Thermal tripping assembly and circuit breaker

Abstract

The embodiment of the utility model provides a thermal tripping assembly and a circuit breaker. A first wire of the thermal tripping assembly comprises a first connecting end and a second connecting end. The first connecting end is electrically connected with the conductive piece. The bimetallic strip is disposed adjacent to the conductive member. The heating part of the bimetallic strip is electrically connected with the second connecting end to form a first conductive loop. One end of the first bimetallic strip is connected with the heating part, and the other end of the first bimetallic strip extends in the direction away from the heating part. The second bimetallic strip comprises a first end and a second end which are oppositely arranged. The first end is connected with the heating part. The second end is disposed adjacent to the conductive member. And the second bimetallic strip is suitable for deforming along with the temperature rise of the heating part, and the second end is suitable for being in contact with the conductive piece under the condition that the value of the current flowing through the heating part reaches a preset tripping current value, so that a second conductive loop is formed between the heating part and the conductive piece. The second bimetal strip is arranged adjacent to the first bimetal strip, and the first bimetal strip can be heated and heated under the condition that the second end is in contact with the conductive piece.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to the field of electrical devices, and more particularly, to a thermal trip assembly and a circuit breaker. BACKGROUND

[0002] In the circuit breaker, the thermal trip assembly cooperates with the four-bar linkage assembly. When the current in the circuit reaches or exceeds a preset safety threshold, the bimetallic strip in the thermal trip assembly is deformed by heat, triggering the four-bar linkage assembly to act to cut off the current, thereby protecting the circuit from overload damage. SUMMARY

[0003] In a first aspect of the present disclosure, a thermal trip assembly is provided. The thermal trip assembly comprises: an electrically conductive member; a first wire comprising a first connecting end and a second connecting end, the first connecting end being electrically connected with the electrically conductive member; and a bimetallic strip disposed adjacent to the electrically conductive member, and comprising: a heating portion electrically connected with the second connecting end to form a first electrically conductive loop between the heating portion and the electrically conductive member; a first bimetallic strip having one end connected with the heating portion and the other end extending towards a direction away from the heating portion; and a second bimetallic strip comprising oppositely disposed first and second ends, the first end being connected with the heating portion and the second end being disposed adjacent to the electrically conductive member, the second bimetallic strip being adapted to deform with the heating portion as the heating portion is heated, and the second end being adapted to contact the electrically conductive member to form a second electrically conductive loop between the heating portion and the electrically conductive member in a case where a value of the current flowing through the heating portion reaches a predetermined trip current value, the second bimetallic strip being disposed adjacent to the first bimetallic strip to heat the first bimetallic strip in the case where the second end contacts the electrically conductive member.

[0004] In some embodiments, the first bimetallic strip, the second bimetallic strip, and the heating portion are integrally formed.

[0005] In some embodiments, the first bimetallic strip and the second bimetallic strip are disposed in parallel and spaced apart.

[0006] In some embodiments, the second bimetallic strip has a length smaller than a length of the first bimetallic strip.

[0007] In some embodiments, the second end of the second bimetallic strip is provided with an electrically conductive contact to connect with the electrically conductive member via the electrically conductive contact.

[0008] In some embodiments, the electrically conductive member comprises a mounting portion adapted to connect with a housing of the circuit breaker and an electrically conductive portion adapted to connect with the second bimetallic strip.

[0009] In some embodiments, a side of the electrically conductive portion facing the second bimetallic strip is provided with an electrically conductive protrusion to make linear contact with the second end via the electrically conductive protrusion.

[0010] In some embodiments, the electrically conductive protrusion is a structure bent from the electrically conductive portion.

[0011] In some embodiments, further comprising: a support coupled to the heating portion of the bimetallic strip; and / or a second wire electrically connected to the conductive member and adapted to be electrically connected to the movable contact of the circuit breaker.

[0012] In a second aspect of the present disclosure, a circuit breaker is provided. The circuit breaker comprises: a housing; an operating assembly rotatably coupled to the housing and adapted to switch between a closed position and an open position; and a thermal trip assembly according to the first aspect of the present disclosure, one end of the first bimetallic strip distal to the heating portion being coupled to the operating assembly.

[0013] In an embodiment of the present disclosure, the thermal trip assembly comprises a conductive member, a first wire and a bimetallic strip. The first wire comprises a first connecting end and a second connecting end. The first connecting end is electrically connected to the conductive member. The bimetallic strip is disposed adjacent to the conductive member. The bimetallic strip comprises a heating portion, a first bimetallic strip and a second bimetallic strip. The heating portion is electrically connected to the second connecting end, and a first conductive loop can be formed between the heating portion and the conductive member. One end of the first bimetallic strip is connected to the heating portion, and the other end thereof extends towards a direction away from the heating portion. The second bimetallic strip comprises oppositely disposed first and second ends. The first end is connected to the heating portion. The second end is disposed adjacent to the conductive member. The second bimetallic strip is adapted to deform with the heating portion being heated, and the second end is adapted to contact the conductive member in a case where a value of the current flowing through the heating portion reaches a predetermined trip current value, so that a second conductive loop is formed between the heating portion and the conductive member. The second bimetallic strip is disposed adjacent to the first bimetallic strip, and can heat the first bimetallic strip in a case where the second end contacts the conductive member. With this arrangement, in a case where the value of the current flowing through the heating portion reaches the predetermined trip current value, the second end of the second bimetallic strip contacts the conductive member, and the second conductive loop is formed between the heating portion and the conductive member. When the current flows through the second bimetallic strip, the temperature of the second bimetallic strip increases. The heat dissipated by the second bimetallic strip can further heat the first bimetallic strip, thereby increasing the response speed and deformation amount of the first bimetallic strip. In a case where the material of the housing expands and deforms to increase the gap between the bimetallic strip and the thermal trip lever, the deformation amount of the first bimetallic strip can meet the trip requirement, and the circuit breaker can timely respond to the trip action, thereby increasing the safety of the circuit.

[0014] It should be understood that the contents described in this part are not intended to limit the key features or important features of the embodiments of the present disclosure, nor are they used to limit the scope of the present disclosure. Other features of the present disclosure will become apparent through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and other features, advantages, and aspects of the present disclosure will become more apparent with reference to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, like reference numerals denote like elements, in which:

[0016] Figure 1 A perspective view of a thermal trip assembly and an operating assembly of an embodiment of the present disclosure is shown, with the electrically conductive member on the back side;

[0017] Figure 2 A perspective view of a thermal trip assembly and an operating assembly of an embodiment of the present disclosure is shown, with the electrically conductive member on the front side;

[0018] Figure 3 A top view of a bimetallic strip of an embodiment of the present disclosure is shown;

[0019] Figure 4 A perspective view of a bimetallic strip of an embodiment of the present disclosure is shown;

[0020] Figure 5 A perspective view of an electrically conductive member of an embodiment of the present disclosure is shown;

[0021] Figure 6 A side view of an electrically conductive member of an embodiment of the present disclosure is shown; and

[0022] Figure 7 An internal structure schematic view of a circuit breaker of an embodiment of the present disclosure is shown.

[0023] Explanation of Reference Numerals:

[0024] 100, thermal trip assembly;

[0025] 10, electrically conductive member; 101, mounting portion; 102, electrically conductive portion; 1021, electrically conductive protrusion; 11, first lead wire; 111, first connection end; 112, second connection end; 12, second lead wire;

[0026] 20, bimetallic strip; 21, first bimetallic strip; 22, second bimetallic strip; 221, first end; 222, second end; 23, heating portion; 24, electrically conductive contact;

[0027] 30, support member;

[0028] 410, housing;

[0029] 420, operating assembly. DETAILED DESCRIPTION

[0030] Preferred embodiments of the present disclosure will be described in greater detail below, with reference to the drawings. While preferred embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the present disclosure to those skilled in the art.

[0031] The term "comprising" and variations thereof as used herein are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Unless otherwise specified, the term "or" as used herein is intended to mean "and / or". The term "based on" means "based, at least in part, on". The terms "one example embodiment" and "an example embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "a first", "a second", etc. can refer to different or the same objects.

[0032] In some conventional circuit breakers, the housing material (e.g., nylon) can expand and deform due to environmental factors such as moisture and heat. This deformation can increase the distance between the thermal trip assembly and the four-bar linkage assembly, which can increase the gap between the bimetallic strip and the thermal trip lever. When the current reaches the appropriate trip condition, the circuit breaker can not respond in time to perform the trip action, which can increase the risk of a circuit failure.

[0033] Embodiments of the present disclosure provide a thermal trip assembly and a circuit breaker. The thermal trip assembly includes an electrically conductive member, a first wire and a bimetallic strip. The first wire includes a first connecting end and a second connecting end. The first connecting end is electrically connected with the electrically conductive member. The bimetallic strip is disposed adjacent to the electrically conductive member. The bimetallic strip includes a heating portion, a first bimetallic strip and a second bimetallic strip. The heating portion is electrically connected with the second connecting end, and a first electrically conductive loop can be formed between the heating portion and the electrically conductive member. One end of the first bimetallic strip is connected with the heating portion, and the other end thereof extends towards a direction away from the heating portion. The second bimetallic strip includes oppositely disposed first and second ends. The first end is connected with the heating portion. The second end is disposed adjacent to the electrically conductive member. The second bimetallic strip is adapted to deform with the heating portion when the heating portion is heated, and the second end is adapted to contact the electrically conductive member when a value of the current flowing through the heating portion reaches a predetermined trip current value, so as to form a second electrically conductive loop between the heating portion and the electrically conductive member. The second bimetallic strip is disposed adjacent to the first bimetallic strip, and can heat the first bimetallic strip when the second end contacts the electrically conductive member. With such an arrangement, when the value of the current flowing through the heating portion reaches the predetermined trip current value, the second end of the second bimetallic strip contacts the electrically conductive member, and the second electrically conductive loop is formed between the heating portion and the electrically conductive member. When the current flows through the second bimetallic strip, the temperature of the second bimetallic strip increases. The heat emitted by the second bimetallic strip can further heat the first bimetallic strip, so as to increase the response speed and deformation amount of the first bimetallic strip. When the expansion deformation of the housing material causes the gap between the bimetallic strip and the thermal trip lever to increase, the deformation amount of the first bimetallic strip can meet the trip requirement, and the circuit breaker can timely respond to the trip action, thereby increasing the safety of the circuit. The principle of the present disclosure will be described in detail below with reference to the accompanying drawings. Figures 1 to 6

[0034] As shown in Figures 1 to 4 , the thermal trip assembly 100 includes an electrically conductive member 10, a first wire 11 and a bimetallic strip 20. The electrically conductive member 10 can be a copper sheet, an aluminum sheet or other alloy with good electrical conductivity. The bimetallic strip 20 is made of two metal materials with different thermal expansion coefficients. When the temperature changes, the bimetallic strip 20 will bend and deform due to the different expansion or contraction degrees of the two metals. In this way, the bimetallic strip 20 can be used as a temperature sensitive element, and thus be applied to temperature control and overcurrent protection devices.

[0035] As shown in Figure 2 ​As shown, in the thermal trip assembly 100, a bimetallic strip 20 is disposed adjacent to the conductive element 10. The bimetallic strip 20 includes a heating element 23, a first bimetallic strip 21, and a second bimetallic strip 22. The heating element 23 is electrically connected to one terminal of the circuit breaker and generates heat through resistance heating. As an example, the resistance of the heating element 23 can be calculated based on a predetermined trip current value. When the current flowing through the heating element 23 reaches or exceeds the predetermined trip current value, the heating element 23 can generate sufficient heat to trigger subsequent action.

[0036] like Figure 2 As shown, the first conductor 11 can be a braided wire or other flexible conductor. In a circuit breaker, the flexible first conductor 11 is easy to arrange and can adapt to limitations in installation space. The first conductor 11 includes a first connecting end 111 and a second connecting end 112. The first connecting end 111 is electrically connected to the conductive element 10, and the second connecting end 112 is electrically connected to the heating element 23. With this arrangement, a first conductive path can be formed between the heating element 23 and the conductive element 10. As current flows, the heating element 23 generates heat due to its own resistance. Here, the engineer can calculate the resistance of the heating element 23 based on a predetermined tripping current value, so that the heating element 23 generates sufficient heat under specific conditions to meet the tripping requirements.

[0037] like Figure 3 and Figure 4 As shown, one end of the first bimetallic strip 21 is connected to the heating element 23, and the other end extends away from the heating element 23. When the temperature of the heating element 23 rises, heat is transferred to the first bimetallic strip 21, causing the temperature of the first bimetallic strip 21 to rise and bend. The end of the first bimetallic strip 21 away from the heating element 23 is coupled to a four-bar linkage mechanism inside the circuit breaker. The deformation of the first bimetallic strip 21 can drive the four-bar linkage mechanism to trip, thereby cutting off the circuit.

[0038] like Figure 3 and Figure 4 As shown, the second bimetallic strip 22 includes a first end 221 and a second end 222 disposed opposite to each other. The first end 221 of the second bimetallic strip 22 is connected to the heating part 23, while the second end 222 of the second bimetallic strip 22 is disposed close to the conductive member 10. When the heating part 23 heats up, the second bimetallic strip 22 also deforms. When the value of the current flowing through the heating part 23 reaches the predetermined tripping current value, the second bimetallic strip 22 deforms due to heat, and its second end 222 contacts the conductive member 10, thereby forming a second conductive circuit between the heating part 23 and the conductive member 10. After the current flows through the second bimetallic strip 22, the second bimetallic strip 22 also heats up. The heat dissipated by the second bimetallic strip 22 further heats the first bimetallic strip 21, thereby increasing the deformation of the first bimetallic strip 21.

[0039] In this way, even if the material of the shell 410 expands and deforms to increase the gap between the bimetallic strip 20 and the thermal trip lever, the first bimetallic strip 21 can still meet the required deformation amount for tripping, ensuring that the circuit breaker responds to the tripping action in a timely manner and improving the safety of the circuit.

[0040] As shown in Figure 3 and Figure 4 , in the thermal trip assembly 100, the first bimetallic strip 21, the second bimetallic strip 22, and the heating portion 23 can adopt an integrated structure. In this way, not only is the manufacturing process simplified, but the processing difficulty and production cost are also reduced. In addition, the integrated structure reduces the assembly steps and avoids reliability problems caused by the connection of multiple components. In mass production, the consistency and quality stability of the product can be ensured.

[0041] It should be understood that in other embodiments, the heating portion 23 can also be a separate element, and the first bimetallic strip 21 and the second bimetallic strip 22 are detachably mounted on the heating portion 23. For example, the first bimetallic strip 21 and the second bimetallic strip 22 are fixed to the heating portion 23 using threaded connections or riveting, etc. When the heating portion 23 is powered and generates heat, the heat can be transferred to the first bimetallic strip 21 and the second bimetallic strip 22, causing the first bimetallic strip 21 and the second bimetallic strip 22 to deform as necessary. The present disclosure is not intended to limit the specific connection method between the first bimetallic strip 21, the second bimetallic strip 22, and the heating portion 23.

[0042] In some embodiments, as shown in Figure 3 and Figure 4 , the first bimetallic strip 21 and the second bimetallic strip 22 are spaced apart. When deformed, they do not interfere with each other, and the first bimetallic strip 21 can independently complete its predetermined mechanical action without being affected by the deformation action of the second bimetallic strip 22.

[0043] As shown in Figure 3 and Figure 4 , the first bimetallic strip 21 and the second bimetallic strip 22 are arranged in parallel. With this arrangement, the heat transfer path between the first bimetallic strip 21 and the second bimetallic strip 22 can be improved. When the second bimetallic strip 22 conducts electricity, the second bimetallic strip 22 heats up and transfers heat to the adjacent first bimetallic strip 21 along its length. Since the first bimetallic strip 21 and the second bimetallic strip 22 are arranged in parallel, the heat exchange efficiency is improved, the heating speed of the first bimetallic strip 21 is accelerated, and the speed and reliability of the tripping response are enhanced.

[0044] In some embodiments, as shown in Figure 3 and Figure 4As shown, the length of the second bimetallic strip 22 is shorter than that of the first bimetallic strip 21. In this way, the first bimetallic strip 21 is directly coupled to the four-bar linkage mechanism and can drive the four-bar linkage mechanism to perform a tripping action after being heated. The second bimetallic strip 22 can be used to generate heat and transfer the heat to the first bimetallic strip 21, so as to cause the first bimetallic strip 21 to generate a larger deformation amount. Here, the shorter second bimetallic strip 22 does not cause physical interference to the operation of the four-bar linkage mechanism.

[0045] In some embodiments, as shown in Figure 3 and Figure 4 The second end 222 of the second bimetallic strip 22 is provided with a conductive contact 24, which can be electrically connected to the conductive member 10. In this way, the conductive contact 24 can improve the electrical conductivity between the second bimetallic strip 22 and the conductive member 10, and ensure stable electrical contact between the two.

[0046] In some embodiments, as shown in Figure 3 and Figure 4 The conductive member 10 includes a mounting portion 101 and a conductive portion 102. The mounting portion 101 can be connected to the housing 410 of the circuit breaker, and the conductive portion 102 can be in electrical contact with the second bimetallic strip 22. As an example, the conductive member 10 can be integrally formed by a bending process to form the mounting portion 101 and the conductive portion 102. In other embodiments, the mounting portion 101 and the conductive portion 102 can be separate elements, and the mounting portion 101 and the conductive portion 102 can be fixed together by screwing or riveting.

[0047] In some embodiments, in order to fix the mounting portion 101 to the housing 410 of the circuit breaker, the housing 410 can be provided with a positioning portion, such as a positioning groove, which is adapted to the mounting portion 101. During assembly, the mounting portion 101 can be inserted into the positioning groove to fix the conductive member 10. At the same time, the conductive portion 102 extends away from the housing 410 to contact or separate from the second end 222 of the second bimetallic strip 22.

[0048] In some embodiments, as shown in Figure 5 and Figure 6 The side of the conductive portion 102 facing the second bimetallic strip 22 is provided with a conductive protrusion 1021. The conductive protrusion 1021 can form a linear contact with the second end 222 of the second bimetallic strip 22. Compared with a surface contact, the linear contact can enhance the stability of the electrical connection, reduce the contact resistance, and ensure a more uniform distribution of current. When the current passes through, the conductive protrusion 1021 can be attached to the second bimetallic strip 22 or the conductive contact 24, and can maintain good contact performance even in a high-temperature or vibration environment.

[0049] In some embodiments, as shown in Figure 5 and Figure 6 The conductive bump 1021 is a structure bent from the conductive part 102. In this way, the manufacturing process can be simplified and the production cost can be reduced. In addition, the conductive bump 1021 bent and shaped has high mechanical strength and can maintain the shape unchanged in repeated use, thereby improving the reliability of long-term use.

[0050] In some embodiments, as shown in Figure 5 and Figure 6 The thermal trip assembly 100 further includes a support 30. The support 30 is coupled to the heating part 23 of the bimetallic strip 20, thereby fixing the bimetallic strip 20 in the housing 410 of the circuit breaker. In this way, the support 30 can maintain the positional relationship between the bimetallic strip 20 and the four-bar linkage mechanism of the circuit breaker. In the case where the current value flowing through the heating part 23 reaches a predetermined trip current value, the bimetallic strip 20 can respond to the temperature change and trigger a trip action.

[0051] In some embodiments, as shown in Figure 1 and Figure 2 The thermal trip assembly 100 further includes a second wire 12. The second wire 12 is electrically connected to the conductive part 10 and is adapted to be connected to the movable contact of the circuit breaker. During the opening and closing process of the circuit breaker, the movable contact changes position, and the second wire 12 in the form of a braid or other flexible wire can adapt to the movement of the movable contact, ensuring that the conductive path is always unobstructed.

[0052] In a second aspect of the present disclosure, a circuit breaker is provided. As shown in Figure 1 Figure 2 Figure 7 The circuit breaker includes a housing 410, an operating assembly 420, and any of the thermal trip assemblies 100 described above. The operating assembly 420 is rotatably coupled to the housing 410 and is adapted to switch between a closed position and an open position. As an example, the operating assembly 420 can be a four-bar linkage mechanism. The end of the first bimetallic strip 21 away from the heating part 23 is coupled to the operating assembly 420.

[0053] In the thermal trip assembly 100 of the circuit breaker, the bimetallic strip 20 is disposed adjacent to the conductive member 10. The bimetallic strip 20 includes a heating portion 23, a first bimetallic strip 21, and a second bimetallic strip 22. The heating portion 23 is electrically connected to the second connecting end 112, and a first conductive loop can be formed between the heating portion 23 and the conductive member 10. The first bimetallic strip 21 has one end connected to the heating portion 23, and the other end extends away from the heating portion 23. The second bimetallic strip 22 includes a first end 221 and a second end 222 disposed opposite to each other. The first end 221 is connected to the heating portion 23. The second end 222 is disposed adjacent to the conductive member 10. The second bimetallic strip 22 is adapted to deform with the heating portion 23 when heated, and the second end 222 is adapted to contact the conductive member 10 when the value of the current flowing through the heating portion 23 reaches a predetermined trip current value, so as to form a second conductive loop between the heating portion 23 and the conductive member 10. The second bimetallic strip 22 is disposed adjacent to the first bimetallic strip 21, and can heat the first bimetallic strip 21 when the second end 222 contacts the conductive member 10. With this arrangement, when the value of the current flowing through the heating portion 23 reaches the predetermined trip current value, the second end 222 of the second bimetallic strip 22 contacts the conductive member 10, and the second conductive loop is formed between the heating portion 23 and the conductive member 10. When the current flows through the second bimetallic strip 22, the temperature of the second bimetallic strip 22 increases. The heat dissipated by the second bimetallic strip 22 can further heat the first bimetallic strip 21, so as to increase the deformation amount of the first bimetallic strip 21. When the material of the housing 410 expands and deforms, and the gap between the bimetallic strip 20 and the thermal trip lever increases, the deformation amount of the first bimetallic strip 21 can meet the trip requirement, and the circuit breaker can timely respond to the trip action, thereby increasing the safety of the circuit.

[0054] Embodiments of the present disclosure have been described above, the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical applications, or technical improvements in the art, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A thermal trip assembly (100) characterized by, Comprising: a conductive piece (10); a first wire (11) comprising a first connecting end (111) and a second connecting end (112), the first connecting end (111) being electrically connected with the conductive piece (10); and a bimetallic piece (20) disposed adjacent to the conductive piece (10) and comprising: a heating portion (23) electrically connected with the second connecting end (112) to form a first conductive loop between the heating portion (23) and the conductive piece (10); a first bimetallic strip (21) having one end connected with the heating portion (23) and the other end extending towards a direction away from the heating portion (23); and a second bimetallic strip (22) comprising oppositely disposed first and second ends (221, 222), the first end (221) being connected with the heating portion (23) and the second end (222) being disposed adjacent to the conductive piece (10), the second bimetallic strip (22) being adapted to deform with the heating portion (23) being heated and the second end (222) being adapted to contact the conductive piece (10) to form a second conductive loop between the heating portion (23) and the conductive piece (10) in a case that a value of an electric current flowing through the heating portion (23) reaches a predetermined tripping current value, the second bimetallic strip (22) being disposed adjacent to the first bimetallic strip (21) to heat and warm up the first bimetallic strip (21) in a case that the second end (222) contacts the conductive piece (10). The first bimetallic strip (21), the second bimetallic strip (22) and the heating portion (23) are integrally formed. The first bimetallic strip (21) and the second bimetallic strip (22) are disposed in parallel and spaced apart.

2. The thermal trip assembly (100) of claim 1, wherein, A length of the second bimetallic strip (22) is less than a length of the first bimetallic strip (21).

3. The thermal trip assembly (100) of claim 1, wherein, The second end (222) of the second bimetallic strip (22) is provided with a conductive contact (24) to connect with the conductive piece (10) via the conductive contact (24).

4. The thermal trip assembly (100) of claim 3, wherein, The conductive piece (10) comprises a mounting portion (101) adapted to connect with a housing (410) of a circuit breaker and a conductive portion (102) adapted to connect with the second bimetallic strip (22).

5. The thermal trip assembly (100) of claim 1, wherein, A side of the conductive portion (102) facing the second bimetallic strip (22) is provided with a conductive protrusion (1021) to linearly contact the second end (222) via the conductive protrusion (1021).

6. The thermal trip assembly (100) of claim 5, wherein, The conductive protrusion (1021) is a structure bent from the conductive portion (102).

7. The thermal trip assembly (100) of claim 6, wherein, Further comprising:

8. The thermal trip assembly (100) of claim 7, wherein, a support piece (30) coupled to the heating portion (23) of the bimetallic piece (20); and / or 9. The trip unit (100) of any of claims 1 to 8, wherein, a second wire (12) electrically connected with the conductive piece (10) and adapted to electrically connect with a movable contact of a circuit breaker. Comprising: a housing (410); 10. A circuit breaker characterized by, an operating assembly (420) rotatably coupled to the housing (410) and adapted to switch between a closed position and an open position; and a bimetallic piece (20) disposed adjacent to the conductive piece (10) and comprising: a heating portion (23) electrically connected with the second connecting end (112) to form a first conductive loop between the heating portion (23) and the conductive piece (10); a first bimetallic strip (21) having one end connected with the heating portion (23) and the other end extending towards a direction away from the heating portion (23); and a second bimetallic strip (22) comprising oppositely disposed first and second ends (221, 222), the first end (221) being connected with the heating portion (23) and the second end (222) being disposed adjacent to the conductive piece (10), the second bimetallic strip (22) being adapted to deform with the heating portion (23) being heated and the second end (222) being adapted to contact the conductive piece (10) to form a second conductive loop between the heating portion (23) and the conductive piece (10) in a case that a value of an electric current flowing through the heating portion (23) reaches a predetermined tripping current value, the second bimetallic strip (22) being disposed adjacent to the first bimetallic strip (21) to heat and warm up the first bimetallic strip (21) in a case that the second end (222) contacts the conductive piece (10). The first bimetallic strip (21), the second bimetallic strip (22) and the heating portion (23) are integrally formed. The first bimetallic strip (21) and the second bimetallic strip (22) are disposed in parallel and spaced apart. A length of the second bimetallic strip (22) is less than a length of the first bimetallic strip (21). The second end (222) of the second bimetallic strip (22) is provided with a conductive contact (24) to connect with the conductive piece (10) via the conductive contact (24). The conductive piece (10) comprises a mounting portion (101) adapted to connect with a housing (410) of a circuit breaker and a conductive portion (102) adapted to connect with the second bimetallic strip (22). A side of the conductive portion (102) facing the second bimetallic strip (22) is provided with a conductive protrusion (1021) to linearly contact the second end (222) via the conductive protrusion (1021). The conductive protrusion (1021) is a structure bent from the conductive portion (102). Further comprising: a support piece (30) coupled to the heating portion (23) of the bimetallic piece (20); and / or a second wire (12) electrically connected with the conductive piece (10) and adapted to electrically connect with a movable contact of a circuit breaker. The thermal trip assembly (100) according to any one of claims 1 to 9, wherein one end of the first bimetallic strip (21) distal to the heating portion (23) is coupled to the operating assembly (420).

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