripping mechanism 50 is engaged with the transfer mechanism 30 to hold the closing state, and disengaged from the transfer mechanism 30 to terminate holding of the closing state. The transfer mechanism 30 includes the lever 32 and the insulating bar 33. The lever 32 turns about the lever shaft center 36 fixed to the housing 2 with the movement of the core plunger 2 3. The lever shaft center 36 is an example of a second shaft center. The insulating bar 33 has the one end

33a turnably connected with the one end 32a of the lever 32, and the opposite end 33b turnably connected with the mover 6. The core plunger 2 3 of the electromagnetic solenoid 2 0 reaches the maximum movement position at which the movement of the plunger 23 is limited before the toggle mechanism constituted by the lever 32 and the insulating bar 33 reaches the dead center. Thus, by setting the maximum movement position of the core plunger 23 to a position immediately before the toggle mechanism reaches the dead center, for example, the closing load of the electromagnetic solenoid 20 required to turn the lever 32 can be rapidly made to be close to 0 because of the leverage effect of the toggle mechanism. This reduces the load on the tripping mechanism 50 in the closing state. Note that the aforementioned position before reaching the dead center is a position at which the dead center is not reached even when production error is present. The maximum movement position is an example of a first position. In addition, in the state in which the core plunger 23 has retracted to the closing completion position after having reached the maximum movement position, the tripping mechanism 50 engages with the transfer mechanism 30 to hold the closing state. The closing completion position is an example of a second position. As a result, because the direction of the frictional force applied to the entire transfer mechanism 30 also changes when the moving direction of the core plunger 2 3 changes to retraction, the load on the tripping mechanism 50 in the closing state is reduced by the effect of reducing the load caused by the frictional force, that is, the hysteresis in the closing load characteristics. Thus, the need for making the tripping mechanism of the circuit breaker a complicated mechanism is reduced, which reduces the size of the

tripping mechanism 50 and improves the assembling performance thereof.
[00 69] In addition, the circuit breaker 1 includes the engaging pin 51 attached to the opposite end 32b of the lever 32 . The engaging pin 51 is an example of an engaging portion. In addition, the tripping mechanism 50 includes the trip lever 52 and the trip bar 54. The trip lever 52 is turnably attached to the housing 2 in a state in which the trip lever 52 is biased in the direction toward the engaging pin 51, maintains the state in contact with the engaging pin 51 in the closing process of transition from the disconnected state to the closing state, and engages with the engaging pin 51 to restrict turning of the lever 32 about the lever shaft center 36 in the state in which the core plunger 23 is at the closing completion position. The trip bar 54 restricts turning of the trip lever 52 and terminates the restriction thereof. As described above, the tripping mechanism 50 can be constituted by at least two members including the trip lever 52 and the trip bar 54 except the engaging pin 51, which reduces the size of the tripping mechanism 50 and improves the assembling performance thereof. In addition, because the engaging pin 51 is in contact with the trip lever 52 from the disconnected state to the closing state, the tripping opera ti on can be easi I. y performed only by changing the amount by which the trip lever 52 can move in the direction away from the engaging pin 51.
[0070] In addition, the trip lever 52 includes the arc-like portion 56 which has an arc shape with its center at the lever shaft center 36 and with which the engaging pin 51 is in contact in a movable manner during the closing process, and a recess 51c that engages with the engaging pin 51 in the closing state. As a result, the position of

the trip lever 52 does not change during the closing process, which prevents the closing load of the electromagnetic solenoid 20 that drives the transfer mechanism 30 from being fluctuated by the trip lever 52 during the closing process.
[0071] The trip lever 52 also includes a semicircular portion 58 that has an are-like portion 58a and a flat portion 58b, and turns about the trip bar shaft center 61 fixed to the housing 2. The trip bar shaft center 61 is an example of a third shaft center. The trip lever 52 is in contact with the flat portion 58b of the semicircular portion 58 and the turning thereof is thus restricted in the disconnected state, and is in contact with the are-like portion 58a of the semicircular portion 58 and the turning thereof is thus restricted in the closing state. This enables the amount by which the trip lever 52 can move in the direction away from the engaging pin 51 to be easily adjusted only by turning the trip lever 52.
[ 0072] Second Embodiment.
A second embodiment is different from the first embodiment in that the tripping mechanism additionally includes a trip latch and a third reset spring between the trip lever and the trip bar. Hereinafter, components having similar functions to those in the first embodiment will be represented by the same reference numerals, the description thereof will not be repeated, and the description will be focused on the difference from the circuit breaker 1 of the first embodiment.
[0073] FIG. 13 is a configuration diagram illustrating a disconnected state of the circuit breaker according to the second embodiment, FIG. 14 is an enlarged view of a tripping mechanism illustrated in FIG. 13, and FIG. 15 is a configuration diagram illustrating a state of the tripping

mechanism at a moment when contacts of the circuit breaker according to the second embodiment are started to be in contact with each other. FIGS. 16 and 17 are configuration diagrams illustrating states of the tripping mechanism in a state in which the maximum closing position of the circuit breaker according to the second embodiment is reached, and FIG. 18 is a configuration diagram illustrating a state of the tripping mechanism in a state in which the closing completion position of the circuit breaker according to the second embodiment is reached. In FIGS. 13 to 18, the housing 2 is illustrated by a broken line.
[0074] As illustrated in FIG. 13, the circuit breaker 1A according to the second embodiment includes the housing 2, the power supply terminal 3, the load side terminal 4, the flexible conductor 5, the mover 6, the mover holder 7, the contact pressure spring 8, the electromagnetic solenoid 20, the transfer mechanism 30, the opening spring 40, and a tripping mechanism 70.
[007 5] As illustrated in FIG. 14, the tripping mechanism 7 0 includes a trip lever 71 that engages with the engaging pin 51 fixed to the opposite end 32b of the lever 32, and a first reset spring 72 having one end attached to the trip lever 71 and the opposite end attached to the housing 2. The tripping mechanism 70 also includes a trip bar 73 that is turned by a driving force of an actuator, which is not illustrated, and a second reset spring 7 4 having one end and the opposite end each of which is attached to corresponding one of the trip bar 7 3 and the housing 2. The tripping mechanism 7 0 further includes a trip latch 75 provided between the trip lever 71 and the trip bar 73, and a third reset spring 76 having one end and the opposite end each of which is attached to corresponding one of the trip latch 75 and the housing 2.

[0076] The trip lever 71 is attached to the housing 2 in such a manner as to be turnable about a trip lever shaft center 80, and has one end 71a with an are-like portion 7 7 coming in contact with the engaging pin 51 during the closing process. The opposite end 71b of the trip lever 71 protrudes frontward, and faces the trip latch 75. A recess 71c that is recessed rearward is formed at a middle portion of the trip lever 71. The recess 71c has an engaging face 79 that engages with the engaging pin 51. The first reset spring 72 biases the trip lever 71 in the counterclockwise direction about the trip lever shaft center 80. [0077] The trip bar 73 has one end 73a attached to the housing 2 in such a manner as to be turnable about a trip bar shaft center 81, and has a semicircular portion 78 having a semicircular shape with its center at the trip bar shaft center 81. The second reset spring 74 biases the opposite end 73b of the trip bar 7 3 in the counterclockwise direction about the trip bar shaft center 81. The trip bar 7 3 turns about the trip bar shaft center 81 by a driving force of an actuator, which is not illustrated. [007 8 ] The trip latch 7 5 has an L shape in side view, and has a central portion 7 5c attached to the housing 2 in such a manner as to be turnable about a trip latch shaft center 82. The third reset spring 7 6 biases the trip latch 7 5 in the counterclockwise direction about the trip latch shaft center 82.
[0079] The state of the circuit breaker 1A illustrated in FIG. 14 is a disconnected state. In the disconnected state illustrated in FIG. 14, the trip lever 71 is biased in the counterclockwise direction by the elastic restoring force of the first reset spring 72. Thus, the state in which the are-like portion 77 formed at the front side of the one end 71a of the trip lever 71 is in contact with the

engaging pin 51 is maintained.
[008 0] In addition, the trip latch 75 is biased in the counterclockwise direction by the elastic restoring force of the third reset spring 7 6, and one end 75a of the trip latch 75 is in contact with the opposite end 71b of the trip lever 71. In addition, the trip bar 7 3 is biased by the elastic restoring force of the second reset spring 74, and the opposite end 7 5b of the trip latch 7 5 comes into contact with a flat portion 7 8b of the semicircular portion 78 of the trip bar 73. Thus, the trip lever 71 is also biased in the counterclockwise direction by the second reset spring 74 and the third reset spring 76 in addition to the first reset spring 72.
[0081 ] Next, the state at the moment when contacts are started to be in contact with each other in the circuit breaker 1A will be explained. The state of the circuit breaker 1A illustrated in FIG. 15 is the state at the moment when the contacts are started to be in contact with each other. The state illustrated in FIG. 15 results only from turning of the engaging pin 51 about the lever shaft center 36 from the state illustrated in FIG. 14 because of the shape of the are-like portion 7 7 of the trip lever 71, and the relative positions of the trip lever 71, the trip bar 7 3 and the trip latch 7 5 constituting the tripping mechanism 7 0 do not change. While the are-like portion 7 7 has such shape characteristics that an arc with its center at the lever shaft center 36 and the shape of the are-like portion 7 7 of the trip lever 71 are concentric, the portion 7 7 need not be an arc.
[0082] Next, the state in which the maximum closing position of the circuit breaker 1A is reached will be explained. In the state illustrated in FIG. 16, the engaging pin 51 is located at position upper than the arc-

like portion 77 of the trip lever 71, and the contact state between the are-like portion 7 7 of the trip lever 71 and the engaging pin 51 is terminated, which makes the trip lever 71 and the engaging pin 51 be in no contact with each other for an instant. Because the trip lever 71 is biased in the counterclockwise direction, the trip lever 71 turns in the counterclockwise direction after becoming in no contact with the engaging pin 51 for an instant, and comes in contact with the engaging pin 51 again.
[0083] As the trip lever 71 turns in the counterclockwise direction from the state illustrated in FIG. 16, the opposite end 71b of the trip lever 71 moves rearward. Thus, the one end 75a of the trip latch 7 5 being in contact with the opposite end 71b of the trip lever 71 moves rearward, and the trip latch 7 5 turns in the counterclockwise direction about the trip latch shaft center 82. Because the trip latch 75 is biased in the counterclockwise direction by the elastic restoring force of the third reset spring 76, the state in which the one end 75a of the trip latch 7 5 is in contact with the opposite end 71b of the trip lever 71 is maintained.
[0084] The turning of the trip latch 75 in the counterclockwise direction causes the opposite end 7 5b of the trip latch 75 to move in the direction away from the semicircular portion 7 8 formed on the trip bar 73, as illustrated in FIG. 17, which terminates the state of the trip bar 7 3 in contact with the flat portion 78b of the semicircular portion 7 8 is terminated. Thus, as illustrated in FIG. 17, the trip bar 73 turns in the clockwise direction by the elastic restoring force of the second reset spring 74, and the are-like portion 7 8a of the semicircular portion 7 8 formed on the trip bar 7 3 comes to a position facing the opposite end 7 5b of the trip latch 7 5

and engages with the opposite end 75b.
[008 5] Next, a change from the state in which the maximum closing position is reached to the state in which the closing completion position is reached in the circuit breaker 1A will be explained. When power supply to the electromagnetic solenoid 20 is completed after the core plunger 2 3 has reached the maximum closing position, the driving of the transfer mechanism 30 by the electromagnetic solenoid 2 0 is terminated, and the pressing of the movable contact 11 against the fixed contact 10 is terminated. Thus, in a manner similar to the circuit breaker 1, the reaction force of the contact pressure spring 8 acts between the fixed contact 10 and the movable contact 11, and the core plunger 2 3 starts moving downward from the maximum closing position illustrated in FIG. 17.
[0086] As the core plunger 23 moves downward from the maximum closing position, the engaging pin 51 moves in the counterclockwise direction about the lever shaft center 36 along with the turning of the lever 32 in the counterclockwise direction about the lever shaft center 36. Thus, as illustrated in FIG. 18, the engaging pin 51 engages with the engaging face 7 9 formed on the recess 71c of the trip lever 71, the closing completion position of the circuit breaker 1A is reached, and the closing operation of the circuit breaker 1A is completed. While the engaging pin 51 is described as an example of an engaging portion that engages with the trip lever 52 in the example described above, the engaging portion that engages with the trip lever 52 is not limited to the engaging pin 51, and may have any shape that can engage with the trip lever 52.
[0087] As described above, when the maximum closing position is reached, the are-like portion 7 8a of the

semicircular portion 7 8 of the trip bar 7 3 engages with th< opposite end 75b of the trip latch 75, and the turning in the clockwise direction of the trip latch 75 is restricted [ 008 8] Thus, even though a force based on the reaction force of the contact pressure spring 8 acts on the trip lever 71 via the engaging pin 51 to turn the trip lever 71 in the counterclockwise direction about the trip lever shaft center 80, turning of the trip lever 71 is restricte< by the trip latch 75, the turning of which in the counterclockwise direction is restricted by the are-like portion 7 8a of the semicircular portion 78, as illustrated in FIG. 18.
[0089] Next, tripping operation of the circuit breaker 1A will be explained. When a tripping command is given to the circuit breaker 1A from the outside while the circuit breaker 1A is in the state at the closing completion position illustrated in FIG. 18, the trip bar 7 3 is driven to turn in the counterclockwise direction by the actuator, which is not illustrated, provided in the circuit breaker 1A.
[0090] The turning of the trip bar 73 in the counterclockwise direction changes the position at which the are-like portion 7 8a of the semicircular portion 7 8 of the trip bar 73 is in contact with the trip latch 7 5 from the are-like portion 7 8a to the flat portion 78b of the semicircular portion 78, and the trip latch 7 5 can then turn in the clockwise direction. As a result, the trip lever 71 turns in the clockwise direction about the trip lever shaft center 8 0 by a force based on the reaction force of the contact pressure spring 8, and operation reverse to that of the tripping mechanism 7 0 from the disconnected state to reach the maximum closing state is performed, and the state thus returns to the disconnected

state illustrated in FIGS. 13 and 14. The tripping of the circuit breaker 1A is thus completed.
[ 0091] As described above, the tripping mechanism 7 0 of the circuit breaker 1A according to the second embodiment includes the trip lever 71, the trip bar 73, and the trip latch 75. The trip lever 71 is turnably attached to the housing 2 in a state in which the trip lever 71 is biased in the direction toward the engaging pin 51, maintains the state in which the trip lever is in contact with the engaging pin 51 in the closing process of transition from the disconnected state to the closing state, and engages with the engaging pin 51 to restrict turning of the lever 32 about the lever shaft center 36 in the closing state. The trip latch 75 has a middle portion turnably supported by the housing 2, and the one end 7 5a coming in contact with the trip lever 71. The trip bar 73 includes the semicircular portion 7 8 that has the are-like portion 7 8a and the flat portion 7 8b, and turns about the trip latch shaft center 82 fixed to the housing 2. The trip latch shaft center 82 is an example of the third shaft center. The opposite end 7 5b of the trip latch 75 is in contact with the flat portion 7 8b of the semicircular portion 7 8 and the turning thereof is thus restricted in the disconnected state, and is in contact with the are-like portion 7 8a of the semicircular portion 7 8 and the turning thereof is thus restricted in the closing state. This enables the tripping mechanism 70 to easily adjust the amount by which the trip lever 71 can move away from the engaging pin 51 only by turning the trip bar 73. [0092] Note that, in the circuit breakers 1 and 1A, the turning direction of the lever 32 from the disconnected state position to the maximum closing position is not limited to the counterclockwise direction about the lever

shaft center 36. The circuit breakers 1 and 1A may have a mechanism additionally including an appropriate link member between the connecting link 31 and the lever 32 to turn the lever 32 in the clockwise direction.
[0093] In addition, the circuit breakers 1 and 1A need not have the configuration in which the engaging pin 51 slides along the are-like portions 56 or 7 7 of the trip levers 52 or 71 with its center at the lever shaft center 36 of the lever 32. In other words, in the circuit breakers and 1A, the shape a Iong which the trip ]overs 52 and 71 and the engaging pin 51 slide relative to each other need not be an arc shape.
[0094] In addition, while the turning of trip levers 52 and 71 is stopped by bringing the trip levers 52 and 71 and the engaging pin 51 in contact with each other, the circuit breakers 1 and 1A may alternatively have a configuration in which a special turning stopper for the trip levers 52 and 71 is provided to stop the turning.
[0095] In addition, while the trip bars 54 and 7 3 are operated to turn in the counterclockwise direction by the actuator, which is not illustrated, in the first and second embodiments described above, the trip bars 54 and 7 3 may alternatively be operated to turn in the counterclockwise direction by a link, which is not illustrated, or manually.
[009 6] Furthermore, while the load side terminal 4 and the movable contact 11 are electrically connected with each other by the flexible conductor 5 in the first and second embodiments described above, the configuration for connecting between the load side terminal 4 and the movable contact 11 need not be the flexible conductor 5. For example, the mover 6, the connecting pin 13, and the mover holder 7 may be conductors, and the load side terminal 4 and the holder shaft center 12a may be electrically

connected with each other by a slip ring or a conductive brush.
[ 0097] In addition, the opening spring 4 0 may be constituted by two or more springs, and the contact pressure spring 8 may also be constituted by two or more springs for the mover 6.
[ 0098] In addition, while the circuit breakers 1 and 1A each have a configuration in which the toggle mechanism constituted by the lever 32 and the insulating bar 33 does not reach the dead center, the circuit breakers 1 and 1A are not limited this configuration. The circuit breakers 1 and 1A may additionally include a mechanism capable of tripping when the advancement position of the core plunger 2 3 reaches the maximum closing position even though the toggle mechanism exceeds the dead center, such as a configuration in which the lever shaft center 36 and the holder shaft center 12a serve as centers of turning, to constitute the closing mechanism without changing the basic performance of the circuit breakers 1 and 1A. [0099] In addition, while the core plunger 2 3 can change its position only in the vertical direction in the circuit breakers 1 and 1A, the moving direction of the core plunger 23 is not limited to the vertical direction, and may be an oblique direction, or can also change during the movement. [0100] The configurations presented in the embodiments above are examples of the present invention, and can be combined with other known technologies or can be partly omitted or modified without departing from the scope of the present invention.
Reference Signs List
[0101] 1, 1A circuit breaker; 2 housing; 2a wall; 3 power supply terminal; 4 load side terminal; 5 flexible

conductor; 5a, 6a, 7a, 31a, 32a, 52a, 54a, 71a, 72a, 73a, 7 5a one end; 5b, 6b, 7b, 31b, 32b, 52b, 54b, 71b, 72b, 7 3b, 7 5b opposite end; 6 mover; 7 mover holder; 7c, 72c middle portion; 8 contact pressure spring; 9 mover stopper; 10 fixed contact; 11 movable contact; 12 holder shaft; 12a holder shaft center; 13, 34, 35, 38 connecting pin; 20 electromagnetic solenoid; 21 yoke; 22 closing coil; 23 core plunger; 2 4 protruding portion; 2 5 gap; 30 transfer mechanism; 31 connecting link; 32 lever; 33 insulating bar; 3 6 lever shaft center; 37 lever shaft; 38b flat portion; 4 0 opening spring; 50, 7 0 tripping mechanism; 51 engaging pin; 52, 71 trip lever; 52c, 71c recess; 53, 72 first reset spring; 54, 73 trip bar; 55, 7 4 second reset spring; 56, 77 are-like portion; 57, 79 engaging face; 58, 78 semicircular portion; 58a, 78a arc¬like portion; 58b, 7 8b flat portion; 59 engaging portion; 60, 8 0 trip lever shaft center; 61, 81 trip bar shaft center; 7 5 trip latch; 7 5c central portion; 7 6 third reset spring; 82 trip latch shaft center.

We Claim :
1. A circuit breaker comprising:
a housing;
a fixed terminal fixed to the housing, a fixed contact being attached to the fixed terminal;
a mover holder connected with the housing in a manner turnable about a first shaft center fixed to the housing;
a mover turnably connected with the mover holder, a movable contact being attached to the mover;
a contact pressure spring to apply pressure to the fixed contact and the movable contact when the fixed contact and the movable contact are in contact with each other;
an electromagnetic solenoid including a plunger that moves linearly;
a transfer mechanism to move the mover with movement of the plunger to change from a disconnected state in which the movable contact is separated from the fixed contact to a closing state in which the movable contact is in contact with and electrically connected with the fixed contact; and
a tripping mechanism to hold the closing state by engaging with the transfer mechanism and terminate the holding of the closing state by disengaging from the transfer mechanism, wherein
the transfer mechanism includes:
a lever to turn about a second shaft center fixed to the housing with the movement of the plunger; and
an insulating bar having one end turnably connected with one end of the lever, and an opposite end turnably connected with the mover,
the plunger reaches, before a toggle mechanism constituted by the lever and the insulating bar reaches a dead center, a first position at which movement of the

plunger is limited, and
the tripping mechanism engages with the transfer mechanism in a state in which the plunger is at a second position after having reached the first position and then having retracted, to hold the closing state.
2 . The circuit breaker according to claim 1, further
comprising:
an engaging portion attached to an opposite end of the lever, wherein
the tripping mechanism includes:
a trip lever turnably attached to the housing in a state in which the trip lever is biased in a direction toward the engaging portion, the trip lever maintaining a state in which the trip lever is in contact with the engaging portion in a closing process of transition from the disconnected state to the closing state, the trip lever engaging with the engaging portion in a state in which the plunger is at the second position to restrict turning of the lever about the second shaft center; and
a trip bar to restrict turning of the trip lever and terminate the restriction.
3 . The circuit breaker according to claim 2, wherein
the trip lever includes:
an arc-like portion having arch shape with its center at the second shaft center, the engaging portion being in contact with the arc-like portion in a movable manner during the closing process; and
a recess to engage with the engaging portion in the closing state.
4. The circuit breaker according to claim 3, wherein

the trip bar includes a semicircular portion having an arc-like portion and a flat portion, and being turnable about a third shaft center fixed to the housing, and
the trip lever is in contact with the flat portion of the semicircular portion so that the turning thereof is restricted in the disconnected state, and is in contact with the arc-like portion of the semicircular portion so that the turning thereof is restricted in the closing state.
5. The circuit breaker according to claim 3, wherein
the tripping mechanism includes a trip latch having a middle portion turnably supported by the housing, and one end coming in contact with the trip lever,
the trip bar includes a semicircular portion having an arc-like portion and a flat portion, the semicircular portion being turnable about a third shaft center fixed to the housing, and
an opposite end of the trip latch is in contact with the flat portion of the semicircular portion so that the turning thereof is restricted in the disconnected state, and is in contact with the arc-like portion of the semicircular portion so that the turning thereof is restricted in the closing state.