Circuit breaker overload protection structure

Abstract

The circuit breaker overload protection structure includes a current transformer, a bimetallic strip, and a rigid conductor mounted within a base. One end of the bimetallic strip is a bendable portion connected to a latch drive of the circuit breaker operating mechanism, and the other end is a connecting portion. One end of the rigid conductor is connected to a terminal block, and the other end passes through the current transformer and connects to the connecting portion of the bimetallic strip. The connecting portion of the bimetallic strip is connected to a movable contact. The circuit breaker overload protection structure of the present invention is disposed between the movable contact and the terminal block, with the bimetallic strip and the current transformer present. This allows overload protection to be provided by the bimetallic strip in the event of a power failure, power supply voltage fault, or circuit board component failure on the control circuit board. When power supply voltage is present on the control circuit board, overload protection is primarily provided by the current transformer. This dual-protection overload feature provides increased reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of low-voltage electrical appliances, and in particular to a circuit breaker overload protection structure. Background Art

[0002] A circuit breaker generally consists of a contact system, arc extinguishing system, operating mechanism, thermal trip system, and electromagnetic system. The electromagnetic system provides short-circuit protection. When a short circuit occurs in the power circuit serving a miniature circuit breaker, the current increases. The magnetic force generated by the high current overcomes the reaction spring, causing the coil push rod to actuate the operating mechanism, instantly tripping the circuit breaker. The thermal trip system provides overcurrent protection and typically utilizes a thermal bimetallic strip. Leveraging the bimetallic strip's long time-delay and inverse-time characteristics, when an overload current passes through the bimetallic strip, it heats and bends, pushing the circuit breaker's trip shaft to trip. Higher currents shorten the actuation time. The advantages of using a thermal bimetallic strip include a simple structure, low cost, and a bimetallic operating characteristic that is independent of the power supply voltage. However, its disadvantages include significant impacts on the overload operating characteristics due to ambient temperature and altitude, poor thermal stability, and a long reset time after actuation.

[0003] The overload characteristics of intelligent circuit breakers currently on the market basically use current transformers or manganese-copper alloy sheets to sample the loop current. The advantages are high sampling accuracy, data upload and recording, adjustable action time, minimal impact from ambient temperature, and intelligent and modular control. The disadvantages are high accuracy requirements for the sampling current transformer, high cost, and relatively complex structure. When a power supply voltage failure occurs or electronic components on the circuit board fail, the product overload protection feature will fail. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a circuit breaker overload protection structure with double protection and overload protection characteristics and higher reliability.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A circuit breaker overload protection structure includes a current transformer, a bimetallic strip, and a rigid conductor installed in a base. One end of the bimetallic strip is a bendable portion connected to a lock drive of a circuit breaker operating mechanism, and the other end is a connecting portion. One end of the rigid conductor is connected to a terminal block, and the other end passes through the current transformer and is connected to the connecting portion of the bimetallic strip. The connecting portion of the bimetallic strip is connected to a moving contact.

[0007] Preferably, the current transformer is located between the terminal block and the arc striking plate, the bimetallic strip is located above the current transformer and on the side of the moving contact and the lock, the bendable portion of the bimetallic strip is connected to the lock drive through a lever, one end of the lever is connected to the lock, and the other end is arranged corresponding to the bendable portion of the bimetallic strip; the connecting portion of the bimetallic strip is connected to the moving contact through a first soft connection; the connecting portion of the bimetallic strip is connected to the arc striking plate through a second soft connection.

[0008] Preferably, an adjusting screw is further included, the bimetallic strip has an adjusting portion connected between the connecting portion and the bendable portion, one end of the adjusting screw abuts against the adjusting portion of the bimetallic strip, and the other end corresponds to the adjusting through hole of the base.

[0009] Preferably, the adjustment through hole is arranged on the top wall of the base, the bimetallic strip and the adjustment screw are located between the top wall of the base and the current transformer, and a mounting groove for installing the adjustment screw is provided on the bottom plate of the base, the mounting groove is connected to the adjustment through hole, and the side walls on both sides of the mounting groove are connected to the top wall of the base.

[0010] Preferably, it also includes a reset spring located between the adjusting screw and the current transformer, one end of the reset spring abuts against the adjusting portion of the bimetallic strip, and the other end abuts against the mounting boss of the base, and the elastic force direction of the reset spring is opposite to the force direction of the adjusting screw.

[0011] Preferably, the mounting boss includes a mounting plate, a first limiting plate and a second limiting plate, the mounting plate is fitted with the bottom plate of the base, the first limiting plate and the second limiting plate are vertically connected to the mounting plate, and the first limiting plate and the second limiting plate are vertically connected, the return spring falls on the mounting plate and is limited between the first limiting plate and the second limiting plate, and the end of the return spring abuts against the first limiting plate of the mounting boss.

[0012] Preferably, the adjustment portion of the bimetallic strip is a U-shaped structure, comprising an adjustment plate, a connecting plate and a baffle connected in sequence, wherein the adjustment plate is connected to the connecting portion, and the baffle is connected to the bendable portion; the adjustment plate falls on the bottom plate of the base, the baffle is spaced apart from the bottom plate, and the adjustment screw passes through the gap between the baffle and the bottom plate and abuts against the adjustment plate.

[0013] Preferably, a handle hole is provided on the top wall of the base, the handle is rotatably installed in the base and one end extends from the handle hole, and the adjustment through hole is provided on one side of the handle hole, between the handle hole and a wiring screw hole.

[0014] Preferably, a first terminal and a second terminal are respectively provided on both sides of the base, an arc extinguishing chamber is provided between the first terminals, the current transformer and the bimetallic strip are provided between the arc extinguishing chamber and the second terminal, an electromagnetic release is provided above the arc extinguishing chamber, a handle is provided above the electromagnetic release, a static contact, an operating mechanism and a moving contact are provided on one side of the electromagnetic release and the arc extinguishing chamber, the bimetallic strip is located above the current transformer and to the side of the moving contact and the lock of the operating mechanism, in the thickness direction of the circuit breaker, the adjusting screw is provided below the bimetallic strip, the adjusting screw and the bimetallic strip are located between the operating mechanism and the second terminal, and the terminal block is connected to the second terminal.

[0015] Preferably, the axial direction of the current transformer faces the top wall of the base.

[0016] The circuit breaker overload protection structure of the present invention is arranged between the moving contact and the terminal block, and has both a bimetallic strip and a current transformer. When the control circuit board has no power supply voltage or a power supply voltage failure, or when a circuit board component fails, the bimetallic strip is used to implement overload protection. When the control circuit board has power supply voltage, the current transformer is used as the main method to implement overload protection. In addition, the current transformer can also perform metering, data monitoring, and data uploading. The overload characteristics of this structural product have dual protection, and the overload protection characteristics are more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a perspective view of a circuit breaker of the present invention;

[0018] Figure 2 is a front view of the circuit breaker of the present invention;

[0019] Figure 3 It is a front view of the base of the present invention;

[0020] Figure 4 It is a three-dimensional diagram of the bimetallic strip of the present invention. DETAILED DESCRIPTION

[0021] The following is combined with Figures 1 to 4 The following examples further illustrate the specific implementation of the circuit breaker overload protection structure of the present invention. The circuit breaker overload protection structure of the present invention is not limited to the description of the following examples.

[0022] like Figure 1-4As shown, the circuit breaker overload protection structure of the present invention includes a current transformer 1, a bimetallic strip 2, a hard wire 40, a terminal block 4, an arc striking plate 5, an adjusting screw 6, a reset spring 7, and a movable contact 8 and a lock catch 9 of an operating mechanism installed in a base 3. One end of the bimetallic strip 2 is a bendable portion 21 that is driven and connected to the lock catch 9 of the operating mechanism, and the other end of the bimetallic strip 2 is a connecting portion 25. One end of the hard wire 40 is connected to the terminal block 4, and the other end of the hard wire 40 passes through the current transformer 1 and is connected to the connecting portion 25 of the bimetallic strip 2. The arc striking plate 5 and the movable contact 8 of the operating mechanism are respectively connected to the connecting portion 25 of the bimetallic strip 2.

[0023] Specifically, the current transformer 1 is located between the terminal block 4 and the arc-striking plate 5. The bimetallic strip 2 is located above the current transformer 1 and to the side of the moving contact 8 and the lock 9. The bendable portion 21 of the bimetallic strip 2 is driven and connected to the lock 9 via a lever 90. One end of the lever 90 is connected to the lock 9, and the other end is arranged corresponding to the bendable portion 21 of the bimetallic strip 2. The connecting portion 25 of the bimetallic strip 2 is connected to the moving contact 8 via a first flexible connection 80. The connecting portion 25 of the bimetallic strip 2 is connected to the arc-striking plate 5 via a second flexible connection 50, so that the arc-striking plate maintains the same voltage as the incoming line during a short-circuit test, which facilitates the arc to quickly jump from the moving contact to the arc-striking plate and then enter the arc extinguishing chamber.

[0024] When a specified overload current appears in the circuit, the current transformer 1 transmits an electrical signal to the control circuit board. The chip analyzes and calculates whether the main circuit is overloaded. If it is overloaded, it outputs a trip signal, drives the motor to rotate, and trips the circuit breaker, achieving overload current protection. Due to the overload current flowing through the bimetallic strip 2, the bendable portion 21 of the bimetallic strip 2 continuously bends and deforms to the right, driving the lever 90 to move. The lever 90 then drives the lock 9 to move, causing the operating mechanism to trip, achieving overload current protection. It should be noted that the working principle of the above-mentioned current transformer 1 or bimetallic strip 2 to achieve overload current protection is prior art.

[0025] A first improvement of the present invention is that the circuit breaker overload protection structure is disposed between the moving contact and the terminal block, with the bimetallic strip 2 and the current transformer 1 present. This allows the bimetallic strip to provide overload protection in the event of a power failure, power supply voltage fault, or component failure on the control circuit board. When the control circuit board has power supply voltage, the current transformer primarily provides overload protection. Furthermore, the current transformer can also perform metering, data monitoring, and data upload functions. This structural product offers dual overload protection, resulting in a more reliable overload protection feature. Furthermore, the circuit breaker overload protection structure is rationally laid out, resulting in a simple and compact overall structure.

[0026] Another improvement of the present invention lies in the structure of the bimetallic strip 2 and the location of the adjusting screw 6 .

[0027] like Figure 4 As shown, the bimetallic strip 2 of the present invention is a "J"-shaped sheet structure, comprising a bendable portion 21, an adjustment portion, and a connecting portion 25 connected in sequence. The bendable portion 21 and the connecting portion 25 are straight flat plate structures. The adjustment portion of the bimetallic strip 2 is a U-shaped structure, comprising an adjustment plate 24, a connecting plate 23, and a baffle 22 connected in sequence. The adjustment plate 24 is connected to the connecting portion 25, and the baffle 22 is connected to the bendable portion 21. The connecting plate 23 is an arc plate. The adjustment plate 24 and the baffle 22 are straight flat plate structures. The width of the adjustment plate 24 is greater than that of the baffle 22. The adjustment plate 24 rests on the bottom plate 33 of the base 3. The baffle 22 and the bottom plate 33 are spaced apart. The adjustment screw 6 passes through the gap between the baffle 22 and the bottom plate 33 and abuts against the adjustment plate 24. The bimetallic sheet with a "J"-shaped structure and a U-shaped adjustment part increases the length of the bimetallic sheet, ensures the heating performance of the bimetallic sheet, avoids the problem of insufficient heating due to insufficient length or excessive temperature rise of the product due to the use of high-resistivity bimetallic sheet, saves space, avoids interference with other components, facilitates the structural layout of the circuit breaker, and facilitates the setting of the adjustment screw, making the structure compact.

[0028] like Figure 1 and Figure 2 As shown, one end of the adjusting screw 6 abuts the top surface of the adjusting plate 24 of the adjusting portion of the bimetallic strip 2, while the other end of the adjusting screw 6 corresponds to the adjusting hole 32 of the base 3. The adjusting hole 32 is provided on the top wall 31 of the base 3. The bimetallic strip 2 and the adjusting screw 6 are located between the top wall 31 of the base 3 and the current transformer 1. The bottom plate 33 of the base 3 is provided with a mounting slot 34 for mounting the adjusting screw 6. The mounting slot 34 is connected to the adjusting hole 32, and the side walls of the mounting slot 34 are connected to the top wall 31 of the base 3. The top wall 31 of the base 3 is provided with a handle hole. The handle is rotatably mounted within the base 3, with one end extending from the handle hole. The adjusting hole 32 is located on one side of the handle hole, between the handle hole and a terminal screw hole. The base 3 is convex in shape, with the handle hole located at the top of the raised portion of the top wall 31. The adjusting hole 32 and the terminal screw hole are located on one side of the raised portion, located on the shoulder of one side of the top wall 31. The position of the adjusting screw is reasonably set, which will not cause interference with other structures, has high versatility, and the overall structure of the product is simple.

[0029] like Figure 1 and Figure 2As shown, the return spring 7 is located between the adjusting screw 6 and the current transformer 1. One end of the return spring 7 abuts against the bottom surface of the adjusting plate 24 of the adjusting portion of the bimetallic strip 2, and the other end of the return spring 7 abuts against the mounting boss 35 of the base 3. The direction of the elastic force of the return spring 7 is opposite to the direction of the force of the adjusting screw 6. The mounting boss 35 includes a mounting plate 351, a first limiting plate 352, and a second limiting plate 353. The mounting plate 351 fits the bottom plate 33 of the base 3. The first limiting plate 352 and the second limiting plate 353 are vertically connected to the mounting plate 351, and the first limiting plate 352 and the second limiting plate 353 are vertically connected. The return spring 7 falls on the mounting plate 351. The return spring 7 is limited between the first limiting plate 352 and the second limiting plate 353. The end of the return spring 7 abuts against the first limiting plate 352 of the mounting boss 35, and the right side of the return spring 7 abuts against the second limiting plate 353 of the mounting boss 35. As shown Figure 2 As shown, after the circuit breaker is assembled, the lever 90 is located to the right of the bendable portion 21 of the bimetallic strip 2, and the adjustment portion of the bimetallic strip 2 is located below and to the right of the bendable portion 21. The position of the bimetallic strip 2 can be adjusted by adjusting the position of the adjustment screw 6 mounted on the base 3 with an adjustment screwdriver. The adjustment screw 6 applies a downward force to the adjustment plate 24 of the adjustment portion of the bimetallic strip 2, causing the bendable portion 21 of the bimetallic strip 2 to move to the right. The gap between the bendable portion 21 and the lever 90 is reduced, thereby shortening the tripping time. If the adjustment screw 6 is screwed in too far, it is necessary to retract it a certain distance. At this time, the return spring 7 mounted on the base 3 resets the bimetallic strip 2, applying an upward elastic force to the bimetallic strip 2.

[0030] The base 3 of the circuit breaker of this embodiment is provided with a first terminal and a second terminal on both sides, an arc extinguishing chamber is provided between the first terminal, and the current transformer 1 and the bimetallic strip 2 are provided between the arc extinguishing chamber and the second terminal. An electromagnetic trip is provided above the arc extinguishing chamber, and a handle is provided above the electromagnetic trip. A static contact, an operating mechanism and a moving contact are provided on one side of the electromagnetic trip and the arc extinguishing chamber. The bimetallic strip 2 is located above the current transformer 1 and to the side of the moving contact 8 and the lock 9 of the operating mechanism. In the thickness direction of the circuit breaker, the adjusting screw 6 is provided below the bimetallic strip 2, and the two are stacked. The adjusting screw The nail 6 and bimetallic strip 2 are located between the operating mechanism and the second terminal. The terminal block 4 is connected to the second terminal. One end of a rigid wire 40 is connected to the terminal block 4. The other end of the rigid wire 40 passes through the current transformer 1 and connects to the connecting portion 25 of the bimetallic strip 2. The connecting portion 25 of the bimetallic strip 2 is connected to the arc striker 5 via a second flexible connection 50. The arc striker 5 extends obliquely from below the moving contact to the bottom of the circuit breaker and into the arc extinguishing chamber. The axial direction of the current transformer 1 is toward the top wall 31 of the base 3, that is, the hole of the current transformer 1 is toward the top of the handle, which is consistent with the length direction of the bimetallic strip 2. The rigid wire and terminal block 4 can be integrally formed or welded as separate components.

[0031] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A circuit breaker overload protection structure, characterized in that: The invention comprises a current transformer (1), a bimetallic strip (2) and a hard wire (40) installed in a base (3); one end of the bimetallic strip (2) is a bendable portion (21) driven and connected to a lock catch (9) of a circuit breaker operating mechanism, and the other end is a connecting portion (25); one end of the hard wire (40) is connected to a terminal block (4), and the other end passes through the current transformer (1) and is connected to the connecting portion (25) of the bimetallic strip (2); the connecting portion (25) of the bimetallic strip (2) is connected to a moving contact (8); It also includes an adjusting screw (6), the bimetallic strip (2) having an adjusting portion connected between the connecting portion (25) and the bendable portion (21), one end of the adjusting screw (6) abutting against the adjusting portion of the bimetallic strip (2), and the other end corresponding to the adjusting through hole (32) of the base (3); The adjustment through hole (32) is provided on the top wall (31) of the base (3), and the bimetallic strip (2) and the adjustment screw (6) are located between the top wall (31) of the base (3) and the current transformer (1).

2. The circuit breaker overload protection structure according to claim 1, characterized in that: The current transformer (1) is located between a terminal block (4) and an arc striking plate (5); the bimetallic strip (2) is located above the current transformer (1) and to the side of a moving contact (8) and a lock catch (9); the bendable portion (21) of the bimetallic strip (2) is connected to the lock catch (9) by a lever (90); one end of the lever (90) is connected to the lock catch (9), and the other end is arranged corresponding to the bendable portion (21) of the bimetallic strip (2); the connecting portion (25) of the bimetallic strip (2) is connected to the moving contact (8) through a first flexible connection (80); and the connecting portion (25) of the bimetallic strip (2) is connected to the arc striking plate (5) through a second flexible connection (50).

3. The circuit breaker overload protection structure according to claim 1, characterized in that: A mounting groove (34) for mounting an adjusting screw (6) is provided on the bottom plate (33) of the base (3); the mounting groove (34) is communicated with the adjusting through hole (32); and the side walls of the mounting groove (34) are connected to the top wall (31) of the base (3).

4. The circuit breaker overload protection structure according to claim 1, characterized in that: The invention also includes a reset spring (7) located between the adjusting screw (6) and the current transformer (1), one end of the reset spring (7) abuts against the adjusting portion of the bimetallic strip (2), and the other end abuts against the mounting boss (35) of the base (3), and the elastic force direction of the reset spring (7) is opposite to the force direction of the adjusting screw (6).

5. The circuit breaker overload protection structure according to claim 4, characterized in that: The mounting boss (35) includes a mounting plate (351), a first limiting plate (352) and a second limiting plate (353); the mounting plate (351) is fitted with the bottom plate (33) of the base (3); the first limiting plate (352) and the second limiting plate (353) are vertically connected to the mounting plate (351); and the first limiting plate (352) and the second limiting plate (353) are vertically connected; the reset spring (7) falls on the mounting plate (351) and is limited between the first limiting plate (352) and the second limiting plate (353); the end of the reset spring (7) is in contact with the first limiting plate (352) of the mounting boss (35).

6. The circuit breaker overload protection structure according to any one of claims 1, 3-5, characterized in that: The adjusting portion of the bimetallic strip (2) is a U-shaped structure, comprising an adjusting plate (24), a connecting plate (23) and a baffle (22) connected in sequence, wherein the adjusting plate (24) is connected to the connecting portion (25), and the baffle (22) is connected to the bendable portion (21); the adjusting plate (24) falls on the bottom plate (33) of the base (3), the baffle (22) and the bottom plate (33) are spaced apart, and the adjusting screw (6) passes through the gap between the baffle (22) and the bottom plate (33) and abuts against the adjusting plate (24).

7. The circuit breaker overload protection structure according to claim 3, characterized in that: A handle hole is provided on the top wall (31) of the base (3). The handle is rotatably mounted in the base (3) and one end extends out of the handle hole. An adjustment through hole (32) is provided on one side of the handle hole and is located between the handle hole and a connection screw hole.

8. The circuit breaker overload protection structure according to claim 1, characterized in that: A first terminal and a second terminal are provided on both sides of the base (3), an arc extinguishing chamber is provided between the first terminal, and the current transformer (1) and the bimetallic strip (2) are provided between the arc extinguishing chamber and the second terminal. An electromagnetic trip is provided above the arc extinguishing chamber, and a handle is provided above the electromagnetic trip. A static contact, an operating mechanism, and a moving contact are provided on one side of the electromagnetic trip and the arc extinguishing chamber. The bimetallic strip (2) is located above the current transformer (1) and to the side of the moving contact (8) and the locking catch (9) of the operating mechanism. In the thickness direction of the circuit breaker, an adjusting screw (6) is provided below the bimetallic strip (2), and the adjusting screw (6) and the bimetallic strip (2) are located between the operating mechanism and the second terminal. The terminal block (4) is connected to the second terminal.

9. The circuit breaker overload protection structure according to claim 1, characterized in that: The axial direction of the current transformer (1) faces the top wall (31) of the base (3).

Images