A current limiting structure and circuit breaker

Abstract

The present invention relates to the technical field of circuit breakers, and specifically to a current limiting structure and a circuit breaker, wherein the current limiting structure includes a variable resistor component, one end of which is suitable for being electrically connected to a heating element in the circuit breaker, and the other end of which is electrically connected to a moving contact in the circuit breaker to be connected in series in the main circuit of the circuit breaker; a linkage mechanism, one end of which is linked to the variable resistor component, and the other end of which is linked to the moving contact; the variable resistor component has a first state in which the resistance value tends to zero when the moving contact and the static contact in the circuit breaker are turned on, and a second state in which the resistance value increases due to the repulsive driving force of the moving contact and the static contact when the current in the main circuit is too large; in the first state, the variable resistor component does not limit the current of the main circuit; in the second state, the linkage mechanism and the moving contact provide driving force in linkage, and the variable resistor component limits the current of the main circuit. Increasing the arc voltage is more conducive to arc extinguishing. There is no need to increase the volume and opening distance of the arc extinguishing chamber to improve the arc extinguishing ability, which reduces the volume of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of circuit breakers, and in particular relates to a current limiting structure and a circuit breaker. Background Art

[0002] A circuit breaker is a switching device that can carry and disconnect current under abnormal circuit conditions within a specified time. The circuit breaker has a moving contact and a stationary contact that can perform on-off operations, and the moving contact is driven by an operating mechanism.

[0003] The operating mechanism of the circuit breaker is operated by a button extending out of the housing, and the moving contact and the static contact in the circuit breaker are driven to make contact or disconnect through multi-stage linkage. When the moving contact and the static contact are in contact, power can be supplied to the load connected to the circuit breaker.

[0004] In order to achieve the breaking index, reduce the actual current during breaking, and protect the internal components from being burned, it is generally necessary to set up overload protection and short-circuit protection devices in the circuit breaker. The purpose of current limiting is usually achieved by increasing the resistance of the main circuit inside the circuit breaker. The existing circuit breaker usually increases the current limiting resistance by: 1. Designing the static contact of the circuit breaker into a coiled serpentine shape, increasing the length of the connecting row to the static contact, thereby increasing the resistance; this method is difficult to process; 2. The connecting row and the static contact are connected together through an S-shaped heating resistor alloy to increase the resistance; this method increases the installation process and reduces reliability; 3. Designing the heating element of the circuit breaker into a curved structure or adding a resistor element at the end of the heating element to increase the loop resistance; this method only increases the local resistance of the heating element and the resistance of most of the existing increased resistor elements is fixed, which will cause the local temperature of the heating element to be too high, affecting the temperature rise of the heating element, making the heating element easy to burn first, resulting in the single-phase circuit breaker being unable to conduct, affecting the performance of the circuit breaker. Moreover, in order to meet the temperature rise of the product, the resistance of the newly added resistor is very small. When the circuit breaker performs short-circuit breaking, the resistor cannot be effectively used to limit the current, which is not conducive to arc extinguishing. In order to improve the arc extinguishing ability, the existing circuit breakers usually increase the arc extinguishing chamber, which makes the volume of the circuit breaker larger and the cost increased. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the technical problem that the method of increasing the current limiting resistor of the circuit breaker in the prior art and adopting a fixed resistor with a very small resistance value is not conducive to arc extinguishing, and in order to improve the arc extinguishing ability, the arc extinguishing chamber is enlarged, resulting in a large volume of the circuit breaker, thereby providing a current limiting structure that is conducive to arc extinguishing and does not require the enlargement of the arc extinguishing chamber, and a circuit breaker with the current limiting structure.

[0006] To this end, an object of the present invention is to provide a current limiting structure, comprising:

[0007] A variable resistor component, one end of which is suitable for being electrically connected to a heating element in a circuit breaker, and the other end of which is electrically connected to a moving contact in the circuit breaker so as to be connected in series in a main circuit of the circuit breaker;

[0008] A linkage mechanism, one end of which is linked to the variable resistor assembly, and the other end of which is linked to the moving contact;

[0009] The variable resistor component has a first state in which the resistance value tends to be zero when the moving contact and the stationary contact in the circuit breaker are conducting, and a second state in which the resistance value increases due to the repulsive driving force of the moving contact and the stationary contact when the main circuit current is too large;

[0010] In the first state, the variable resistor component does not limit the current of the main circuit; in the second state, the linkage mechanism and the moving contact cooperate to provide the driving force, and the variable resistor component limits the current of the main circuit.

[0011] Preferably, the current limiting structure and the variable resistance component include:

[0012] Resistor body;

[0013] The selection part is linked to the linkage mechanism and is driven by the moving contact to select a required resistance value in the first state and the second state.

[0014] Preferably, in the current limiting structure, the resistor body comprises:

[0015] A frame, on which at least one first terminal is provided, and the heating element is suitable for connecting to the first terminal through a first wire;

[0016] A resistance wire is wound around a portion of the frame;

[0017] A slide bar, arranged above the frame and having two ends thereof respectively provided with a second terminal, wherein the moving contact is suitable for connecting with any of the second terminals through a second wire;

[0018] The selection part is a slider, which is sleeved on the slide bar and connected to the linkage mechanism. The slider abuts against the resistance wire in the second state and abuts against the frame in the first state;

[0019] The frame, the sliding rod and the sliding block are all conductors.

[0020] Preferably, the current limiting structure and the slider include:

[0021] A main body, on which a sliding hole extending along the axis direction of the sliding rod is formed, and the main body is slidably sleeved on the sliding rod through the sliding hole;

[0022] A sliding sheet is formed at one end of the main body facing the frame, and is suitable for being pressed onto the resistance wire in the second state and being pressed onto the frame in the first state.

[0023] Preferably, in the current limiting structure, the sliding vane and the body are integrally formed.

[0024] Preferably, the current limiting structure, the frame comprises:

[0025] A first frame is arranged below the slide bar in parallel with the axis direction of the slide bar and is in the shape of a round rod. The cross section of the slide sheet (142) is in an arc shape matching the first frame (111). The resistance wire is wound on the first frame;

[0026] At least one second frame is supported below the first frame, and the first terminal is arranged at a position of the first frame where the resistance wire is not wound or on the second frame.

[0027] Preferably, in the current limiting structure, the second frame includes two, which are spaced apart and arranged oppositely at the bottoms of both ends of the first frame;

[0028] The first connecting posts include two, which are respectively arranged on the two second frames.

[0029] Preferably, in the current limiting structure, when in the first state, a reserved distance is provided between the position of the sliding piece and the resistance wire; and / or

[0030] When the first state is switched to the second state, the resistance value increases geometrically.

[0031] Preferably, the current limiting structure and the linkage mechanism include:

[0032] A connecting rod, the extension direction of which is parallel to the axial direction of the sliding rod, and the two ends of the connecting rod are respectively formed with a first connecting portion and a second connecting portion;

[0033] The slider is provided with a first matching portion corresponding to the first connecting portion, and the moving contact is provided with a second matching portion corresponding to the second connecting portion;

[0034] The second connecting portion is slidably fitted in the second fitting portion; the connecting rod, the slider and the second fitting portion constitute a cam slider structure.

[0035] Preferably, in the current limiting structure, the second connecting portion is a convex column, the second matching portion is a curved groove provided at an end away from the movable contact and the static contact where the movable contact is in conduction, and the center of the curved groove is located at a side of the movable contact away from the variable resistor assembly;

[0036] In the first state, the slider is pressed against an end of the frame away from the moving contact;

[0037] When the moving contact is disconnected from the stationary contact, the slider is driven by the cam slider structure to slide toward the moving contact and press on the resistance wire to switch to the second state;

[0038] The first matching portion is a connecting column which is arranged perpendicular to the axis of the sliding rod and on the end of the sliding block away from the resistance wire, and the first connecting portion is an axial hole which is rotatably connected to the connecting column.

[0039] Another object of the present invention is to provide a circuit breaker, comprising any of the current limiting structures described above.

[0040] The technical solution of the present invention has the following advantages:

[0041] 1. The current limiting structure provided by the present invention is provided with a variable resistor component. When a short circuit occurs in the main circuit and an excessive current is generated, the moving contact and the static contact are disconnected. The moving contact disconnection drives the resistance value of the variable resistor component to switch to a current limiting value for the main circuit through a linkage mechanism. The increase in resistance during disconnection is equivalent to an increase in the arc voltage, which is more conducive to arc extinguishing. Therefore, there is no need to increase the volume and opening distance of the arc extinguishing chamber to improve the arc extinguishing ability, which reduces the volume of the product and also reduces the design troubles.

[0042] 2. In the current limiting structure provided by the present invention, when the moving contact and the stationary contact are closed and turned on, the resistance value of the variable resistor component tends to zero, thereby not affecting the temperature rise of the heating element.

[0043] 3. The current limiting structure provided by the present invention has a second connecting portion as a convex column, a second matching portion as a curved groove provided at the end away from the movable contact and the static contact, and the center of the curved groove is located at the side of the movable contact away from the variable resistor assembly; the convex column is slidably connected in the curved groove, and the connecting rod, the slider and the curved groove constitute a cam slider structure. The cam slider structure realizes the linkage between the variable resistor assembly and the movable contact, and the linkage mechanism is used to increase the resistance when the movable contact is disconnected, so as to achieve the purpose of current limiting, and the structure is simple.

[0044] 4. The current limiting structure provided by the present invention is applicable to both AC circuit breakers and DC circuit breakers. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 Schematic diagram of the structure of the current limiting structure in Example 1 of the present invention;

[0047] Figure 2 This is a schematic structural diagram of a variable resistor component of a current limiting structure in Embodiment 1 of the present invention;

[0048] Figure 3 This is a schematic structural diagram of a moving contact of a current limiting structure in Embodiment 1 of the present invention;

[0049] Figure 4 This is a schematic structural diagram of a slider of a current limiting structure in Example 1 of the present invention;

[0050] Figure 5 It is a structural schematic diagram of the linkage mechanism of the current limiting structure in Example 1 of the present invention;

[0051] Figure 6 It is a structural schematic diagram of the current limiting structure and the operating mechanism assembly in an embodiment of the present invention;

[0052] Figure 7 is a schematic diagram of the three-dimensional structure of a circuit breaker in Embodiment 2 of the present invention;

[0053] Figure 8 for Figure 7 Schematic diagram of the longitudinal cross-sectional structure of a circuit breaker.

[0054] Description of reference numerals:

[0055] 1-variable resistor assembly; 11-frame; 111-first frame; 112-second frame; 12-resistance wire; 13-sliding rod; 14-sliding block; 141-body; 142-sliding sheet; 143-sliding hole; 144-first matching portion; 15-first terminal; 16-second terminal; 17-first wire; 18-second wire;

[0056] 2-linkage mechanism; 20-connecting rod; 21-first connecting part; 22-second connecting part;

[0057] 3-moving contact; 31-second matching portion;

[0058] 4-static contact;

[0059] 5-Heating element;

[0060] 6-Operating mechanism;

[0061] 7- Shell. DETAILED DESCRIPTION

[0062] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Example 1

[0064] The current limiting structure of this embodiment, see Figures 1 to 5 As shown, it includes a variable resistor component 1 and a linkage mechanism 2. One end of the variable resistor component 1 is suitable for being electrically connected to the heating element 5 in the circuit breaker, and the other end is electrically connected to the moving contact 3 in the circuit breaker to be connected in series in the main circuit of the circuit breaker. One end of the linkage mechanism 2 is linked to the variable resistor component 1, and the other end is linked to the moving contact 3. The variable resistor component 1 has a first state in which the resistance value tends to zero when the moving contact 3 is turned on with the static contact 4 in the circuit breaker, and a second state in which the resistance value increases due to the repulsive driving force of the moving contact 3 and the static contact 4 when the current in the main circuit is too large. In the first state, the variable resistor component 1 does not limit the current of the main circuit. In the second state, the linkage mechanism 2 and the moving contact 3 are linked to provide driving force, and the variable resistor component 1 limits the current of the circuit. Through the setting of the variable resistor component 1, when the moving contact 3 and the static contact 4 are closed and turned on, the resistance value of the variable resistor component 1 tends to zero, thereby not affecting the temperature rise of the heating element 5. When a short circuit occurs in the main circuit and an excessive current is generated, the moving contact 3 and the static contact 4 are separated and disconnected, and the moving contact 3 deflects in a direction away from the static contact 4 to drive the linkage mechanism 2 to jointly drive the variable resistor component 1 to increase the resistance value to limit the current of the main circuit. The increase in resistance during disconnection is equivalent to increasing the arc voltage, which is more conducive to arc extinguishing. Therefore, there is no need to increase the volume and opening distance of the arc extinguishing chamber to improve the arc extinguishing ability, which reduces the volume of the product and reduces design troubles.

[0065] Preferably, the variable resistor assembly 1 includes a resistor body and a selection part, the selection part is linked to the linkage mechanism 2, and is driven by the moving contact 3 to select the required resistance value in the first state and the second state. The variable resistor assembly 1 can be a potentiometer on the existing market, and the selection part is a knob or a sliding resistor. Preferably, the variable resistor assembly 1 is a sliding resistor, specifically, Figure 2 As shown, the resistor body includes a frame 11, a resistance wire 12 and a slide bar 13, and the selected part is a slider 14. The frame 11 is provided with at least one first terminal 15, and the heating element 5 is suitable for connecting with the first terminal 15 through a first wire 17. The resistance wire 12 is wound around a part of the frame 11, as shown in FIG. Figure 2As shown, the resistance wire 12 is wound around the middle part of the frame 11, and the two end parts are not wound with the resistance wire 12. The slide bar 13 is arranged above the frame 11 and has a second terminal 16 at each end. The moving contact 3 is suitable for connecting with any second terminal 16 through a second wire 18. Specifically, in this embodiment, the moving contact 3 is connected to the end of the slide bar 13 away from the moving contact 3 through the second wire 18, that is, Figure 2 The slider 14 is sleeved on the slide bar 13 and connected to the linkage mechanism 2. The slider 14 abuts against the resistance wire 12 in the second state and abuts against the frame 11 in the first state. The frame 11, the slide bar 13 and the slider 14 are all conductors, and the specific material is not limited, so that when the switch is closed, even if the slider 14 is not connected to the resistance wire 12, the main circuit can form a closed circuit through the frame 11 made of conductor material.

[0066] More specifically, Figure 4 As shown in FIG. 1 , the slider 14 includes a body 141 and a slide plate 142. The body 141 is provided with a slide hole extending along the axis direction of the slide rod 13. Figure 4 The axis of the sliding hole 143 shown in the figure extends in the horizontal direction, and the body 141 is slidably sleeved on the sliding rod 13 through the sliding hole 143. The sliding sheet 142 is formed at one end of the slider 14 facing the frame 11, that is, Figure 2 The lower end of the slider 14 shown is suitable for being pressed onto the resistance wire 12 in the second state and being pressed onto the frame 11 in the first state. Preferably, the slider 142 is integrally formed with the body 141. More preferably, the cross section of the slider 142 is arc-shaped.

[0067] Preferably, the frame 11 includes a first frame 111 and two second frames 112. Figure 2 As shown, the first frame 111 is arranged below the slide bar 13 in parallel with the axis direction of the slide bar 13. Two second frames 112 are arranged at intervals and opposite to each other at the bottom of the two ends of the first frame 111, and are arranged perpendicular to the first frame 111. The first connecting posts 15 include two, and each second frame 112 is provided with a first connecting post 15. The heating element 5 is suitable for connecting with any first connecting post 15 through a first wire 17, such as Figure 2 As shown, the heating element 5 is connected to the first terminal 15 on the second frame 112 on the right side, that is, close to the heating element 5, through the first wire 17. Optionally, there may be only one second frame 112. Optionally, there may be only one first terminal 15, which may be set at a position of the first frame 111 where the resistance wire 12 is not wound, or may be set on the second frame 112. Preferably, the first terminal 15 is set on the second frame 112.

[0068] Preferably, the first frame 111 is in the shape of a round rod, and the cross section of the slide 142 is in the shape of an arc that matches the first frame 111, so that the connection between the slide 142 and the first frame 111 or the resistance wire 12 is more reliable.

[0069] Preferably, in the first state, a reserved spacing is provided between the position of the slide 142 and the resistance wire 12. The purpose of such a design is to reduce the matching accuracy. Preferably, when the first state is switched to the second state, the resistance value increases geometrically. No detailed description or limitation is given, and those skilled in the art can set the diameter of the first frame 111 and / or the length or cross-sectional area of ​​the resistance wire 12 according to actual conditions.

[0070] Preferably, the linkage mechanism 2 includes a connecting rod 20, such as Figure 2 As shown, the extension direction of the connecting rod 20 is parallel to the axial direction of the sliding rod 13, and the two ends of the connecting rod 20 are respectively formed with a first connecting portion 21 and a second connecting portion 22. The slider 14 is provided with a first matching portion 144 corresponding to the first connecting portion 21, and the moving contact 3 is provided with a second matching portion 31 corresponding to the second connecting portion 22. Specifically, as Figure 5 As shown, the second connecting portion 22 is a convex column. Figure 3 As shown in FIG. 1 , the second matching portion 31 is a curved groove opened at the end away from the movable contact 3 and the static contact 4, and the center of the curved groove is located on the side of the movable contact 3 away from the variable resistor assembly 1. The protrusion is slidably connected in the curved groove, and the connecting rod 20, the slider 14 and the curved groove constitute a cam slider structure. In the first state, the slider 14 is pressed on the end of the frame 11 away from the movable contact 3, as shown in FIG. Figure 2 The right end of the first frame 111 is not wound with the resistance wire 12. In the second state, the slider 14 is driven by the cam slider structure to move toward the direction close to the moving contact 3, that is, Figure 2 As shown, the slider 14 slides to the left and is pressed onto the resistance wire 12. As an alternative embodiment, the center of the curved groove can also be located on one side of the variable resistor assembly 1. Correspondingly, in the first state, the slider 14 is pressed onto the frame 11, specifically the end of the first frame 111 close to the moving contact 3, that is, the left end. In the second state, the slider 14 is driven by the cam slider structure to move away from the moving contact 3, that is, as shown in FIG. Figure 2 As shown, the resistor 12 is slid to the right and crimped onto the resistor wire 12. Specifically, as Figure 4 As shown, the first matching portion 144 is a connecting column that is perpendicular to the axis of the sliding rod 13, that is, vertically arranged at the end of the body 141 away from the resistance wire 12. Figure 5 As shown, the first connecting portion 21 is a circular axial hole arranged along the vertical axis and rotatably matched with the connecting column.

[0071] It should be noted that the current limiting structure of this embodiment is applicable to both AC circuit breakers and DC circuit breakers, and only needs to occupy a very small portion of the space of the housing of the circuit breaker.

[0072] Example 2

[0073] The circuit breaker of this embodiment, such as Figures 1 to 8 As shown, it includes a housing 7, a contact assembly installed in the housing 7, an operating mechanism 6 installed on the housing 7 for driving the contact assembly to close / open the switch, and the current limiting structure in Example 1. The contact assembly is arranged in the housing 7, and includes a moving contact 3 and a static contact 4. The operating mechanism 6 is linked to the moving contact 3 through a linkage assembly. The current limiting structure is installed in the installation cavity for installing the contact assembly in the housing 7, and is linked to the moving contact 3 of the contact assembly through a linkage mechanism 2. Since the above-mentioned current limiting structure is adopted, it also has at least the advantages of the current limiting structure of the above-mentioned embodiment 1, which will not be repeated here. At the same time, due to the current limiting structure of this embodiment, the increase in resistance during disconnection is equivalent to an increase in the arc voltage, which is conducive to arc extinguishing. Therefore, there is no need to increase the volume and opening distance of the arc extinguishing chamber to improve the arc extinguishing ability, which reduces the volume of the product and reduces the design troubles. It should be noted that the current limiting structure of this embodiment is applicable to AC circuit breakers and DC circuit breakers, and only needs to occupy a very small part of the space of the housing of the circuit breaker.

[0074] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A current limiting structure, characterized in that: include: A variable resistor component (1), one end of which is suitable for being electrically connected to a heating element (5) in a circuit breaker, and the other end of which is electrically connected to a moving contact (3) in the circuit breaker so as to be connected in series in a main circuit of the circuit breaker; A linkage mechanism (2), one end of which is linkage-connected to the variable resistance component (1), and the other end of which is linkage-connected to the moving contact (3); The variable resistor component (1) has a first state in which the resistance value tends to be zero when the moving contact (3) and the stationary contact (4) in the circuit breaker are conducting, and a second state in which the resistance value increases due to the repulsive driving force of the moving contact (3) and the stationary contact (4) when the main circuit current is too large; In the first state, the variable resistance component (1) does not limit the current of the main circuit; In the second state, the linkage mechanism (2) and the moving contact (3) work in conjunction to provide the driving force, and the variable resistance component (1) limits the current of the main circuit; The variable resistor component (1) comprises: a resistor body; A selection part, linked to the linkage mechanism, driven by the moving contact to select a desired resistance value in the first state and the second state; The resistor body comprises: A frame (11) is provided with at least one first terminal (15), and the heating element (5) is suitable for connecting to the first terminal (15) through a first wire (17); A resistance wire (12) is wound around a portion of the frame (11); A slide bar (13) is arranged above the frame (11) and has two ends thereof respectively provided with a second terminal (16), and the moving contact (3) is suitable for connecting with any of the second terminals (16) through a second wire (18); The selection part is a slider (14), which is sleeved on the slide rod (13) and connected to the linkage mechanism (2); the slider (14) abuts against the resistance wire (12) in the second state and abuts against the frame (11) in the first state; The frame (11), the sliding rod (13) and the sliding block (14) are all conductors; The linkage mechanism (2) comprises: A connecting rod (20) extending in a direction parallel to the axial direction of the sliding rod (13), and a first connecting portion (21) and a second connecting portion (22) are respectively formed at two ends of the connecting rod (20); The slider (14) is provided with a first matching portion (144) corresponding to the first connecting portion (21), and the moving contact (3) is provided with a second matching portion (31) corresponding to the second connecting portion (22); The second connecting portion (22) is slidably fitted in the second fitting portion (31), and the connecting rod (20), the slider (14) and the second fitting portion (31) form a cam slider structure.

2. The current limiting structure according to claim 1, characterized in that: The slider (14) comprises: A main body (141) is provided with a sliding hole (143) extending along the axial direction of the sliding rod (13), and the main body (141) is slidably sleeved on the sliding rod (13) through the sliding hole (143); A sliding sheet (142) is formed at one end of the main body (141) facing the frame (11), and is suitable for being crimped onto the resistance wire (12) in the second state and being crimped onto the frame (11) in the first state.

3. The current limiting structure according to claim 2, characterized in that: The sliding sheet (142) and the main body (141) are integrally formed.

4. The current limiting structure according to claim 2 or 3, characterized in that: The frame (11) comprises: The first frame (111) is arranged below the slide bar (13) in parallel with the axial direction of the slide bar (13) and is in the shape of a round rod. The cross section of the slide sheet (142) is in the shape of an arc that matches the first frame (111). The resistance wire (12) is wound around the first frame (111); At least one second frame (112) is supported below the first frame (111), and the first terminal (15) is arranged at a position of the first frame (111) where the resistance wire (12) is not wound or on the second frame (112).

5. The current limiting structure according to claim 2, characterized in that: In the first state, a reserved distance is provided between the position of the sliding sheet (142) and the resistance wire (12); and / or When the first state is switched to the second state, the resistance value increases geometrically.

6. The current limiting structure according to claim 1, characterized in that: The second connecting portion (22) is a convex column, and the second matching portion (31) is a curved groove formed at an end away from the movable contact (3) and the end where the movable contact (4) is in conduction, and the center of the curved groove is located at a side of the movable contact (3) away from the variable resistor assembly (1); In the first state, the slider (14) is pressed against an end of the frame (11) away from the moving contact (3); When the moving contact (3) and the stationary contact (4) are disconnected, the slider (14) is driven by the cam slider structure to slide in a direction close to the moving contact (3) and is pressed onto the resistance wire (12) to switch to the second state; The first matching portion (144) is a connecting column arranged perpendicular to the axis of the sliding rod (13) on the end of the sliding block (14) away from the resistance wire (12), and the first connecting portion (21) is an axial hole rotatably connected to the connecting column.

7. A circuit breaker, characterized in that: It comprises the current limiting structure as described in any one of claims 1 to 6.

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