JP2024173169A - Circuit breaker moving contact device - Google Patents

Abstract

To obtain a circuit breaker capable of performing a stable short circuit breaking only by reviewing a shape of the existed component without adding a component such as an expensive mold body or the like.SOLUTION: A base part that is contacted to a bottom part of a movable contactor and an arc movable element, and has a separation wall for securing their interval in a constant, and a vibration suppression member in which a pair of side parts having a penetration hole into which a first coupling pin is inserted is integrally formed are supported by a contact arm with the movable contactor and the arc movable element. Thus, since a vibration to a left and right direction of the movable contact can be suppressed, an operation is not only stabilized, but also previously prevents an arc residence at a contact point by, specifically, contacting the movable contact on an outer side to a circuit interrupter because the vibration suppression member is arranged at a neighbor of the movable contact. Also, since the vibration suppression member is only supported with the first coupling pin, the number of components can be reduced as possible.SELECTED DRAWING: Figure 3

Description

This disclosure relates to the movable contact device of a circuit breaker such as a molded case circuit breaker or earth leakage circuit breaker, and more specifically, to the prevention of adhesion of molten metal that occurs when a short circuit is interrupted to the opening and closing mechanism.

Circuit breakers not only have the function of opening and closing an electric circuit by operating the operating handle provided on the circuit breaker, i.e., the switch function, but also have the important role of interrupting the electric circuit to prevent the burning of electric wires and load equipment caused by the flow of overcurrent. As is well known, overcurrent detection is performed broadly by various methods such as thermal, electromagnetic, and electronic, but it is also well known that for larger overcurrents, i.e. short-circuit currents, the movable contactor is quickly rotated by the electromagnetic repulsive force generated between the contacts, without waiting for the activation of these methods.

The rotation of the movable contact generates an arc between the contacts, but this arc is attracted to the arc-extinguishing chamber by magnetic action, and is extinguished by the increase in arc resistance caused by stretching and cooling, thus achieving the above-mentioned "interruption of the electric circuit," i.e., short-circuit interruption. It is also known that the attraction can be made more powerful by the arc-extinguishing gas that is generated when the arc comes into contact with an arc insulating member provided near the movable contact (see, for example, Patent Documents 1 and 2).

However, there is a risk that some of this arc-extinguishing gas may flow into the switching mechanism or overcurrent detection device, leading to insulation deterioration, particularly between phases. In addition, molten contact material and other materials that evaporate due to the heat of the arc may scatter into the surrounding area as the gas flows in, adversely affecting the operation and response of the switching mechanism and overcurrent detection device (particularly thermal or electromagnetic types). For this reason, a circuit breaker is known that isolates the moving contact device from other parts (see, for example, Patent Document 3).

Japanese Unexamined Patent Publication No. 62-71140 JP 2008-41250 A JP 2006-236798 A

The current value at the time of breaking a short circuit in the electric circuit, i.e., the short circuit current, is defined as the "rated short circuit breaking capacity" in, for example, JIS (Japanese Industrial Standards) C8201-2-1, and it is well known that each manufacturer is working to improve the product variations so that a circuit breaker with an appropriate value can be selected according to the condition of the electric circuit, i.e., the distance from the transformer, the thickness of the electric wire, etc. On the other hand, in order to improve this, standardization of the product or platform development is essential, especially in order to promote compatibility with costs, and it is difficult to say that it is a good idea to add an expensive molded body (middle cover 3 in Patent Document 3) just to isolate the moving contact device to a product that does not require a high rated short circuit breaking capacity.

In this regard, Patent Documents 1 and 2 teach that there is no equivalent to the middle cover, and therefore that it is a so-called general-purpose product. Therefore, especially in Patent Document 2, since there is no contact arm (contact portion support member 24 in Patent Document 1), even if the arc resistance is increased by some means, it is expected that it will be quite difficult to upgrade the rated short-circuit breaking capacity because it will lead to an increase in the flow rate of arc-extinguishing gas. In addition, in Patent Document 1, the arc insulating member (shielding member 94) does not wrap around the contact joint surface of the movable contact (contact portion arm 76), and there is a shortage of the desired amount of arc-extinguishing gas, and furthermore, there is the possibility of molten material being present in the gap (recess) between adjacent movable contacts, so it must be said that upgrading the rated short-circuit breaking capacity itself is difficult.

This disclosure has been made to solve the problems described above, and aims to obtain a circuit breaker that can perform stable short-circuit interruption by simply reviewing the shape of existing components without adding any additional components.

The movable contact device of the circuit breaker according to this disclosure comprises a crossbar supported to rotate in conjunction with the opening and closing mechanism, a main body and a first side and a second side extending from both ends of the main body in a bent manner and facing each other, the main body being fixed to a contact arm, and a plurality of movable contacts held rotatably on the contact arm by shafts inserted into holes provided in the first and second sides, and a vibration suppressing member is interposed between the movable contacts adjacent to the first and second sides and the first and second sides.

As explained above, this disclosure can provide a highly reliable circuit breaker that performs stable short circuit interruption.

1 is a front view showing an open state of a circuit breaker according to a first embodiment of the present disclosure; FIG. 2 is a side cross-sectional view of FIG. 3 is an enlarged view of the opening/closing mechanism in FIG. 2 in a tripped state. FIG. FIG. 4 is a cross-sectional view of the movable contact device in FIG. 2 or FIG. 3 . FIG. 4 is an external perspective view of the vibration suppression member shown in FIG. 2 or FIG. 3 . FIG. 9 is a view equivalent to FIG. 5 and shows a third embodiment of the present disclosure.

Embodiment 1.
Fig. 1 is a front view showing the open state of the circuit breaker in the first embodiment of this disclosure, and the right half of the drawing omits the illustration of the cover and the operating handle, which are parts constituting the housing of the circuit breaker. Fig. 2 and Fig. 3 are side views mainly focusing on the opening and closing mechanism, Fig. 2 similarly shows the open state of the circuit breaker, and Fig. 3 shows its tripped state, and Fig. 2 in particular shows the entire side of some parts and devices, generally showing a cross section along line A-A in Fig. 1. Figs. 4 and 5 are cross-sectional and external perspective views of the vibration suppression member, which is the key point of this disclosure, and Fig. 4 shows the contact arm and the movable contactor along line B-B in Fig. 3.

The configuration and operation of the circuit breaker in this disclosure are well known, as shown in, for example, JP 2019-212389 A, except for the vibration suppression member. That is, in FIG. 1 and FIG. 2, the insulating housing of the three-pole circuit breaker 101 is composed of a cover 1 and a base 2, and the base 2 is provided with an opening/closing mechanism 51 equipped with an operating handle 3, and arc extinguishing devices 52 and current transformers 4 for the number of poles (three in this disclosure). The operating handle 3 protrudes from the handle window 1a of the cover 1 and can be operated in the ON or OFF direction. In addition, based on the positional relationship between the arc extinguishing device 52 and the current transformer 4, or the position of the operating handle 3 of the circuit breaker 101 in the open state, the upper side (left side in FIG. 2) on the paper is, for example, the power supply side terminal 5 for connecting the power supply side electric wire, and the lower side (right side in FIG. 2) is, for example, the load side terminal 12 for connecting the load side electric wire.

The fixed contact 7 fixed to one end of the fixed contactor 6 formed integrally with the power supply side terminal 5 comes into contact with and separates from the movable contact 8 fixed to one end of the movable contactor 9, thereby opening and closing the circuit breaker 101, i.e., turning on and off the electric path through the power supply side electric wire and the load side electric wire. This opening and closing is performed in response to the operation of the opening and closing mechanism unit 51, which is connected to the contact arm 14 supporting the movable contactor 9 by the first connecting pin 13. Note that the circuit breaker 101 in this disclosure is intended to be used as a main circuit breaker for buildings and factories, for example, and therefore the electric current of the electric path reaches about 1,000 amperes. Therefore, the movable contactor 9 in particular is required to have a conductor size commensurate with the heat generated by the electric current, or an appropriate contact pressure function and an opening and closing durability function, so that multiple pieces, specifically, two pieces on each side of the arc movable element 33 described later, are arranged as shown in FIG. 4. Therefore, the aforementioned support by the contact arm 14 in this disclosure is provided by a total of five pieces per pole, more specifically, by fitting the first connecting pin 13 into holes provided in the first side portion 14b1 and second side portion 14b2, which are bent and extend from both ends of the main body portion 14a of the contact arm 14 and face each other, as well as the movable contactor 9 and arc movable member 33.

Returning to FIG. 2, the movable contact 9 and the arc movable element 33 each have a shunt 10 joined to the other end, and this shunt 10 is connected to the load side terminal 12 that passes through the current transformer 4 via a relay conductor 11. Therefore, the current path in the ON operation, i.e., in the closed state (not shown), is the power supply side terminal 5-fixed contact 6-fixed contact 7-movable contact 8-movable contact 9-shunt 10-relay conductor 11-load side terminal 12, and this current is detected by the current transformer 4. The aforementioned contact pressure in this closed state is obtained by a first contact pressure spring 15 arranged between the movable contact 9 and the contact arm 14.

When the tripping relay 16 determines that an overcurrent condition exists as a result of detection by the current transformer 4, the opening and closing mechanism 51 responds and cuts off the electrical circuit. Therefore, the detection method leading to this cutoff corresponds to the "electronic type" described in Section 0002, but in either method, the arc generated during the cutoff is guided to the arc extinguishing device 52 by the arc runner 17 fixed to the fixed contact 6, and is cut off by this arc extinguishing device 52, completing the cutoff including the electrical connection.

Next, the configuration of the opening/closing mechanism 51 will be described. The opening/closing mechanism 51 is a so-called unit consisting of a roughly U-shaped handle arm 19 pivotally supported by a pivot shaft 19a on a pair of opposing frames 18, and an operating handle 3 attached to the handle arm 19. Inside, i.e., in the space created by the pair of frames 18 facing each other, there are members such as a receiver 21 supported by a second connecting pin 20 pivotally supported on the frame 18, a cradle 22 which is similarly pivotally supported on the frame 18 by its pivot shaft 22a and engages with the receiver 21 in the open and closed states, an upper link 23 pivotally supported on the cradle 22, a lower link 25 which is connected to the upper link 23 via a spring pin 24 to form a toggle link, and a main spring 26 whose driven side 26a is tensioned on the spring pin 24 and whose driving side 26b is tensioned on the handle arm 19.

The contact arm 14 is supported on the frame 18 by the third connecting pin 27 and connected to the lower link 25 by the fourth connecting pin 28, so that it rotates around the third connecting pin 27 as the center of rotation in response to the movement of the toggle link, i.e., the opening and closing operation described above is performed. As is clear from FIG. 1, the opening and closing mechanism 51 is installed only on the center pole of the three poles, so the right and left pole contact arms 14 have the crossbar 30, an insulator attached to the fixing member 29 fixed to the contact arm 14, extending left and right on the page, i.e., crossing the three poles, so it goes without saying that the three contact arms 14 operate simultaneously.

Next, a series of operations of the circuit breaker 101 will be explained. As is clear from the explanation so far, the state in which the receiving plate 21 and the cradle 22 are engaged is the open or closed state, and conversely, the state in which this engagement is released as shown in Figure 3 indicates that a break has been performed, and will hereafter be referred to as the "trip state." Needless to say, the closed state is when the fixed contact 7 and the movable contact 8 are in contact, and the open or trip state is when they are separated.

2, when the operating handle 3 is rotated counterclockwise on the paper, the spring pin 24 moves upward on the paper about the pivot axis 19a of the handle arm 19, specifically in a direction that stretches the toggle link in a roughly dogleg shape, changing the load direction of the main spring 26. This change causes the contact arm 14 to rotate counterclockwise about the third connecting pin 27, i.e., in a direction in which the movable contact 8 contacts the fixed contact 7, and transitions to a closed state due to the biasing force of the first pressure spring 15 as described above. Note that, at this contact, due to the positional relationship between the movable contact 9 and the arc movable contact 33 and the difference in load between the first pressure spring 15 and the second pressure spring 34, the arc fixed contact 31 and the arc movable contact 32 come into contact first, and current flow in the circuit begins. Then, as the toggle link extends, i.e., the contact arm 14 rotates further, the contact surfaces of the arc fixed contact 31 and the arc movable contact 32 become the fulcrum, and the fixed contact 7 and the movable contact 8 described above come into contact. This causes the fulcrum to move, i.e., the contact surfaces of the fixed contact 7 and the movable contact 8 now become the fulcrum in conjunction with the contact pressure of the first contact pressure spring 15, and the arc movable contact 32 separates from the arc fixed contact 31. In this way, the current path of "fixed contact 6 - fixed contact 7 - movable contact 8 - movable contact 9" described in Section 0015 is obtained.

The transition from this closed state to the open state shown in Figure 2 can be made in the opposite manner, that is, by rotating the operating handle 3 clockwise until the load direction of the main spring 26 changes, the toggle link returns to an approximately dogleg shape and the contact arm 14 immediately rotates clockwise, causing the movable contact 8 to separate from the fixed contact 7 and breaking the electrical path through the power supply wire and the load wire. The relationship between the movable contact 9 and the arc movable contact 33 at this time will be explained in the next section "Closed → Trip".

The switch returns to the closed state described in paragraph 0020, and as described above, when the tripping relay 16 determines that an overcurrent state exists as a result of detection by the current transformer 4, the connecting plate 35 provided on the reset mechanism 53 pushes in the trip bar 37 journaled on the frame 18 by the fifth connecting pin 36. When the trip bar 37 rotates due to this pushing, the receiving plate 21 also rotates, and the engagement between the receiving plate 21 and the cradle 22, which is biased in the counterclockwise direction, is released. When the cradle 22 rotates counterclockwise, the driving side 26b moves relative to the spring pin 24, and finally an upward force begins to act on the spring pin 24, causing the lower link 25 to rotate the contact arm 14 in the clockwise direction, i.e., as shown in FIG. 3, the fixed contact 7 and the movable contact 8 are separated, resulting in a tripped state.

At the moment the fixed contact 7 and the movable contact 8 are separated, electricity flows between the two contacts 7, 8 due to the arc generated between them, and as described above, the arc fixed contact 31 and the arc movable contact 32, which are separated in the closed state, come into contact as the arc movable element 33 is rotated counterclockwise around the first connecting pin 13 by the pressing force of the second pressure spring 34. This contact also allows electricity to flow between the two contacts 31, 32, but as the contact arm 14 rotates clockwise as described above, the contact between the arc fixed contact 31 and the arc movable contact 32 is maintained, and the movable contact 8 opens while extending the arc from the fixed contact 7 with this contact point as a fulcrum. This stretching increases the arc resistance, and the current just before the completion of the interruption moves to the contact point between the arc fixed contact 31 and the arc moving contact 32, but further rotation of the contact arm 14 causes the arc moving contact 32 to separate from the arc fixed contact 31, and the arc generated at this time is attracted by the arc runner 17 to the arc extinguishing device 52, where it is cut off and extinguished. Note that the arc fixed contact 31 and the arc moving contact 32 are exposed to more arcs, that is, to improve resistance to wear due to arc sparks or to prevent welding, it is preferable that they are tungsten-silver alloy contacts or zinc oxide-silver alloy contacts, rather than silver alloy contacts as the fixed contact 7 and the moving contact 8.

When the operating handle 3 is rotated clockwise from the tripped state in Fig. 3, a downward force acts on the spring pin 24, slightly bending the toggle link, which is in a roughly L-shape, while the fourth connecting pin 28 remains stationary. This bending causes the cradle 22, which is always engaged with the upper link 23 via the sixth connecting pin 38, to begin rotating clockwise around the pivot 22a. During this rotation, the receiving plate 21, which is biased counterclockwise, is once rotated clockwise, and the link engages with the receiving plate 21, i.e., returning to the open state shown in Fig. 2. As is well known, this transition from the tripped state to the open state is generally called the "reset operation."

Finally, we will explain the vibration suppression member 39, which is the key point of this disclosure. As described in paragraph 0014, since the movable contact 9 is composed of multiple sheets including the arc movable element 33, or as suggested in Patent Document 2, it is necessary to prevent attraction due to electromagnetic force generated by the continuous flow of a current of about 1,000 amperes. Therefore, in this disclosure, as shown in FIG. 5, the vibration suppression member 39 is integrally molded from an insulating material, with a base 39a having a partition wall 39a1 that contacts the bottom of the movable contact 9 and the arc movable element 33 and keeps the gap constant, and a pair of side parts 39b having a through hole 39b1 through which the first connecting pin 13 passes, and is supported by the contact arm 14 together with the movable contact 9 and the arc movable element 33, as shown in FIG. 4.

As a result, similar to Patent Document 2, the movement of the movable contact 9 in the left-right direction on the paper surface of FIG. 1 during opening and closing or during the process leading to the trip state can be suppressed, and not only does this stabilize the operation, but because this movement suppression member 39 is located near the movable contact 8, it is possible to prevent the outer movable contact 9 from touching the arc extinguishing device and causing the arc to remain at this contact point. This prevents the adhesion of molten metal that occurs with short circuit interruption to the opening and closing mechanism without revising the shape of the insulating casing, i.e., the cover 1 and base 2, or adding another molded body inside, and is therefore expected to improve the rated short circuit interruption capacity. In addition, since the movement suppression member 39 is only supported together by the first connecting pin 13, the number of parts can be minimized and assembly is also improved.

Embodiment 2.
In the first embodiment, it is described that the vibration suppression member 39 is molded as a single unit from an insulating material, but if this insulating material is molded from a material with arc insulation properties, such as polyethylene terephthalate, nylon 66, or nylon 46, not only will the arc generated between the two contacts 7, 8 be extinguished by the arc-extinguishing gas that is generated when the contact comes into contact with the vibration suppression member 39, but it is also expected that the adhesion of conductive debris between the movable contacts 9, or between the movable contact 9 and the arc movable member 33, and deformation of the contact pressure springs 15, 34 due to high heat will be prevented.

Embodiment 3.
6 is an external perspective view of the vibration suppression member in the third embodiment of this disclosure. The vibration suppression member 40 is molded from a material having an arc insulation function, as in the second embodiment, and the base 40a is provided with a first partition wall 40a1 and a second partition wall 40a2. As described in Section 0023, the arc mover 33 is ultimately responsible for cutting and extinguishing the arc, and as is clear from FIG. 1, it needs to be located closer to the arc extinguishing device 52. Therefore, the second partition wall 40a2 covers the side surface of the arc mover 33. As a result, there is no arc retention due to contact between the arc mover 33 and the arc extinguishing device 52, and improvement in interruption performance can be expected.

7 fixed contact, 8 movable contact, 9 movable contactor, 13 first connecting pin,
14 contact arm, 14a main body,
14b1 first side portion, 14b2 second side portion, 30 crossbar, 33 arc mover,
39 Vibration suppression member, 39a Base, 39a1 Partition wall,
39b side portion, 39b1 through hole, 51 opening/closing mechanism portion, 101 circuit breaker.

Claims (4)

A crossbar supported so as to rotate in conjunction with the opening/closing mechanism;
a contact arm including a main body portion and a first side portion and a second side portion that are bent and extend from both ends of the main body portion and opposed to each other, the main body portion being fixed to the crossbar;
a plurality of movable contacts rotatably held on the contact arm by shafts inserted through holes formed in the first side portion and the second side portion;
A movable contact device of a circuit breaker, characterized in that a vibration suppression member is interposed between a movable contactor adjacent to the first side portion and the second side portion among the plurality of movable contactors and this first side portion and second side portion. The movable contact device of the circuit breaker according to claim 1, characterized in that the vibration suppression member is composed of a side portion having a through hole through which the shaft fits and a base portion having a partition wall that keeps the spacing between the multiple movable contacts constant. The movable contact device of the circuit breaker according to claim 2, characterized in that the vibration suppression member is made of a material that generates an arc-extinguishing gas when it comes into contact with the arc generated between the movable contact and the fixed contact that repeatedly makes and breaks contact. The movable contact device of a circuit breaker according to claim 3, characterized in that at least one of the plurality of movable contacts is an arc movable contact to which current is passed by the arc, and the partition wall in contact with the arc movable contact extends in a direction perpendicular to the axis.

Images