JP3573607B2 - Circuit breaker - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit breaker that opens (trips off) a contact portion that constitutes a main circuit to cut off a current circuit, and particularly detects an overcurrent to open a contact portion ( The present invention relates to a circuit breaker having an overcurrent protection function for interrupting a current circuit.
[0002]
[Prior art]
In a circuit breaker, generally, a fixed contact block having a fixed contact and a movable contact block having a movable contact are arranged in a closed internal space of a case formed of a synthetic resin material. A main circuit through which a large load current flows is formed between the pair of electrode terminals. When the load current becomes excessive, the overcurrent detection device provided in the case detects the load current, and the opening operation (so-called trip operation) is performed by a contact opening mechanism connected to the movable contact base. )I do. As a means for performing the opening operation of the contact opening mechanism in response to an overcurrent detection signal from the overcurrent detection device, a so-called electromagnetic actuator (tripping device) that normally operates using electromagnetic action is used. It's being used.
[0003]
In particular, in such a circuit breaker, a so-called release type electromagnetic actuator (a trip device) is used because of its low power consumption. In the release type electromagnetic actuator, for example, as shown in the attached FIG. 5, in a normal state, the movable core 51 is attracted by the permanent magnet 52, and the pressing force by the spring 53 that applies an operating force to the movable core 1. And is stationary at a predetermined position. However, when a current is applied to the coil 54, the coil 54 generates an electromagnetic flux, which lowers the attraction force by the permanent magnet 2 of the movable core 1 to break the balance, thereby releasing (release) the movable core 1. ) To enable operation by the pressing force of the spring 53. Such a release type electromagnetic actuator is already known, for example, from Japanese Patent Application Laid-Open No. 5-182578.
[0004]
Further, in the circuit breaker, in the circuit breaker using the release type electromagnetic actuator described above, in order to reliably perform the tripping operation of the circuit breaker and to reduce the size of the device including the electromagnetic actuator. It is necessary to secure a larger stroke by the electromagnetic actuator, that is, a larger movement amount of the core portion (movable core 1) which is a movable portion thereof. However, in the release type electromagnetic actuator having the conventional structure as described above, since the entire actuator device is surrounded by the yoke, the operation stroke can be achieved only about 2 to 3 mm.
[0005]
Therefore, for example, according to Japanese Unexamined Patent Publication No. Hei 5-334953, in a circuit breaker using a release type electromagnetic actuator, it is already performed to make the distal end portion of the release type electromagnetic actuator open. In other words, the distal end portion (left end portion) of the release type electromagnetic actuator is opened, and the core portion (movable core 51), which is a movable portion, can jump out of the end surface of the yoke 55 and move. According to this, it becomes possible to largely secure the stroke of the core portion (movable core 51) as compared with the structure shown in FIG. By adopting such a structure, for example, it is possible to reduce the outer dimensions by about 20% compared to the conventional release type electromagnetic actuator and to increase the operation stroke to about 4 to 6 mm.
[0006]
[Problems to be solved by the invention]
However, as described above, in the prior art circuit breaker employing a release type electromagnetic actuator having an open end portion as a means for performing the opening operation of the contact opening (tripping) mechanism, Furthermore, the following problems are pointed out.
[0007]
That is, the failure of the electromagnetic actuator due to dust. In general, in an industrial circuit breaker according to the present invention, a large current of 100 amperes or more flows. When the contact is opened and cut off, a large amount of heat is temporarily generated in the breaker. As a result, a part of a metal part such as a conductor including a contact is melted and becomes minute dust, and a part of a case made of a synthetic resin material is gasified by this heat, and as a result, a minute minute A gas stream with dust (explosion) is generated. This gas flow is scattered to each part in the case having the closed structure, and therefore, the above-described electromagnetic actuator accommodated in the case is also exposed to the gas flow containing such dust, and dust is contained therein. Will be introduced.
[0008]
In addition, according to the results of studies by the present inventors, in particular, among such dusts, particularly, dust having a diameter of 0.3 mm or more, when it enters a movable portion forming a magnetic circuit in an electromagnetic actuator, the dust is reduced. It acts as a magnetic gap in the part and affects its operation. In other words, such a magnetic gap makes it impossible to secure a sufficient magnetic flux density in the magnetic circuit, causing a failure of the circuit breaker and causing the most important reduction in reliability of such a device. In particular, in such a release type electromagnetic actuator, in order to increase the efficiency of the device, a permanent magnet is attached to a part thereof to form a part of a magnetic circuit. It is easy to be attracted.
[0009]
That is, in the above-described conventional technology, measures against a gas flow accompanied with dust generated when the circuit breaker is shut off are provided in the circuit breaker, particularly, for the movable portion of the electromagnetic actuator which is important for ensuring its reliability. It has not been done yet.
[0010]
Therefore, in the present invention, in view of the above-described problems in the related art, it is possible to reduce the size of the device including an electromagnetic actuator for driving the contact release mechanism, and particularly, to reduce the size of the contact. An object of the present invention is to provide a highly reliable circuit breaker that protects the electromagnetic actuator from an adverse effect due to a gas flow including dust generated at the time of tripping.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a fixed contact base provided with a fixed contact and a movable contact in the internal space of a case formed of a synthetic resin material surrounding the periphery to form an internal space. by arranging the movable contact base to form a main circuit current flows between the pair of electrode terminals, and, in the said case, means for detecting an overcurrent flowing through the main circuit, the opening of the movable contact base A circuit breaker comprising: a contact opening mechanism that performs an operation; and an electromagnetic drive that drives the contact opening mechanism in response to a detection signal from the overcurrent detection unit. formed to jump out from the end surface of the yoke is constituted by release type electromagnetic actuator for moving or one, the end face of the side of the yoke which the core portion pops out, the gas generated in said casing by opening and closing of the main circuit Attaching a dustproof member for preventing the entry of dust contained in the dust-screening member is a labyrinth structure, the dust-proof member of the labyrinth structure includes a protrusion extending from the end surface of the yoke, provided inside the protruding portion And an outer cylindrical body attached to the tip of the core part, and a middle cylindrical body disposed in a space between the core part inside the middle cylindrical body .
[0014]
In addition, according to the present invention, in the above-described circuit breaker, the dustproof member having the labyrinth structure prevents the passage of dust of 0.3 mm or more.
[0015]
According to the present invention, in the above-described circuit breaker, a gap between an inner diameter of the protruding portion forming the labyrinth and an outer shape of the outer cylindrical body is set to 0.3 mm or less.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0017]
First, FIGS. 3 and 4 show the appearance and the internal structure of a circuit breaker according to an embodiment of the present invention.
[0018]
That is, in this industrial circuit breaker, a case 1 made of a synthetic resin material which is an insulating material and a cover 2 which is a lid thereof have a closed internal space formed around the inside thereof. Inside, the components of the circuit breaker described below are housed. In FIG. 1, reference numerals 30, 30,..., 40, 40,... Represent one pair for each phase of the three-phase currents extracted from the opposite end faces of the case 1 of the circuit breaker. Electrode terminals provided in upper and lower stages are shown, and reference numeral 9 denotes a handle 9 for manually operating the opening / closing mechanism.
[0019]
The internal structure of the circuit breaker is shown in FIG. 4, and as is apparent from the figure, a fixed contact table 3 fixedly disposed in the internal space of the case 1 and a fixed contact table 3 A fixed contact 4 that is electrically joined, a movable contact stand 6 that is arranged facing the fixed contact 4, and a movable contact 5 that is electrically joined to the movable contact stand are arranged. A flexible stranded wire 7 electrically connected to the movable contact stand 6 is electrically connected between the movable contact stand 6 and the terminal stand 8 to form a main circuit. Reference numeral 10 in the figure denotes an opening / closing mechanism for opening and closing the main circuit. The handle 9 described above for manually operating the opening / closing mechanism is attached to the opening / closing mechanism 10. Although not shown, the case 1 further includes an overcurrent detection device that detects an overcurrent flowing in the main circuit, and operates in response to the overcurrent detection by the overcurrent detection device. An electromagnetic actuator 20, which is an overcurrent trip device that automatically trips (opens) the mechanism, is provided.
[0020]
Note that the circuit breaker whose outline has been described above is usually mounted on a wall with the power supply side up and the load side down at the time of use (installation). Therefore, dust and dirt in the air may enter into the case and further into the circuit breaker and the like (including the electromagnetic actuator 20). When the circuit breaker is automatically tripped (opened) in the event of a short circuit, the melt generated from the vicinity of the arc extinguishing device in the case 1 falls down to the electromagnetic actuator 20 by the generated gas flow. (Similar to a kind of explosion phenomenon).
[0021]
As already described above, when dust generated for the above-mentioned reason adheres to the movable core inside the electromagnetic actuator 20 constituting this overcurrent trip device or the contact surface between the movable core and the fixed core. However, if it adheres to a part constituting the magnetic circuit, the suction force of the fixed core of the release type electromagnetic actuator decreases, and the movable core cannot be held in the attracted state, so that the circuit breaker is reset. No longer possible, reducing its reliability and eventually rendering the circuit breaker unusable.
[0022]
Therefore, according to the present invention, in a circuit breaker having such a release type electromagnet tripping device, a structure is adopted in which the dust does not enter and adhere to the inside of the electromagnetic actuator which is the tripping device. FIG. 1 shows a specific structure of such an electromagnetic actuator. FIG. 1A shows a state when the electromagnetic actuator 20 is not operating, and FIG. 1B shows a state when the electromagnetic actuator 20 is operating.
[0023]
In FIG. 1, in the electromagnetic actuator 20, an electromagnetic coil 25 and a magnet (permanent magnet) 26 are arranged in the axial direction inside a cylindrical yoke 21 formed of a member having excellent magnetic permeability such as iron. I have. A core divided into two, that is, a movable core 22 and a fixed core 23, is disposed inside the movable core 22, and the movable core 22 is pressed against a member provided in a part thereof. In addition, a rod-shaped operation rod 24 for operating the above-described opening / closing mechanism 10 is integrally formed. The operating rod 24 has the other end (the right side in the figure) projected through a through hole opened in the fixed core 23 to form a disk-shaped spring receiving portion 241 at the end. Also, reference numeral 31 in the drawing is a member such as a laminated iron plate that also constitutes a part of the yoke, and reference numeral 30 in the drawing is configured integrally with the movable core 22 by pressing the receiving portion 241. This is an operation spring that moves the operation rod 24 in the direction of the arrow in the figure.
[0024]
In the electromagnetic actuator 20, which is a release type electromagnet trip device, the cylindrical guide member 28 attached to the tip (left end in the figure) has a large opening as is clear from the figure. This allows the movable core 22 to protrude beyond the end face of the yoke 21 (the end face on the left side in the figure). A cylindrical cap member 29 is attached to the distal end of the operating rod 24 extending from the movable core 22, and a small gap g is provided between the outer periphery of the cap member 29 and the inner diameter of the guide member 28. Are opposed to each other.
[0025]
Further, inside the cap member 29, a pipe member 27, which is also a tubular middle cylinder, is disposed so as to protrude beyond the end face (the left end face in the figure) of the yoke 21. The movable core 22 is slidably provided inside the pipe member 27. The pipe member 27 has one end (the left end in the figure) squeezed and the other end (the right end in the figure) a yoke 21. And the bobbin of the magnet 25 so as to be sandwiched and fixed. The distal end of the operating rod 24 protrudes to the outside via a small opening opened at one end (left end in the figure) of the pipe member 27. Further, a return spring 32 is provided between the cap member 29 attached to the tip of the operation rod 24 and the end face of the movable core 22, whereby the movable core 22 is always moved with respect to the cap member 29. The pressing force is applied in the returning direction, and these usually move integrally.
[0026]
According to the electromagnetic actuator 20 having such a structure, the movable core 22 integrally formed with the operation rod 24 has its tip (left end in the figure) moved by the guide member 28 provided on the end surface of the yoke 21 to control the amount of movement. Since there is no limitation, as shown in FIG. 1B, it is possible to secure a distance of about 4 to 6 mm that is sufficient for stably operating the opening / closing mechanism, that is, a sufficient stroke. become. According to this structure, as is apparent from the figure, the tip (left end in the figure) is formed by the guide member 28, the cap member 29, and the pipe member 27 forming the middle cylinder. A so-called labyrinth is formed. Therefore, even if the circuit breaker is exposed to a gas flow containing dust generated during the tripping (opening) operation, it is possible to prevent dust from being introduced into the electromagnetic actuator 20.
[0027]
Dust and the like generated at the time of tripping (opening) operation of the circuit breaker include dust having various particle diameters. When the dust enters the inside of the electromagnetic actuator 20 and adheres to a movable part or the like. In this case, the operation of the actuator is adversely affected. In particular, among these, for example, according to the results of experiments and studies confirmed by the present inventors, etc., in order to operate the opening / closing mechanism employed in the automatic tripping (opening) operation of such an industrial circuit breaker. In the electromagnetic actuator used, when dust of about 0.3 mm or more invades, the suction state of the movable core 23 cannot be maintained, thereby causing a problem that the reset operation of the circuit breaker cannot be performed.
[0028]
According to the study by the present inventors, when the dust of 0.3 mm or more invades between the movable core 22 and the fixed core 23, this phenomenon causes the movable core 22 to enter A gap is formed between the magnetic core and the fixed core 23, and the contact portion of the magnetic circuit (that is, the connecting portion between the movable core 22 and the fixed core 23) causes insufficient suction force on the movable core 22. It is believed that there is. That is, the relationship between the gap d between the movable core 22 and the fixed core 23 and the suction force F acting between them is generally the third power of the gap d as shown in FIG. The relationship is inversely proportional, which is considered to be caused by a sharp decrease due to a gap of about 0.3 mm or more.
[0029]
Therefore, in the present invention, it is preferable to prevent the particles having such a particle size from entering the inside of the electromagnetic actuator by setting the gap of a part of the labyrinth passage to 0.3 mm or less. Specifically, as is clear from FIG. 1A, in the above embodiment, the inner diameter of the cap member 29 forming a part of the labyrinth passage and the operation extending integrally from the movable core 22 are described. The gap (gap) g formed between the rod 24 and the inner diameter of the cap member 29 attached to the tip of the rod 24 is set to 0.3 mm or less.
[0030]
【The invention's effect】
As is apparent from the above detailed description, according to the circuit breaker of the present invention, in the release type electromagnetic actuator which operates the opening mechanism for releasing (opening) the contacts forming the main circuit, the movable core thereof is provided. By projecting from the end surface of the yoke to secure a sufficient working stroke, and by attaching a dustproof member for preventing intrusion of dust contained in the gas flow generated in the case by opening and closing the main circuit. In addition, the electromagnetic actuator is protected from adverse effects due to the gas flow including dust, and thus a small, stable, and highly reliable circuit breaker can be provided.
[0031]
Further, the dustproof member has a labyrinth structure, and a part of the gap is prevented from invading the electromagnetic actuator with dust of 0.3 mm or less, so that intrusion of particles that particularly adversely affect the electromagnetic actuator is surely prevented. It is possible to provide a circuit breaker with stable operation and high reliability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an internal configuration of a release type electromagnetic actuator which is a tripping device of a circuit breaker according to an embodiment of the present invention, and FIG. (B) is a figure which shows the state at the time of operation.
FIG. 2 is a diagram illustrating a relationship between a gap of an abutting portion and a suction force in a magnetic circuit for explaining an adverse effect of dust in the release type electromagnetic actuator of the circuit breaker of the present invention.
FIG. 3 is a perspective view showing the appearance of the circuit breaker of the present invention.
FIG. 4 is a sectional view showing the internal structure of the circuit breaker of the present invention.
FIG. 5 is a sectional view showing an internal configuration of a release type electromagnetic actuator employed in a circuit breaker according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Case 2 Cover 3 Fixed contact stand 4 Fixed contact 5 Movable contact 6 Movable contact stand 7 Flexible stranded wire 8 Conductor 9 Handle 10 Opening / closing mechanism 20 Tripping device (electromagnetic actuator)
21 yoke 22 movable core 23 fixed core 24 operating rod 25 coil 26 magnet (permanent magnet)
27 Pipe member 28 Guide member 29 Cap member 30 Operation spring

Claims (3)

A pair of electrode terminals is provided by disposing a fixed contact block having a fixed contact and a movable contact block having a movable contact in the internal space of a case formed of a synthetic resin material surrounding the periphery to form an internal space. current flows to form a main circuit between, and, in the said case, means for detecting an overcurrent flowing through the main circuit, a contact opening mechanism for the movable contact base of opening operation, the overcurrent detection A circuit breaker comprising: an electromagnetic drive device that drives the contact opening mechanism according to a detection signal from the means.
The electromagnetic drive device is constituted by a release type electromagnetic actuator that moves out of the end surface of the yoke forming the magnetic circuit forming the core portion ,
And, on the end surface of the yoke on the side where the core portion protrudes, a dustproof member for preventing intrusion of dust contained in a gas flow generated in the case by opening and closing the main circuit is attached ,
The dustproof member has a labyrinth structure,
The dustproof member having a labyrinth structure includes a protruding portion extending from an end surface of a yoke, an outer cylindrical body provided inside the protruding portion and attached to a tip of the core portion, and the core portion inside the middle cylindrical body. And a middle cylinder disposed in a space between the circuit breaker and the circuit breaker. The circuit breaker according to claim 1 ,
The circuit breaker, wherein the dustproof member having the labyrinth structure prevents the passage of dust of 0.3 mm or more. 3. The circuit breaker according to claim 2 , wherein a gap between an inner diameter of the protruding portion forming the labyrinth and an outer shape of the outer cylindrical body is 0.3 mm or less.

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