Circuit breaker

Abstract

To provide a circuit breaker capable of obtaining a stable energization force with a spring member for pressing a movable contact to a stationary contact by preventing oscillation of a trajectory of the spring member and preventing an arc and metal particles from sneaking to the spring member.SOLUTION: A circuit breaker comprises: a crossbar 30 including a bottom face part 30d, which includes a clearance 30c, and an arm part 30e; a movable contactor 9 in which a movable contact 8, which can be in contact with and separated from a stationary contact, is provided in one end and a lock pin 31 is provided in the other end; a pressure contact spring 33 of which the one end side is disposed between the bottom face part 30d and the arm part 30e of the crossbar 30 and the other end side is disposed on the side of the lock pin 31 and which applies torque for pressing the movable contact 8 to the stationary contact to the movable contactor 9; and a spring receiving part 32 which is engaged to the lock pin 31 and includes a spring receiving plate 32c for receiving the other end of the pressure contact spring 33. The spring receiving part 32 includes a lower plate 32 rising from the spring receiving plate 32c, the lower plate 32a closes the clearance 30c of the bottom face part 30d, and a tip end side of the lower plate 32 is held by the bottom face part 30d.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a circuit breaker. [Background technology]

[0002] A circuit breaker has two functions: it opens and closes an electric circuit using an operating handle, and it also breaks the electric circuit when an overcurrent flows. The electric circuit is opened and closed when a movable contactor pivotally supported on a crossbar is rotated and separated from a fixed contactor. When the electric circuit is closed, it is necessary to ensure a stable contact pressure of the movable contactor against the fixed contactor in order to establish electrical contact between the movable contactor and the fixed contactor.

[0003] Therefore, in Patent Document 1, a spring member is provided between a holder serving as a crossbar that supports one end of the movable contact and an operating pin provided on one end side of the movable contact, which urges the movable contact to rotate in the direction in which it is pressed by the fixed contact, and a retaining member is provided between the spring member and the operating pin, which has an engaging surface that engages with the operating pin and a spring receiving surface that receives one end of the spring member, thereby efficiently transmitting the compressive force of the spring member to the movable contactor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-31953 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the recess that forms the spring bearing surface that receives one end of the spring member is shallow, leaving the spring member exposed at the bottom of the crossbar. This causes the spring member to oscillate, resulting in a loss of biasing force. Furthermore, when the electrical circuit is interrupted, most of the arc gas generated at the switching contacts is extinguished by the arc extinguishing device. However, metal particles generated along with the arc at the switching contacts and some of the arc are scattered, and this can travel through the arc extinguishing device and other devices to the bottom of the crossbar and into the spring member, reducing the biasing force.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a circuit breaker that can prevent the spring member from vibrating orbitally, prevent arcs and metal particles from getting around the spring member, and obtain a stable biasing force from the spring member to press the movable contact against the fixed contact. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the circuit breaker of the present disclosure includes a crossbar having a bottom surface with a gap and arms extending diagonally upward from the bottom surface, the arms being connected to a switching mechanism that opens and closes an electric circuit and rotates in response to the operation of the switching mechanism, a movable contactor pivotally supported by the crossbar and having a movable contact at one end that can engage and separate from a fixed contact and a locking pin at the other end, a pressure spring having one end disposed between the bottom surface of the crossbar and the arms and the other end disposed on the locking pin side of the movable contactor, which applies a rotational force to the movable contactor that presses the movable contact against the fixed contact, and a spring retainer having a first plate engaged with the locking pin and receiving the other end of the pressure spring. The spring retainer includes a second plate rising from the first plate, which closes the gap in the bottom surface and has a tip end held by the bottom surface. [Effects of the Invention]

[0008] The circuit breaker of the present disclosure has the following advantages: it is possible to prevent the spring member from vibrating orbitally, it is possible to prevent arcs and metal particles from getting around the spring member, and it is possible to obtain a stable biasing force from the spring member for pressing the movable contact against the fixed contact. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view showing an ON state of a circuit breaker according to an embodiment; [Figure 2] FIG. 1 is a cross-sectional view showing a tripped state of a circuit breaker according to an embodiment of the present invention; [Figure 3] FIG. 1 is a cross-sectional view showing an OFF state of a circuit breaker according to an embodiment; [Figure 4] FIG. 1 is a cross-sectional view showing an on state of a circuit breaker according to an embodiment; [Figure 5] FIG. 1 is an enlarged, partially cutaway view of a circuit breaker in a reset state according to an embodiment; [Figure 6] FIG. 1 is an enlarged view showing a configuration around a movable contact of a circuit breaker in an on-state according to an embodiment; [Figure 7] FIG. 1 is an enlarged view showing a configuration around a movable contact of a circuit breaker in an OFF state according to an embodiment; [Figure 8] FIG. 1 is a perspective view showing a configuration of a spring receiving portion of a circuit breaker according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a circuit breaker according to an embodiment will be described in detail with reference to the drawings.

[0011] Embodiment FIG. 1 is a front view showing a circuit breaker 101 according to an embodiment in an ON state. In FIG. 1, a cover 1, which is one component constituting the housing of the circuit breaker 101, is not shown in the right half. FIG. 2 is a cross-sectional view showing a tripped state of the circuit breaker 101 according to an embodiment. FIG. 3 is a cross-sectional view showing an OFF state of the circuit breaker 101 according to an embodiment. FIG. 4 is a cross-sectional view showing an ON state of the circuit breaker 101 according to an embodiment. FIGS. 2, 3, and 4 are cross-sectional views taken along line II-II shown in FIG. 1. The circuit breaker 101 includes a molded case circuit breaker, an earth leakage circuit breaker, etc. The circuit breaker 101 according to the embodiment is a three-pole circuit breaker.

[0012] As shown in FIG. 1, the insulating housing of the circuit breaker 101 is composed of a cover 1 and a base 2. Circuit breaker units for multiple phases, the number of which corresponds to the number of poles, are arranged in parallel on the base 2. In the case of FIG. 1, three circuit breaker units are arranged. The base 2 is also provided with power supply side terminals 4, the number of which corresponds to the number of poles connected to the power supply side wires, and load side terminals 5, the number of which corresponds to the number of poles connected to the load side wires. A switching mechanism 40 having a well-known toggle link mechanism and an operating handle 3 is arranged in the center of the base 2. The operating handle 3 protrudes from a handle window 1a in the cover 1 and can be operated in an on or off direction. The base 2 is also provided with arc extinguishing devices 41, the number of which corresponds to the number of poles (three in this disclosure).

[0013] As shown in FIGS. 1 to 4 , each of the three circuit breaker units includes a fixed contactor 6, a fixed contact 7, a movable contactor 9, a movable contactor 8, and a tripping device 42. The fixed contactor 7 is fixed to one end of the fixed contactor 6, which is formed integrally with the source terminal 4. The load terminal 5 is connected to one end of the movable contactor 9 via the tripping device 42. The movable contactor 8 is fixed to the other end of the movable contactor 9. The movable contactor 9 is rotatably held by a crossbar 30. The movable contactor 8 makes contact with and separates from the fixed contact 7, thereby opening and closing the circuit breaker 101, i.e., turning on and off the electrical path between the source terminal 4 and the load terminal 5. The circuit breaker 101 is opened and closed by the crossbar 30, which is connected to a toggle link of the switching mechanism 40, and the movable contactor 9, which is supported by the crossbar 30 via a shaft 45, being driven clockwise or counterclockwise in response to the operation of the switching mechanism 40. The contact pressure between the fixed contact 7 and the movable contact 8 in the ON state is obtained by a contact pressure spring 33 provided between the spring bearing portion 30b of the crossbar 30 and the spring bearing portion 32 engaged with the locking pin 31 of the movable contactor 9, as will be described in detail later. An arc extinguishing device 41 provided in each circuit breaking unit cuts off the arc generated between the fixed contactor 6 and the movable contactor 9.

[0014] Next, the configuration of the switching mechanism 40 will be described. FIG. 5 is an enlarged, partially cutaway view of the switching mechanism 40 of the circuit breaker 101 in the reset state according to the embodiment. As shown in FIGS. 2 to 5, the switching mechanism 40 includes a pair of opposing frames 11, a trip bar 12, a latch 13, a catch 14, a receiving plate 15, a cradle 16, an upper link 17, a lower link 18, a spring pin 19, and a main spring 20. The operating handle 3 is manually operated. A handle arm 22 is attached to the operating handle 3. The frame 11 is fixed to the base 2. The handle arm 22 is rotatably supported by the frame 11. The handle arm 22 rotates around a rotation center 43. The operating handle 3 protrudes upward from the cover 1 and is manually rotated around the rotation center 43. Rotation of the operating handle 3 causes the handle arm 22 to rotate together with the operating handle 3 around the rotation center point 43. The handle arm 22 is in an intermediate position in the trip state shown in Fig. 2, in a right-inclined position in the off state shown in Fig. 3, and in a left-inclined position in the on state shown in Fig. 4.

[0015] The upper end of the upper link 17 is rotatably supported at a link support point 44 of the cradle 16. The upper end of the lower link 18 is rotatably connected to the lower end of the upper link 17 via a spring pin 19. The upper link 17 and the lower link 18 form a toggle link. The lower end of the lower link 18 is rotatably connected to the crossbar 30. The main spring 20 has a drive side 20a and a driven side 20b, with the drive side 20a connected to the handle arm 22 and the driven side 20b connected to the spring pin 19.

[0016] Next, the ON / OFF operation of the movable contact 8 relative to the fixed contact 7 will be described. In the OFF state shown in FIG. 3, the movable contact 8 is separated from the fixed contact 7, and the fixed contact 7 and the movable contact 8 are in the OFF state. In this OFF state, the handle arm 22 is in a right-tilted position, and the lower link 18 is also in a right-tilted position. When the operating handle 3 is operated counterclockwise in the OFF state shown in FIG. 3, the handle arm 22 together with the operating handle 3 rotates counterclockwise around the rotation center point 43, and the handle arm 22 rotates to the left-tilted position shown in FIG. 4. This rotation of the handle arm 22 causes the drive side 20a of the main spring 20 to move counterclockwise around the rotation center point 43 of the handle arm 22. The counterclockwise movement of the drive side 20a of the main spring 20 changes the load direction of the main spring 20, and the spring pin 19 moves upward from the position shown in FIG. 3. Movement of spring pin 19 causes lower link 18 to rotate crossbar 30 counterclockwise. Because movable contactor 9 is pivotally supported on crossbar 30 by shaft 45, when crossbar 30 rotates counterclockwise, movable contactor 9 rotates counterclockwise around shaft 45. This causes movable contact 8 on movable contactor 9 to contact fixed contact 7, resulting in the ON state shown in FIG. 4. In this ON state, cradle 16 is held in engagement with one rotating end of receiving plate 15. The other rotating end of receiving plate 15 is engaged with catch 14, which is engaged with latch 13, maintaining the ON state.

[0017] In the ON state shown in FIG. 4, when the operating handle 3 is operated clockwise, the handle arm 22 together with the operating handle 3 rotates clockwise around the rotation center 43. As a result, the handle arm 22 rotates to the right-tilted position shown in FIG. 3. This rotation of the handle arm 22 causes the drive side 20a of the main spring 20 to move clockwise around the rotation center 43 of the handle arm 22. The movement of the drive side 20a of the main spring 20 changes the load direction of the main spring 20, and the spring pin 19 moves downward from the position shown in FIG. 4. This movement of the spring pin 19 returns the lower link 18 to the right-tilted state as shown in FIG. 3, and the crossbar 30 rotates clockwise. When the crossbar 30 rotates clockwise, the movable contact 9 rotates clockwise around the axis 45. As a result, the movable contact 8 on the movable contact 9 separates from the fixed contact 7, resulting in the OFF state. In this OFF state, the cradle 16 is held in engagement with one of the rotational ends of the receiving plate 15. The other rotational end of the receiving plate 15 is locked by the catch plate 14, and the catch plate 14 is locked by the latch 13, thereby maintaining the OFF state.

[0018] Next, the tripping operation will be described. In the ON state shown in FIG. 4, when the tripping device 42 is activated due to an overcurrent or the like, the trip bar 12, which cooperates with the latch 13, is pushed into the tripping device 42, causing the trip bar 12 and the latch 13 to rotate counterclockwise. As the latch 13 rotates, the catch 14 and the catch 15 rotate around the pivot 14a and the pivot 15a, respectively, disengaging the catch 15 from the cradle 16. Because the cradle 16 is constantly biased counterclockwise by the main spring 20, disengaging the catch 15 causes it to rotate counterclockwise. This rotation of the cradle 16 places the upper link 17 in the left-tilted position shown in FIG. 2, changes the load direction of the main spring 20, and moves the spring pin 19 downward from the position shown in FIG. 4. Due to the movement of the spring pin 19, the lower link 18 returns to the right-tilted position as shown in FIG. 2, causing the crossbar 30 to rotate clockwise. When the crossbar 30 rotates clockwise, the movable contactor 9 rotates clockwise about the axis 45. As a result, the movable contact 8 on the movable contactor 9 separates from the fixed contact 7, resulting in a tripped state.

[0019] In a main circuit breaker where the current flowing through the circuit is around several hundred to several thousand amperes, it is necessary to increase the biasing force of the main spring 20 to stably maintain the ON state. Therefore, the force required for the trip device 42 to push in the trip bar 12, i.e., the tripping load, is insufficient. Therefore, a three-stage latch structure is provided in which a stopper plate 14 and a receiving plate 15 are interposed between the latch 13 and the cradle 16 to reduce the tripping load of the trip bar 12 biased by the main spring 20.

[0020] Next, the reset operation, which is the operation for transitioning from the trip state shown in Fig. 2 to the off state shown in Fig. 3, will be described. When the operating handle 3 is rotated clockwise in the trip state shown in Fig. 2, the handle arm 22 rotates the cradle 16 clockwise, and the cradle 16 begins to rotate clockwise about the rotation axis 16a. During this rotation, the receptacle 15, which is biased toward the line-side terminal 4, is temporarily moved toward the load-side terminal 5. When the cradle 16 further rotates and disengages from the receptacle 15, the receptacle 15 moves toward the line-side terminal 4, and the reset state shown in Fig. 5 is reached. When the reset operation using the operating handle 3 is completed in this reset state, the cradle 16 engages with the receptacle 15 due to the biasing force of the main spring 20, and the device returns to the off state shown in Fig. 3.

[0021] Next, a configuration for applying contact pressure between the fixed contact 7 and the movable contact 8 in the ON state will be described. Fig. 6 is an enlarged view showing the configuration around the movable contactor 9 of the circuit breaker 101 in the ON state according to the embodiment. Fig. 7 is an enlarged view showing the configuration around the movable contactor 9 of the circuit breaker 101 in the OFF state according to the embodiment. Fig. 8 is a perspective view showing the configuration of the spring bearing portion 32 of the circuit breaker 101 according to the embodiment.

[0022] Contact pressure applying portions 34 that apply contact pressure between the fixed contact 7 and the movable contact 8 are provided on both sides of the movable contact 9. The contact pressure applying portions 34 include a contact pressure spring 33, a spring receiving portion 32, a locking pin 31, and an acting arm 35. As shown in FIG. 8, the spring receiving portion 32 and the acting arm 35 are integrally configured. The contact pressure spring 33 is disposed between a spring receiving portion 30b serving as a first spring receiving portion formed on the crossbar 30 and a spring receiving portion 32 serving as a second spring receiving portion formed on the movable contact 9 side.

[0023] The crossbar 30 has a bottom surface 30d in which a gap 30c is formed, a spring bearing portion 30b, and an arm portion 30e extending obliquely upward from the bottom surface 30d via the spring bearing portion 30b, with the spring bearing portion 30b being provided between the bottom surface 30d and the arm portion 30e. The arm portion 30e is connected to a switching mechanism portion 40 that opens and closes the electrical circuit.

[0024] The spring bearing portion 32 is connected to the movable contactor 9 by a locking pin 31 and an operating arm portion 35. The locking pin 31 is inserted into a pin hole 35b of the operating arm portion 35. The locking pin 31 is locked to the operating arm portion 35 through the pin hole 35b. A protrusion 35a that functions as a stopper is provided at the bottom of the operating arm portion 35.

[0025] 8, the spring receiving portion 32 has a spring receiving plate 32c as a first plate that abuts against the contact pressure spring 33, an upper plate 32b, and a lower plate 32a as a second plate. The lower plate 32a rises vertically from the spring receiving plate 32c and extends long.

[0026] The spring bearing portion 32 can freely rotate in the clockwise direction around the locking pin 31. In the counterclockwise direction, the protrusion 35a of the operating arm 35 functions as a stopper, so the spring bearing portion 32 stops at a position corresponding to the ON state where the movable contact 8 abuts against the fixed contact 7. When the movable contact 8 abuts against the fixed contact 7 in the ON state, as shown in FIG. 6, the contact pressure spring 33 contracts, and the force of the contact pressure spring is transmitted via the spring bearing portion 32 to the position of the locking pin 31 separated from the shaft 45, which is the rotation axis of the movable contactor 9. This applies a rotational force to the movable contactor 9 in a direction pressing the movable contactor 9 against the fixed contactor 6. As a result, contact pressure can be generated between the fixed contact 7 and the movable contactor 8.

[0027] Here, the crossbar 30 rotates around the axis 45, which is the rotation axis of the movable contact 9, but a gap 30c is formed in the bottom surface 30d of the crossbar 30 so as not to hinder the contraction of the contact pressure spring 33. Because of this gap 30c, if the lower plate 32a of the spring receiving portion 32 is only about the same length as the upper plate 32b, the contact pressure spring 33 will bend toward the bottom surface of the crossbar 30, causing the trajectory of the contact pressure spring 33 to oscillate. Furthermore, after the contact pressure applying portion 34 is assembled, if the trajectory of the contact pressure spring 33 oscillates, it is necessary to adjust the position of the contact pressure spring 33 to correct the trajectory.

[0028] In addition, some of the arc gas, metal particles, and soot generated between the fixed contact 7 and the movable contact 8 may find their way through the gap 30c at the bottom surface 30d of the crossbar 30 via the arc extinguishing device 41 or the like to the contact pressure spring 33, as shown by the arrow K in Figure 2, causing the contact pressure spring 33 to malfunction or wear out.

[0029] Therefore, in this embodiment, the length of the lower plate 32a of the spring receiving portion 32 is set so as to close the gap 30c and so that the tip side of the lower plate 32a is held by the upper surface 30a of the bottom surface 30d of the crossbar 30. In addition, the upper surface 30a of the bottom surface 30d of the crossbar 30 is shaped to have a flat surface on which the lower plate 32a of the spring receiving portion 32 can slide, and is shaped like a step that allows the lower plate 32a of the spring receiving portion 32 to be stored.

[0030] As described above, the upper surface 30a of the bottom surface 30d of the crossbar 30 is formed in a stepped shape with a flat surface that can accommodate the lower plate 32a of the spring receiving portion 32, so that the lower plate 32a and the upper surface 30a of the bottom surface 30d can be kept parallel to each other, and the direction of the line of force of the contact pressure spring 33 can be stably maintained. Therefore, the spring receiving portion 32 slides on the flat upper surface 30a of the bottom surface 30d of the crossbar 30 in response to the expansion and contraction of the contact pressure spring 33, so that the expansion and contraction of the contact pressure spring 33 is not hindered. Furthermore, because the contact pressure spring 33 can be assembled by aligning the lower plate 32a of the spring receiving portion 32 with the upper surface 30a of the bottom surface 30d of the crossbar 30, the contact pressure spring 33 will not bend toward the bottom surface of the crossbar 30 when the contact pressure applying portion 34 is assembled, and therefore adjustment of the position of the contact pressure spring 33 after assembly is not required, improving ease of assembly.

[0031] Furthermore, since the gap 30c at the bottom surface 30d of the crossbar 30 is closed by the lower plate 32a, the arc gas, metal particles, etc. generated upon short-circuit breaking are prevented from flowing into the contact pressure spring 33 without the need to redesign the shape of the cover 1 and base 2 or add another molded body inside the insulating housing, and it is expected that the rated short-circuit breaking capacity can be increased without increasing the number of parts.

[0032] In this way, in this embodiment, it is possible to prevent the trajectory of the pressure spring 33 from vibrating, to prevent arcs and metal particles from getting around the pressure spring 33, and to obtain a stable biasing force from the pressure spring 33 for pressing the movable contact 8 against the fixed contact 7.

[0033] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, the configurations of each embodiment may be combined as appropriate, and some of the configurations may be omitted or modified within the scope of the gist of the present disclosure. [Explanation of symbols]

[0034] 1 cover, 1a handle window hole, 2 base, 3 operating handle, 4 power supply side terminal, 5 load side terminal, 6 fixed contact, 7 fixed contact, 8 moving contact, 9 moving contact, 11 frame, 12 trip bar, 13 latch, 14 stopper, 14a, 15a, 16a pivot shaft, 15 receiving plate, 16 cradle, 17 upper link, 18 lower link, 19 spring pin, 20 main spring, 20a driving side, 20b driven side, 22 handle arm, 30 crossbar, 30a upper surface, 30b, 32 spring receiving portion, 30c gap, 30d bottom portion, 30e arm portion, 31 locking pin, 32a lower plate, 32b upper plate, 32c spring receiving plate, 33 contact pressure spring, 34 contact pressure applying portion, 35 Working arm, 35a convex portion, 35b pin hole, 40 opening / closing mechanism, 41 arc extinguishing device, 42 tripping device, 43 pivot center point, 44 link support point, 45 shaft, 101 circuit breaker.

Claims

1. a crossbar having a bottom surface portion with a gap and an arm portion extending obliquely upward from the bottom surface portion, the arm portion being connected to a switching mechanism portion that opens and closes an electric circuit, the crossbar rotating in response to the operation of the switching mechanism portion; a movable contactor pivotally supported on the crossbar, the movable contact being provided at one end with a movable contact that can be brought into contact with and separated from a fixed contact, and a locking pin being provided at the other end; a contact pressure spring, one end of which is disposed between the bottom surface portion and the arm portion of the crossbar and the other end of which is disposed on the locking pin side of the movable contact, for applying a rotational force to the movable contact to press the movable contact against the fixed contact; a spring receiving portion having a first plate engaged with the locking pin and receiving the other end of the contact pressure spring; The spring receiving portion includes a second plate rising from the first plate, and the second plate closes the gap in the bottom surface portion so that the tip side of the second plate is held by the bottom surface portion.

2. The circuit breaker according to claim 1, wherein a step having a flat surface on which the second plate slides is provided on the upper surface of the bottom portion.

3. 3. The circuit breaker according to claim 1, further comprising an arc extinguishing device capable of extinguishing an arc generated between the fixed contact and the movable contact, wherein metal particles passing from the arc extinguishing device through the gap are blocked by the second plate.

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