Plastic shell type circuit breaker

Abstract

The invention relates to the technical field of circuit breakers, and discloses a plastic shell type circuit breaker which comprises a shell, a tripping mechanism and a contact assembly, the contact assembly comprises a moving contact and a static contact, the plastic shell type circuit breaker further comprises an overload protection mechanism, the overload protection mechanism comprises a first bimetallic strip and a time delay assembly, the first bimetallic strip is vertically arranged, and the time delay assembly is arranged in the shell. The lower end of the first bimetallic strip is connected to the moving contact, the upper end of the first bimetallic strip corresponds to the tripping mechanism, the delay assembly comprises a displacement control module and a second bimetallic strip, the displacement control module is driven by thermal deformation of the second bimetallic strip, and a bending path of the first bimetallic strip is limited or released through displacement state switching, so that delay tripping judgment is realized. The invention provides a plastic shell type circuit breaker which can solve or at least alleviate the problems that a traditional circuit breaker is unreliable in time delay adjustment, prone to being interfered by environment temperature and poor in stability.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers, and particularly to a molded case circuit breaker. Background Art

[0002] In traditional molded case circuit breakers, when a current greater than the rated current passes through the circuit breaker, the bimetallic strip is heated and bent. The bending amount of the bimetallic strip is greater than the gap between the bimetallic strip and the traction rod. The traction rod is pushed by the adjusting screw on the bimetallic strip and rotates forward to trip the circuit breaker, thereby realizing the overload protection of the circuit and equipment. Therefore, the gap between the bimetallic strip and the traction rod determines the rated current in the molded case circuit breaker.

[0003] However, circuit breakers similar to the above have at least the following technical defects: Unreliable delay adjustment: The method of controlling the gap by adjusting the screw cannot adjust the delay time after encapsulation; Environmental temperature interference: The upper and lower circuit breakers are prone to mis-triggering due to heat dissipation differences. The upper circuit breaker may trip prior to the lower circuit breaker in a high-temperature environment, resulting in a large-scale power outage; Reset and stability problems: The linear displacement trigger of the bimetallic strip is prone to jamming, resulting in delayed or misjudged tripping actions.

[0004] In an actual circuit, circuit breakers are usually arranged in multiple stages. When an overload occurs in a certain lower-level circuit, both the lower-level circuit breaker on this lower-level circuit and the upper-level circuit breaker to which this lower-level circuit belongs will overheat. And due to the heat dissipation rate, the bending of the bimetallic strip is irreversible in a short time. The working environments of the upper-level circuit breaker and the lower-level circuit breaker are different. When the environmental temperature of the upper-level circuit breaker is higher than that of the lower-level circuit breaker, it may occur that the upper-level circuit breaker disconnects prior to the lower-level circuit breaker, or after the lower-level circuit breaker disconnects, the upper-level circuit breaker still disconnects, causing all lower-level circuits to be in a disconnected state. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art, solve or at least alleviate the problems of unreliable delay adjustment, susceptibility to environmental temperature interference, and poor stability of traditional circuit breakers, and provide a molded case circuit breaker.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A molded case circuit breaker, comprising a housing, a tripping mechanism, and a contact assembly. The contact assembly includes a moving contact and a stationary contact, and further includes an overload protection mechanism. The overload protection mechanism includes a first bimetallic strip and a delay component. The first bimetallic strip is vertically arranged, the lower end of the first bimetallic strip is connected to the moving contact, and the upper end corresponds to the tripping mechanism; The delay component includes a displacement control module and a second bimetallic strip. The displacement control module is driven by the thermal deformation of the second bimetallic strip and restricts or releases the bending path of the first bimetallic strip by switching the displacement state to achieve delayed tripping judgment.

[0007] In order to further realize the present invention, the following technical solutions may be preferably selected: Preferably, the displacement control module includes a limit rod and a first spring, and the initial position of the limit rod blocks the bending of the first bimetallic strip; when the thermal deformation of the second bimetallic strip reaches a threshold value, the limit rod disengages from the blocking position, releasing the force-accumulating bending path of the first bimetallic strip.

[0008] Preferably, the limit rod is longitudinally slidably arranged in the housing, the lower end of the limit rod is located between the first bimetallic strip and the tripping mechanism, the second bimetallic strip is transversely arranged, the rear end is connected to the moving contact, and the front end is pressed against the upper end of the limit rod, forming a dual response mechanism of heat conduction and mechanical linkage.

[0009] Preferably, the moving contact comprises a vertical section and a horizontal section, the lower end of the first bimetallic strip is connected to the vertical section, and the rear end of the second bimetallic strip is connected to the horizontal section.

[0010] Preferably, the overload protection mechanism further includes a regulating component, which includes a second spring and a regulating screw. The pressure of the second spring on the second bimetallic strip is changed by the regulating screw, and the delay time is corrected to adapt to the ambient temperature.

[0011] Preferably, the regulating screw is threadably sleeved on the housing and its upper end is exposed outside the housing, and the upper and lower ends of the second spring respectively abut against the lower end of the regulating screw and the front end of the second bimetallic strip.

[0012] Preferably, the elastic force ratio of the second spring to the first spring is 1:1.5-2.0.

[0013] Preferably, the housing is provided with a thermometer, and the thermometer is used to measure and display the air temperature in the housing.

[0014] Preferably, it also includes a short-circuit protection mechanism, which includes a rotating armature and a short-circuit electromagnet. The rotating armature is pivotally connected to the housing through a torsion spring, and the short-circuit electromagnet coil is connected in series to the main circuit of the circuit breaker. When a short circuit occurs, the electromagnet attracts the lower end of the armature to drive the tripping mechanism to operate.

[0015] Preferably, a buffer gasket is provided on a side of the upper end of the rotating armature facing the tripping mechanism.

[0016] The beneficial effects of the present invention are: 1. The present invention limits the first bimetallic strip by a limit rod to prevent the first bimetallic strip from hitting the tripping mechanism. When the load continues to increase, the bending displacement of the second bimetallic strip causes the limit rod to separate from the first bimetallic strip. At this time, the upper end of the first bimetallic strip quickly and forcefully hits the tripping mechanism. The linear displacement of the bimetallic strip in the traditional overload protection is changed to a segmented displacement to improve the accuracy of the judgment, and the strip is in a power storage state when not triggered, ensuring that there is enough position and force when triggered, thereby avoiding jamming during transmission.

[0017] 2. The present invention adjusts the elastic force of the second spring by changing the height position of the regulating screw relative to the housing. The second bimetallic strip must overcome the elastic force of the second spring when bending upward. By adjusting the elastic force of the second spring, the delay time can be controlled according to the ambient temperature to avoid the upper circuit breaker being disconnected before the lower circuit breaker.

[0018] 3. The elastic force of the second spring of the present invention can also offset the elastic force of the first spring, preventing the second bimetallic strip from bending when the elastic force of the first spring is larger; at the same time, after the first bimetallic strip bends and triggers the tripping mechanism, the elastic force of the second spring is first reduced by the regulating screw to move the limit rod upward to ensure the first bimetallic strip is reset, and then the regulating screw is reset after the first bimetallic strip is reset. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural cross-sectional view of the present invention.

[0020] Figure 2 It is a schematic diagram of the structure of the present invention.

[0021] Figure 3 For the present invention Figure 1 Enlarged view of point A in the middle.

[0022] Figure 4 It is a schematic diagram of the structure of the present invention with the housing and the front head removed.

[0023] Figure 5 It is a structural schematic diagram of the overload protection mechanism of the present invention.

[0024] Figure 6 It is a schematic structural diagram of the moving contact of the present invention.

[0025] The accompanying drawings are marked as follows: 1-housing; 2-tripping mechanism; 3-moving contact; 4-stationary contact; 5-first bimetallic strip; 6-second bimetallic strip; 7-limiting rod; 8-second spring; 9-regulating screw; 10-rotating armature; 301-vertical section; 302-horizontal section. DETAILED DESCRIPTION

[0026] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present invention.

[0028] Embodiment 1 In a traditional plastic case circuit breaker, when a current greater than the rated current passes through the circuit breaker, the bimetallic strip is heated and bent. The bending amount of the bimetallic strip is greater than the gap between the bimetallic strip and the traction rod. The traction rod is pushed by the adjusting screw on the bimetallic strip and rotates forward to trip the circuit breaker, thereby realizing the overload protection of the line and equipment. Therefore, the gap between the bimetallic strip and the traction rod determines the rated current in the plastic case circuit breaker.

[0029] In an actual circuit, circuit breakers are usually set in multiple levels. When an overload occurs in a certain lower-level circuit, both the lower-level circuit breaker on this lower-level circuit and the upper-level circuit breaker to which this lower-level circuit belongs will overheat. And due to the heat dissipation rate, the bending of the bimetallic strip is irreversible in a short time, and the working environments of the upper-level circuit breaker and the lower-level circuit breaker are different. When the ambient temperature of the upper-level circuit breaker is higher than that of the lower-level circuit breaker, it may occur that the upper-level circuit breaker disconnects before the lower-level circuit breaker, or after the lower-level circuit breaker disconnects, the upper-level circuit breaker still disconnects, resulting in all lower-level circuits being in a disconnected state.

[0030] Referring to Figures 1 - 6 , this embodiment discloses a plastic case circuit breaker, which includes a housing 1, an operating mechanism, a tripping mechanism 2, and a contact assembly. The contact assembly includes a moving contact 3 and a static contact 4. The tripping mechanism 2 is used to drive the moving contact 3 to separate from the static contact 4; It also includes an overload protection mechanism. The overload protection mechanism includes a first bimetallic strip 5 which is vertically arranged. The lower end of the first bimetallic strip 5 is thermally connected to the moving contact 3, and the upper end of the first bimetallic strip 5 corresponds to the tripping mechanism 2. When the current increases and is overloaded, the temperature of the moving contact 3 rises. After the first bimetallic strip 5 rises with the temperature of the moving contact 3, the upper end of the first bimetallic strip 5 bends towards the tripping mechanism 2, and the tripping mechanism 2 trips, causing the moving contact 3 to disconnect from the static contact 4. The structure of the tripping mechanism 2 here is a conventional design and will not be elaborated in detail in this embodiment.

[0031] The overload protection mechanism also includes a delay component. When the current is relatively large but not large enough, the first bimetallic strip 5 does not drive the tripping mechanism 2. After waiting for a period of time, if the temperature continues to rise, then the first bimetallic strip 5 drives the tripping mechanism 2 to trip. If the temperature does not continue to rise, then the first bimetallic strip 5 does not drive the tripping mechanism 2 to trip.

[0032] The delay component includes a limit rod 7 and a second bimetallic strip 6. The limit rod 7 is longitudinally slidably arranged in the housing 1 and is located between the tripping mechanism 2 and the first bimetallic strip 5. The second bimetallic strip 6 is horizontally arranged. The rear end of the second bimetallic strip 6 is thermally connected to the moving contact 3, and the front end of the second bimetallic strip 6 presses against the upper end of the limit rod 7.

[0033] When the load is relatively large but not large enough, the front end of the second bimetallic strip 6 bends upward, and the limit rod 7 moves upward with the bending of the second bimetallic strip 6. However, the lower end of the limit rod 7 still remains between the tripping mechanism 2 and the first bimetallic strip 5, preventing the first bimetallic strip 5 from bending and pressing against the tripping mechanism 2.

[0034] When the load does not continue to increase, the front end of the second bimetallic strip 6 no longer bends upward, and the limit rod 7 maintains its current position. When the lower end of the limit rod 7 blocks the upper end of the first bimetallic strip 5 from pressing against the tripping mechanism 2.

[0035] When the load continues to increase, the front end of the second bimetallic strip 6 continues to bend upward, and the limit rod 7 continues to move upward. When the lower end of the limit rod 7 disengages from between the tripping mechanism 2 and the first bimetallic strip 5, the upper end of the first bimetallic strip 5 presses against the tripping mechanism 2, causing the tripping mechanism 2 to trip.

[0036] After the first bimetallic strip 5 is bent by heat, it is blocked by the limit rod 7, and the first bimetallic strip 5 stores energy by its own elasticity. When the limit rod 7 moves upward and disengages from the first bimetallic strip 5, the first bimetallic strip 5 quickly bends towards the tripping mechanism 2, ensuring the stability and rapidity of the action of the tripping mechanism 2.

[0037] A first spring is arranged between the limit rod 7 and the housing 1. The first spring drives the limit rod 7 to move upward relative to the housing 1, enabling the limit rod 7 to move upward when the second bimetallic strip 6 bends upward, so as to disengage from the first bimetallic strip 5.

[0038] It also includes a short-circuit protection mechanism, which is used to drive the tripping mechanism 2 to trip when a short circuit occurs. The short-circuit protection mechanism includes a rotating armature 10 and a short-circuit electromagnet. The middle part of the rotating armature 10 is rotated and arranged on the housing 1 through a torsion spring. The upper end of the rotating armature 10 is far away from the tripping mechanism 2. The short-circuit electromagnet is located on the side of the lower end of the rotating armature 10 away from the tripping mechanism 2 and its coil is connected in series to the main circuit of the circuit breaker. When the circuit is short-circuited or severely overloaded, the short-circuit electromagnet attracts the lower end of the rotating armature 10, so that the upper end of the rotating armature 10 abuts against the tripping mechanism 2, so that the tripping mechanism 2 is actuated, and the moving contact 3 is separated from the static contact 4. A buffer gasket is provided on the side of the upper end of the rotating armature 10 facing the tripping mechanism 2.

[0039] The moving contact 3 includes a vertical section 301 and a horizontal section 302 . The horizontal section 302 is located on a side of the vertical section 301 away from the tripping mechanism 2 and above the vertical section 301 . The lower end of the first bimetallic strip 5 is connected to the vertical section 301 , and the rear end of the second bimetallic strip 6 is connected to the horizontal section 302 .

[0040] The present invention limits the first bimetallic strip 5 by the limiting rod 7 to prevent the first bimetallic strip 5 from hitting the tripping mechanism 2. When the load continues to increase, the bending displacement of the second bimetallic strip 6 causes the limiting rod 7 to separate from the first bimetallic strip 5. At this time, the upper end of the first bimetallic strip 5 quickly and forcefully hits the tripping mechanism 2. The linear displacement of the bimetallic strip in the traditional overload protection is changed to a segmented displacement to improve the accuracy of the judgment, and it is in a power storage state when not triggered, ensuring that there is enough position and force when triggered, avoiding jamming during transmission.

[0041] Embodiment 2 The bending amount of the bimetallic strip of a traditional circuit breaker is greater than the gap between the bimetallic strip and the pull rod. The pull rod is pushed by the adjusting screw on the bimetallic strip, and the pull rod is rotated forward to trip the circuit breaker. The delay time is controlled by changing the distance between the adjusting screw and the pull rod. After the circuit breaker is packaged, the delay time cannot be adjusted. When the ambient temperatures of the upper and lower circuit breakers are different, the upper circuit breaker may still be disconnected before the lower circuit breaker.

[0042] Furthermore, in the first embodiment, the limiting rod 7 is driven to move upward by the first spring. When the elastic force of the first spring is large, the limiting rod 7 is likely to drive the second bimetallic strip 6 to bend, causing the limiting rod 7 to be separated from the first bimetallic strip 5 earlier, and the first bimetallic strip 5 is not easy to reset after bending and triggering the tripping mechanism 2. When the elastic force of the first spring is small, the first spring is likely to fail and cannot move upward in time when overloaded.

[0043] Reference Figures 1 - 6, in this embodiment, the overload protection mechanism further includes a regulation component, which includes a second spring 8 and a regulation screw 9. The second spring 8 is longitudinally arranged above the second bimetal 6. The regulation screw 9 is arranged on the housing, and the upper end of the regulation screw 9 protrudes from the housing. The upper end of the second spring 8 abuts against the regulation screw 9, and the lower end abuts against the front end of the second bimetal 6.

[0044] Among them, the ratio of the elastic force of the second spring 8 to that of the first spring is 1:1.5 - 2.0.

[0045] In addition, the housing 1 is provided with a thermometer, which is used to measure and display the air temperature inside the housing 1, so as to adjust the elastic force of the second spring 8 more accurately according to the temperature.

[0046] By changing the height position of the regulation screw 9 relative to the housing, the elastic force of the second spring 8 is adjusted. When the second bimetal 6 bends upward, it needs to overcome the elastic force of the second spring 8. By adjusting the elastic force of the second spring 8, when controlling the delay time, the delay time can be adjusted according to the ambient temperature, so as to avoid the upper circuit breaker disconnecting before the lower circuit breaker.

[0047] Moreover, the elastic force of the second spring 8 can also offset the elastic force of the first spring, avoiding the second bimetal 6 being bent when the elastic force of the first spring is large. At the same time, after the first bimetal 5 bends to trigger the tripping mechanism 2, first reduce the elastic force of the second spring 8 through the regulation screw 9 to make the limiting rod 7 move upward to ensure the reset of the first bimetal 5, and then reset the regulation screw 9 after the first bimetal 5 is reset.

[0048] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitution or change, and should be covered by the protection scope of the present invention.

Claims

1. A plastic case circuit breaker, comprising a housing, a tripping mechanism and a contact assembly, the contact assembly comprising a moving contact and a static contact, characterized in that, It also includes an overload protection mechanism, which includes a first bimetallic strip and a delay assembly, wherein the first bimetallic strip is vertically arranged, the lower end of the first bimetallic strip is connected to the moving contact, and the upper end corresponds to the tripping mechanism; The delay component includes a displacement control module and a second bimetallic strip. The displacement control module is driven by the thermal deformation of the second bimetallic strip and restricts or releases the bending path of the first bimetallic strip by switching the displacement state to achieve delayed tripping judgment.

2. The plastic case circuit breaker according to claim 1, characterized in that, The displacement control module includes a limit rod and a first spring. The initial position of the limit rod blocks the bending of the first bimetallic strip. When the thermal deformation of the second bimetallic strip reaches a threshold, the limit rod disengages from the blocking position, releasing the force-accumulating bending path of the first bimetallic strip.

3. The plastic case circuit breaker according to claim 2, wherein, The limit rod is longitudinally slidably arranged in the shell, and the lower end of the limit rod is located between the first bimetallic strip and the tripping mechanism. The second bimetallic strip is transversely arranged, with the rear end connected to the moving contact and the front end pressing against the upper end of the limit rod, thereby forming a dual response mechanism of heat conduction and mechanical linkage.

4. The plastic case circuit breaker according to claim 3, characterized in that, The moving contact comprises a vertical section and a horizontal section. The lower end of the first bimetallic strip is connected to the vertical section, and the rear end of the second bimetallic strip is connected to the horizontal section.

5. The plastic case circuit breaker according to claim 2, characterized in that, The overload protection mechanism also includes a regulating component, which includes a second spring and a regulating screw. The pressure of the second spring on the second bimetallic strip is changed by the regulating screw, and the delay time is corrected to adapt to the ambient temperature.

6. The plastic case circuit breaker according to claim 5, characterized in that, The regulating screw is threadedly sleeved on the housing and its upper end is exposed outside the housing. The upper and lower ends of the second spring respectively abut against the lower end of the regulating screw and the front end of the second bimetallic strip.

7. The plastic case circuit breaker according to claim 5, wherein, The elastic force ratio of the second spring to the first spring is 1:1.5-2.

0.

8. The plastic case circuit breaker according to claim 5, characterized in that, The shell is provided with a thermometer, and the thermometer is used to measure and display the air temperature in the shell.

9. The plastic case circuit breaker according to claim 1, characterized in that, It also includes a short-circuit protection mechanism, which includes a rotating armature and a short-circuit electromagnet. The rotating armature is pivotally connected to the housing through a torsion spring, and the short-circuit electromagnet coil is connected in series to the main circuit of the circuit breaker. When a short circuit occurs, the electromagnet attracts the lower end of the armature to drive the tripping mechanism to operate.

10. The plastic case circuit breaker according to claim 9, wherein, A buffer gasket is provided on one side of the upper end of the rotating armature facing the tripping mechanism.

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