JP2012248357A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an arc gas exhaust structure of a circuit breaker so as to improve assembly workability and a support function for a protecting sheet which covers a gas exhaust port opened on a cover of a main body case from the outside.SOLUTION: In a circuit breaker, function components including a fixed contact 7, a movable contact 8 and an arc-erasing device 10 are packaged in a main body case 1 overlaying a base 2 with a cover 3. The fixed contact 7 is disposed while extending to a bottom side in a breaking chamber by drawing a power source side terminal 5 to a terminal block 2a of the base 2. On the cover 3, a gas exhaust port 3b opposed with the arc-erasing device 10 is opened on a wall surface of a shield wall 3a covering a power source side end face and, thereafter, a flexible protecting sheet 15 is laid over the wall surface of the shield wall 3a while covering the gas exhaust port from the outside. On the protecting sheet 15, a supporter section 15b is formed while extending its fixed terminal side, and the supporter section 15b is folded, held and fixed between a distal end of the shield wall 3a of the cover 3 and a bent portion 7a of the fixed contact 7 in the state of assembling the main body case 1.

Description

  The present invention relates to a circuit breaker for wiring breakers, earth leakage breakers, and the like, and more particularly, an exhaust structure that discharges arc gas generated in a shut-off chamber inside a main body case to the outside of the main body case when an overcurrent is interrupted. About.

  The circuit breaker mentioned above is a molded resin body case consisting of a box-shaped base with power circuit side and load side main circuit terminal blocks formed at both ends and a cover that is placed on top of the base. , Fixed contact, movable contact, grid-type arc extinguishing device, switching mechanism, and overcurrent trip device. When the overcurrent tripping device is activated by detecting the overcurrent flowing through the main circuit, the switching mechanism trips and opens the movable contact, where the arc generated between the fixed contact and the movable contact is detected. It is well known that current is cut off by pushing into the arc extinguishing device.

  Next, FIG. 4 shows a conventional structure (for example, see FIG. 5 of Patent Document 1) of the circuit breaker (tripolar circuit breaker). In the figure, 1 is a main body case made of a molded resin comprising a base 2, a cover 3 and a top cover 4, 5 is a power supply side terminal, 6 is a load side terminal, 7 is a fixed contact formed integrally with the power supply side terminal 5, 8 is a rotating movable contact, 9 is a contact holder holding the movable contact 8, and 10 is a grid type eraser disposed in the shut-off chamber of the main body case 1 along the opening movement path of the movable contact 8. An arc device, 11 is a toggle link type opening / closing mechanism portion that links the contact holder 9 to drive the movable contact 8 to an opening / closing position, 12 is an opening / closing operation handle, and 13 is an overcurrent tripping device.

  Here, in the base 2 of the main body case 1, the power source side terminals 5 and the load side terminals 6 are arranged on the terminal blocks 2 a formed at both ends thereof, and the fixed contact 7 formed integrally with the power source side terminal 5 is The arc extinguishing device 10 is extended to the bottom side of the shut-off chamber and is fixed to the base 2 with fastening screws 14. Reference numeral 2b denotes an inter-electrode insulation barrier that is erected on the left and right sides of the terminal block 2a of each electrode.

  On the other hand, the cover 3 attached on the base 2 is connected to the arc-extinguishing device 10 of each pole on the wall surface (hereinafter referred to as “shielding wall 3a”) facing the arc-extinguishing device 10 on the power source side. The gas exhaust port 3b corresponding to the above is opened, and the arc gas generated in the shut-off chamber when the overcurrent is interrupted is released from the arc extinguishing device 10 to the outside of the case through the gas exhaust port 3b. Reference numeral 3c denotes an inter-electrode insulating barrier that protrudes from the end of the cover 3 in accordance with the inter-electrode insulating barrier 2b of the base 2 described above.

  In FIG. 4, the circuit breaker operation handle 12 is drawn in a horizontal position with the handlebar facing upward, but when the circuit breaker is installed in a panel such as a control panel, the operation handle 12 is faced to the front. The power supply side terminal 5 is installed on a support rail or the like on the panel side in a vertically oriented posture with the power side terminal 5 facing upward.

  For this reason, in a state where the circuit breaker is installed in the panel, the gas exhaust port 3b opened in the cover 3 faces upward, and in this state, foreign matter and dust falling from above are blocked from the main body case 1 through the gas exhaust port 3b. There is a risk of entering the room. Therefore, in the conventional circuit breaker, a flexible protective sheet 15 is provided so as to cover the gas exhaust port 3b opened in the shielding wall 3a of the cover 3 from the outside. The protective sheet 15 functions as a kind of diaphragm check valve, and the protective sheet 15 normally closes the gas exhaust port 3 b opened in the cover 3. When the overcurrent is interrupted, the protective sheet 15 is bent outward by receiving the gas pressure of the arc gas generated in the shut-off chamber of the main body case 1 to open the gas exhaust port 3b, and the arc gas is removed from the main case 1 through the arc extinguishing device 10. To the direction.

  This protective sheet 15 is made of an insulating sheet having a thickness of about 0.4 mm having flame retardancy, heat resistance, and flexibility (for example, Nomex paper: product name of DuPont). And in the circuit breaker currently disclosed by patent document 1, as shown in FIGS. 5-7, the arm-shaped support piece 15a is formed in the right-and-left both sides edge of the protection sheet 15, and this support piece 15a is formed in the main body case 1. Is inserted into and held in a slit-like engagement groove formed at the base of the interelectrode insulating barriers 2b and 3c across the base 2 and the cover 3, and further protected by an engagement claw 3d formed at the upper end of the shielding wall 3a. The front end of the sheet 15 is hooked and held in the closed position.

JP 2010-251035 A

By the way, the conventional arc gas exhaust structure shown in FIGS. 5 to 7 has the following problems in terms of the function of holding the protective sheet and the assembling work thereof.
That is, in order to assemble the protective sheet 15 to the main body case 1 in the product assembly process of the circuit breaker, support pieces 15a formed on both the left and right sides of the protective sheet 15 are formed on the inter-electrode insulation barrier 3c of the cover 3 as a work procedure. Then, it is inserted into the slit-like engagement groove and temporarily held (see FIG. 7). Next, in this state, the cover 3 is attached downward on the base 2 in which the functional parts are incorporated. 3 is bolted.

  In this assembling method, the position of the protective sheet 15 temporarily held on the cover 3 may be shifted during the attaching operation of the cover 3 or may be accidentally detached from the cover 3, and the cover 3 is placed on the base 2. When attaching, the tip of the protective sheet 15 projecting downward from the cover 3 is likely to contact the base 2 and shift its position. For this reason, it is necessary to meticulously engage and hold the protective sheet 15 at a predetermined position. There is a problem of assembly workability that requires attention and labor.

  In addition, when a large current such as a short-circuit current is interrupted, the gas pressure of the arc gas (arrow P in FIG. 5) blown from the interrupting chamber through the arc extinguishing device 10 to the gas exhaust port 3b of the cover 3 increases. There is a possibility that the support piece 15a of the protective sheet 15 inserted and held in the engagement groove of the cover 3 is easily pulled out and blown off to the outside of the main body case 1 together with the arc gas and falls off.

  The present invention has been made in view of the above points, and its object is to improve the arc gas exhaust structure so as to solve the above problems and to improve the assembling workability and support function of the protective sheet as compared with the conventional structure. Another object of the present invention is to provide a circuit breaker.

In order to achieve the above object, according to the present invention, a main body case made of a molded resin comprising a base in which power supply side and load side terminals are arranged at both ends and a cover that is overlapped and adhered on the base, A circuit breaker comprising a fixed contact, a movable contact, a grid-type arc extinguishing device, a switching mechanism, and an overcurrent trip device, wherein the fixed contact extends to the bottom of the base on the power supply side. A gas exhaust port facing the arc extinguishing device is opened on the wall surface of the shielding wall that covers the power supply side end surface of the cover, and the cover is covered with the gas exhaust port from the outside so that the wall surface of the shielding wall can be covered. In what laid a flexible protective sheet,
In the assembled state of the main body case in which the fixed end side is extended to the protective sheet to form a support piece portion and the cover is attached to the base, the support piece portion is attached to the tip of the cover shielding wall and the fixed contact. And sandwiched and fixed between the two (claim 1).

In the above configuration,
(1) The shielding wall of the cover is set so that the tip thereof faces the inclined surface of the bent portion formed in the fixed contact (claim 2).
(2) On the fixed end side of the protective sheet, hook-like engagement tabs are formed on the left and right side edges of the protective sheet in addition to the support piece, and the engagement tabs are used as base insulation barriers. The protective sheet is held in an upright position by being inserted into the formed vertical slit-shaped guide groove (claim 3).

According to said structure, there exist the following effects in terms of the assembly workability | operativity of a protective sheet, and a support function.
First, the work procedure for assembling the protective sheet to the main body case of the circuit breaker does not require the work of inserting the protective sheet into the end face of the cover and temporarily holding it to the cover as in the conventional structure, and was placed on the terminal block of the base. The protective sheet support piece is inserted on the stationary contact that extends from the power supply terminal toward the shut-off chamber and positioned at a predetermined position, and the cover is placed on the base. To wear. Thereby, the support piece portion of the protective sheet is sandwiched and fixed at this position so as to be folded between the bent portion formed in the fixed contact and the front end of the shielding wall of the cover facing the inclined surface of the bent portion. Therefore, compared with the conventional structure, the mounting operation of the protective sheet is simplified and the assembling workability can be greatly improved.

  Further, according to this protective sheet folding support structure, even if the arc gas pressure in the circuit breaker generated when the circuit breaker interrupts the current is applied to the protective sheet, the protective sheet support piece is detached from the sandwiched portion and It can be held securely and securely so that it is not blown out. In addition, the support sheet portion of the protective sheet is sandwiched between the tip of the shielding wall and the fixed contact so as to be in close contact with each other. Dust can be prevented from entering.

It is side sectional drawing of the power supply side part of the circuit breaker showing the support structure of the protection sheet by the Example of this invention. FIG. 2 is an external perspective view of a power source side end of the main body case and a protective sheet in FIG. 1. It is a perspective sectional view of the structure corresponding to FIG. It is side sectional drawing showing the whole structure of the circuit breaker for wiring used as the implementation object of this invention. It is side sectional drawing showing the protection sheet support structure of the circuit breaker currently disclosed by patent document 1. FIG. It is a disassembled perspective view of the main body case corresponding to the circuit breaker of FIG. It is explanatory drawing showing the attachment work procedure of the protection sheet | seat in FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG. 5, and the description is abbreviate | omitted.
In the circuit breaker of the illustrated embodiment, the protective sheet 15 laid on the front surface of the shielding wall 3a so as to cover the gas exhaust port 3b opened to the shielding wall 3a of the cover 3 from the outside has a predetermined structure with the following support structure. Engaged and supported in position.

    That is, the illustrated embodiment made of an insulating sheet having a thickness of about 0.4 mm having flame retardancy, heat resistance and flexibility as in the conventional product (for example, Nomex paper: product name of DuPont). The protective sheet 15 includes a support piece 15b extending in the longitudinal direction from the fixed end side (lower part) of the sheet, as shown in FIG. 2, instead of the arm-like support pieces 15a on the left and right side edges shown in FIG. , And hook-shaped engagement tabs 15c projecting from the left and right side edges.

  On the other hand, the shielding wall 3a formed at the power supply side end of the cover 3 has a fixed contact whose tip 3a-1 extends from the rear end of the power supply side terminal 5 disposed on the terminal block 2a of the base 2 toward the shutoff chamber. The length of the wall is set so as to face the bent portion 7a formed in the middle portion of the child 7 and abut against the inclined surface. The base 2 is formed with slit-like guide grooves 2b-1 in the vertical direction along the bases of the interelectrode insulating barriers 2b erected on the left and right sides of the terminal block 2a.

  When the protective sheet 15 is assembled to the main body case 1, as an assembling procedure, first, the engagement tabs 15 c formed on the left and right side edges of the protective sheet 15 are first attached to the base 2 on which the functional parts are mounted from above. It inserts in the slit-shaped guide groove 2b-1 formed in the base part of the intermediate | middle insulation barrier 2b, and sends the protection sheet 15 to a predetermined position along this guide groove 2b-1. As a result, the support piece 15b extending to the front end side of the protective sheet 15 overlaps the fixed contact 7, and the front end hangs down as shown in the drawing along the inclined surface of the bent portion 7a. Moreover, the upper half part (free end side) of the protective sheet 15 is maintained in a standing posture along the guide groove 2b-1.

  In this state, when the cover 3 is fitted on and attached to the base 2, the support piece 15 b of the protective sheet 15 is attached to the tip 3 a-1 of the shielding wall 3 a formed on the cover 3 and the bent portion 7 a of the fixed contact 7. And is clamped and fixed in a folded state as shown in the figure. Further, the upper half (free end side) of the protective sheet 15 is erected so as to cover the gas exhaust port 3b opened in the shielding wall 3a from the outside and extends to the front side of the shielding wall 3a. The assembly work is completed by hooking the upper edge of the sheet 15 on the engaging claw 3d formed on the front surface of the upper end of the shielding wall 3a.

  According to the support structure of the protective sheet 15 described above, the work procedure when assembling to the main body case 1 is simplified and the assembly workability is greatly improved as compared with the conventional support structure described with reference to FIGS. The Further, when the protective sheet 15 is assembled, there is no gap between the tip of the shielding wall 3a of the cover 3 and the fixed contact 7 mounted on the base 2, so that dust enters the blocking chamber from the surroundings. Can be prevented.

  On the other hand, when the circuit breaker is on, the protective sheet 15 is represented by a chain line in FIG. 1 in response to the arc gas pressure (arrow P in FIG. 1) generated in the shut-off chamber of the main body case 1 when an excessive current such as a short circuit current is interrupted. Even if the outer side of the shielding wall 3a is curved, the fixed side end of the protective sheet 15 is folded between the front end of the shielding wall 3a and the bent portion 7a of the stationary contact 7 as described above and firmly fixed. Therefore, the protective sheet 15 can be safely held without fear of being blown out of the main body case 1 together with the arc gas. In addition, after the current is interrupted, the protective sheet 15 can be continuously used by hooking the tip of the protective sheet 15 to the engaging claw 3d of the cover 3 and returning it to the original position.

DESCRIPTION OF SYMBOLS 1 Main body case 2 Base 2a Terminal block 2b Between-electrode insulation barrier 2b-1 Guide groove 3 Cover 3a Shielding wall 3b Gas exhaust port 5 Power supply side terminal 7 Fixed contact 7a Backward bending part 8 Movable contact 10 Arc-extinguishing device 11 Opening and closing Mechanism part 15 Protection sheet 15b Support piece part 15c Engagement tab

Claims (3)

A fixed resin contact, movable contact, grid-type arc extinguishing device is mounted on a main body case made of mold resin, which consists of a base with power supply and load side terminals arranged at both ends and a cover that is placed on top of the base. , A circuit breaker with a switch mechanism and an overcurrent trip device.
The stationary contact extends at the bottom of the base on the power supply side, and a gas exhaust port facing the arc extinguishing device is opened on the wall surface of the shielding wall covering the end surface on the power supply side of the cover, and then the gas In which a flexible protective sheet is laid on the wall surface of the shielding wall covering the exhaust port from the outside,
In the protective sheet, a support piece portion is formed by extending the fixed end side in the longitudinal direction, and in the assembled state of the main body case with the cover attached to the base, the support piece portion is connected to the tip of the shielding wall of the cover. A circuit breaker characterized by being sandwiched and fixed between a fixed contact.   2. The circuit breaker according to claim 1, wherein the shielding wall of the cover is opposed to an inclined surface of a bent portion formed in the fixed contact.   The circuit breaker according to claim 1, wherein hook-like engagement tabs are formed on the left and right side edges of the protective sheet in addition to the support piece portion on the fixed end side of the protective sheet. Is inserted into a slit-shaped guide groove formed in the inter-electrode insulating barrier of the base, and the protective sheet is held in an upright position.