JPH0810577B2 - Overcurrent protection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an overcurrent protection device, and more particularly to an overcurrent protection device used in place of a fuse for overcurrent protection built into a circuit device.

BACKGROUND ART Conventionally, as this type of overcurrent protection device, Japanese Patent Publication No.
There is an overcurrent switch disclosed in Japanese Patent Publication No. 45505. This is the casing 1 as shown in FIGS. 9 and 10.
It has an operating shaft 5 that projects more freely so that it can move back and forth.
The contacts introduced into the main electric path are closed when is pushed toward the casing 1, and the contacts are opened when an overcurrent passes through the main electric path. The contact is a fixed contact 23 fixed to one end of a first terminal plate 21 fixed to the casing 1.
And the movable contact 24 fixed to one place of the latch link 31 having an L-shaped cross section.
Is connected to the movable contact 24 by a latch spring 27.
Is urged in such a direction as to separate from the fixed contact 23. Further, the operation shaft 5 is biased by a shaft return spring 57 in a direction projecting from the casing 1. On the other hand, a bimetal plate 41 is electrically and mechanically connected to one end of the second terminal plate 22, and a locking projection 44 is provided on one end of the bimetal plate 41. Therefore, when the operating shaft 5 is pushed in,
One end of the latch link 31 engages with the locking protrusion 44 in a state where the spring force is accumulated in the shaft return spring 57. That is, the main electric path is formed by the route of the first terminal plate 21, the latch link 31, the bimetal plate 41, and the second terminal plate 22. In this state, when an overcurrent is applied to the main circuit, the bimetal plate 41 bends to release the engagement between the latch link 31 and the locking projection 44, and the operating shaft 5 is moved by the spring force of the shaft return spring 57. The contacts are opened by the spring force of the latch spring 27 and the shaft return spring 57 while protruding from the casing 1.

In such a conventional overcurrent switch, the contact is opened when the operation button 5 is pushed into the casing 1 regardless of whether the contact is open or closed. Therefore, when an external force acts on the operation button 5, the contact is opened. There was a problem that the state of became unstable.

[Object of the Invention] The present invention has been made in view of the above points, and its main purpose is to reset the contact to the closed state by pushing the operation button in the contact opened state. When resetting the mechanism that keeps the contacts closed before resetting the contacts afterwards, the contacts will be closed if the mechanism is not reset even if the operation button is pushed halfway. To prevent the contacts from fluttering due to halfway pushing of the operation button.
If the contact is closed, even if the operation button is pushed again, the pushing force of the operation button does not act on the movable contact so that the contact does not flutter when the operation button is pushed after closing the contact. Another object of the present invention is to provide an overcurrent protection device.

DISCLOSURE OF THE INVENTION (Structure) In the present invention, a contact device into which a main circuit is inserted,
A latch device that holds the contact device in the open state in a latched state in which the force in the direction to open the contact device is accumulated, and a latch device that releases the latched state of the latch device when overcurrent passes through the main circuit and A tripping device that opens the contact device is installed in the casing, an operation button that sets the latch device in the latched state is inserted into the casing so that it can move forward and backward, and a button return spring causes one end to protrude from the casing. In the overcurrent protection device biased to the contact position, the contact position is provided with a terminal plate having a fixed contact and a movable contact separating from and contacting the fixed contact, and the movable contact is swingable in the direction separating from and contacting the fixed contact. The movable contact has a movable contact that is spring-biased in a direction to bring the movable contact into contact with the fixed contact, and the movable contact has a hooking piece that projects in a direction away from the fixed contact at the other end, and the latch device is The movable contact is separated from the fixed contact by a latch link that is rotatably supported by a rotary shaft that is orthogonal to the plane in which the moving contact swings and that holds one end of the movable contact at a position different from the movable contact. And a latch spring for urging the latch link in a direction, and the tripping device is inserted into the main electric circuit, and a bimetal plate having a locking portion that engages with the latch link in a state where the latch spring accumulates a force. And a heating device that releases the engaged state of the latch link and the bimetal plate by heating the bimetal plate when an overcurrent passes through the main circuit, and the movable contact has a state in which the latch link is engaged with the bimetal plate. Is movable within a range where the movable contact is separated from and contacted with the fixed contact, and the operation button is pushed into the casing when the contact between the latch link and the bimetal plate is released. Is At the same time, the hooking surface of the movable contactor is provided with a hooking surface at the other end for keeping the open state against the spring force of the contact pressure spring by applying a pressing force, and the hooking surface presses the hooking piece. The intermediate part is provided with a pressing surface that rotates the latch link to the position where it will be engaged with the bimetal plate later, and the operation button is attached to the latch link so that the latch link is engaged with the bimetal plate and the protrusion from the casing is prohibited. An overcurrent characterized by comprising an engaging latch piece, wherein the engagement position of the operation button with respect to the latch link is set so that the engaging surface is separated from the engaging piece at the position where the engaging piece engages with the latch link. A protection device is disclosed.

Thus, according to the above configuration, when the operation button is pushed in with the contact opened, the hooking piece of the movable contact is pressed against the hooking surface of the operation button, and the contact is kept open. The latching link is pushed by the pushing surface provided in the middle portion of the operation button to engage with the bimetal plate. After that, if the pushing force of the operation button is released, the latch piece of the operation button is engaged with the latch link to keep the protrusion from the casing, and at this position, the hooking surface is removed from the hooking piece. The contact is closed by the spring force that urges the movable contact apart. After all, when the contact is reset to the closed state, the mechanism that keeps the contact closed is reset first, and then the contact is reset to the closed state, so even if you push the operation button halfway, the mechanism resets. If not, the contacts are not closed, and the fluttering of the contacts due to halfway pressing of the operation button is prevented. Also, when the contact is closed, the contact surface of the operation button and the hook of the movable contact, which were in contact with each other in the open state, move away from each other, and the movable contact moves. For example, even if the operation button is pushed in again, the hooking surface of the operation button does not come into contact with the hooking piece of the movable contact, and the pressing force of the operation button does not act on the movable contactor. It is possible to prevent the open / closed state of the contacts from fluttering when the operation button is pushed in later. Moreover, the force for bringing the movable contact into contact with the fixed contact is only the spring force for urging the movable contact, and the pressing force of the operation button is independent of the contact pressure of the contact, so that a constant contact pressure can be maintained. You can do it.

(Embodiment 1) As shown in FIG. 1, a contact device 2 inserted in a main electric circuit.
And a latch device 3 for holding the contact device 2 in the open state in a latch state in which a force in the direction of opening the contact device 2 is accumulated, and a latch state of the latch device 3 is released when an overcurrent passes through the main circuit. And a tripping device 4 for opening the contact device 2 are housed in an elongated tubular casing 1, and an operating button 5 for setting the latch device 3 in a latched state is provided in the casing 1.
It is inserted so that it can move back and forth along the longitudinal direction of the. In the following description, the direction perpendicular to the plane of FIG.
The left-right direction and the up-down direction will be described as the left-right direction, the front-back direction, and the up-down direction, respectively, and the paper spine side of FIG. 1 will be described as the left side, and the left side of FIG. 1 will be described as the front side.

As shown in FIG. 2, the casing 1 is formed into a long and slender tubular shape that is long in the front-rear direction by a pair of left and right half-split bodies 11a, 11b and a cap 12 attached to the front ends of the half-split bodies 11a, 11b. Each of the half-divided bodies 11a, 11b is formed in a shape in which one of the left and right side surfaces and the front surface are opened, and inside the pair of upper and lower positioning recesses 13 formed on the rear end side surface of the one half-divided body 11a. The left and right half halves 11a and 11b are butted against each other with a pair of positioning protrusions (not shown) projectingly provided on the rear end side surface of the half halve 11b. In this manner, the cap 1 is attached to the outer peripheral surface of the front end portion of the half-split bodies 11a and 11b in a state where both half-split bodies 11a and 11b are combined.
2 is fitted. The cap 12 is formed in a tubular shape,
Locking step portion 1 formed on the outer peripheral surface of the front end portion of each half body 11a, 11b
The cap 12 is fitted so that the rear end surface of the cap 12 abuts on the cap 4.
The inner diameter of the front end portion of the cap 12 is a guide cylinder portion 15 that is set smaller than the inner diameter of the cylinder portion that joins the half-faced bodies 11a and 11b. Here, the connecting portion between the half-split bodies 11a and 11b and the cap 12 has a non-circular cross-sectional shape in a plane orthogonal to the front-rear direction, so that the half-split bodies 11a and 11b and the cap 12 do not rotate relative to each other. It has become.

The contact device 2 is inserted into the main electric path as described above, and the main electric paths are respectively attached to the rear end portions of the casing 1 and the rear end portions thereof project from the rear end surface of the casing 1.
A frame 6 made of a conductive material such as a copper alloy for holding the terminal plate 21 and the second terminal plate 22, the contact device 2, the latch device 3, and the trip device 4, the first terminal plate 21 and the frame 6. A movable contactor 25 having a pair of movable contacts 24a, 24b that separates from and contact the fixed contacts 23a, 23b respectively provided on the first and second terminals, and a resistance heater 26 for electrically connecting the second terminal plate 22 and the frame 6 to each other. Is formed by. That is, the main circuit is the first
Terminal plate 21-Movable contact 25-Frame 6-Resistance heater 26-
That is, the second terminal plate 22 is formed. Also,
The contact device 2 that opens and closes this main circuit is the first fixed contact 23a.
A movable terminal 25 having a first terminal plate 21 provided with a frame 6, a frame 6 having a second fixed contact 23b, a pair of movable contacts 24a and 24b that separates and contacts the fixed contacts 23a and 23b, and a movable contact. Biasing the central part of 25 downward, the movable contacts 24a, 24b and the fixed contact 23
and a contact pressure spring 27 for obtaining a contact pressure between a and 23b. The first terminal plate 21 is provided with a holding protrusion 21a at the rear portion, and the portion where the holding protrusion 21a is formed is press-fitted into the holding groove 16 formed at the rear end portion of the casing 1 so that the casing 1 is placed at a fixed position. It is fixed. A first fixed contact 23a is fixed to the upper surface of the front end portion of the first terminal plate 21. Frame 6
As shown in FIG. 2, a vertical piece 61b extends upward from the rear edge of the base piece 61a to which the second fixed contact 23b is fixed, and the rear end portion of the base piece 61a extends from the upper edge of the vertical piece 61b. A horizontal piece 61c extending in parallel to the rear side, and a connecting piece 61d extending upward from the right edge of the horizontal piece 61c is formed.A coupling projection 62 projects from the upper edge of the connecting piece 61d. It is set up. On the other hand, at the front end of the frame 6, a holding piece 61e extends upward from the front edge of the base piece 61a, and the first spring receiving piece 61f parallel to the base piece 61a extends from the upper edge of the holding knit 61e to the right. The second spring receiving piece 61g is formed so as to extend rightward from the front end of the holding piece 61e extending toward the front side of the base piece 61a. Spring receiving protrusions 63 and 64 are provided on the lower surface of the first spring receiving piece 61f and on the front surface of the second spring receiving piece 61g, respectively. Also,
A bearing hole 65 penetrating in the left-right direction is formed in the holding piece 61e. The second terminal plate 22 is connected to the front end of the connecting piece 61d of the frame 6 so as to be spaced apart from the connecting piece 61d on the left side and extend in parallel.
have a. The movable contact 25 is a pair of left and right movable contacts 24.
a, 24b, the hook piece 25a is extended upward from the rear edge,
The engaging piece 25b is formed in a shape extending upward from the front end edge. A spring receiving protrusion is provided on the upper surface of the center of the movable contact 25.
25c is projected, and both ends of the contact pressure spring 27 are attached to the spring receiving protrusion 25c and the spring receiving protrusion 63 provided on the first spring receiving piece 61f of the frame 6, and the center of the movable contact 25 is attached. The part is urged downward. The connection piece 22a of the second terminal plate 22 and the connection piece 61b of the frame 6 are electrically and mechanically connected to respective terminals of the resistance heater 26, and the second terminal plate 22 and the frame 6 are connected via the resistance heater 26. Are electrically connected.
Here, the resistance heater 26 is arranged along the left-right direction.

The latch device 3 includes a latch link 31 formed of an insulating material such as synthetic resin. The latch link 31 has a locking surface 31a on the upper front surface, and an inclined surface 31b on the upper rear surface that reduces the distance from the engaging surface 31a toward the upper side. In addition, on the right side surface of the latch link 31, a cylindrical tube shaft 31
The protrusion c is provided, and the pressing protrusion 31d is provided so as to be spaced upward from the cylindrical shaft 31c. The front end of the movable contact 25 is loosely fitted between the cylindrical shaft 31c and the pressing projection 31d,
The rear end of 25 can swing up and down. Further, the engaging piece 25b of the movable contact 25 is locked to the front surface of the pressing protrusion 31d. The tip end of the cylinder shaft 31c and the left side surface of the latch link 31 pass through, and the rotary shaft 32 is inserted there.
A latch piece 31e extends from the lower part of the front surface of the latch link 31, and the tip of the latch piece 31e is bent to the right. Bearing hole formed in the frame 6 at the left end of the rotary shaft 32
The flange 32a, which is inserted into the rotary shaft 32 and is provided on the rotary shaft 32, is locked to the right side surface of the holding piece 61e of the frame 6, whereby the rotary shaft 36 is prevented from coming out to the left. The right end of the rotary shaft 32 is inserted into the cylinder shaft 31c of the latch link 31, and rotatably supports the latch link 31 with respect to the frame 6. Axis of rotation
Both ends of 32 are supported by bearing recesses 17 formed in the inner peripheral surfaces of the pair of halves 11a and 11b. A latch spring 33 is mounted between the collar 32a of the rotary shaft 32 and the latch link 31. The latch spring 33 has an L-shaped first engaging portion 33a that is engaged with the upper surface of the latch piece 31e of the latch link 31 at one end, and has a first spring receiving piece of the frame 6 at the other end. It has a second locking portion 33b that is locked to the front edge of 61f and biases the latch link 31 to the forward rotation side. That is, in the state where the lower surface of the movable contact 25 at the front end of the movable contact 25 is in contact with the cylindrical shaft 31c, the pressing protrusion 31d applies a counterclockwise force to the engaging piece 25b. The rear end of the movable contact 25 is urged to move upward with the peripheral surface of the cylindrical shaft 31c as a fulcrum. The spring force of the latch spring 33 is set to be larger than the spring force of the contact pressure spring 27. Thus the latch link
A force acts on the movable contact 25 by the 31 and the latch spring 33 in a direction of separating the fixed contacts 23a, 23b and the movable contacts 24a, 24b from each other. The latch link 31 is made of an insulating material as described above, and is interposed between the holding piece 61e of the frame 6 and the front end of the movable contact 25. Therefore, the front end of the movable contact 25 is a frame. It is insulated against 6. The latch device 3 includes the latch link 31, the trip device 4 for locking the latch link 31 in a latched state in which the spring force is accumulated in the latch spring 33, and the latch link from the state in which the spring force of the latch spring 33 is released. It is composed of an operation button 5 for returning 31 to the latched state.

The trip device 4 has an elongated bimetal plate 41 that is long in the front and rear. Bimetal plate 41 with a frame 6 at the rear end
A coupling hole 42 for integrally coupling the bimetal plate 41 to the frame 6 is formed by inserting and crimping the coupling protrusion 62 of the above, and a locking piece 43 is extended to the left side at the front end portion. . A resistance heater 26 as a heat generating device is in close contact with the lower surface of the rear end portion of the bimetal plate 41, and when the resistance heater 26 heats the bimetal plate 41, the front end portion of the bimetal plate 41 is set to warp upward and curve. ing. Locking piece 43
Has a positional relationship such that the locking surface 31a of the latch link 31 can be locked to the rear edge of the locking piece 43. In the state where the latch link 31 and the bimetal plate 41 are engaged, the spring force of the latch spring 33 is accumulated, and in this state, the rear end portion of the movable contact 25 is moved downward by the spring force of the contact pressure spring 27, The fixed contacts 23a, 23b are in contact with the movable contacts 24a, 24b.

The operation button 5 is formed of an insulating material such as a synthetic resin into a cylindrical shape whose rear surface is open. A drive piece 51 extends rearward from the upper portion of the rear surface of the operation button 5, and a left side edge of the drive piece 51 is cut out in a rectangular shape to form a position regulation recess 52. Further, the rear surface of the drive piece 51 is formed with a hook portion 53 that is inclined downward as it goes rearward. A latch piece 54, which is shorter than the drive piece 51, extends rearward from the lower portion of the rear surface of the operation button 5. Similar to the drive piece 51, the latch piece 54 and the left side edge are cut out in a rectangular shape to form a latch recess 55. The upper portion of the latch link 31 is inserted into the position regulation recess 52, and the hook portion 53, which is the rear end surface of the drive piece 51, is set so as to be positioned corresponding to the hook piece 25a of the movable contact 25. The front end of the latch piece 31e of the latch link 31 can be inserted into the latch recess 55, and when the latch piece 31e of the latch link 31 and the latch piece 54 of the operation button 5 are engaged with each other, The positional relationship is set so that the front end surface is flush with the front surface of the casing 1. A spring receiving projection 56 is provided in the operation button 5 so as to project rearward. The spring receiving projection 56 and the spring receiving projection 64 formed on the second spring receiving piece 61g of the frame 6 are provided with a button return spring 57. The operation button 5 is urged forward by the spring force of the button return spring 57. The outer peripheral surface of the front end portion of the operation button 5 is formed in a shape that matches the inner peripheral surface of the guide tube portion 15 formed at the front end portion of the cap 12, and the operation button 5 can be smoothly operated back and forth without shaking. It is like this. Locking protrusions 58 are provided on the upper surface and the lower surface of the operation button 5, respectively. The guide tube portion 15 at the front end portion of the cap 12 and the rear end portion of the cap 12 formed to have a diameter larger than that of the guide tube portion 15. The locking projection 58 is provided on the step portion 18 formed between
Is locked, the amount of protrusion of the operation button 5 to the front of the casing 1 is restricted.

With the above configuration, the contact device 2 excluding the first terminal plate 21,
The latch device 3 excluding the operation button 5 and the button return spring 57, and the trip device 4 are held by the frame 6.
Therefore, the first terminal plate 21 is mounted on the one half-divided body 11a, and after the frame 6 is installed in the one half-divided body 11a with each member mounted on the frame 6, the operation button 5 and the button are pressed. The assembly is completed by mounting the return spring 57, then connecting the other half body 11b, and finally fitting the cap 12, and the fine parts are mounted in the frame 6 in advance. This makes the work easier. In addition, each part can be adjusted in a state where each part is incorporated in the frame 6 before being incorporated in the casing 1, and the adjustment work becomes easy particularly in a small-sized device. As shown in FIGS. 3 and 4, the half-split body 11a
Positioning ribs 19 are provided on the inner peripheral surface of, and by placing the resistance heater 26 on the positioning ribs 19,
The position is set so that the resistance heater 26 is in close contact with the lower surface of the bimetal plate 41. That is, the resistance heater 26
The distance between the bimetal plate 41 and the bimetal plate 41 is prevented from varying depending on the product, and the operating current for releasing the latched state can be set to a substantially constant value.

(Operation) The operation will be described below. Fixed contacts 23a, 23b and movable contact 2
As shown in FIGS. 5 and 7, the locking surface 31a of the latch link 31 is located at the rear edge of the locking piece 43 of the bimetal plate 41 when the contacts in contact with 4a and 24b are closed. It is in the latched state with abutting, and the latch spring 33 has a latch link.
The spring force that biases 31 toward the forward rotation side is accumulated. In the latched state, the movable contact 25 has the hooking piece 25a with the operation button 5
The position corresponding to the rear of the hook portion 53 of the movable contact 24a, 24b
Is held by the latch link 31 so as to be swingable between the fixed contacts 23a and 23b. That is, in the latched state, the movable contact 25 does not receive the pressing force from the pressing protrusion 25b, so that it is pressed downward by the contact pressure spring 27, and as a result, the movable contacts 24a, 24b and the fixed contacts 23a, 23b come into contact with each other. Of. Here, the contact pressure of the contact point is set only by the spring force of the contact pressure spring and is independent of the spring force of the latch spring 33.Therefore, the force for driving the latch link 31 and the contact pressure of the contact point are Can be set independently, which simplifies the design. In the latched state of the operation button 5, the latch piece 54 meshes with the latch piece 31e of the latch link 31, and the front surface of the operation button 5 and the front surface of the casing 1 are substantially flush with each other while the spring force of the button return spring 57 is accumulated. Is set to. That is, the latched state can be confirmed by the position of the operation button 5. The pressing surface 59, which is the front side surface of the position regulation recess 52 of the operation button 5, is separated from the locking surface 31a of the latch link 31 to the front side.

When an overcurrent flows in the main circuit between the first terminal plate 21 and the second terminal plate 22 in the above-described mode, the resistance heater 26 generates heat, the bimetal plate 41 is heated, and the front end portion of the bimetal plate 41 moves upward. Bend to. As a result, the locking surface 31a and the locking piece 4
The engagement state with 3 is released, and the latch force of the latch spring 33 causes the latch link 31 to rotate forward. Since the spring force of the latch spring 33 is set to be larger than the spring force of the contact pressure spring 27,
As shown in FIG. 6, the front end portion of the movable contact 25 is pressed downward by the pressing protrusion 31d in front of the fulcrum with the cylinder shaft 31c of the latch link 31 as the fulcrum, and the movable contact 2 is pressed by this pressing force.
5 The rear end moves upward, and the movable contacts 24a and 24b are fixed contacts.
Separate from 23a and 23b. Here, by inserting the two contacts in series in the main circuit and forming the latch link 31 with an insulating material, the latch link 31 is not inserted into the main circuit and the contact is opened. At latch device 3
Since no arc is generated in the latch device 3, welding or wear of the latch device 3 does not occur. That is, since the latch device 3 is not damaged when the contacts are opened, it can be repeatedly used. Further, when the latch link 31 is rotated forward, the engagement state between the latch piece 31e of the latch link 31 and the latch piece 54 of the operation button 5 is released, and the operation button 5 is pressed by the spring force of the button return spring 57. Project from the front of the. The protrusion amount of the operation button 5 from the front surface of the casing 1 is restricted by the positional relationship between the locking protrusion 58 formed on the operation button 5 and the step portion 18 formed on the inner circumference of the cap 12. In this way, when the contact is opened, the operation button 5 projects from the casing 1, so that the state of the contact can be confirmed by the operation button 5. Here, even when the operation button 5 cannot be projected from the front surface of the casing 1 due to an external force acting on the operation button 5 due to a situation such that the front surface of the operation button 5 is in contact with the wall surface, as described above, Latch link
Since there is a certain amount of gap between the locking surface 31a of 31 and the pressing surface 59 of the operation button 5, the latch link 31 can rotate at an angle corresponding to this gap, and thus the contacts can be opened. You can That is, the latch link 31 has the operation button 5
The contacts can be opened without moving, which is so-called trip-free. When the latch link 31 is released from the engagement state with the bimetal plate 41 and rotated by a certain angle, the front end edge of the latch piece 31e comes into contact with the stopper surface 9 in the casing 1 to stop the rotation. . Further, the fixed contact 23b is provided on the frame 6 so that the frame 6 serves as a conductive path, and the movable contact 25 short-circuits the fixed contact 23a provided on the first terminal plate 21 and the fixed contact 23b provided on the frame 6. Because I am
It is not necessary to connect a connection line to the movable contact 25, and the connection line does not hinder the movement of the movable contact 25.

To return the contact from the open state to the closed state, the operation button 5 may be pushed into the casing 1. That is, when the operation button 5 is pushed in, the pressing surface 59 of the operation button 5 presses the locking surface 31a of the latch link 31 to rotate the latch link 31 backward against the spring force of the latch spring 33, and the latch link 31
The bimetal plate 41 is pressed upward by the inclined surface 31b and the bimetal plate 41 is bent upward. Here, when the front surface of the operation button 5 is pushed to a position substantially matching the front surface of the casing 1, the front surface of the engaging piece 25a of the movable contact 25 comes into contact with the hooking portion 53 formed at the rear end of the operation button 5. Contact, movable contact 2
5 is locked by the operation button 5 and cannot move downward. Further, when the operation button 5 is pushed in, as shown in FIG. 8, the locking surface 31a of the latch link 31 causes the locking piece 43 of the bimetal plate 41 to move.
Moves behind the trailing edge. Here, since the front end portion of the bimetal plate 41 is released and inverted by the upward pressing force received from the latch link 31, a “snap” is generated.
And a slight shock is felt on the operation button 5,
It is possible to confirm that it is in the latched state. That is, when the operation button 5 is pushed in with the contact opened, the hooking piece 25a of the movable contact 25 is pressed against the hooking surface 53 of the operation button 5 to keep the contact open, and in the meantime, the operation button 5 is pressed. The latching link 31 is engaged with the bimetal plate 41 by the latching link 31 being pushed by the pressing surface 59 provided at the intermediate portion of the above and rolling backward. Here, since the operation button 5 is restricted from moving backward by the movable contact 25, it cannot be moved backward beyond a predetermined amount (set to about 1.25 mm). When the pressing force on the operation button 5 is released from this state, the locking surface 31a of the latch link 31 comes into contact with the rear edge of the locking piece 43 of the bimetal plate 41 to be in the latched state,
The movable contact 25 is released from being bound to the operation button 5 and moved downward by the spring force of the contact pressure spring 27, so that the movable contact 24
The contacts a and 24b come into contact with the fixed contacts 23a and 23b to close the contacts. As described above, by pushing the operation button 5 rearward of the front surface of the casing 1, the latch link 31 and the bimetal plate 41 can be securely engaged with each other to be in the latched state. Therefore, the contact is closed. Therefore, the contact is the operation button 5
Irrespective of the moving speed of the contact, the contact changes from the open state to the closed state at a constant speed set by the spring force of the contact pressure spring, which prevents contact fluttering and the like, and is always constant when the contact is closed. The contact pressure that is obtained is obtained.

[Advantages of the Invention] As described above, according to the present invention, the movable contact can be swung within a range in which the movable contact is adjacent to the fixed contact when the latch link is engaged with the bimetal plate. When the operation button is pushed into the casing when the contact between the contact and the bimetal plate is released, the spring force of the contact spring can be increased by using the pushing force of the hook of the movable contact. The end face is provided with a catching surface that keeps the contact open, and the intermediate part has a pressing surface that rotates the latch link to the position where it engages the bimetal plate after the catching surface presses the catching piece. Is equipped with a latch piece that engages with the latch link so that the protrusion from the casing is prohibited when the latch link engages with the bimetal plate. Since the engagement position of the operation button with the latch link is set so that is separated from the hooking piece, when resetting from the open state to the closed state, the operation button is pushed into the casing by a predetermined amount to be in the latched state. Until then, the movable contact is held in the open state by the operation button, and the contact is closed by releasing the pressing force applied to the operation button. Moreover, once the contact is closed, the movable contact is operated. The contacts do not open even if the operation button is pushed again, regardless of the operation of the button. That is, even if the operation button is pressed by an external force, the contact pressure of the contact does not become unstable, and a constant contact pressure can be maintained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an exploded perspective view of the same as above, FIG. 3 is an exploded perspective view of an essential part of the same, and FIG. FIG. 8 to FIG. 8 are operation explanatory views of the same as above, and FIG. 9 and FIG. 10 are operation explanatory views of a conventional example. 1 is a casing, 2 is a contact device, 3 is a latch device, 4 is a drawer device, 5 is an operation button, 6 is a frame, 21 is a first terminal plate, 22 is a second terminal plate, 23a and 23b are fixed contacts, and 24a. , 24b is a movable contact, 25 is a movable contactor, 25a is a hooking piece, 26 is a resistance heater, 27 is a contact pressure spring, 31 is a latch link, 31a is a locking surface, 32 is a rotating shaft, 33 is a latch spring, 41 Is a bimetal plate,
43 is a locking piece, 53 is a hooking surface, 54 is a latch piece, and 59 is a pressing surface.

Claims (1)

[Claims] 1. A contact device which is inserted into a main current, a latch device which holds the contact device in a closed state in a latch state in which a force for opening the contact device is accumulated, and an overcurrent passes through a main circuit. The tripping device that releases the latched state of the latch device and opens the contact device by the above force is housed in the casing, and the operation button that sets the latch device to the latched state is inserted into the casing so that it can move back and forth. In addition, in the overcurrent protection device in which one end is urged by the button return spring in the direction of protruding from the casing, the contact device includes a terminal plate having a fixed contact and a movable contact having a movable contact that separates from and contacts the fixed contact. The movable contact has a movable contact that is swingable in a direction in which it separates from and comes in contact with the fixed contact, and is biased by a spring in a direction to bring the movable contact into contact with the fixed contact. The latching device is provided at the other end, and the latch device is rotatably supported by the rotary shaft that is orthogonal to the plane on which the movable contact swings, and holds the one end of the movable contact at a position different from the movable contact. And a latch spring for biasing the latch link in a rotational direction for separating the movable contact from the fixed contact, and the trip device engages with the latch link in a state in which the bias force is accumulated in the latch spring. It has a bimetal plate with a locking part, and a heating device that is inserted into the main circuit and heats the bimetal plate when overcurrent passes through the main circuit to release the engagement between the latch link and the bimetal plate. When the latch link is engaged with the bimetal plate, the movable contact can be swung within a range in which the movable contact is brought into contact with and separated from the fixed contact, and the operation button shows the engagement state between the latch link and the bimetal plate. Contact released When the operating button is pushed into the casing in the open state, the hooking surface that keeps the open state against the spring force of the contact pressure spring is applied to the other end by applying a pressing force to the hooking piece of the movable contactor. In addition, the intermediate portion has a pressing surface for rotating the latch link to the position for engaging the bimetal plate after the engaging surface presses the engaging piece, and the operation button is provided from the casing with the latch link engaged with the bimetal plate. Is equipped with a latch piece that engages with the latch link so that the protrusion of the button is prohibited.When the latch piece engages with the latch link, the engaging position of the operation button with respect to the latch link is set so that the engaging surface is separated from the engaging piece. An overcurrent protection device characterized by being configured.