Three-phase thermal element assembly of molded case circuit breaker

Abstract

The utility model relates to a three-phase thermal element assembly of a molded case circuit breaker. The technical problem to be solved by the utility model is to provide the three-phase thermal element assembly of the molded case circuit breaker. The technical scheme adopted by the utility model is as follows: the thermal element comprises a thermal element, a bracket, a main bimetallic plate, an auxiliary bimetallic plate, a rivet and a pre-tightening spring, the thermal element comprises a thermal element internal connection part which is horizontally arranged, and the thermal element internal connection part is sequentially and vertically bent to form a thermal element supporting part, a thermal element extending part and a thermal element external connection part which are vertically arranged; the thermal element external connection part is provided with a thermal element waist-shaped hole, and the thermal element supporting part is provided with a thermal element riveting hole. Compared with the prior art, the main bimetallic plate and the auxiliary bimetallic plate adopt a superposed mounting structure, and the sensing part of the auxiliary bimetallic plate can apply auxiliary thrust to the mounting part of the main bimetallic plate after being heated, so that the bending response of the main bimetallic plate in an overload state is more sensitive, the driving force is larger, and the action reliability is high.

Description

Technical Field

[0001] This utility model relates to a three-phase thermal element assembly for a molded case circuit breaker. Background Technology

[0002] The tripping system of a molded case circuit breaker typically includes a magnetic tripping mechanism and a thermal tripping mechanism. The three-phase thermal element assembly is the core component of the thermal tripping mechanism, primarily composed of a bimetallic strip structure, used to achieve overload protection. When a sustained current overload occurs, the bimetallic strip in the three-phase thermal element assembly bends and deforms due to Joule heating, actuating the levers or interlocking mechanisms inside the circuit breaker, thus automatically tripping the circuit breaker. Existing three-phase thermal element assemblies in molded case circuit breakers generally use a single bimetallic strip structure, which has the following problems: A single bimetallic strip, after being heated, relies solely on its own bending deformation to drive the tripping mechanism, resulting in limited output thrust. Especially when the current overload is small or the ambient temperature is low, insufficient bending displacement can easily cause delayed tripping or even failure of the circuit breaker. The reliability and stability of the circuit breaker's tripping mechanism are poor. Therefore, improvements and optimizations are needed to address these issues. Utility Model Content

[0003] To solve the above problems, the technical problem to be solved by this utility model is to provide a three-phase thermal element assembly for a molded case circuit breaker.

[0004] The technical solution adopted by the three-phase thermal element assembly of the molded case circuit breaker of this utility model is characterized by comprising a thermal element, a bracket disposed on the thermal element, a main bimetallic plate, a secondary bimetallic plate, rivets, and a preload spring. The thermal element includes a horizontally arranged inner part, which is vertically bent in sequence to form a vertically arranged thermal element support, a horizontally arranged thermal element extension, and a horizontally arranged outer part. The outer part of the thermal element is provided with a waist-shaped hole for the thermal element. The thermal element support is provided with a riveting hole for the thermal element. The main bimetallic plate includes a main bimetallic plate mounting part and a main bimetallic plate sensing part. The main bimetallic plate mounting part is provided with a main bimetallic plate mating hole. The secondary bimetallic plate includes a secondary bimetallic plate mounting part and a secondary bimetallic plate sensing part. The secondary bimetallic plate mounting part is provided with a secondary bimetallic plate riveting hole. The diameter of the main bimetallic plate mating hole is larger than the diameter of the secondary bimetallic plate riveting hole. The secondary bimetallic plate sensing part and the main bimetallic plate mounting part are fitted together.

[0005] The bracket includes a bracket receiving portion that fits onto the inner part of the heat element. The left and right ends of the bracket receiving portion are bent vertically upward to form an inner support portion and an outer support portion that are respectively arranged opposite to each other. The inner support portion has a horizontally penetrating inner riveting hole, and the outer support portion has an outer riveting hole corresponding to the inner riveting hole. The main bimetallic plate mounting portion and the secondary bimetallic plate mounting portion are both vertically placed between the outer support portion and the inner support portion, and their bottoms abut against the bracket receiving portion. The rivets sequentially rivet the outer riveting hole, the secondary bimetallic plate riveting hole, the inner riveting hole, and the heat element riveting hole together. The main bimetallic plate mating hole is sleeved on the rivet and is placed between the outer support portion and the secondary bimetallic plate mounting portion. The preload spring is sleeved on the rivet, with one end abutting against the inner side of the outer support portion and the other end abutting against the main bimetallic plate mounting portion.

[0006] The number of rivets and the number of preload springs are both two.

[0007] The bottom of the main bimetallic plate mounting part is provided with a main bimetallic plate guide protrusion, and the bracket receiving part is provided with a bracket guide groove corresponding to the main bimetallic plate guide protrusion. The height of the main bimetallic plate guide protrusion is greater than the depth of the bracket guide groove.

[0008] The main bimetallic plate guide protrusion has an arc-shaped structure, and there are two of each of the main bimetallic plate guide protrusion and the bracket guide groove.

[0009] The bottom of the sub-bimetallic plate mounting part is provided with a sub-bimetallic plate limiting protrusion, the height of which is less than the depth of the bracket guide groove.

[0010] The bracket receiving part is provided with a bracket reinforcement hole in the middle, and the inner part of the heat element is provided with a heat element connection hole that is connected to the bracket reinforcement hole.

[0011] The advantages of this utility model of three-phase thermal element assembly for molded case circuit breakers are: the main bimetallic plate and the auxiliary bimetallic plate adopt a stacked installation structure, and the sensing part of the auxiliary bimetallic plate can apply an auxiliary thrust to the mounting part of the main bimetallic plate after being heated, making the bending response of the main bimetallic plate more sensitive and the driving force greater under overload conditions, effectively solving the problems of insufficient bending driving force and unreliable circuit breaker operation of traditional single bimetallic plates. Attached Figure Description

[0012] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0013] Figure 1 This is a schematic diagram of the structure of the three-phase thermal element assembly of the molded case circuit breaker of this utility model;

[0014] Figure 2 This is a schematic diagram of the structure of the thermal element of this utility model;

[0015] Figure 3 This is a schematic diagram of the structure of the main bimetallic plate of this utility model;

[0016] Figure 4 This is a schematic diagram of the structure of the secondary bimetallic plate of this utility model;

[0017] Figure 5 This is a structural schematic diagram of the bracket of this utility model. Detailed Implementation

[0018] like Figure 1-5As shown, the three-phase thermal element assembly of the molded case circuit breaker of this utility model includes a thermal element 1, a bracket 4 mounted on the thermal element 1, a main bimetallic plate 2, a secondary bimetallic plate 3, rivets 6, and a preload spring 5. The thermal element 1 includes a horizontally arranged inner portion 8, which is vertically bent in sequence to form a vertically arranged thermal element support portion 9, a horizontally arranged thermal element extension portion 10, and a horizontally arranged outer portion 11. The outer portion 11 is provided with a thermal element waist-shaped hole 12, and the thermal element support portion 9 is provided with a thermal element riveting hole 13. The main bimetallic plate 2 includes a main bimetallic plate mounting portion 15 and a main bimetallic plate sensing portion 16. The main bimetallic plate mounting portion 15 is... The system includes a main bimetallic plate mating hole 17. The secondary bimetallic plate 3 includes a secondary bimetallic plate mounting part 20 and a secondary bimetallic plate sensing part 21. The secondary bimetallic plate mounting part 20 has a secondary bimetallic plate riveting hole 23. The diameter of the main bimetallic plate mating hole 17 is larger than the diameter of the secondary bimetallic plate riveting hole 23. The secondary bimetallic plate sensing part 21 and the main bimetallic plate mounting part 15 are fitted together. The bracket 4 includes a bracket receiving part 26 that is fitted onto the inner part 8 of the thermal element. The left and right ends of the bracket receiving part 26 are bent vertically upward to form an inner bracket support part 28 and an outer bracket support part 27, which are respectively arranged opposite to each other. The inner bracket support part 28 has a horizontally penetrating inner bracket riveting hole 29. The outer support portion 27 of the bracket is provided with an outer riveting hole 30 corresponding to the inner riveting hole 29 of the bracket. The main bimetallic plate mounting portion 15 and the secondary bimetallic plate mounting portion 20 are both vertically positioned between the outer support portion 27 and the inner support portion 28 of the bracket, with their bottoms abutting against the bracket receiving portion 26. The rivet 6 sequentially rivets the outer riveting hole 30, the secondary bimetallic plate riveting hole 23, the inner riveting hole 29 of the bracket, and the heat element riveting hole 13 together. The main bimetallic plate mating hole 17 is sleeved on the rivet 6 and is positioned between the outer support portion 27 and the secondary bimetallic plate mounting portion 20. The preload spring 5 is sleeved on the rivet 6. One end abuts against the inner side of the outer support part 27 of the bracket, and the other end abuts against the main bimetallic plate mounting part 15. The main bimetallic plate 2 and the auxiliary bimetallic plate 3 adopt a stacked mounting structure. After being heated, the auxiliary bimetallic plate sensing part 21 can apply an auxiliary thrust to the main bimetallic plate mounting part 15, making the bending response of the main bimetallic plate 2 more sensitive and the driving force greater under overload conditions. This effectively solves the problems of insufficient bending driving force and unreliable circuit breaker operation of traditional single bimetallic plates. The preload spring 5 can provide buffering and pre-compression when the bimetallic plate bends, making the operation process smoother and avoiding mechanism jamming or malfunction caused by instantaneous impact. At the same time, it can quickly return to the initial position after disconnection, improving the reset accuracy and service life of the circuit breaker.

[0019] The number of rivets 6 and preload springs 5 ​​are both two. Their symmetrical distribution ensures that the main and auxiliary bimetallic plates are subjected to uniform force during the heating process, avoiding structural deformation or response delay caused by single-point force, and further improving the stability and repeatability of the circuit breaker's thermal tripping action.

[0020] The bottom of the main bimetallic plate mounting part 15 is provided with a main bimetallic plate guide protrusion 18, and the bracket receiving part 26 is provided with a bracket guide groove 31 corresponding to the main bimetallic plate guide protrusion 18, so that it maintains a stable linear displacement path during the process of being pushed by bending under heat, preventing lateral deviation or jamming, thereby ensuring sensitive and reliable operation. The height of the main bimetallic plate guide protrusion 18 is greater than the depth of the bracket guide groove 31, which effectively reduces the contact resistance when the main bimetallic plate moves.

[0021] The main bimetallic plate guide protrusion 18 has an arc-shaped structure, and there are two of both the main bimetallic plate guide protrusion 18 and the bracket guide groove 31.

[0022] The bottom of the secondary bimetallic plate mounting part 20 is provided with a secondary bimetallic plate limiting protrusion 24. The height of the secondary bimetallic plate limiting protrusion 24 is less than the depth of the bracket guide groove 31, so the limiting is reliable and stable.

[0023] The bracket receiving part 26 is provided with a bracket reinforcement hole 32 in the middle, and the inner part of the heat element 8 is provided with a heat element connection hole 33 that is opposite to the bracket reinforcement hole 32, which improves the assembly stability and vibration resistance.

[0024] Operating principle: When an overload current flows through the heating element 1, it causes the main bimetallic plate 2 and the auxiliary bimetallic plate 3 to generate Joule heat, causing the temperature to rise continuously. When the preset temperature threshold is reached, both the main bimetallic plate sensing part 16 and the auxiliary bimetallic plate sensing part 21 bend. The bending of the auxiliary bimetallic plate sensing part 21 causes it to exert a thrust, pushing the main bimetallic plate mounting part 15 of the main bimetallic plate 2 to move horizontally to the side of the bracket outer support part 27 under the action of the pre-tension spring 5. Meanwhile, the upper end of the main bimetallic plate sensing part 16 pushes the lever mechanism inside the circuit breaker, triggering the mechanical interlocking device, causing the circuit breaker to open. The auxiliary bimetallic plate 3 plays an auxiliary thrust role in ensuring that the main bimetallic plate 2 operates in place.

[0025] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model are included within the protection scope of the present utility model.

Claims

1. A three-phase thermal element assembly for a molded case circuit breaker, characterized in that: The system includes a heating element (1), a bracket (4) mounted on the heating element (1), a main bimetallic plate (2), a secondary bimetallic plate (3), rivets (6), and a preload spring (5). The heating element (1) includes a horizontally arranged inner heating element portion (8), which is vertically bent in sequence to form a vertically arranged heating element support portion (9), a horizontally arranged heating element extension portion (10), and a horizontally arranged outer heating element portion (11). The outer heating element portion (11) is provided with a heating element waist-shaped hole (12), and the heating element support portion (9) is provided with a heating element riveting hole (13). The main bimetallic plate (2), secondary bimetallic plate (3), rivets (6), and preload spring (5) are also included. The metal plate (2) includes a main bimetallic plate mounting part (15) and a main bimetallic plate sensing part (16). The main bimetallic plate mounting part (15) is provided with a main bimetallic plate docking hole (17). The secondary bimetallic plate (3) includes a secondary bimetallic plate mounting part (20) and a secondary bimetallic plate sensing part (21). The secondary bimetallic plate mounting part (20) is provided with a secondary bimetallic plate riveting hole (23). The diameter of the main bimetallic plate docking hole (17) is larger than the diameter of the secondary bimetallic plate riveting hole (23). The secondary bimetallic plate sensing part (21) is fitted to the main bimetallic plate mounting part (15). The bracket (4) includes a bracket receiving part (26) attached to the inner part (8) of the heat element. The left and right ends of the bracket receiving part (26) are bent vertically upward to form an inner support part (28) and an outer support part (27) respectively. The inner support part (28) is provided with a horizontally penetrating inner riveting hole (29). The outer support part (27) is provided with an outer riveting hole (30) corresponding to the inner riveting hole (29). The main bimetallic plate mounting part (15) and the secondary bimetallic plate mounting part (20) are both vertically placed on the outer support part (27) and the inner support part (28). Between 28), their bottoms all abut against the support portion (26) of the bracket. The rivet (6) sequentially rivets the outer rivet hole (30) of the bracket, the rivet hole (23) of the secondary bimetallic plate, the rivet hole (29) of the bracket and the rivet hole (13) of the heat element together. The main bimetallic plate mating hole (17) is sleeved on the rivet (6) and is placed between the outer support portion (27) of the bracket and the mounting portion (20) of the secondary bimetallic plate. The preload spring (5) is sleeved on the rivet (6), with one end abutting against the inner side of the outer support portion (27) of the bracket and the other end abutting against the mounting portion (15) of the main bimetallic plate.

2. The three-phase thermal element assembly of the molded case circuit breaker according to claim 1, characterized in that: The number of rivets (6) and preload springs (5) is two.

3. The three-phase thermal element assembly of the molded case circuit breaker according to claim 1, characterized in that: The bottom of the main bimetallic plate mounting part (15) is provided with a main bimetallic plate guide protrusion (18), and the bracket receiving part (26) is provided with a bracket guide groove (31) corresponding to the main bimetallic plate guide protrusion (18). The height of the main bimetallic plate guide protrusion (18) is greater than the depth of the bracket guide groove (31).

4. The three-phase thermal element assembly of the molded case circuit breaker according to claim 3, characterized in that: The main bimetallic plate guide protrusion (18) has an arc-shaped structure, and there are two of each of the main bimetallic plate guide protrusion (18) and the bracket guide groove (31).

5. The three-phase thermal element assembly of the molded case circuit breaker according to claim 3, characterized in that: The bottom of the sub-bimetallic plate mounting part (20) is provided with a sub-bimetallic plate limiting protrusion (24), the height of which is less than the depth of the bracket guide groove (31).

6. The three-phase thermal element assembly of the molded case circuit breaker according to claim 1, characterized in that: The bracket receiving part (26) is provided with a bracket reinforcement hole (32) in the middle, and the inner part of the heat element (8) is provided with a heat element connection hole (33) that is connected to the bracket reinforcement hole (32).

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