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 1008310, JAPAN THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. 2 DESCRIPTION Field [0001] The present invention relates to a circuit 5 breaker including an electromagnetic operation mechanism unit including a fixed contact and a movable contact, the electromagnetic operation mechanism unit being for a closing operation that brings the movable contact into contact with the fixed contact or a tripping operation that 10 moves the movable contact away from the fixed contact. Background [0002] Conventionally, a spring-operated circuit breaker and an electromagnetically operated circuit breaker are 15 known as circuit breakers that open and close an electric circuit. As disclosed in Patent Literature 1, the springoperated circuit breaker performs the closing operation and the tripping operation for the movable contact using energy unleashed when the accumulated spring force is made open. 20 [0003] In addition, as disclosed in Patent Literature 2, the electromagnetically operated circuit breaker includes an electromagnetic operation mechanism unit coupled to a movable contact facing a fixed contact via a transmission unit, and performs the closing operation and the tripping 25 operation for the movable contact by causing the transmission unit to transmit a driving force from the electromagnetic operation mechanism unit. Citation List 30 Patent Literature [0004] Patent Literature 1: Japanese Patent Application Laid-open No. 6-89650 Patent Literature 2: Japanese Patent Application Laid-open 3 No. 2008-159270 Summary Technical Problem 5 [0005] Generally, the circuit breaker is often used as a main circuit breaker in buildings, factories, and the like and, in the unlikely event of a failure, is required to be restored in a short time. For this reason, there are cases where the entire failed circuit breaker is replaced; 10 however, if there is no space for placing a spare circuit breaker and there is no replacement circuit breaker, energization is stopped for a long time. Therefore, only a failed component in the circuit breaker is replaced and repaired in some cases. 15 [0006] Since the spring-operated circuit breaker uses a spring having a large load in the closing action, and the circuit breaker is always in a state with a large load exerted, a work to replace components in the circuit breaker is not easy. 20 [0007] Since the electromagnetically operated circuit breaker uses the energy of the electromagnetic coil, there is no closing spring like the spring-operated circuit breaker. However, for example, when the electromagnetic operation mechanism unit is damaged, it is difficult to 25 detach the electromagnetic operation mechanism unit and the transmission unit from each other because a coupling unit for coupling the electromagnetic operation mechanism unit to the transmission unit is located in a frame, and a replacement work for the electromagnetic operation 30 mechanism unit or a part related to the electromagnetic operation mechanism unit has not been easy. [0008] The present invention has been made in view of the above problems, and it is an object thereof to obtain a 4 circuit breaker that allows a replacement work for an electromagnetic operation mechanism unit or a part related to the electromagnetic operation mechanism unit to be easily performed. 5 Solution to Problem [0009] In order to solve the above-described problems and achieve the object, a circuit breaker according to the present invention includes: a stator including a fixed 10 contact; a mover including a movable contact; a transmission unit; an electromagnetic operation mechanism unit; a coupling unit; an urging member; and a frame. The transmission unit includes a rotating member, and moves the mover in line with the rotation of the rotating member to 15 make contact and isolation between the fixed contact and the movable contact. The electromagnetic operation mechanism unit includes a shaft and moves the shaft linearly. The coupling unit couples the transmission unit and the shaft, and rotates the rotating member in line with 20 the movement of the shaft. The urging member applies a force to the rotating member in a rotation direction that isolates the movable contact from the fixed contact. In a state in which the shaft is inclined in a first direction with respect to a movement direction of the shaft by the 25 force of the urging member, the frame faces at least a part of a coupling pin of the coupling unit coupled to the shaft in an axial direction of the rotating member, and covers at least the part of the coupling pin. The frame includes an opening at a position where the entire coupling pin is 30 exposed when viewed from the axial direction of the rotating member in a state in which the shaft is inclined in a second direction, which is an opposite direction to the first direction with respect to the movement direction. 5 Advantageous Effects of Invention [0010] According to the present invention, there is an effect that a replacement work for an electromagnetic 5 operation mechanism unit or a part related to the electromagnetic operation mechanism unit can be performed easily. Brief Description of Drawings 10 [0011] FIG. 1 is a diagram illustrating a configuration example of a circuit breaker according to a first embodiment. FIG. 2 is a diagram illustrating a configuration inside a housing of the circuit breaker according to the first 15 embodiment. FIG. 3 is an enlarged diagram of an upper part of an electromagnetic operation mechanism unit according to the first embodiment. FIG. 4 is an enlarged diagram of the electromagnetic 20 operation mechanism unit, a coupling unit, and a machine operation mechanism unit according to the first embodiment. FIG. 5 is a diagram illustrating a closing completion state of the circuit breaker according to the first embodiment. FIG. 6 is an explanatory diagram of a method of replacing 25 the electromagnetic operation mechanism unit or the machine operation mechanism unit according to the first embodiment. FIG. 7 is a diagram illustrating another example of a configuration for restricting a downward movement of a drive shaft according to the first embodiment. 30 FIG. 8 is a diagram illustrating another example of a configuration for restricting a downward movement of the drive shaft according to the first embodiment. FIG. 9 is an explanatory diagram of a method of replacing 6 the electromagnetic operation mechanism unit or the machine operation mechanism unit according to the first embodiment. FIG. 10 is an explanatory diagram of a method of replacing the electromagnetic operation mechanism unit or the machine 5 operation mechanism unit according to the first embodiment. FIG. 11 is a side view illustrating a relationship between a frame, a coupling pin, a coupling link, and a bearing portion according to the first embodiment. FIG. 12 is an explanatory diagram of a method of replacing 10 the electromagnetic operation mechanism unit or the machine operation mechanism unit according to the first embodiment. Description of Embodiments [0012] Hereinafter, a circuit breaker according to 15 embodiments of the present invention will be described in detail with reference to the drawings. Note that this invention is not limited by these embodiments. [0013] First Embodiment. FIG. 1 is a diagram illustrating a configuration example of 20 a circuit breaker according to a first embodiment. The circuit breaker according to the first embodiment is, for example, a circuit breaker that opens and closes an electric circuit of a low-voltage distribution line or the like. Note that, for convenience of explanation, it is 25 assumed in the following that a positive Z-axis direction is an upward direction, a negative Z-axis direction is a downward direction, a positive X-axis direction is a right direction, a negative X-axis direction is a left direction, a positive Y-axis direction is a forward direction, and a 30 negative Y-axis direction is a backward direction. [0014] As illustrated in FIG. 1, the circuit breaker 1 according to the first embodiment includes a housing 2 formed of an insulating member, a power supply-side fixed 7 conductor 10 connected to a power supply-side conductor (not illustrated), a load-side fixed conductor 20 connected to a load-side conductor (not illustrated), a mover 30 including a movable contact 30a, and a flexible conductor 5 40 having flexibility to electrically connect the load-side fixed conductor 20 and the mover 30 to each other. [0015] Space portions 4 and 5 partitioned by an insulating wall 3 are formed inside the housing 2. The power supply-side fixed conductor 10 extends from the 10 outside of the housing 2 to the space portion 4 and passes through a wall portion 6 of the housing 2. One end portion 101 of the power supply-side fixed conductor 10 protrudes to the outside and is connected to the power supply-side conductor (not illustrated), while another end portion 102 15 of the power supply-side fixed conductor 10 is disposed in the space portion 4 and a fixed contact 10a is fixed to the another end portion 102. [0016] Similarly to the power supply-side fixed conductor 10, the load-side fixed conductor 20 extends from 20 the outside of the housing 2 to the space portion 4 and passes through the wall portion 6 of the housing 2. One end portion 201 of the load-side fixed conductor 20 protrudes to the outside and is connected to the load-side conductor (not illustrated), while another end portion 202 25 of the load-side fixed conductor 20 is disposed in the space portion 4. [0017] The movable contact 30a is provided at one end portion 301 of the mover 30, and another end portion 302 of the mover 30 is fixed to one end portion 401 of the 30 flexible conductor 40. Another end portion 402 of the flexible conductor 40 is fixed to the another end portion 202 of the load-side fixed conductor 20. [0018] In addition, the circuit breaker 1 includes a 8 holder 50 rotatably attached to the another end portion 202 of the load-side fixed conductor 20, a contact pressure spring 51 held by the holder 50, and a mover pin 52 rotatably held in the holder 50. The contact pressure 5 spring 51 urges the mover 30 in a direction that rotates the mover 30 in a clockwise direction about the mover pin 52, and imparts a contact pressure between the fixed contact 10a and the movable contact 30a when the movable contact 30a provided in the mover 30 is connected to the 10 fixed contact 10a. [0019] The circuit breaker 1 includes a transmission unit 60 coupled to the mover 30, an electromagnetic operation mechanism unit 70 that moves the mover 30 via the transmission unit 60, a coupling unit 80 that couples the 15 transmission unit 60 and the electromagnetic operation mechanism unit 70 to each other, and a machine operation mechanism unit 90 that maintains the circuit breaker 1 in a closing completion state and releases the circuit breaker 1 from the closing completion state. Note that the 20 transmission unit 60 is disposed across the space portions 4 and 5, while the electromagnetic operation mechanism unit 70, the coupling unit 80, and the machine operation mechanism unit 90 are disposed in the space portion 5. In addition, a mounting table 7, at least a part of which is 25 positioned below the electromagnetic operation mechanism unit 70 and which is fixed to the housing 2, is disposed in the space portion 5. The mounting table 7 is constituted by, for example, a shelf, a frame, or a case. [0020] Here, a closed state means a state in which the 30 fixed contact 10a and the movable contact 30a are in contact with each other, and a closing action or a closing operation indicates an action or operation to move the movable contact 30a to bring the movable contact 30a into 9 contact with the fixed contact 10a. A tripping action or a tripping operation indicates an action or operation to move the movable contact 30a away from the fixed contact 10a. [0021] FIG. 2 is a diagram illustrating a configuration 5 inside the housing 2 of the circuit breaker 1 according to the first embodiment, FIG. 3 is an enlarged diagram of an upper part of the electromagnetic operation mechanism unit 70 illustrated in FIG. 2, and FIG. 4 is an enlarged diagram of the electromagnetic operation mechanism unit 70, the 10 coupling unit 80, and the machine operation mechanism unit 90 illustrated in FIG. 2. [0022] As illustrated in FIG. 2, the transmission unit 60 includes an operation arm 61 whose one end portion 611 is rotatably coupled to the mover 30 by the mover pin 52, a 15 coupling plate 62, which is an example of a rotating member whose one end portion 621 is rotatably coupled to another end portion 612 of the operation arm 61 by a link pin 63, and a shaft 64 that is fixed to a central portion of the coupling plate 62 and rotates about an axis 65. 20 [0023] The electromagnetic operation mechanism unit 70 is disposed below the coupling plate 62. Note that the electromagnetic operation mechanism unit 70 and the insulating wall 3 are fixed by a fixing unit (not illustrated). 25 [0024] As illustrated in FIG. 2, the electromagnetic operation mechanism unit 70 includes a yoke 71 formed of a magnetic material, a coil 72 fixed inside the yoke 71, a movable iron core 73 capable of reciprocating linearly in an up-down direction, a drive shaft 74 fixed to the movable 30 iron core 73, and a bearing portion 75 that guides the drive shaft 74 to allow the drive shaft 74 to reciprocate linearly in the up-down direction. The drive shaft 74 reciprocates in the up-down direction at a position with an 10 interval from the axis 65 in the left direction. Note that the movable iron core 73 and the drive shaft 74 are only required to be fixed, and the method for fixing the movable iron core 73 and the drive shaft 74 is not particularly 5 specified. [0025] As illustrated in FIG. 3, the drive shaft 74 is disposed inside the yoke 71 and inside the bearing portion 75 with a gap 76 therebetween. The drive shaft 74 moves in the up-down direction inside the yoke 71 and the bearing 10 portion 75 in a state in which the gap 76 is maintained constant by energization to the coil 72. [0026] As illustrated in FIG. 4, the coupling unit 80 that couples the transmission unit 60 and the electromagnetic operation mechanism unit 70 to each other 15 includes coupling pins 81 and 82 and a coupling link 83. One coupling hole 84 of the coupling link 83 is pivoted, by the coupling pin 81, into a coupling hole 77 formed on a tip portion of the drive shaft 74, which is illustrated in FIG. 3. Another coupling hole 85 of the coupling link 83 20 is pivoted, by the coupling pin 82, into a coupling hole (not illustrated) formed in a middle portion of the coupling plate 62. [0027] As illustrated in FIG. 4, the machine operation mechanism unit 90 includes a frame 91 fixed to the housing 25 2, an opening spring 92 spanned between the frame 91 and the coupling plate 62, and a trip bar 93 pivotally supported by the frame 91 so as to be rotatable, and a latch 94 formed in an L-shape. [0028] The frame 91 is coupled to the insulating wall 3 30 by a fixing member (not illustrated). The fixing member that fixes the frame 91 to the insulating wall 3 employs, for example, a fixing technique such as pin caulking. The frame 91 faces a part of the transmission unit 60 and at 11 least a part of the coupling unit 80 when viewed from an extending direction of the axis 65, which is the axial direction of the coupling plate 62, and covers a part of the transmission unit 60 and at least a part of the 5 coupling unit 80. Note that, in the state illustrated in FIG. 4, a wall portion 91a of the frame 91 on a rear side is illustrated; however, similarly to the wall portion 91a on the rear side, a wall portion that covers a part of the transmission unit 60 and at least a part of the coupling 10 unit 80 is also provided in the frame 91 on a front side. [0029] The frame 91 is provided with an opening 97 for a worker to release the coupling between the transmission unit 60 and the electromagnetic operation mechanism unit 70. The opening 97 illustrated in FIG. 4 is formed in the 15 vicinity of the coupling pin 81 such that the coupling pin 81 can be removed without removing the frame 91 from the housing 2. Note that the relationship between the opening 97 and the coupling pin 81 will be described in detail later. 20 [0030] One end portion 921 of the opening spring 92 is held by a coupling pin 95, and the coupling pin 95 is introduced into a coupling hole (not illustrated) formed in the coupling plate 62. In addition, another end portion 922 of the opening spring 92 is held by a coupling pin 96, 25 and the coupling pin 96 is introduced into a coupling hole (not illustrated) formed in the frame 91. With this configuration, the opening spring 92 is put into a state of being spanned between the frame 91 and the coupling plate 62. 30 [0031] In a state in which the opening spring 92 is spanned between the frame 91 and the coupling plate 62, the opening spring 92 serves as a tension spring in which energy is stored up when the coupling plate 62 is rotated 12 in the clockwise direction about the axis 65 of the shaft 64. The opening spring 92 imparts a force in a counterclockwise direction about the axis 65 to the coupling plate 62. 5 [0032] A shaft 99 extending in a front-rear direction is fixed to a bent portion of the trip bar 93, and the shaft 99 is rotatably introduced into a rotation hole (not illustrated) provided in the frame 91. As illustrated in FIG. 4, the latch 94 includes a semicircular portion 98 10 formed in a semicircular shape and, as will be described later, when the circuit breaker 1 is in the closing completion state, the trip bar 93 is locked by an arc part of the semicircular portion 98 in the latch 94. [0033] In the state illustrated in FIG. 1, the fixed 15 contact 10a and the movable contact 30a are separated from each other, and the circuit breaker 1 is in a tripped state. The action of the circuit breaker 1 when the closing operation is performed from the state illustrated in FIG. 1 will be described. FIG. 5 is a diagram illustrating the 20 circuit breaker 1 while being in the closing completion state. [0034] When the movable iron core 73 is moved upward by energization to the coil 72 of the electromagnetic operation mechanism unit 70 from the tripped state 25 illustrated in FIG. 1, the drive shaft 74 fixed to the movable iron core 73 also moves upward in line with the upward movement of the movable iron core 73. [0035] When the drive shaft 74 moves upward, the coupling plate 62 coupled to the drive shaft 74 by the 30 coupling unit 80 is driven via the coupling unit 80 and rotates in the clockwise direction about the axis 65. As the shaft 64 rotates in the clockwise direction, as illustrated in FIG. 5, the coupling plate 62 and the 13 operation arm 61 are driven, and the coupling plate 62 and the operation arm 61 are put into a state of being linearly disposed. [0036] With this action, the mover 30 moves in the right 5 direction, and the movable contact 30a make contact with the fixed contact 10a. Then, a contact pressure is imparted between the fixed contact 10a and the movable contact 30a by the contact pressure spring 51, and the closing completion state is maintained. In the closing 10 completion state, the power supply-side fixed conductor 10 is electrically connected to the load-side fixed conductor 20 via the fixed contact 10a, the movable contact 30a, the mover 30, and the flexible conductor 40. [0037] In addition, when the coupling plate 62 rotates 15 in the clockwise direction about the axis 65, an engaging portion 66 of the coupling plate 62 moves the latch 94 in the counterclockwise direction. Then, the latch 94 engages with the semicircular portion 98 of the trip bar 93, and the latch 94 is held by the trip bar 93 at a closing 20 completion position. Note that the latch 94 and the trip bar 93 are urged by a spring force such that a mechanical opening action can be executed. [0038] The action of the circuit breaker 1 when a tripping operation that disconnects the movable contact 30a 25 from the fixed contact 10a is performed from the closing completion state illustrated in FIG. 5 will be described. In the closing completion state illustrated in FIG. 5, the opening spring 92 is in an accumulated state and is applying a force in a direction in which the coupling plate 30 62 rotates in the counterclockwise direction about the axis 65 of the shaft 64. [0039] When the trip bar 93 rotates clockwise, the trip bar 93 and the latch 94 are disengaged. Therefore, the 14 coupling plate 62 is rotated in the counterclockwise direction by the opening spring 92, and the another end portion 612 of the operation arm 61 is moved upward in line with the rotation of the coupling plate 62 in the 5 counterclockwise direction. [0040] When the another end portion 612 of the operation arm 61 moves upward, the one end portion 611 of the operation arm 61 moves in the left direction. Therefore, the mover 30 moves in the left direction, and the movable 10 contact 30a moves away from the fixed contact 10a. With these movements, an electric circuit including the power supply-side fixed conductor 10 and the load-side fixed conductor 20 is broken in the circuit breaker 1. [0041] Next, a method of replacing the electromagnetic 15 operation mechanism unit 70 or the machine operation mechanism unit 90 will be described. FIGS. 6, 9, 10 and 12 are explanatory diagrams of a method of replacing the electromagnetic operation mechanism unit 70 or the machine operation mechanism unit 90; FIGS. 7 and 8 are diagrams 20 illustrating another example of a configuration for restricting a downward movement of the drive shaft 74, and FIG. 11 is a side view illustrating a relationship between the frame 91, the coupling pin 81, the coupling link 83, and the bearing portion 75. 25 [0042] When the circuit breaker 1 is in the closing completion state, as illustrated in FIG. 5, the engaging portion 66 formed in the another end portion 622 of the coupling plate 62 is engaged with the trip bar 93, and the trip bar 93 is in a state in which the rotation thereof is 30 restricted by the latch 94. Therefore, even in a state in which no current is given to the coil 72 of the electromagnetic operation mechanism unit 70, the closing completion state illustrated in FIG. 5 is maintained. 15 [0043] While the drive shaft 74 is in a state of not being driven by the electromagnetic operation mechanism unit 70, as illustrated in FIG. 6, a lock block 78 is temporarily installed below the drive shaft 74, and the 5 downward movement of the drive shaft 74 is restricted by bringing the movable iron core 73 into contact with the lock block 78. Then, in a state in which the downward movement of the drive shaft 74 is restricted, the trip bar 93 and the latch 94 are disengaged. 10 [0044] When a force in the counterclockwise direction is applied to the coupling plate 62 in a state in which the drive shaft 74 is not driven by the electromagnetic operation mechanism unit 70, a force acts on the drive shaft 74 via the coupling unit 80 in a direction 15 intersecting the up-down direction, which is the movement direction of the drive shaft 74. Since the gap 76 is formed between the drive shaft 74 and the bearing portion 75 as illustrated in FIG. 3, when the left side of the drive shaft 74 is pushed against the bearing portion 75, 20 the drive shaft 74 is put into a state of being inclined in the left direction with respect to the up-down direction. [0045] Here, the installation of the lock block 78 described above is performed by the worker mounting the lock block 78 on the mounting table 7; however, the circuit 25 breaker 1 only needs to be configured such that the lock block 78 is disposed below the movable iron core 73, and the installation of the lock block 78 is not limited to the above-described example. [0046] For example, the circuit breaker 1 may be 30 configured to automatically dispose the lock block 78 so as to be disposed below the movable iron core 73. Specifically, as illustrated in FIG. 7, the circuit breaker 1 may have a configuration including a lifting mechanism 79 16 that lifts and lowers the lock block 78. In this case, the lifting mechanism 79 moves the lock block 78 upward and restricts the downward movement of the drive shaft 74 when an operation button (not illustrated) is operated by the 5 worker. Note that the lifting mechanism 79 may be configured to move the lock block 78 upward only when the coil 72 of the electromagnetic operation mechanism unit 70 is not energized. [0047] In addition, instead of the lifting mechanism 79, 10 the circuit breaker 1 may be configured to move the lock block 78 to below the movable iron core 73 by moving the lock block 78 in a left-right direction or the up-down direction, and restrict the downward movement of the drive shaft 74. 15 [0048] Furthermore, in the example described above, the downward movement of the drive shaft 74 is restricted by the lock block 78; however, the downward movement of the drive shaft 74 may be restricted by another locking member instead of the lock block 78. For example, in the 20 electromagnetic operation mechanism unit 70 illustrated in FIG. 8, the yoke 71 is provided with a plurality of through-holes 8, and a locking member 9 is inserted into the plurality of through-holes 8. In this state, the movement of the locking member 9 in the up-down direction 25 is restricted, and the drive shaft 74 is positioned above the locking member 9. Therefore, as illustrated in FIG. 8, the movable iron core 73 makes contact with the locking member 9, and the downward movement of the drive shaft 74 is restricted by the locking member 9. 30 [0049] Note that, in the example illustrated in FIG. 8, the through-holes 8 are provided in the yoke 71; however, a member including the through-hole 8 may be fixed to the lower side of the yoke 71 illustrated in FIG. 6 such that 17 the downward movement of the drive shaft 74 is restricted by inserting the locking member 9 into the through-hole 8 of the member fixed to the yoke 71, as in the example illustrated in FIG. 8. 5 [0050] As illustrated in FIG. 9, when the left side of the drive shaft 74 is pushed against the bearing portion 75, a state in which only a part of the coupling pin 81 is exposed from the opening 97 formed in the frame 91 when viewed from the Y-axis direction, which is the axial 10 direction of the coupling plate 62, is obtained. By pressing the drive shaft 74 in the right direction with a tool or hand in the state illustrated in FIG. 9, the drive shaft 74 is switched from a state in which the left side of the drive shaft 74 is pushed against the bearing portion 75 15 to a state in which the right side of the drive shaft 74 is pushed against the bearing portion 75, as illustrated in FIG. 10. [0051] In the state illustrated in FIG. 10, the right side of the drive shaft 74 is pushed against the bearing 20 portion 75, and the drive shaft 74 is inclined in the right direction with respect to the up-down direction; in this state, the entire coupling pin 81 is exposed from the opening 97 formed in the frame 91 when viewed from the axial direction of the coupling plate 62. Therefore, the 25 coupling pin 81 can be simply removed from the circuit breaker 1 by pulling or pressing the coupling pin 81 in the Y-axis direction, which is the front-rear direction, with a tool or hand. [0052] Then, by removing the coupling pin 81, the 30 transmission unit 60 and the electromagnetic operation mechanism unit 70 can be detached from each other, and the electromagnetic operation mechanism unit 70 can be safely replaced. In addition, since the transmission unit 60 and 18 the electromagnetic operation mechanism unit 70 can be detached from each other, a state in which the force from the electromagnetic operation mechanism unit 70 does not act on the machine operation mechanism unit 90 is obtained; 5 accordingly, a part related to the electromagnetic operation mechanism unit 70, such as the machine operation mechanism unit 90, can also be safely replaced. [0053] Furthermore, when the circuit breaker 1 is in the tripped state, the opening 97 of the frame 91 is in a state 10 in which only a part of the coupling pin 81 is exposed from the opening 97 when viewed from the axial direction of the coupling plate 62, as illustrated in FIG. 4. Additionally, in a state in which a current is supplied to the coil 72, the electromagnetic operation mechanism unit 70 keeps the 15 drive shaft 74 in an extended state in the up-down direction. [0054] Therefore, during a period until the tripped state illustrated in FIG. 4 is switched to the closing completion state illustrated in FIG. 5 by the current 20 supply to the coil 72, the drive shaft 74 moves in the updown direction while remaining in a state in which only a part of the coupling pin 81 is exposed from the opening 97 when viewed from the axial direction of the coupling plate 62. 25 [0055] That is, the circuit breaker 1 is not switched to a state in which the whole coupling pin 81 is exposed from the opening 97 when viewed from the axial direction of the coupling plate 62, during a period until the tripped state is switched to the closing completion state. Accordingly, 30 the coupling pin 81 cannot be removed during a period until the tripped state is switched to the closing completion state. [0056] Additionally, an interval between the frame 91 19 and the coupling pin 81 in the Y-axis direction is set to a length at which the coupling between the coupling link 83 and the drive shaft 74 by the coupling pin 81 is not released. For example, as illustrated in FIG. 11, an 5 interval D1 between the coupling pin 81 and the frame 91 is set to be shorter than a depth D2 of the coupling hole 77. [0057] With this configuration, even when a retaining ring that prevents the coupling pin 81 from falling off is not attached to the coupling pin 81, the coupling pin 81 10 can be prevented from falling off from the drive shaft 74 during the opening/closing action, and the circuit breaker 1 can be prevented from becoming inactive. Note that the interval D1 between the coupling pin 81 and the frame 91 only needs to be set such that the coupling pin 81 does not 15 fall off from one of the drive shaft 74 and the coupling link 83, and the coupling relationship between the drive shaft 74 and the coupling pin 81 is not limited to the example illustrated in FIG. 11. [0058] When a retaining ring is attached to the coupling 20 pin 81 and the coupling pin 81 is held with the retaining ring, a special tool is required for the replacement work for the electromagnetic operation mechanism unit 70 and the like; additionally, a space inside the frame 91 is small and thus removing and attaching the retaining ring is not 25 easy in some cases. On the other hand, even when no retaining ring is attached to the coupling pin 81, the coupling pin 81 can be prevented from falling off from the drive shaft 74 during the opening/closing action, and the replacement work for the electromagnetic operation 30 mechanism unit 70 and the like can be facilitated. [0059] In addition, when the circuit breaker 1 is in the tripped state, a state in which only a part of the coupling pin 81 is exposed from the opening 97 formed in the frame 20 91 when viewed from the axial direction of the coupling plate 62 is obtained as illustrated in FIG. 4. Furthermore, in the state illustrated in FIG. 4, the coupling pin 95 is put into a state of being locked to the frame 91, and no 5 force acts on the coupling plate 62 in the counterclockwise direction by the opening spring 92. [0060] Accordingly, in the state illustrated in FIG. 4, no force acts on the drive shaft 74 in the left-right direction. By pressing the drive shaft 74 in the right 10 direction with a tool or hand from the state illustrated in FIG. 4, the entire coupling pin 81 can be put into a state of being exposed from the frame 91 as illustrated in FIG. 12. As a consequence, the coupling pin 81 can be removed. [0061] Note that the circuit breaker 1 is not limited to 15 a configuration in which, when the drive shaft 74 is driven by the electromagnetic operation mechanism unit 70, the drive shaft 74 moves along the up-down direction and the drive shaft 74 does not tilt with respect to the up-down direction. That is, the circuit breaker 1 may have a 20 configuration in which the drive shaft 74 is put into a state of being inclined in the left direction with respect to the up-down direction by the force of the opening spring 92 while the drive shaft 74 is driven by the electromagnetic operation mechanism unit 70. In this case, 25 the opening 97 of the frame 91 may be formed such that the entire coupling pin 81 is exposed from the opening 97 when viewed from the axial direction of the coupling plate 62 in a case where the drive shaft 74 does not tilt with respect to the up-down direction. 30 [0062] In addition, in the above description, the drive shaft 74 is inclined in the left direction with respect to the up-down direction by the force of the opening spring 92, which is a spring member; however, a force in the left 21 direction can also be applied to the drive shaft 74 by an urging member other than the spring member. The urging member other than the opening spring 92 is an elastic member such as rubber, for example. 5 [0063] Furthermore, in the above description, the transmission unit 60 and the electromagnetic operation mechanism unit 70 are coupled by the coupling pins 81 and 82 and the coupling link 83; however, the configuration of the coupling unit 80 is not limited to the above-described 10 example. For example, the circuit breaker 1 may have a configuration in which the transmission unit 60 and the electromagnetic operation mechanism unit 70 are coupled by the coupling unit 80 including a plurality of coupling links. In this case, the opening 97 is formed such that at 15 least one coupling pin of the plurality of coupling links and the opening 97 have the relationship between the coupling pin 81 and the opening 97 described above. Alternatively, the opening 97 may be formed such that the relationship between a plurality of coupling pins and the 20 opening 97 is equal to the relationship between the coupling pin 81 and the opening 97. [0064] Additionally, in the circuit breaker 1 described above, the shaft 64 is fixed to the coupling plate 62; however, the circuit breaker 1 may have a configuration in 25 which the shaft 64 is fixed to the frame 91, and the coupling plate 62 is attached to the shaft 64 so as to be rotatable about the axis 65. [0065] Moreover, the transmission unit 60 is not limited to the configuration described above. For example, the 30 transmission unit 60 may have a configuration in which the mover 30 is coupled to a tip portion of one rotating member that rotates about the axis 65. For example, the circuit breaker 1 may have a configuration in which the another end 22 portion 612 of the operation arm 61 is attached to the shaft 64 so as to be rotatable about the axis 65 without providing the coupling plate 62. In addition, the transmission unit 60 may have a configuration including one 5 or more link members between the operation arm 61 and the coupling plate 62. [0066] Furthermore, the circuit breaker 1 described above has a configuration in which the operation arm 61 and the mover 30 are directly coupled to each other; however, a 10 configuration in which one or more members are interposed between the operation arm 61 and the mover 30 to indirectly couple the operation arm 61 and the mover 30 may be employed. [0067] Additionally, the circuit breaker 1 described 15 above has a configuration in which the coupling plate 62 is inclined in the left direction with respect to the up-down direction by the force of the opening spring 92; however, the direction of inclination caused by the force of the opening spring 92 is not limited to the left direction and 20 may be the right direction. In this case, the opening 97 is disposed such that the entire coupling pin 81 is exposed from the opening 97 when viewed from the axial direction of the coupling plate 62, by pressing the drive shaft 74 in the left direction with a tool or hand. 25 [0068] As described thus far, the circuit breaker 1 according to the first embodiment includes: the power supply-side fixed conductor 10, which is a stator including the fixed contact 10a; the mover 30 including the movable contact 30a; the transmission unit 60; the electromagnetic 30 operation mechanism unit 70; the coupling unit 80; the opening spring 92, which is an urging member; and the frame 91. The transmission unit 60 includes the coupling plate 62, which is an example of the rotating member, and moves 23 the mover 30 in line with the rotation of the coupling plate 62 to make contact and isolation between the fixed contact 10a and the movable contact 30a. Furthermore, the electromagnetic operation mechanism unit 70 includes the 5 drive shaft 74 and moves the drive shaft 74 linearly. The coupling unit 80 couples the transmission unit 60 and the drive shaft 74 to each other, and rotates the coupling plate 62 in line with the movement of the drive shaft 74. The opening spring 92 applies a force to the coupling plate 10 62 in the counterclockwise direction, which is a rotation direction to isolate the movable contact 30a from the fixed contact 10a. In a state in which the coupling plate 62 is inclined in a first direction, which is one of the left direction and the right direction with respect to the up15 down direction, by the force of the opening spring 92, the frame 91 faces at least a part of the coupling pin 81, which is an example of a coupling member of the coupling unit 80 coupled to the drive shaft 74, in the axial direction of the coupling plate 62, and covers at least the 20 part of the coupling pin 81. With this configuration, the coupling pin 81 can be prevented from falling off during the closing action and the tripping action of the circuit breaker 1, and the circuit breaker 1 can be prevented from becoming inactive due to the falling-off of the coupling 25 pin 81. Moreover, the frame 91 includes the opening 97 at a position where the entire coupling pin 81 is exposed when viewed from the axial direction of the coupling plate 62 in a state in which the drive shaft 74 is inclined in a second direction, which is an opposite direction to the first 30 direction with respect to the up-down direction. With this configuration, for example, when the circuit breaker 1 is in the state illustrated in FIG. 6, the entire coupling pin 81 can be exposed by moving the drive shaft 74 to the right 24 direction, and the replacement work for the electromagnetic operation mechanism unit 70 and the like can be facilitated. [0069] In addition, the frame 91 covers at least a part of the coupling pin 81 in a state in which the drive shaft 5 74 is not inclined with respect to the up-down direction. With this configuration, even when the drive shaft 74 is not inclined with respect to the up-down direction during the closing action and the tripping action, the coupling pin 81 can be prevented from falling off. 10 [0070] Furthermore, the transmission unit 60 includes the operation arm 61, which is an example of an arm member of which the another end portion 612 is rotatably coupled to the coupling plate 62, which is an example of a plate member that rotates around the axis 65, and in which the 15 mover 30 is coupled to the one end portion 611. The opening spring 92 is spanned between the frame 91 and the coupling plate 62. The coupling unit 80 couples the coupling plate 62 and the drive shaft 74 to each other. With this configuration, a force can be applied to the 20 drive shaft 74 in a direction intersecting the up-down direction by the opening spring 92 of the machine operation mechanism unit 90, and an increase in the number of components constituting the circuit breaker 1 can be suppressed, as compared with a case where an urging member 25 is independently provided. [0071] The configuration illustrated in the above embodiments indicates examples of the content of the present invention and can be combined with another known technology. A part of the configuration can also be 30 omitted and modified without departing from the gist of the present invention. Reference Signs List 25 [0072] 1 circuit breaker; 2 housing; 3 insulating wall; 4, 5 space portion; 6 wall portion; 7 mounting table; 8 through-hole; 9 locking member; 10 power supply-side fixed conductor; 10a fixed contact; 20 load5 side fixed conductor; 30 mover; 30a movable contact; 40 flexible conductor; 50 holder; 51 contact pressure spring; 52 mover pin; 60 transmission unit; 61 operation arm; 62 coupling plate; 63 link pin; 64 shaft; 65 axis; 66 engaging portion; 70 electromagnetic operation 10 mechanism unit; 71 yoke; 72 coil; 73 movable iron core; 74 drive shaft; 75 bearing portion; 76 gap; 77 coupling hole; 78 lock block; 79 lifting mechanism; 80 coupling unit; 81, 82, 95, 96 coupling pin; 83 coupling link; 84, 85 coupling hole; 90 machine operation mechanism unit; 91 15 frame; 92 opening spring; 93 trip bar; 94 latch; 97 opening; 101, 201, 301, 401, 611, 621, 921 one end portion; 102, 202, 302, 402, 612, 622, 922 another end portion. 26 We Claim: 1. A circuit breaker comprising: a stator including a fixed contact; 5 a mover including a movable contact; a transmission unit including a rotating member, to move the mover in line with rotation of the rotating member to make contact and isolation between the fixed contact and the movable contact; 10 an electromagnetic operation mechanism unit including a shaft, to move the shaft linearly; a coupling unit to couple the transmission unit and the shaft to each other, and rotate the rotating member in line with movement of the shaft; 15 an urging member to apply a force to the rotating member in a rotation direction that isolates the movable contact from the fixed contact; and a frame, in a state in which the shaft is inclined in a first direction with respect to a movement direction of 20 the shaft by the force of the urging member, to face at least a part of the coupling pin of the coupling unit coupled to the shaft in an axial direction of the rotating member, and cover the at least a part of the coupling pin, wherein 25 the frame includes an opening at a position where the entire coupling pin is exposed when viewed from the axial direction in a state in which the shaft is inclined in a second direction, which is an opposite direction to the first direction with 30 respect to the movement direction. 2. The circuit breaker according to claim 1, wherein the frame covers at least a part of the coupling pin 27 in a state in which the shaft is not inclined with respect to the movement direction. 3. The circuit breaker according to claim 1 or 2, wherein 5 the rotating member is a plate member to rotate around an axis, the transmission unit includes an arm member in which the mover is coupled to one end portion and of which another end portion is rotatably coupled to the plate 10 member, the urging member is a spring member spanned between the frame and the plate member, and the coupling unit couples the plate member and the shaft to each other.