JPH058851U - Circuit breaker bimetal device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a bimetal device for a circuit breaker which can improve the reliability of operation without using an oil dash pot, an indirectly heated bimetal device, or the like. [Structure] A bimetal that detects an overcurrent by displacing the trip link is attached as a heat dissipation suppressing member having a thermal conductivity smaller than that of the metal material forming the bimetal (for example, by coating a polymer material such as fluororesin). Or Hg or Sn
However, the heat generated by Joule heat is not easily dissipated to the outside air, and the amount of deformation of the bimetal is increased.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circuit breaker bimetal device for overcurrent detection.

[0002]

[Prior Art]

 A bimetal device of a circuit breaker that detects overcurrent is deformed by Joule heat by a predetermined amount when a current of a certain magnitude than the rated current flows. Due to this deformation, the trip link that locks the latch link of the opening / closing mechanism is displaced to release the lock. Therefore, the bimetal device is inserted in series in the electric circuit in the circuit breaker.

[0003]

[Problems to be solved by the device]

 By the way, the normal circuit breaker has a short-circuit current detection device that instantaneously interrupts the electric circuit when a short-circuit current flows. The magnitude of the arc energy generated between the contacts when this operates depends on the load content of the circuit rather than the rating of the circuit breaker. It is desirable to reduce the resistance of the bimetal device so that it is not blown out by an instantaneous short-circuit current. Then, in the case of overcurrent detection, the magnitude of the rated current has an effect, so that a small rated current has a small Joule heat, and therefore the amount of deformation of the bimetallic device is small. Attempting to remove the latch link from the trip link with such a small amount of deformation reduces the certainty of its operation. As a countermeasure to this, an oil dash pot or an indirectly heated bimetal device is generally used, but this countermeasure requires an increase in the number of parts and an extra space.

The present invention has been made in view of the above circumstances, and an object of the present invention is to cut off a circuit that can improve the reliability of operation without using an oil dash pot, an indirectly heated bimetal device, or the like. To provide the bimetal device of the vessel.

[0005]

[Means for Solving the Problems]

 In order to solve such a problem, a bimetal device of a circuit breaker according to the present invention is inserted in an electric circuit in a circuit breaker and locks a latch link of a switching mechanism when an overcurrent flows. In a bimetal device of a circuit breaker that displaces the tripping link that is engaged and thereby releases the lock to detect overcurrent, the bimetal has a thermal conductivity smaller than that of the metal material forming the bimetal. A heat dissipation suppressing member is attached to the heat dissipation suppressing member.

As a specific example of depositing the heat dissipation suppressing member, a polymer material is coated around the bimetal, or a metal material having a low thermal conductivity is plated.

[0007]

[Action]

 According to this configuration, when a current of a certain magnitude than the rated current flows and the bimetal device generates heat due to Joule heat, this heat is suppressed by the heat dissipation suppressing member, and therefore the heat is suppressed as compared to the case without the heat dissipation suppressing member. As a result, the amount of deformation of the bimetal device can be increased.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a body, which has a box shape with one side surface opened, and forms a housing together with a lid (not shown) attached so as to close the opening. Therefore, FIGS. 1 and 4 show a state in which the lid is removed. The body 1 has a first fixed shaft 1a that serves as a turning shaft of a handle described later, a second fixed shaft 1b that serves as a turning shaft of a cradle, a handle opening 1c, and an exhaust opening 1d. It is equipped with side terminal device 2 and load side terminal device 3. Reference numeral 1e is a support portion of a trip link described later.

Reference numeral 4 denotes a handle, which has an operating portion 4a and a connecting portion 4b which pivotally supports a movable contact described later, and an intermediate portion is pivotally supported by the first fixed shaft 1a. A movable contact 5 has a base end pivotally supported by the connecting portion 4b, a movable contact 6 at the other end, and a first spring hooking portion 5a at the middle portion. Reference numeral 7 denotes a fixed contact, which is provided on the fixed contact plate 8 which also functions as a power source side terminal plate so as to come into contact with and separate from the movable contact 6 by the operation of the movable contact 5. Reference numeral 9 is a load side terminal plate, which is bent into an L shape inside the body 1, and a bimetal device, which will be described later, is fixed to the tip portion thereof.

Reference numeral 10 denotes a bimetal device, which has a long plate-like shape and whose base end is fixed to the load-side terminal plate 9 and whose other end is in contact with a trip link, which will be described later, and the heat-dissipating material that is attached to its periphery. And a restraining member 12. The bimetal 11 is formed of a general material, for example, a Fe—Ni alloy. The heat radiation suppressing member 12 is made of a polymer material having a thermal conductivity smaller than that of Fe-Ni alloy such as fluororesin, and as shown in FIG. It is coated (adhered) so as to substantially cover the entire peripheral surface except the joint surface between the end and the braided wire 13. Reference numeral 14 is a fixed iron piece, which is fixed in a U shape so as to surround the middle portion of the bimetal 11, and detects the short-circuit current together with the trip link. The braided wire 13 electrically connects the bimetal 11 and the movable contact 5 to each other.

Reference numeral 15 denotes a trip link, which is made of a magnetic plate material and has a U-shape composed of a short piece 15a and a long piece 15b. The middle portion faces the fixed iron piece 14, and the short piece 15a abuts on the other end of the bimetal 11. A portion of the intermediate portion near the tip is swingably supported by the support portion 1e of the body 1. In addition, the middle of the long piece 15b has a locking portion 15c for locking the latch link (the cradle described later in this embodiment) of the opening / closing mechanism, and the tip of the middle portion together with the body 1 has a return spring 16c. Is compressed and suspended. This trip link 15 is displaced against the spring force of the return spring 16 when an overcurrent flows through the bimetal 11 and is deformed, and when a short-circuit current flows through the bimetal 11, together with the fixed iron piece 14. It forms a magnetic path and is instantly attracted to the fixed iron piece 14 against the spring force of the return spring 16. As described above, the bimetal device 10, the fixed iron piece 14, the trip link 15, and the like constitute an abnormal current detection device.

Reference numeral 17 is a cradle (latch link of the opening / closing mechanism), the base end of which is pivotally supported by the second fixed shaft 1b, and the end of which is a locked portion 17a which is locked by a locking portion 15c, and an intermediate portion. It has a second hooking portion 17b on its part. Reference numeral 17c is a set pin for re-locking by the handle 4 after the locked portion 17a is disengaged from the locking portion 15c. Reference numeral 18 denotes a reversing spring, which is tensioned and suspended on both spring hook portions 5a and 17b. These spring-hanging portions 5a and 17b are in the normal state and in the contact point contact state, and when the locked portion 17a is locked to the locking portion 15c, the reversing spring 18 has a contact pressure function, and The cradle 17 is rotated when the lock is released by the operation of the current detecting means, and the reversing spring 18 is provided at a position where the movable contact 5 is rotated so that the contact is opened soon.

In FIG. 1, the handle 4 is in the ON position in the contact state, and the reversing spring 18 performs the contact pressure function. In this state, when the handle 4 is rotated clockwise to the off position, the action of connecting the pivotal support portion of the movable contact 5 (connecting portion 4b of the handle 4) and each center of the first spring hooking portion 5a. The line L is located on the opposite side to the line of action M connecting the centers of the second spring hooking portion 17b and the first spring hooking portion 5a of the cradle 17, so that the reversing bar 18 is moved. Is separated from the fixed contact 7 and the contact is opened. When the abnormal current detecting means operates in the contact state, the locked portion 17a is disengaged from the locking portion 15c as shown in FIG. 3, so that the cradle 17 is rotated clockwise by the reversing spring 18, and eventually the second portion. The center of the spring hooking portion 17b crosses the line of action L, and as shown in FIG. 4, the reaction spring 18 separates the movable contact 5 from the fixed contact 7 and opens the contact (trip operation). ..

In the operation of the abnormal current detection means, when an overcurrent flows and the bimetal 11 is deformed, since the heat dissipation suppressing member 12 is attached to the periphery of the bimetal 11, heat dissipation from the bimetal 11 to the outside air is prevented. Therefore, the energy due to the Joule heat can be effectively used, and a large deformation amount X can be obtained as compared with the case without the heat dissipation suppressing member 12.

The heat radiation suppressing member 12 is not limited to the fluororesin, but may be any material having a heat resistant temperature of about 200 ° C. and capable of forming a thin film, such as a polymer such as polyimide or polyaryl sulfone. Material may be used. Also, instead of coating with a polymer material, a metal material with a lower thermal conductivity than the material of the bimetal 11 (Fe, Ni, Zn, Cu, etc.), for example, a metal material such as Hg, Sn, etc., is plated. Good.

[0017]

The bimetal device of the circuit breaker of the present invention suppresses heat dissipation by the heat dissipation suppressing member when the bimetal device generates Joule heat and a certain amount of current flows than the rated current. Therefore, the amount of deformation of the bimetal device can be made larger than that without the heat radiation suppressing member, so that the reliability of the operation can be improved without using an oil dash pot or an indirectly heated bimetal device. Becomes

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a main part thereof.

FIG. 3 is an enlarged front view of main parts for explaining the operation thereof.

FIG. 4 is a front view showing the trip state.

[Explanation of symbols]

 1 Body 4 Handle 5 Moving contact 10 Bimetal device 11 Bimetal 12 Heat dissipation suppressing member 15 Tripping link 15c Locking part 17 Cradle (latch link of opening / closing mechanism) 17a Locked part 18 Reversing spring

Claims (1)

[Claims for utility model registration] [Claim 1] A trip link that is inserted into an electric circuit in a circuit breaker and that locks a latch link of an opening / closing mechanism when an overcurrent flows. In the bimetal device of the circuit breaker for displacing, thereby disengaging the lock and detecting overcurrent, the heat dissipation suppressing member having a thermal conductivity smaller than that of the metal material forming the bimetal is attached to the bimetal. A circuit breaker bimetal device.