CN113130263A

CN113130263A - Moving contact system of low-voltage molded case circuit breaker

Info

Publication number: CN113130263A
Application number: CN202110542146.9A
Authority: CN
Inventors: 吴超鹏; 令狐绍江; 卢山念; 袁辉; 袁波; 高腾飞; 陆俊谦; 臧卫
Original assignee: Zhejiang Tengen Electric Co Ltd
Current assignee: Zhejiang Tengen Electric Co Ltd
Priority date: 2021-05-18
Filing date: 2021-05-18
Publication date: 2021-07-16
Anticipated expiration: 2041-05-18
Also published as: CN113130263B

Abstract

The invention provides a moving contact system of a low-voltage molded case circuit breaker, which comprises: a housing; the moving contact component comprises a first conducting rod and a second conducting rod, wherein the first conducting rod and the second conducting rod are hinged and are provided with a rotating center; the first conducting rod is provided with a contact, the contact is arranged at one end of the first conducting rod far away from the second conducting rod, and the movable contact component has a normal state and a repulsion state; the normal state is a state for realizing closing by matching with the static contact, and the repulsion state is that an included angle a is formed between the first conducting rod and the second conducting rod, and the included angle a is an obtuse angle; the locking component is connected with the movable contact component and is used for giving a locking force F1 for keeping the normal state to the movable contact component when the movable contact component is in the normal state; the electric repulsion force pushes the first conducting rod Fc in the short-circuit fault; locking force F1 is less than urging force Fc; the circuit breaker can increase the opening distance and improve the breaking capacity of the product.

Description

Moving contact system of low-voltage molded case circuit breaker

Technical Field

The invention relates to the technical field of circuit breakers, in particular to a moving contact system of a low-voltage molded case circuit breaker.

Background

The low-voltage moulded case circuit breaker is a protective electric appliance, has certain current-limiting breaking capacity, and when a circuit is short-circuited, the circuit breaker cuts off fault current through tripping to guarantee equipment and personal safety.

When the plastic shell circuit breaker is in short-circuit breaking, a moving contact and a fixed contact of a contact mechanism are separated and disconnected, electric arcs can be generated between the moving contact and the fixed contact, and by increasing the opening distance between the moving contact and the fixed contact, the electric arc voltage can be rapidly increased, so that the increase of fault current is limited, and the electromagnetic effect of short-circuit current is reduced.

Disclosure of Invention

Therefore, the invention aims to overcome the defects of short opening distance and general current limiting effect in the prior art, and provides the moving contact system of the low-voltage molded case circuit breaker, which can increase the opening distance and improve the breaking capacity of the circuit breaker.

Therefore, the invention provides a moving contact system of a low-voltage molded case circuit breaker, which comprises: a housing; the moving contact component comprises a first conducting rod and a second conducting rod, wherein the first conducting rod and the second conducting rod are hinged and are provided with a rotating center; the first conducting rod is provided with a contact, the contact is arranged at one end of the first conducting rod far away from the second conducting rod, and the movable contact component has a normal state and a repulsion state; the normal state is a state for realizing closing by matching with the static contact, and the repulsion state is that an included angle a is formed between the first conducting rod and the second conducting rod, and the included angle a is an obtuse angle; the locking component is connected with the movable contact component and is used for giving a locking force F1 for keeping the normal state to the movable contact component when the movable contact component is in the normal state; the electric repulsion force pushes the first conducting rod Fc in the short-circuit fault; locking force F1 is less than urging force Fc.

Further: the shell is internally provided with a resetting piece, the resetting piece is positioned near the tail end of the motion trail of the moving contact component and is used for being in contact with the first conducting rod in the repulsion state, and therefore the first conducting rod is reset to the conventional state from the repulsion state.

Further: when the movable contact assembly is in the repulsion state, the locking assembly has a locking force F2 which gives the movable contact assembly a repulsion state, the contact force of the reset piece and the first conducting rod is Ff, and the locking force F2 is smaller than the contact force Ff.

Further: the locking assembly includes: the first rotating cavity is arranged on one conducting rod and positioned on one side of the rotating center, and a limiting boss, a first cavity and a second cavity are arranged in the first rotating cavity and positioned on two sides of the limiting boss; the first contact shaft is arranged on the other conducting rod and can penetrate through the first rotating cavity; in a normal state, the first contact shaft is located in the first cavity; in a repelling state, the first contact shaft is positioned in the second cavity;

and one end of the elastic part is connected with the first contact shaft or the conducting rod provided with the first contact shaft, the other end of the elastic part is connected with the conducting rod provided with the first rotating cavity or the shell, and the elastic part accumulates energy when the first contact shaft spans the limiting boss and releases the energy after the first contact shaft spans the limiting boss.

Further: the cross section of the upper surface of the limiting lug boss is an outward convex curve, the curvatures of all positions of the curve are the same or are formed by compounding arcs with different curvatures or are formed by compounding two ends of a straight line and an arc in the middle.

Further: the conducting rod provided with the first rotating cavity is also provided with a second rotating cavity, and the second rotating cavity and the first rotating cavity are respectively arranged at two sides of the rotating center; and a second contact shaft is also arranged on the other conducting rod and penetrates into the second rotating cavity.

Further: the conducting rod provided with the first rotating cavity is provided with two mounting plates, a mounting groove is formed between the two mounting plates, and the first rotating cavity and the limiting boss are arranged on the two mounting plates; and a connecting plate inserted into the mounting groove is formed on the other conducting rod, and the first contact shaft is arranged in the two first rotating cavities in a penetrating manner.

Further: the elastic piece is a tension spring, one end of the tension spring is hooked on the first contact shaft through a connecting hook ring, and the other end of the tension spring is fixed on a conducting rod provided with a first rotating cavity.

Further: the two tension springs are provided, and the connecting shackle of the two tension springs is respectively fixed at two ends of the first contact shaft; the other ends of the two tension springs are connected together or the other ends of the two tension springs are respectively fixed with a conducting rod provided with a first rotating cavity.

Further: the first contact shaft is provided with a limiting structure for limiting the connection hook ring to be separated along the axial direction of the first contact shaft; the limiting structure is a limiting groove and/or a limiting part which is positioned at the end part of the first contact shaft and protrudes.

The technical scheme of the invention has the following advantages:

1. according to the moving contact structure of the low-voltage molded case circuit breaker, the moving contact component is divided into the first conducting rod and the second conducting rod, the first conducting rod and the second conducting rod are hinged, when the moving contact is separated from the static contact due to a short-circuit fault, the second conducting rod can gradually pull away a distance from the static contact, in the process, the first conducting rod is influenced by electric repulsion force to damage a conventional state, and therefore the first conducting rod can rotate anticlockwise along a hinged point (finally reaches a repelling position), so that the distance between the moving contact component and the static contact (the distance between two contacts) can be increased undoubtedly, the increase of fault current is limited, and the electromagnetic effect of the short-circuit current is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural view of the interior of a circuit breaker housing;

figure 2 is a schematic view of another angle of the interior of the circuit breaker housing;

FIG. 3 is a schematic view of a connection structure of a circuit breaker cover plate and a limiting shaft;

fig. 4 is a schematic view of a connection structure of the movable contact system;

fig. 5 is a schematic view of a disassembled structure of parts of the moving contact system;

FIG. 6 is an enlarged view of portion A of FIG. 5;

FIG. 7 is a schematic diagram of a specific structure of a first contact shaft;

fig. 8 is a schematic structural diagram of the movable contact assembly in a normal state;

fig. 9 is a schematic structural diagram of the movable contact assembly in a repelling state.

Reference numerals: 1. a housing; 2. a moving contact assembly; 21. a first conductive rod; 22. a second conductive rod; 23. a contact; 3. a locking assembly; 31. a first rotating chamber; 32. a first contact shaft; 33. an elastic member; 4. a limiting boss; 5. a first chamber; 51. a second chamber; 6. mounting a plate; 61. mounting grooves; 7. a connecting plate; 71. a second contact shaft; 72. a second rotary chamber; 8. a connecting shaft; 81. connecting a shackle; 82. a groove; 9. a limiting groove; 91. a card slot; 92. a reset member.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Examples

The embodiment provides a moving contact system of low-voltage molded case circuit breaker, which comprises: a housing 1; the moving contact assembly 2 comprises a first conducting rod 21 and a second conducting rod 22, wherein the first conducting rod 21 and the second conducting rod 22 are hinged and have a rotating center; a contact 23 is arranged on the first conducting rod 21, the contact 23 is arranged at one end of the first conducting rod 21 far away from the second conducting rod 22, and the movable contact assembly 2 has a normal state and a repulsion state; the normal state is a state for realizing closing by matching with a static contact, and the repulsion state is that an included angle a is formed between the first conducting rod 21 and the second conducting rod 22, and the included angle a is an obtuse angle; a locking assembly 3 connected with the movable contact assembly 2 and used for giving a locking force F1 for keeping the normal state to the movable contact assembly 2 when the movable contact assembly is in the normal state; an urging force Fc of the electrically-operated repulsive force against the first conductive rod 21 at the time of short-circuit failure; locking force F1 is less than urging force Fc.

The specific improvement is as follows: as shown in fig. 1-5: the moving contact is divided into a first conducting rod 21 and a second conducting rod 22, in the breaking process, the second conducting rod 22 and the first conducting rod 21 are driven by an operating mechanism to rotate clockwise together, in the rotating process, the first conducting rod 21 can rotate clockwise again by taking a rotating center as a reference point under the action of an electric repulsive force F c, so that the opening distance is increased, therefore, through the arrangement of the first conducting rod 21 and the second conducting rod 22, after the moving contact and the static contact are repelled, the opening distance can be increased for the second time, the breaking capacity is increased, through the arrangement of the locking component 3, the first conducting rod 21 and the second conducting rod 22 can be effectively ensured to be kept stable in a specific state (for example, a conventional state capable of realizing closing along with the static contact, can remain stable in the effect of locking the subassembly, be favorable to the normal combined floodgate of circuit breaker). The first conducting rod 21 and the second conducting rod 22 can rotate, so that the separation distance can be increased for two times after the moving contact and the static contact are separated, and the breaking capacity of a product is improved.

As a switchable implementation: a reset member 92 is disposed in the housing 1, and the reset member 92 is located near the end of the motion trajectory of the movable contact assembly 2 and is used for contacting the first conductive rod 21 in the repulsion state, so as to reset the first conductive rod 21 from the repulsion state to the normal state.

The specific improvement is as follows: the reset element 92 may be a limit rod or a cover plate, the reset element 92 is disposed near a terminal position of a motion track of the movable contact assembly 2, where the terminal position is a limit position after the movable contact assembly 2 is disconnected, such a design is that, if the movable contact assembly is in a repulsion state and gradually moves to the limit position, after the first conductive rod 21 collides with and continuously contacts the limit rod or the cover plate, under the effect of a contact force Ff, the movable contact assembly 2 is reset to a normal state, that is, the first conductive rod 21 is not deflected, and for this embodiment, it corresponds to that the first conductive rod 21 and the second conductive rod 22 are reset to the same straight line again.

As a switchable implementation: the locking assembly 3 comprises: at least one first rotating cavity 31, wherein a limiting boss 4 is arranged in the first rotating cavity, and a first cavity 5 and a second cavity 51 are arranged on two sides of the limiting boss 4; a first contact shaft 32 that can pass through the first rotation chamber 31; in the normal state, the first contact shaft 32 is arranged in the first cavity 5; in the repelled state, the first contact shaft 32 is located within the second cavity 51; and an elastic member 33 having one end connected to the first contact shaft 32 or the first conductive rod 21 and the other end connected to the second conductive rod 22 or the housing 1, wherein the elastic member 33 accumulates energy before the first contact shaft 32 crosses the limit boss 4 and releases the energy after the first contact shaft crosses the limit boss 4. In a normal state, the locking assembly 3 gives the movable contact assembly 2 a locking force F1 (smaller than the electric repulsive force Fc), where the locking force F1 is formed by combining two forces, one is a friction force when the first contact shaft 32 moves (a friction force between the wall of the first cavity 5 and the limit boss 4), and the other is a deformation force to the elastic member 33. Similarly, in the repulsion state, the locking member 3 also gives a locking force to the movable contact assembly 2, where the locking force is F2 (smaller than the contact force Ff), where F2 is also formed by combining two forces, one is the friction force when the first contact shaft 32 moves (the friction force between the wall of the second chamber 51 and the limit boss 4), and the other is the deformation force to the elastic member 33.

The specific improvement is as follows: as shown in fig. 5 and 6: the locking assembly 3 comprises at least one first rotating cavity 31, a limiting boss 4 is arranged in the first rotating cavity 31, the limiting boss 4 divides the first rotating cavity 31 into a first cavity 5 and a second cavity 51, a first contact shaft 32 is further arranged in the first rotating cavity 31, the first contact shaft 32 is used for connecting the first conducting rod 21 and the second conducting rod 22, when the locking assembly is in a normal state, a contact 23 on the first conducting rod 21 is in contact with a fixed contact, and the first contact shaft 32 is located in the first cavity 5; when the circuit is disconnected, the first conducting rod 21 is separated from the fixed contact, because the electric repulsive force Fc is greater than the locking force F1, the first contact shaft 32 moves towards the second cavity 51 along the limiting boss 4, and when the movement exceeds the dead point position (i.e. the top point) of the limiting boss 4, the force of the elastic element 33 accelerates the first contact shaft 32 to move towards the second cavity 51 until the first contact shaft is stable (at this time, the movable contact assembly 2 is in a repulsion state), so that the separation distance can be increased, and the disconnection capability of the product is improved. When the movable contact assembly 2 moves to the breaking limit position continuously, the first conductive rod 21 collides with and continuously contacts the reset element 92, under the action of the contact force Ff, because the contact force Ff is greater than the locking force F2, the first contact shaft 32 moves towards the first cavity 5 along the limiting boss 4, and when the contact force Ff moves over the dead point position (i.e. the top point) of the limiting boss 4, the force of the elastic element 33 accelerates the first contact shaft 32 to move towards the first cavity 5 until the contact force is stable (at this time, the movable contact assembly 2 is in the normal state), so that the original position can be recovered to wait for the next closing.

As a switchable implementation: the first rotating cavity 31 is formed on the first conductive rod 21 or the second conductive rod 22, and the first contact shaft 32 can penetrate through the first rotating cavity 31 to connect the first conductive rod 21 and the second conductive rod 22.

As a switchable implementation: the second conducting rod 22 has the vicinity first conducting rod 21, and be two mounting panels 6 of relative parallel arrangement, and be located two mounting groove 61 between the mounting panel 6, two first rotatory chamber 31 and two the mirror image shaping is gone up at two mounting panels 6 to spacing boss 4, the shaping is gone up to first conducting rod 21 has the insertion connecting plate 7 in the mounting groove 61, first contact axle 32 is worn to locate in two first rotatory chambers 31.

The specific improvement is as follows: as shown in fig. 5 and 6: the last mounting panel 6 that has set up two parallel arrangement of second conducting rod 22, mounting groove 61 has been formed between two mounting panels 6, connecting plate 7 has been set up on the first conducting rod 21, connecting plate 7 can insert and accomplish the connection of first conducting rod 21 and second conducting rod 22 in the mounting groove 61, setting through mounting panel 6 and mounting groove 61, can make things convenient for the articulated rotation of first conducting rod 21 and second conducting rod 22, and the medial surface of two mounting panels 6 contacts with first conducting rod 21 respectively, increase electrically conductive area, it is better to make electrically conductive effect.

As a switchable implementation: be equipped with second contact axle 71 on the connecting plate 7, the shaping has the confession on the mounting panel 6 second contact axle 71 wears to establish and restricts the second rotary cavity 72 of its orbit of rotating.

The specific improvement is as follows: as shown in fig. 4, 5 and 6: a second contact shaft 71 is fixed on the connecting plate 7; the mounting plate 6 is formed with a second rotating cavity 72, the second rotating cavity 72 and the first rotating cavity 31 are respectively disposed at two sides of the rotating center, and the second contact shaft 71 penetrates into the second rotating cavity 72, which is beneficial to the stability of the rotation between the first conductive rod 21 and the second conductive rod 22.

As a switchable implementation: the elastic member 33 is a tension spring, one end of the tension spring is hooked on the first contact shaft 32 through a connecting hook ring 81, and the other end of the tension spring is fixed on the second conductive rod 22.

The specific improvement is as follows: as shown in fig. 3, 4 and 5: the elastic element 33 is a tension spring, one end of the tension spring is hooked on the first contact shaft 32, the other end is fixed on the second conducting rod 22, (due to the limit function of the limit boss 4, when the first contact shaft 32 is located in the first cavity 5, the tension spring will not automatically jump to the second cavity 51, at this time, the tension spring is in a stretching state, when the short circuit is broken, the first conducting rod 21 drives the first contact shaft 32 to cross the limit boss 4 under the action of large electric repulsion force, and jump to the second cavity 51, the tension spring contracts, the first conducting rod 21 and the second conducting rod 22 are in a repelling state, the first conducting rod 21 is locked under the action of tension of the tension spring, so that the first conducting rod cannot fall down), the shell 1 is provided with a cover plate and a limit shaft, when the moving contact component is repelled to the highest position, the first conducting rod 21 is contacted with the limit shaft, the first conductor bar 21 and the second conductor bar 22 are reset from the repulsion state due to the interference of the stopper shaft.

As a switchable implementation: the extension springs are two, the two extension springs are respectively located on two side surfaces of the second conducting rod 22, a connecting shackle 81 is respectively arranged on the two extension springs, and the two connecting shackles 81 are respectively fixed at two ends of the first contact shaft 32.

The specific improvement is as follows: as shown in fig. 4 and 5: the extension spring is provided with the connecting shackle 81, and through the setting of connecting shackle 81, can make the extension spring produce the linkage relation with first contact axle 32 and first conducting rod 21, the extension spring sets up two and is located the both sides face of second conducting rod 22 respectively, so helps the effort balance in first contact axle 32 both sides, makes first contact axle 32 can be more stable when strideing across spacing boss 4.

As a switchable implementation: the two tension springs are connected through a connecting shaft 8, and a groove 82 for the connecting shaft 8 to be clamped is formed in the second conducting rod 22.

As a switchable implementation: the groove 82 is used for clamping the connecting shaft and the second conducting rod.

As a switchable implementation: the cross section of the upper surface of the limiting boss 4 is a convex curve, the curvatures of all positions of the curve are the same (namely, an arc surface with the same radius) or are formed by compounding arc lines with different curvatures or by compounding the arc lines with straight lines at two ends and the arc line in the middle. The convex curve configuration facilitates sliding movement of the first contact shaft 32 in a curve.

The specific improvement is as follows: through the arrangement of the groove 82, the connecting shaft 8 can be fixedly connected with the second conducting rod 22, and the connecting shaft 8 cannot be easily separated due to the arrangement of the L-shaped groove.

As a switchable implementation: the first contact shaft 32 is provided with a limiting structure for limiting the connection shackle 81 to be separated along the axial direction of the first contact shaft 32; the limiting structure is a limiting groove 9 and/or a limiting part which is positioned at the end part of the first contact shaft 32 and protrudes.

The specific improvement is as follows: as shown in fig. 7, the limiting structure is a combination of a limiting part 9 and a limiting part, that is, a limiting groove 9 for the connecting shackle 81 to be clamped in and a clamping groove 91 suitable for installing a clamping spring are formed on the first contact shaft 32, and the clamping spring abuts against the outer side surface of the connecting shackle 81.

Through the setting of spacing groove 9 and jump ring, can effectually prevent that the spring from rocking and breaking away from first contact axle 32.

The working principle of the moving contact system of the low-voltage molded case circuit breaker is as follows:

in the normal state: the first conductor bar and the second conductor bar 22 are in a straight angle state as shown in fig. 8, and at this time, the first contact shaft 32 of the first conductor bar 21 is clamped in the first cavity 5 under the pulling force of the tension spring.

When the short circuit is opened: because the electric repulsion force is rapidly increased, the first conductive rod 21 rotates clockwise along the hinge point with the second conductive rod 22 under the action of the larger electric repulsion force, the first contact shaft 32 of the first conductive rod 21 rotates into the second cavity 51 from the first cavity 5 after overcoming the pulling force of the elastic member 33 and the resistance of the limit boss 4, and is clamped in the second cavity 51 under the pulling force of the elastic member 33 (i.e. in a repulsion state as shown in fig. 9, at this time, the first conductive rod 21 does not fall off), then the first conductive rod 21 and the second conductive rod 22 as an integral component continue to separate from the static contact under the driving of the electric repulsion force and the operating mechanism, until the first conductive rod 21 receives the limit action of the cover plate and the limit shaft when rotating to the highest point, after the pulling force of the first contact shaft 32 of the first conductive rod 21 overcomes the pulling force of the elastic member 33 and the resistance of the limit boss 4, from the second cavity 51 back into the first cavity 5, the first conductive rod 21 and the second conductive rod 22 are disposed at a straight angle as shown in fig. 4.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. A movable contact system of a low-voltage molded case circuit breaker is characterized by comprising:

a housing (1);

the movable contact assembly (2) comprises a first conducting rod (21) and a second conducting rod (22), wherein the first conducting rod (21) and the second conducting rod (22) are hinged and have a rotating center; a contact (23) is arranged on the first conducting rod (21), the contact (23) is arranged at one end of the first conducting rod (21) far away from the second conducting rod (22), and the movable contact component (2) has a normal state and a repulsion state; the normal state is a state for realizing closing by matching with a static contact, and the repulsion state is that an included angle a is formed between a first conductive rod (21) and a second conductive rod (22), and the included angle a is an obtuse angle;

a locking assembly (3) connected to the movable contact assembly (2) for imparting a locking force F1 for maintaining a normal state to the movable contact assembly (2) when it is in the normal state;

an urging force Fc of the electrically-operated repulsive force against the first conductive rod (21) at the time of short-circuit failure;

locking force F1 is less than urging force Fc.

2. The movable contact system of a low-voltage molded case circuit breaker according to claim 1, wherein: a reset piece (92) is arranged in the shell (1), and the reset piece (92) is located near the tail end of the motion trail of the movable contact component (2) and is used for being in contact with the first conducting rod (21) in the repulsion state, so that the first conducting rod (21) is reset to the normal state from the repulsion state.

3. The movable contact system of a low-voltage molded case circuit breaker according to claim 2, wherein: when the moving contact component (2) is in a repulsion state, the locking component (3) has a locking force F2 which gives the moving contact component (2) a repulsion state, the contact force of the resetting piece (92) and the first conducting rod (21) is Ff, and the locking force F2 is smaller than the contact force Ff.

4. The movable contact system of a low-voltage molded case circuit breaker according to claim 3, wherein: the locking assembly (3) comprises:

the first rotating cavity (31) is arranged on one conducting rod and is positioned on one side of the rotating center, a limiting boss (4) is arranged in the first rotating cavity (31), and a first cavity (5) and a second cavity (51) are positioned on two sides of the limiting boss (4);

a first contact shaft (32) arranged on the other conductive rod and capable of passing through the first rotating cavity (31); in a normal state, the first contact shaft (32) is located within the first cavity (5); in a repelled state, the first contact shaft (32) is located within the second cavity (51);

elastic component (33), one end with first contact axle (32) or be provided with the conducting rod of first contact axle (32) and link to each other, the other end links to each other with conducting rod or casing (1) that are provided with first rotatory chamber, elastic component (33) are in first contact axle (32) are strideed across accumulate energy when spacing boss (4), and it stridees across release energy behind spacing boss (4).

5. The movable contact system of a low-voltage molded case circuit breaker according to claim 4, wherein: the cross section of the upper surface of the limiting boss (4) is a convex curve, the curvatures of all positions of the curve are the same or are formed by compounding arcs with different curvatures or are formed by compounding arcs with straight lines at two ends and arcs in the middle.

6. The movable contact system of a low-voltage molded case circuit breaker according to claim 4, wherein: a second rotating cavity (72) is also arranged on the conducting rod provided with the first rotating cavity (31), and the second rotating cavity (72) and the first rotating cavity (31) are respectively arranged at two sides of the rotating center; and a second contact shaft (71) is also arranged on the other conducting rod, and the second contact shaft (71) penetrates into the second rotating cavity (72).

7. The movable contact system of a low-voltage molded case circuit breaker according to claim 4, 5 or 6, wherein: the conducting rod provided with the first rotating cavity (31) is provided with two mounting plates (6), a mounting groove (61) is formed between the two mounting plates (6), and the first rotating cavity (31) and the limiting boss (4) are arranged on the two mounting plates (6); and a connecting plate (7) inserted into the mounting groove (61) is formed on the other conducting rod, and the first contact shaft (32) penetrates through the two first rotating cavities (31).

8. The movable contact system of a low-voltage molded case circuit breaker according to claim 7, wherein: elastic component (33) are the extension spring, the one end of extension spring through connect shackle (81) hook hang in on first contact axle (32), the other end is fixed in on the conducting rod that is equipped with first rotatory chamber (31).

9. The movable contact system of a low-voltage molded case circuit breaker according to claim 8, wherein: the number of the tension springs is two, and connecting shackles (81) of the two tension springs are respectively fixed at two ends of the first contact shaft (32); the other ends of the two tension springs are connected together or the other ends of the two tension springs are respectively fixed with a conductive rod provided with a first rotating cavity (31).

10. The movable contact system of a low-voltage molded case circuit breaker according to claim 6 or 7, wherein: the first contact shaft (32) is provided with a limiting structure for limiting the connection shackle (81) to be separated along the axial direction of the first contact shaft (32); the limiting structure is a limiting groove (9) and/or a limiting part which is positioned at the end part of the first contact shaft (32) and protrudes.