JP7797082B2 - circuit breaker - Google Patents

Description

The present invention relates to a circuit breaker.

As described in Patent Document 1, a circuit breaker is equipped with a movable contactor having a movable contact and a fixed contactor having a fixed contact, and when the movable contact separates from the fixed contact, an arc and arc gas are generated between the two contacts. To deal with this, an arc extinguishing device is provided to immediately interrupt the arc, and an exhaust port is provided to exhaust the arc gas to the outside of the circuit breaker. In Patent Document 1, an exhaust port is provided below the terminal screw provided for connecting the electric wire to the fixed contactor, and the arc gas is exhausted.

Utility Model Registration No. 3035548

However, parts of contacts and arc extinguishing devices melted by the arc are caught in the arc gas as flying debris. If this debris adheres to the terminal screw, it may prevent the terminal screw from rotating and making it impossible to remove.

The inventors of this invention have thoroughly investigated this issue and attempted to solve it. The problem that this invention aims to solve is to prevent debris contained in the arc gas from adhering to the terminal screw, making it impossible to remove the terminal screw.

To solve the above problem, a circuit breaker is provided that includes a movable contactor having a movable contact, a fixed contactor having a fixed contact and a terminal screw hole, a terminal screw that is inserted into the terminal screw hole, and an exhaust space for exhausting arc gas that is generated when the movable contact separates from the fixed contact, and a screw protector that protects the lower end of the terminal screw from the arc gas is provided in the exhaust space located below the terminal screw hole.

It is also preferable to provide a vent hole in the fixed contactor that serves as a path for arc gas from the fixed contact to the exhaust space, and to position the screw protector in the exhaust space between the terminal screw and the vent hole.

It is also preferable to provide a nut in the exhaust space that can be threaded onto the terminal screw to secure the electric wire to the fixed contact, and to configure the screw protector to have a surface that protrudes downward from the nut and is larger in the left-right direction than the threaded portion of the terminal screw.

Furthermore, it is preferable that the circuit breaker is provided with a movable contactor having a movable contact, a fixed contactor having a fixed contact and terminal screw holes, and a plurality of terminal screws to be inserted into the terminal screw holes, wherein adjacent terminal screw holes are located at different heights, an exhaust space for exhausting arc gas generated when the movable contact separates from the fixed contact is provided below the terminal screw hole located at a lower position, and a screw protector is provided in the exhaust space to protect the lower end of the terminal screw from the arc gas.

This invention makes it possible to prevent debris contained in the arc gas from adhering to the terminal screw, making it impossible to remove the terminal screw.

FIG. 1 is a perspective view of a circuit breaker according to an embodiment. FIG. 2 is a perspective view showing the left side of the circuit breaker when the circuit breaker is cut off according to the embodiment. 3 is an enlarged view of the exhaust space and its surroundings in FIG. 2, with the terminal screws omitted. 1 is a diagram showing an example of the behavior of arc gas when a screw protection member is installed, where the dashed line shows the behavior of arc gas. FIG. 5 is an exploded perspective view of the structure shown in FIG. 4 excluding a crossbar and a spring. 10 is a diagram showing the positional relationship between the vent hole of the fixed contact, the terminal screw, the screw protector, and the nut. FIG. 4 is a diagram illustrating an example in which the screw protection member in FIG. 3 is replaced with a screw protection protrusion. FIG. 10 is a diagram showing the positional relationship between the vent hole of the fixed contact, the terminal screw, the screw protection protrusion, and the nut. FIG. This is a diagram showing an example of using a nut as a thread protector, where the dashed line shows the behavior of the arc gas.

The following describes an embodiment of the invention. In the following description, when the terminal screw 70 is inserted into the terminal screw hole 62 and fixed, the side where the head of the terminal screw 70 is located is the upper side, and the side where the threaded portion 71 is located is the lower side.

As can be seen from Figures 1 to 4, the circuit breaker 1 of this embodiment comprises a movable contactor 50 having a movable contact 51, a fixed contactor 60 having a fixed contact 61 and a terminal screw hole 62, a terminal screw 70 inserted into the terminal screw hole 62, and an exhaust space Ea for exhausting arc gas generated when the movable contact 51 separates from the fixed contact 61. In this circuit breaker 1, a screw protector is provided in the exhaust space Ea located below the terminal screw hole 62 to protect the lower end of the terminal screw 70 from the arc gas. This makes it possible to prevent debris contained in the arc gas from adhering to the terminal screw 70 and making it impossible to remove the terminal screw 70.

Generally, the circuit breaker 1 comprises a movable contactor 50 having a movable contact 51 and a fixed contactor 60 having a fixed contact 61, and by moving the movable contactor 50, the movable contactor 51 and the fixed contactor 61 can be switched between a contacting state and a separated state.

In the circuit breaker 1 of this embodiment, a terminal screw 70 is provided to secure an electric wire to the fixed contact 60, and the fixed contact 60 is provided with a terminal screw hole 62 through which the terminal screw 70 can be inserted. The terminal screw 70 can be threaded into a female thread, but in this embodiment, the terminal screw 70 can be threaded into a nut 41 provided below the terminal screw hole 62.

In addition, the movable contact 51 and fixed contact 61 of the circuit breaker 1 of this embodiment are arranged inside the case 10, which forms the main outer shell, and are designed to allow arc gas generated inside the case 10 to be guided to the outside of the case 10.

The circuit breaker 1 also includes an arc extinguishing device 42 for immediately interrupting the arc that occurs along with the arc gas, and a dust barrier 43 for preventing dust from entering the circuit breaker 1 from the outside. The arc extinguishing device 42 is positioned adjacent to the fixed contact 61, and the elastically deformable dust barrier 43 is positioned near a specific opening provided in the case 10. The dust barrier 43 can deform when the internal pressure of the case 10 increases due to the generation of an arc, allowing arc gas and the like to be discharged from the adjacent opening.

In addition, the case 10 of this embodiment is constructed by combining a base 11 and a cover 12. Many of the components housed in the base 11 are covered by the cover 12 and are normally inaccessible. There are various components that can be included in the circuit breaker 1, including a crossbar 44, a spring 45, a handle 46, a bimetal, a trip device, and a trigger lever.

By moving downward, the crossbar 44 presses the movable contactor 50 downward, bringing the movable contact 51 into contact with the fixed contact 61. By moving upward, the crossbar 44 releases the pressure on the movable contactor 50, allowing the movable contact 51 to separate from the fixed contact 61. A spring 45 housed inside the circuit breaker 1 biases the movable contactor 50 upward, helping the movable contact 51 separate from the fixed contact 61 when the crossbar 44 moves upward.

The handle 46 allows the crossbar 44 to be moved upward or downward from outside the case 10. The bimetal detects overcurrent and is used for tripping. The trip device can trip using a signal from a leakage circuit board that detects leakage current. The trigger lever can turn off the handle 46 and move the crossbar 44 upward by tripping using the bimetal or trip device.

The fixed contact 60 of this embodiment is provided on the power supply side of the circuit breaker 1 and includes a first surface 60a to which the terminal screw 70 is connected, a second surface 60b formed by bending the inner end of the first surface 60a so as to extend downward, and a third surface 60c extending from the end of the second surface 60b so as to be generally parallel to the first surface 60a but away from the first surface 60a. It also includes a fourth surface 60d extending downward from the end of the first surface 60a opposite the second surface 60b and generally parallel to the second surface 60b (see Figure 5).

Below the first surface 60a, an arc gas exhaust space Ea is provided, and a nut 41 that threads onto the terminal screw 70 is housed in this area. The second surface 60b is provided with a vent 64 that exhausts the arc gas into the exhaust space Ea. The third surface 60c is provided with a fixed contact 61. The fourth surface 60d is inserted into the base 11 to prevent the fixed contact 60 from shifting (see Figure 3).

The arc extinguishing device 42 of this embodiment includes multiple grids 42a arranged at intervals and a holding frame 42b that holds them, and is positioned between the second surface 60b of the fixed contact 60 and the fixed contact 61. The holding frame 42b also has holes 42c formed in positions corresponding to the vent holes 64 formed in the second surface 60b of the fixed contact 60, allowing arc gas to pass through the holes 42c and vent holes 64 of the arc extinguishing device 42 and move to the exhaust space Ea.

In this embodiment, the dust barrier 43 is disposed between the second surface 60b of the fixed contact 60 and the arc extinguishing device 42. This dust barrier 43 has holes 43a formed in positions corresponding to the ventilation holes 64 formed in the second surface 60b of the fixed contact 60, allowing arc gas to pass through the holes 42c of the arc extinguishing device 42, the holes 43a of the dust barrier 43, and the ventilation holes 64 and move to the exhaust space Ea.

In this embodiment, the base 11 is provided with an outer exhaust port 14 at the end of the base 11 on the power supply side, which exhausts arc gas from the exhaust space Ea to the outside. Therefore, in this embodiment, arc gas generated when the movable contact 51 and the fixed contact 61 separate can be exhausted to the outside of the circuit breaker 1 by passing through the hole 42c of the arc extinguishing device 42, the hole 43a of the dust barrier 43, the vent 64, the exhaust space Ea, and the outer exhaust port 14, in that order.

In this embodiment, an exhaust space Ea is provided below the terminal screw hole 62 of the fixed contactor 60. In this exhaust space Ea, a screw protector is provided to prevent the lower end of the threaded portion 71 of the terminal screw 70 from being exposed to arc gas, making it difficult to remove the terminal screw 70. The screw protector is preferably located between the terminal screw 70 and the second surface 60b of the fixed contactor 60. In particular, it is preferable to provide a vent hole 64 in the fixed contactor 60, which serves as a path for arc gas from the fixed contactor 61 to the exhaust space Ea, and to configure the screw protector in the exhaust space Ea to be located between the terminal screw 70 and the vent hole 64.

Incidentally, because the arc gas needs to be exhausted to the outside through the outer exhaust port 14, it is not preferable to provide a screw protection part that blocks the ventilation port 64 formed on the second surface 60b of the fixed contact 60 and prevents the arc gas from being exhausted from the ventilation port 64 into the exhaust space Ea. In this configuration, the screw protection part is not provided in the exhaust space Ea.

In the example shown in Figure 1, the screw protector is positioned to allow the arc gas to be exhausted to the outside of the circuit breaker 1 by passing through the hole 42c of the arc extinguishing device 42, the hole 43a of the dust barrier 43, the vent 64, the exhaust space Ea, and the outer exhaust port 14 in that order, while preventing the underside of the threaded portion 71 of the terminal screw 70 from being exposed to the arc gas. Therefore, it is preferable that the screw protector be capable of changing the path of the arc gas.

In the case of a circuit breaker 1 in which the terminal screws 70 of adjacent poles are at different heights, as in the example shown in Figure 1, a screw protector can be provided in the exhaust space Ea of a pole whose terminal screw 70 is located lower than its adjacent terminal screw 70. A screw protector may or may not be provided in the exhaust space Ea of a pole whose terminal screw 70 is located higher than its adjacent terminal screw 70.

This is because, if the lower end of the threaded portion 71 of the terminal screw 70 located in the exhaust space Ea is not exposed to the arc gas, it is unlikely that debris will adhere to the threaded portion 71. In other words, if the threaded portion 71 of the terminal screw 70 is positioned sufficiently higher than the ventilation opening 64 or the outer exhaust opening 14, it will be less likely to be exposed to the arc gas, and it may not be necessary to provide a screw protector.

For this reason, it is preferable to provide a circuit breaker 1 that includes a movable contactor 50 having a movable contact 51, a fixed contactor 60 having a fixed contact 61 and terminal screw holes 62, and a plurality of terminal screws 70 inserted into the terminal screw holes 62, where adjacent terminal screw holes 62 are located at different heights, an exhaust space Ea for exhausting arc gas generated when the movable contact 51 separates from the fixed contact 61 is provided below the terminal screw holes 62 that are located at lower positions, and a screw protector that protects the lower end of the terminal screw 70 from the arc gas is provided in the exhaust space Ea.

Next, we will explain examples of different screw protection configurations. First, we will explain the case where the screw protection member 81, which serves as the screw protection member, is provided separately from the case 10. In the example shown in Figures 2 to 6, the screw protection member 81 is composed of a plate-shaped member, but the shape does not have to be the same as in such an example. In this example, the screw protection member 81 is inserted from above into a groove provided in the base 11, and the nut 41 and the first surface 60a of the fixed contact 60 are assembled so that they are positioned above the screw protection member 81. In this case, it is preferable to position the screw protection member 81 between the lower end side of the threaded portion 71 of the terminal screw 70 and the second surface 60b of the fixed contact 60.

In the example shown in Figures 2 to 4, the presence of the screw protection member 81 changes the path of the arc gas to the left, right, and below the threaded portion 71 of the terminal screw 70.

When the terminal screw 70 is tightened without an electric wire connected to the terminal portion, the threaded portion 71 of the terminal screw 70 protrudes most into the exhaust space Ea. In this way, when the threaded portion 71 of the terminal screw 70 protrudes most into the exhaust space Ea, it is preferable to make the vertical length of the screw protector longer than the vertical length of the threaded portion 71 of the terminal screw 70 that protrudes below the nut 41.

The left-right length of the screw protector may be greater than the left-right length of the vent 64 or the left-right length of the threaded portion 71 of the terminal screw 70, but it is preferable that the left-right length of the screw protector be greater than the longer of the left-right lengths of the vent 64 and the threaded portion 71 of the terminal screw 70. It is also preferable that the screw protector be configured to have a surface that protrudes downward from the nut 41 that is larger than the left-right length of the threaded portion 71 of the terminal screw 70.

In any case, the vertical and horizontal lengths of the screw protector are preferably configured so that when the arc gas changes course due to the screw protector and passes through the exhaust space Ea, most of the arc gas passes away from passing through the lower end side of the threaded portion 71 of the terminal screw 70.

It is preferable that the nut 41 and the thread protection member 81 always be in contact to prevent arc gas from passing between them. However, there is no problem if a gap occurs between the nut 41 and the thread protection member 81 due to assembly errors.

Next, we will explain an example in which the screw protection part is integral with the base 11. In the example shown in Figures 7 and 8, the screw protection protrusion 83 that protrudes upward is formed on the base 11, but the screw protection protrusion 83 may also protrude from either the left or right direction.

In this case, it is preferable to position the screw protection protrusion 83 between the lower end of the threaded portion 71 of the terminal screw 70 and the second surface 60b of the fixed contact 60. Also, in Figures 7 and 8, the screw protection protrusion 83 is configured so that the left and right ends of the surface facing the second surface 60b of the fixed contact 60 are separated from the second surface 60b. This makes it easier for gas to be discharged from the left and right sides.

In the example shown in Figures 7 and 8, the surface of the screw protection protrusion 83 facing the second surface 60b of the fixed contact 60 is shaped to have a chamfered, inclined surface, but it may have a different shape, such as an arc shape. Furthermore, taking into account the discharge path, etc., it may be configured so that either one of the left or right ends is separated from the second surface 60b. The same applies to the screw protection member 81.

In the example shown in Figures 7 and 8, the screw protection protrusion 83 is positioned so as to create a gap between it and the second surface 60b of the fixed contact 60, but in cases where the ventilation hole 64 provided on the second surface 60b is relatively large, the screw protection protrusion 83 may be positioned so that it comes into contact with the second surface 60b of the fixed contact 60. This also applies to the screw protection member 81.

In this example, the screw protection protrusion 83 changes the path of the arc gas to the left or right of the threaded portion 71 of the terminal screw 70. It is preferable that the upper end of the screw protection protrusion 83 be positioned so that it comes into contact with the nut 41 or is spaced slightly from the nut 41. It is also preferable that the left and right ends of the screw protection protrusion 83 form inclined surfaces to make it easier to guide the arc gas in the left-right direction.

Next, we will explain the case where the nut 41 functions as a screw protector. In the example shown in Figure 9, one nut 41 covers the threaded portion 71 of the terminal screw 70 all the way to the bottom end. However, multiple nuts 41 may be used to cover the threaded portion 71 all the way to the bottom end.

It is preferable that the vertical length of the nut 41 that is placed in the exhaust space Ea and threaded onto the terminal screw 70 be approximately the same as or longer than the vertical length of the threaded portion 71 of the terminal screw 70 located in the exhaust space Ea. In other words, it is preferable to use a nut 41 that is long enough to cover the entire threaded portion 71 of the terminal screw 70 located in the exhaust space Ea in a side view. By using such a nut 41 as a screw protector, the path of the arc gas can be changed to the left, right, and below the threaded portion 71 of the terminal screw 70.

The present invention has been described above using exemplary embodiments, but the present invention is not limited to the above embodiments and can be implemented in various forms.

REFERENCE SIGNS LIST 1 Circuit breaker 41 Nut 50 Movable contact 51 Movable contact 60 Fixed contact 61 Fixed contact 62 Terminal screw hole 64 Vent 70 Terminal screw 71 Threaded portion

Claims (2)

A circuit breaker comprising: a movable contactor having a movable contact; a fixed contactor having a fixed contact and a terminal screw hole; a terminal screw inserted into the terminal screw hole; and an exhaust space for exhausting arc gas generated when the movable contact separates from the fixed contact,
A screw protection section is provided in the exhaust space below the terminal screw hole to protect the lower end of the terminal screw from arc gas .
The fixed contact is provided with a vent hole that serves as a path for arc gas from the fixed contact to the exhaust space,
A circuit breaker in which the screw protector provided in the exhaust space is located between the terminal screw and the ventilation hole . A nut is provided in the exhaust space, which can be screwed onto the terminal screw to fix the electric wire to the fixed contact,
2. The circuit breaker according to claim 1 , wherein the screw protector has a surface that is larger in the left-right direction than the threaded portion of the terminal screw that protrudes downward from the nut.