Contact pressure control mechanism and molded case circuit breaker

Abstract

The utility model relates to a contact pressure control mechanism and a molded case circuit breaker. The contact pressure control mechanism comprises a contact support. One end of the movable contact bridge is rotationally connected with the contact support, and the other end of the movable contact bridge is close to and attached to the static contact bridge along with forward rotation or far away from the static contact bridge along with reverse rotation; the movable contact bridge is provided with a sliding end; the lever is rotationally arranged on the contact support and comprises a first limiting surface and a second limiting surface which are obliquely connected; the sliding end abuts against the first limiting face and the second limiting face in a sliding mode. Two ends of the contact spring are respectively connected with the lever and the contact support, so that the second limiting surface abuts against the sliding end and provides forward rotation torque for the movable contact bridge during closing; and when the movable contact bridge is separated, the movable contact bridge rotates reversely. According to the utility model, the anti-falling capability is realized after the moving contact bridge is repelled, the moment applied to the moving contact bridge in the repelling process is stable, the repelling speed is high, the current limiting capability is strong, and the short-circuit protection capability of the circuit breaker is facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection equipment, in particular to a contact pressure control mechanism and a molded case circuit breaker. Background Art

[0002] Molded case circuit breakers are used in AC and DC low-voltage power grids to connect and disconnect current. They are generally composed of an operating mechanism, an arc extinguishing system, a contact system, a casing, and a trip unit. The contact system is an important part and plays an important role in reliability and breaking capacity.

[0003] The contact system of a molded case circuit breaker is connected through the contact between the moving contact bridge and the static contact bridge. The contact support is equipped with a contact spring. When the circuit is closed, the contact spring provides contact force between the moving and static contacts, and the moving contact bridge has an overtravel to ensure contact reliability. In the connected state, an electric repulsion force is generated between the moving and static contacts. When a short-circuit current is generated, the electric repulsion force increases sharply. Under the action of the electric repulsion force, the moving contact bridge quickly overcomes the spring force of the contact spring to separate the moving and static contacts. However, in this process, the spring force increases with the separation distance. The moving contact bridge will fall after rotating an angle and re-contact the static contact bridge. This action will occur multiple times before the operating mechanism performs the tripping action, thereby generating multiple arcs and damaging the moving and static contacts. The moving and static contacts may even be welded together and cannot be opened, and the circuit breaker loses its basic protection function.

[0004] Existing patent CN102427001A discloses a contact pressure control mechanism for a molded case low-voltage circuit breaker. Contact pressure is generated by a contact spring pressing against the front side of the upper end of a lever, and then the rear side of the upper end of the lever applies force to the moving contact bridge. The two continuous surfaces of the rear side of the upper end of the lever have a certain angle. In the process of repelling and clamping the moving contact bridge, the lever will deflect significantly around the axis of the lower end, and the spring will also twist and deform accordingly, thereby reducing the spring force, affecting the reliability and service life of the circuit breaker. Summary of the Invention

[0005] The purpose of the utility model is to provide a contact pressure control mechanism and a molded case circuit breaker in order to overcome the defects of the contact system of the existing molded case circuit breaker such as easy damage and short service life.

[0006] The purpose of the utility model can be achieved through the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a contact pressure control mechanism, comprising:

[0008] Contact support;

[0009] A movable contact bridge, one end of which is rotatably connected to the contact support, and the other end of which approaches and fits the stationary contact bridge as it rotates in the forward direction, or moves away from the stationary contact bridge as it rotates in the reverse direction; a sliding end is provided on the movable contact bridge;

[0010] The lever is rotatably mounted on the contact support and comprises a first limiting surface and a second limiting surface that are obliquely connected; the sliding end is in sliding contact with the first limiting surface and the second limiting surface;

[0011] The contact spring has two ends connected to the lever and the contact support, and can drive the lever to rotate in the opposite direction so that

[0012] When closing the circuit breaker, the second limit surface abuts against the sliding end and provides a forward rotational torque for the moving contact bridge; when the short-circuit current is large enough to cause the moving contact bridge and the static contact bridge to be repelled, and the circuit breaker has not yet triggered the trip, the moving contact bridge rotates in the opposite direction, and the sliding end slides from the second limit surface to the first limit surface, the first limit surface abuts against the sliding end, and provides a reverse rotational torque for the moving contact bridge.

[0013] In some specific embodiments, a first hole groove is provided on the contact support, and a first through hole of a moving contact bridge is provided on the moving contact bridge. A first connecting shaft passes through the first through hole of the moving contact bridge and into the first hole groove, so that the moving contact bridge and the contact support rotate around the first connecting shaft.

[0014] In some specific embodiments, a third hole is provided on the contact support, and a lever through hole is provided on the lever. A second connecting shaft passes through the lever through hole and into the third hole, so that the contact support and the lever rotate around the second connecting shaft.

[0015] In some specific embodiments, the axis of the third hole is parallel to the axis of the first hole.

[0016] In some specific embodiments, a third limiting surface for limiting the reverse rotation of the moving contact bridge is provided on the contact support.

[0017] In some specific embodiments, a second through hole of the moving contact bridge is provided at the bottom of the moving contact bridge, a sliding shaft passes through the second through hole of the moving contact bridge, and the end of the sliding shaft slides along the second limiting surface and the first limiting surface.

[0018] In some specific embodiments, a spring hole for fixing one end of the contact spring is formed on the lever.

[0019] In some specific embodiments, a second hole is formed on the contact support, the other end of the contact spring is sleeved on the third connecting shaft, and the third connecting shaft is also inserted into the second hole.

[0020] In some specific embodiments, the axis of the second hole is parallel to the axis of the first hole of the contact support, and the spring hole is also oriented toward the second hole.

[0021] The second technical solution of the present invention is to provide a molded case circuit breaker, including the contact pressure control mechanism as described in one of the above technical solutions, and including a shell that accommodates the contact pressure control mechanism. When the molded case circuit breaker trips, the shell is used to limit the reverse rotation of the moving contact bridge to reset it.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention provides a stable torque on the moving contact bridge during the opening process, a fast opening speed, and a strong current limiting capability. When the opening reaches a certain angle, there is a stage where the torque provided by the contact spring decreases to 0, which increases the opening speed and is beneficial to the short-circuit protection capability of the circuit breaker.

[0024] (2) The utility model has the ability to prevent the moving contact bridge from falling after being opened, reducing contact wear during the disconnection process and increasing the service life of the molded case circuit breaker.

[0025] (3) The utility model uses a tension spring as a contact spring. When the moving contact bridge is subjected to electric repulsion and moves, the spring always remains straight and does not twist, thereby improving the service life of the spring and the reliability of the circuit breaker.

[0026] (4) The lever in the utility model applies force to the moving contact bridge through the riveted shaft, and the structure is reliable and durable.

[0027] (5) As a contact pressure control mechanism that can be used for multiple moving contact bridges, the utility model has good short-term tolerance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of the utility model when the contacts are closed;

[0029] Figure 2 This is a schematic diagram of the structure of the utility model when the contacts are open;

[0030] Figure 3 This is a schematic diagram of the structure of the utility model when the contacts are opened;

[0031] Figure 4 This is a schematic cross-sectional structural diagram of the contact support in the present utility model;

[0032] Figure 5 It is a structural diagram of the lever in the utility model;

[0033] Figure 6This is a schematic diagram of the structure of the dynamic contact bridge in the utility model;

[0034] Figure 7 It is a schematic diagram of part of the internal structure of the utility model;

[0035] Figure 8 This is a schematic diagram of the force and lever arm when the utility model is closed;

[0036] Figure 9 It is a schematic diagram of the force and lever arm when the utility model is repelled and opened.

[0037] The following are marked in the figure:

[0038] 1 is the contact support, 11 is the first hole slot, 12 is the second hole slot, 13 is the third hole slot, 14 is the third limiting surface, 2 is the moving contact bridge, 21 is the first through hole of the moving contact bridge, 22 is the top surface, 23 is the second through hole of the moving contact bridge, 3 is the first connecting shaft, 4 is the lever, 41 is the first limiting surface, 42 is the second limiting surface, 43 is the lever through hole, 44 is the spring hole, 5 is the contact spring, 6 is the third connecting shaft, 7 is the second connecting shaft, 8 is the sliding shaft, 9 is the static contact bridge, and 10 is the housing. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0041] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0042] In the following embodiments, unless otherwise specified, functional components or structures are conventional components or structures used in the art to achieve corresponding functions.

[0043] Example 1:

[0044] like Figure 1-7As shown, this embodiment provides a contact pressure control mechanism, including a contact support 1; a movable contact bridge 2, one end of which is rotatably connected to the contact support 1, and the other end of which approaches and fits the stationary contact bridge 9 as it rotates in the forward direction, or moves away from the stationary contact bridge 9 as it rotates in the reverse direction; a sliding end is provided on the movable contact bridge 2; a lever 4 is rotatably provided on the contact support 1, and includes a first limiting surface 41 and a second limiting surface 42 that are obliquely connected; the sliding end slides against the first limiting surface 41 and the second limiting surface 42; a contact spring 5 , the two ends are respectively connected to the lever 4 and the contact support 1, and can drive the lever 4 to rotate in the opposite direction, so that when the circuit breaker is closed, the second limit surface 42 abuts against the sliding end and provides a positive rotation torque for the moving contact bridge 2; when the short-circuit current is large enough to cause the moving contact bridge 2 and the static contact bridge 9 to be repelled, and the circuit breaker has not yet triggered the trip, the moving contact bridge 2 rotates in the opposite direction, and the sliding end slides from the second limit surface 42 to the first limit surface 41, and the first limit surface 41 abuts against the sliding end and provides a reverse rotation torque for the moving contact bridge 2.

[0045] Through this embodiment, when the contact pressure control mechanism is in the closed state, the contact spring 5 applies a torque to the moving contact bridge 2 through the lever 4, thereby providing contact pressure, so that the moving contact bridge 2 is in stable contact with the static contact bridge 9, that is, the contact spring 5 applies a clockwise torque to the moving contact bridge 2 through the lever 4, that is, providing a positive rotational torque to the moving contact bridge 2, and the moving contact bridge 2 contacts the second limit surface 42, providing contact pressure when closing.

[0046] When the short-circuit current is large enough to cause the moving contact bridge 2 and the stationary contact bridge 9 to repel each other, and the circuit breaker has not yet tripped, an electromotive repulsive force is generated between the moving contact bridge 2 and the stationary contact bridge 9. Under the action of this electromotive repulsive force, the moving contact bridge 2 rotates. When it rotates to a certain angle, the direction of the force exerted by the lever 4 on the moving contact bridge 2 changes, and the direction of the torque exerted on the moving contact bridge 2 by the contact spring 5 changes. The moving contact bridge 2 rotates until it is stuck between the contact support 1 and the lever 4. At this time, the moving contact bridge 2 reaches the repelled state. That is, a huge electromotive repulsive force is generated at the point where the moving contact bridge 2 contacts the stationary contact bridge 9, causing the moving contact bridge 2 to separate from the stationary contact bridge 9. At this time, the moving contact bridge 2 rotates counterclockwise and disengages from the second limit surface 42. The direction of the torque exerted by the contact spring 5 on the moving contact bridge 2 through the lever 4 changes from clockwise to counterclockwise, providing the moving contact bridge 2 with a reverse rotational torque. At this time, the contact pressure control mechanism is in the repelled state. Since the direction of the torque applied by the lever 4 to the moving contact bridge 2 is counterclockwise, the moving contact bridge 2 is subjected to anti-drop contact pressure after being pushed open, which can effectively improve the current limiting capacity and accelerate the breaking speed, reduce contact wear during the breaking process, and increase the service life of the molded case circuit breaker.

[0047] When the short-circuit current is large enough to cause the circuit breaker to trigger the tripping action after the movable contact bridge 2 and the static contact bridge 9 are repelled, the contact pressure control mechanism rotates counterclockwise as a whole, so that the movable contact bridge 2 touches the limiting surface such as the packaging shell of the contact pressure control mechanism. Under the limiting action of the limiting surface, the movable contact bridge 2 overcomes the counterclockwise torque in the repelled state and rotates clockwise relative to the contact support 1, thereby rebounding and resetting.

[0048] In this embodiment, the contact support 1 and the movable contact bridge 2, as well as the contact support 1 and the lever 4, are rotatably connected via connecting shafts. For example, the contact support 1 is provided with a first slot 11, and the movable contact bridge 2 is provided with a first movable contact bridge through-hole 21. The first connecting shaft 3 passes through the first movable contact bridge through-hole 21 and into the first slot 11, allowing the movable contact bridge 2 and the contact support 1 to rotate about the first connecting shaft 3. The contact support 1 is provided with a third slot 13, and the lever 4 is provided with a lever through-hole 43. The second connecting shaft 7 passes through the lever through-hole 43 and into the third slot 13, allowing the contact support 1 and the lever 4 to rotate about the second connecting shaft 7. Furthermore, the axis of the third slot 13 is parallel to the axis of the first slot 11, so that the rotation plane of the movable contact bridge 2 and the rotation plane of the lever 4 are parallel to each other.

[0049] The second limiting surface 42 is perpendicular to the horizontal plane, and the first limiting surface 41 is inclined toward the stationary contact bridge 9. This allows the movable contact bridge 2 to utilize the slope of the first limiting surface 41 when moving away from the second limiting surface 42 in the opposite direction. The arc transition between the first limiting surface 41 and the second limiting surface 42 ensures smooth changes in the torque applied to the movable contact bridge 2, thereby ensuring smooth and rapid opening of the contact pressure control mechanism.

[0050] The contact support 1 is provided with a third limiting surface 14 for limiting the reverse rotation of the moving contact bridge 2. On the one hand, it limits the maximum angle of reverse rotation of the moving contact bridge 2 to avoid affecting the service life of the contact spring 5; on the other hand, it is also to ensure that when the contact pressure control mechanism is tripped, the moving contact bridge 2 can be limited in a suitable position to rebound and complete reset.

[0051] Therefore, when the short-circuit current is large enough to cause the moving contact bridge 2 and the static contact bridge 9 to be repelled, but the circuit breaker has not yet tripped, the moving contact bridge 2 is subjected to the electric repulsive force, and the direction of the torque applied by the contact spring 5 to the moving contact bridge 2 through the lever 4 changes from clockwise to counterclockwise, that is, providing the moving contact bridge 2 with a reverse rotation torque. Finally, the third limit surface 14 on the contact support 1 abuts against the top surface 22 of the moving contact bridge 2. At this time, the contact pressure control mechanism is in the repelled state.

[0052] When the short-circuit current is high enough to cause the moving contact bridge 2 and the stationary contact bridge 9 to be pulled apart and the circuit breaker to trip, the contact pressure control mechanism as a whole rotates counterclockwise, causing the moving contact bridge 2 to strike a limiting surface, such as the housing of the contact pressure control mechanism. Under the limiting force of the limiting surface, the moving contact bridge 2 rebounds to its initial position. That is, under the limiting action of the limiting surface, the moving contact bridge 2 overcomes the counterclockwise torque in the pulled-apart state and rebounds clockwise relative to the contact support 1, thereby contacting the second limiting surface 42 again and restoring the moving contact bridge 2.

[0053] To enhance the smoothness and durability of the sliding between the movable contact bridge 2 and the lever 4, in this embodiment, a second movable contact bridge through-hole 23 is provided at the bottom of the movable contact bridge 2. A sliding shaft 8 passes through the second movable contact bridge through-hole 23. The ends of the sliding shaft 8 serve as sliding ends, sliding along the second limiting surface 42 and the first limiting surface 41. The sliding shaft 8 can be riveted to the second movable contact bridge through-hole 23 to form a riveted shaft. The lever 4 applies force to the movable contact bridge 2 through the riveted shaft, resulting in a reliable and durable structure.

[0054] In this embodiment, the contact spring 5 is a tension spring, and the lever 4 is provided with a spring hole 44 for securing one end of the contact spring 5. The contact support 1 is provided with a second slot 12, and the other end of the contact spring 5 is sleeved on the third connecting shaft 6, which is also inserted into the second slot 12.

[0055] Since the first hole slot 11 connects the contact support 1 and the moving contact bridge 2, the spring hole 44 connects the lever 4 and the contact spring 5, the axis of the second hole slot 12 is parallel to the axis of the first hole slot 11, and the spring hole 44 is also facing the direction of the second hole slot 12, so that the contact support 1, the contact spring 5 and the lever 4 can act synergistically on the moving contact bridge 2, and the contact spring 5 always remains straight during operation and will not twist, thereby improving the service life of the contact spring 5 and the reliability of the molded case circuit breaker.

[0056] Therefore, in the contact pressure control mechanism of the first embodiment, when the contact pressure control mechanism is in the closed state, the sliding shaft 8 at the bottom of the movable contact bridge 2 contacts the second limit surface 42 of the lever 4, and the contact spring 5 applies a clockwise torque to the movable contact bridge 2 through the lever 4, providing the contact pressure when closing. Figure 8 The acceptance and force arm schematic diagram of the closing state is shown, F1 is the force of the contact spring 5 on the lever 4, L1 is the force arm of F1 on the lever 4 relative to the rotation center of the lever 4; F2 is the force applied by the lever 4 on the moving contact bridge 2, L2 is the force arm of F2 relative to the rotation center of the lever 4, L3 is the force arm of F2 relative to the rotation center of the moving contact bridge 2; F3 is the force of the static contact bridge 9 on the moving contact bridge 2, L4 is the force arm of F3 relative to the rotation center of the moving contact bridge 2.

[0057] When the short-circuit current is large enough to cause the moving contact bridge 2 and the static contact bridge 9 to be repelled, but the circuit breaker has not yet tripped, a huge electric repulsive force is generated at the contact position between the moving contact bridge 2 and the static contact bridge 9, and the moving contact bridge 2 is separated from the static contact bridge 9. The moving contact bridge 2 rotates counterclockwise with the axis of the first hole groove 11 (i.e., the first connecting shaft 3) as the rotation center, and the sliding shaft 8 slides from the second limiting surface 42 to the first limiting surface 41. At this time, the direction of the torque applied by the contact spring 5 to the moving contact bridge 2 through the lever 4 changes from clockwise to counterclockwise, and finally the third limiting surface 14 on the contact support 1 presses against the top surface 22 of the moving contact bridge 2. At this time, the contact pressure control mechanism is in a repelled state.

[0058] When the short-circuit current is large enough to cause the circuit breaker to trigger the tripping action after the moving contact bridge 2 and the static contact bridge 9 are repelled, the contact pressure control mechanism rotates counterclockwise to the opening position. Under the limiting action of the limiting surface such as the packaging shell of the contact pressure control mechanism, the moving contact bridge 2 overcomes the counterclockwise torque in the repelled state and rotates clockwise around the axis of the first hole groove 11 (i.e., the first connecting shaft 3) relative to the contact support 1. The sliding shaft 8 slides from the first limiting surface 41 to the second limiting surface 42, thereby resetting the moving contact bridge 2.

[0059] Figure 9 Figure 1 is a schematic diagram of the forces and lever arms in the repulsive state. During the repulsive process, the sliding shaft 8 first slides upward from the bottom on the second limit surface 42, and the lever 4 rotates a small angle clockwise. At this time, the contact spring 5 is stretched, and the spring force F1 increases. Simultaneously, the position of the spring hole 44 changes, the direction of the force applied by the contact spring 5 changes, and the torque L1 decreases. As the sliding shaft 8 slides upward, it moves away from the rotation center of the lever 4, and the lever arm L2 increases. The angle of the lever 4's force F2 on the sliding shaft 8 changes, and the lever arm L3 decreases. As the lever arms L1, L2, and L3 change, although the spring force F1 gradually increases, the torque applied to the moving contact bridge 2 does not change much. In other words, the rotational torque applied to the moving contact bridge 2 remains stable during this process. When the sliding shaft 8 slides through the transition surface from the second limit surface 42 to the first limit surface 41, the force arm L3 will gradually decrease to 0 and then gradually increase. The contact surface between the sliding shaft 8 and the lever 4 is converted to the first limit surface 41. At this time, the force of the lever 4 on the moving contact bridge 2 is counterclockwise relative to the rotation center of the moving contact bridge 2. The moving contact bridge 2 rotates counterclockwise until the top surface 22 touches the third limit surface 14 and then stops. At this time, it reaches the repelling position. In the process of the sliding shaft 8 passing through the transition surface, when the force wall L3 is 0, the moving contact bridge 2 is not affected by the force of the contact spring 5, thereby accelerating the repelling speed of the moving contact bridge 2, which is helpful for current limiting and arc extinguishing capabilities.

[0060] Example 2:

[0061] This embodiment provides a molded case circuit breaker, which includes the contact pressure control mechanism of Example 1 and a housing 10 that accommodates the contact pressure control structure. When the molded case circuit breaker trips, the housing 10 is used to limit the reverse rotation of the moving contact bridge 2 to reset it.

[0062] When a short circuit occurs in the line and triggers the tripping action, the contact pressure control mechanism rotates counterclockwise as a whole, causing the moving contact bridge 2 to touch the housing 10. Under the limiting action of the housing 10, the moving contact bridge 2 rebounds, overcomes the counterclockwise torque in the repelled state, and rotates clockwise relative to the contact support 1, thereby rebounding and resetting.

[0063] The above description of the embodiments is intended to facilitate understanding and use of the utility model by those skilled in the art. Those skilled in the art will readily be able to make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the utility model is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of this utility model without departing from the scope of this utility model should be within the scope of protection of this utility model.

Claims

1. A contact pressure control mechanism, characterized in that: include: Contact support (1); The movable contact bridge (2) has one end rotatably connected to the contact support (1), and the other end approaches and fits the stationary contact bridge (9) as it rotates in the forward direction, or moves away from the stationary contact bridge (9) as it rotates in the reverse direction; a sliding end is provided on the movable contact bridge (2); A lever (4) is rotatably mounted on the contact support (1), comprising a first limiting surface (41) and a second limiting surface (42) connected in an oblique manner; the sliding end is slidably abutted against the first limiting surface (41) and the second limiting surface (42); The contact spring (5) has two ends connected to the lever (4) and the contact support (1) respectively, and can drive the lever (4) to rotate in the opposite direction so that When the circuit breaker is closed, the second limit surface (42) contacts the sliding end and provides a forward rotational torque to the moving contact bridge (2); when the short-circuit current is large enough to cause the moving contact bridge (2) and the static contact bridge (9) to be separated and the circuit breaker has not yet triggered a trip, the moving contact bridge (2) rotates in the reverse direction, and the sliding end slides from the second limit surface (42) to the first limit surface (41), and the first limit surface (41) contacts the sliding end and provides a reverse rotational torque to the moving contact bridge (2).

2. The contact pressure control mechanism according to claim 1, characterized in that: The contact support (1) is provided with a first hole groove (11), and the movable contact bridge (2) is provided with a first through hole (21) of the movable contact bridge. A first connecting shaft (3) passes through the first through hole (21) of the movable contact bridge and penetrates into the first hole groove (11), so that the movable contact bridge (2) and the contact support (1) rotate around the first connecting shaft (3).

3. The contact pressure control mechanism according to claim 2, characterized in that: A third hole groove (13) is provided on the contact support (1), and a lever through hole (43) is provided on the lever (4). A second connecting shaft (7) passes through the lever through hole (43) and penetrates into the third hole groove (13), so that the contact support (1) and the lever (4) rotate around the second connecting shaft (7).

4. The contact pressure control mechanism according to claim 3, characterized in that: The axis of the third hole groove (13) is parallel to the axis of the first hole groove (11).

5. The contact pressure control mechanism according to claim 1, characterized in that: The contact support (1) is provided with a third limiting surface (14) for limiting the reverse rotation of the movable contact bridge (2).

6. The contact pressure control mechanism according to claim 1, characterized in that: A second through hole (23) of the movable contact bridge is provided at the bottom of the movable contact bridge (2), a sliding shaft (8) passes through the second through hole (23) of the movable contact bridge, and an end of the sliding shaft (8) serves as the sliding end to slide along the second limiting surface (42) and the first limiting surface (41).

7. The contact pressure control mechanism according to claim 1, characterized in that: The lever (4) is provided with a spring hole (44) for fixing one end of the contact spring (5).

8. The contact pressure control mechanism according to claim 7, characterized in that: The contact support (1) is provided with a second hole slot (12), the other end of the contact spring (5) is sleeved on the third connecting shaft (6), and the third connecting shaft (6) is also inserted into the second hole slot (12).

9. The contact pressure control mechanism according to claim 8, characterized in that: The axis of the second hole slot (12) is parallel to the axis of the first hole slot (11) of the contact support (1), and the spring hole (44) is also oriented toward the second hole slot (12).

10. A molded case circuit breaker comprising the contact pressure control mechanism according to any one of claims 1 to 9, characterized in that: It comprises a housing (10) for accommodating the contact pressure control mechanism. When the molded case circuit breaker trips, the housing (10) is used to limit the reverse rotation of the moving contact bridge (2) to reset it.

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