A plastic housing type circuit breaker

Abstract

The application 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, further comprises an overload protection mechanism, the overload protection mechanism comprises a first bimetal and a time delay assembly, the first bimetal is vertically arranged, the lower end of the first bimetal is connected to the moving contact, and the upper end corresponds to the tripping mechanism, the time delay assembly comprises a displacement control module and a second bimetal, the displacement control module is driven by the thermal deformation of the second bimetal, the bending path of the first bimetal is limited or released through displacement state switching, and time delay tripping determination is realized. The application provides a plastic shell type circuit breaker which can solve or at least alleviate the problems of unreliable time delay adjustment of a traditional circuit breaker, easy disturbance by environmental temperature and poor stability.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and more particularly to a plastic-cased circuit breaker. Background Technology

[0002] In a traditional molded case circuit breaker, when a current greater than the rated current passes through the circuit breaker, the bimetallic strip is heated and bends. 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, causing the traction rod to rotate forward and trip the circuit breaker, thereby achieving overload protection for the line 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 like the ones described above have at least the following technical defects:

[0004] Delay adjustment is unreliable: the delay time cannot be adjusted after packaging by controlling the gap through adjusting screws;

[0005] Ambient temperature interference: Due to differences in heat dissipation, upstream and downstream circuit breakers are prone to false triggering. The upstream circuit breaker may trip before the downstream circuit breaker due to high temperature environment, causing a large-scale power outage.

[0006] Reset and stability issues: The linear displacement trigger of the bimetallic strip is prone to jamming, which can lead to delays or misjudgments in the tripping action.

[0007] In actual circuits, circuit breakers are usually configured in multiple stages. When an overload occurs in a downstream circuit, both the downstream circuit breaker and the upstream circuit breaker associated with that downstream circuit will overheat. Furthermore, due to the rate of heat dissipation, the bending of the bimetallic strip is irreversible in a short time. Since the operating environments of the upstream and downstream circuit breakers are at different temperatures, if the ambient temperature of the upstream circuit breaker is higher than that of the downstream circuit breaker, the upstream circuit breaker may trip before the downstream circuit breaker, or the downstream circuit breaker may trip while the upstream circuit breaker remains open, resulting in all downstream circuits being disconnected. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art, solve or at least alleviate the problems of unreliable delay adjustment, susceptibility to ambient temperature interference, and poor stability of traditional circuit breakers, and to provide a plastic-cased circuit breaker.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a plastic-cased circuit breaker, comprising a casing, a tripping mechanism, and a contact assembly, wherein the contact assembly includes a moving contact and a stationary contact, and further includes an overload protection mechanism, wherein the overload protection mechanism includes a first bimetallic strip and a time delay component, 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;

[0010] 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, thereby realizing the delayed tripping determination.

[0011] To further realize the present invention, the following technical solutions may be preferred:

[0012] Preferably, the displacement control module includes a limiting rod and a first spring. The limiting rod initially blocks the bending of the first bimetallic strip. When the deformation of the second bimetallic strip due to heat reaches a threshold, the limiting rod disengages from the blocking position, releasing the stored bending path of the first bimetallic strip.

[0013] Preferably, the limiting rod is longitudinally slidably disposed within the housing, with the lower end of the limiting rod located between the first bimetallic strip and the tripping mechanism, and the second bimetallic strip being laterally disposed, with its rear end connected to the moving contact and its front end pressing against the upper end of the limiting rod, thus forming a dual response mechanism of thermal conduction and mechanical linkage.

[0014] Preferably, the moving contact includes a vertical section and a horizontal section, with the lower end of the first bimetallic strip connected to the vertical section and the rear end of the second bimetallic strip connected to the horizontal section.

[0015] Preferably, the overload protection mechanism further includes an adjustment component, which includes a second spring and an adjustment screw. The adjustment screw changes the pressure of the second spring on the second bimetallic strip, and corrects the delay time to adapt to the ambient temperature.

[0016] Preferably, the adjusting screw is threaded onto 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 adjusting screw and the front end of the second bimetallic strip.

[0017] Preferably, the ratio of the elastic force of the second spring to that of the first spring is 1:1.5-2.0.

[0018] Preferably, the housing is equipped with a thermometer for measuring and displaying the air temperature inside the housing.

[0019] 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 via a torsion spring, and the coil of the short-circuit electromagnet is connected in series with the main circuit of the circuit breaker. When a short circuit occurs, the electromagnet attracts the lower end of the armature, driving the tripping mechanism to operate.

[0020] Preferably, a buffer pad is provided on the side of the rotating armature facing the release mechanism at its upper end.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention limits the first bimetallic strip by using a limiting rod to prevent it from contacting the tripping mechanism. As the load continues to increase, the bending displacement of the second bimetallic strip causes the limiting rod to disengage from the first bimetallic strip. At this time, the upper end of the first bimetallic strip quickly and forcefully contacts the tripping mechanism. By changing the linear displacement of the bimetallic strip in traditional overload protection to a segmented displacement, the accuracy of the judgment is improved. Furthermore, it is in a storage state when not triggered, ensuring sufficient position and force when triggered, thus avoiding jamming during transmission.

[0023] 2. This invention adjusts the elastic force of the second spring by changing the height position of the adjusting screw relative to the outer shell. When the second bimetallic strip bends upward, it must overcome the elastic force of the second spring. By adjusting the elastic force of the second spring, the delay time can be controlled according to the ambient temperature, thus preventing the upstream circuit breaker from tripping before the downstream circuit breaker.

[0024] 3. The elastic force of the second spring of the present invention can also counteract the elastic force of the first spring, so as to prevent the second bimetallic strip from bending when the elastic force of the first spring is too large; at the same time, after the first bimetallic strip triggers the tripping mechanism by bending, the elastic force of the second spring is reduced by adjusting the screw first, so that the limit rod moves up to ensure the first bimetallic strip is reset, and the adjusting screw is reset after the first bimetallic strip is reset. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the structure of the present invention.

[0027] Figure 3 For the present invention Figure 1 Enlarged view of point A in the middle.

[0028] Figure 4 This is a schematic diagram of the structure of the present invention with the outer shell and front protrusion removed.

[0029] Figure 5 This is a schematic diagram of the overload protection mechanism of the present invention.

[0030] Figure 6 This is a schematic diagram of the structure of the moving contact of the present invention.

[0031] The attached figures are labeled as follows:

[0032] 1-Housing; 2-Triggering mechanism; 3-Moving contact; 4-Stationary contact; 5-First bimetallic strip; 6-Second bimetallic strip; 7-Limiting rod; 8-Second spring; 9-Adjusting screw; 10-Rotating armature; 301-Vertical section; 302-Horizontal section. Detailed Implementation

[0033] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] In a traditional molded case circuit breaker, when a current greater than the rated current passes through the circuit breaker, the bimetallic strip is heated and bends. 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, causing the traction rod to rotate forward and trip the circuit breaker, thereby achieving overload protection for the line and equipment. Therefore, the gap between the bimetallic strip and the traction rod determines the rated current in the molded case circuit breaker.

[0037] In actual circuits, circuit breakers are usually configured in multiple stages. When an overload occurs in a downstream circuit, both the downstream circuit breaker and the upstream circuit breaker associated with that downstream circuit will overheat. Furthermore, due to the rate of heat dissipation, the bending of the bimetallic strip is irreversible in a short time. Since the operating environments of the upstream and downstream circuit breakers are at different temperatures, if the ambient temperature of the upstream circuit breaker is higher than that of the downstream circuit breaker, the upstream circuit breaker may trip before the downstream circuit breaker, or the downstream circuit breaker may trip while the upstream circuit breaker remains open, resulting in all downstream circuits being disconnected.

[0038] Reference Figures 1-6 This embodiment discloses a plastic-cased circuit breaker, including a housing 1, an operating mechanism, a tripping mechanism 2, and a contact assembly. The contact assembly includes a moving contact 3 and a stationary contact 4. The tripping mechanism 2 is used to drive the moving contact 3 to separate from the stationary contact 4.

[0039] It also includes an overload protection mechanism, which 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 an overload occurs, the temperature of the moving contact 3 rises. As the temperature of the moving contact 3 rises, the upper end of the first bimetallic strip 5 bends toward the tripping mechanism 2, and the tripping mechanism 2 trips, causing the moving contact 3 to disconnect from the stationary contact 4. The structure of the tripping mechanism 2 here is a conventional design, and it will not be described in detail in this embodiment.

[0040] The overload protection mechanism also includes a time 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 a period of time, if the temperature continues to rise, the first bimetallic strip 5 drives the tripping mechanism 2 to trip. If the temperature does not continue to rise, the first bimetallic strip 5 does not drive the tripping mechanism 2 to trip.

[0041] The delay component includes a limiting rod 7 and a second bimetallic strip 6. The limiting rod 7 is longitudinally slidably disposed in the housing 1 and located between the tripping mechanism 2 and the first bimetallic strip 5. The second bimetallic strip 6 is laterally disposed. The rear end of the second bimetallic strip 6 is thermally connected to the moving contact 3. The front end of the second bimetallic strip 6 is pressed against the upper end of the limiting rod 7.

[0042] When the load is relatively large but not large enough, the front end of the second bimetallic strip 6 bends upward, and the limiting rod 7 moves upward with the bending of the second bimetallic strip 6. However, the lower end of the limiting rod 7 is still located between the tripping mechanism 2 and the first bimetallic strip 5, preventing the first bimetallic strip 5 from bending and hitting the tripping mechanism 2.

[0043] 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 remains in its current position. When the lower end of the limit rod 7 blocks the upper end of the first bimetallic strip 5 from reaching the release mechanism 2.

[0044] As the load continues to increase, the front end of the second bimetallic strip 6 continues to bend upward, and the limiting rod 7 continues to move upward. When the lower end of the limiting rod 7 disengages from the release mechanism 2 and the first bimetallic strip 5, the upper end of the first bimetallic strip 5 abuts against the release mechanism 2, causing the release mechanism 2 to release.

[0045] After the first bimetallic strip 5 is heated and bent, it is blocked by the limiting rod 7. The first bimetallic strip 5 stores force by its own elasticity. When the limiting rod 7 moves upward and disengages from the first bimetallic strip 5, the first bimetallic strip 5 quickly bends towards the release mechanism 2, ensuring the stability and speed of the release mechanism 2.

[0046] A first spring is provided between the limiting rod 7 and the housing 1. The first spring drives the limiting rod 7 to move upward relative to the housing 1, so that when the second bimetallic strip 6 bends upward, the limiting rod 7 can move upward and thus disengage from the first bimetallic strip 5.

[0047] 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 rotatably mounted on the housing 1 via a torsion spring. The upper end of the rotating armature 10 is 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 with the main circuit of the circuit breaker. When a short circuit or severe overload occurs in the circuit, the short-circuit electromagnet attracts the lower end of the rotating armature 10, causing the upper end of the rotating armature 10 to abut against the tripping mechanism 2, causing the tripping mechanism 2 to operate, and the moving contact 3 to separate from the stationary contact 4. A buffer pad is provided on the side of the upper end of the rotating armature 10 facing the tripping mechanism 2.

[0048] The moving contact 3 includes a vertical section 301 and a horizontal section 302. The horizontal section 302 is located on the 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.

[0049] This invention uses a limiting rod 7 to limit the first bimetallic strip 5, preventing it from contacting the tripping mechanism 2. As the load continues to increase, the bending displacement of the second bimetallic strip 6 causes the limiting rod 7 to disengage from the first bimetallic strip 5. At this point, the upper end of the first bimetallic strip 5 quickly and forcefully contacts the tripping mechanism 2. This invention changes the linear displacement of the bimetallic strip in traditional overload protection to a segmented displacement, improving the accuracy of the judgment. Furthermore, it maintains a stored-force state when not triggered, ensuring sufficient position and force upon triggering and preventing jamming during transmission.

[0050] Example 2

[0051] In traditional circuit breakers, the bending of the bimetallic strip exceeds the gap between the bimetallic strip and the traction rod. The traction rod is pushed by the adjusting screw on the bimetallic strip, causing it to rotate forward and trip the circuit breaker. The delay time is controlled by changing the distance between the adjusting screw and the traction rod. However, once the circuit breaker is encapsulated, the delay time cannot be adjusted. Furthermore, when the ambient temperatures of the upstream and downstream circuit breakers are different, the upstream circuit breaker may still trip before the downstream circuit breaker.

[0052] Furthermore, in Embodiment 1, the limiting rod 7 is driven upward by the first spring. When the spring force of the first spring is large, the limiting rod 7 is prone to bending the second bimetallic strip 6, causing the limiting rod 7 to disengage from the first bimetallic strip 5 prematurely. Moreover, the first bimetallic strip 5 is not easy to reset after the bending triggers the tripping mechanism 2. When the spring force of the first spring is small, the first spring is prone to failure and cannot move upward in time under overload.

[0053] Reference Figures 1-6In this embodiment, the overload protection mechanism further includes a control component, which includes a second spring 8 and a control screw 9. The second spring 8 is longitudinally disposed above the second bimetallic strip 6, and the control screw 9 is disposed in the housing. The upper end of the control screw 9 protrudes from the housing, and the upper end of the second spring 8 abuts against the control screw 9 and the lower end abuts against the front end of the second bimetallic strip 6.

[0054] The ratio of the elastic force of the second spring 8 to that of the first spring is 1:1.5-2.0.

[0055] In addition, the housing 1 is equipped with a thermometer, which is used to measure and display the air temperature inside the housing 1, so as to adjust the spring force of the second spring 8 more accurately according to the temperature.

[0056] The spring force of the second spring 8 is adjusted by changing the height position of the adjusting screw 9 relative to the housing. When the second bimetallic strip 6 bends upward, it must overcome the spring force of the second spring 8. By adjusting the spring force of the second spring 8, the delay time can be controlled. The delay time can be adjusted according to the ambient temperature to prevent the upstream circuit breaker from tripping before the downstream circuit breaker.

[0057] Furthermore, the elastic force of the second spring 8 can also counteract the elastic force of the first spring, preventing the second bimetallic strip 6 from bending when the elastic force of the first spring is too large. At the same time, after the first bimetallic strip 5 triggers the tripping mechanism 2 by bending, the elastic force of the second spring 8 is reduced by adjusting the screw 9, causing the limit rod 7 to move upward, ensuring that the first bimetallic strip 5 is reset. After the first bimetallic strip 5 is reset, the adjusting screw 9 is reset.

[0058] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A plastic-cased circuit breaker, comprising a housing, a tripping mechanism, and a contact assembly, wherein the contact assembly includes a moving contact and a stationary contact, characterized in that, It also includes an overload protection mechanism, which includes a first bimetallic strip and a time delay component. The first bimetallic strip is vertically arranged, with its lower end connected to the moving contact and its upper end corresponding 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, thereby realizing the delayed tripping determination. The displacement control module includes a limiting rod and a first spring. The limiting rod initially blocks the bending of the first bimetallic strip. When the deformation of the second bimetallic strip due to heat reaches a threshold, the limiting rod disengages from the blocking position, releasing the stored bending path of the first bimetallic strip. The limiting rod is longitudinally slidably disposed inside the housing, with its lower end located between the first bimetallic strip and the tripping mechanism. The second bimetallic strip is arranged laterally, with its rear end connected to the moving contact and its front end pressing against the upper end of the limiting rod, thus forming a dual response mechanism of thermal conduction and mechanical linkage.

2. The plastic-cased circuit breaker according to claim 1, characterized in that, The moving contact includes a vertical section and a horizontal section, with the lower end of the first bimetallic strip connected to the vertical section and the rear end of the second bimetallic strip connected to the horizontal section.

3. The plastic-cased circuit breaker according to claim 1, characterized in that, The overload protection mechanism also includes a control component, which includes a second spring and a control screw. The control screw changes the pressure of the second spring on the second bimetallic strip, and corrects the delay time to adapt to the ambient temperature.

4. The plastic-cased circuit breaker according to claim 3, characterized in that, The adjusting screw is threaded onto the housing with its upper end exposed outside the housing. The upper and lower ends of the second spring respectively abut against the lower end of the adjusting screw and the front end of the second bimetallic strip.

5. The plastic-cased circuit breaker according to claim 3, characterized in that, The ratio of the elastic force of the second spring to that of the first spring is 1:1.5-2.

0.

6. The plastic-cased circuit breaker according to claim 3, characterized in that, The housing is equipped with a thermometer, which is used to measure and display the air temperature inside the housing.

7. The plastic-cased 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 via a torsion spring, and the coil of the short-circuit electromagnet is connected in series with the main circuit of the circuit breaker. When a short circuit occurs, the short-circuit electromagnet attracts the lower end of the rotating armature, driving the tripping mechanism to operate.

8. The plastic-cased circuit breaker according to claim 7, characterized in that, The upper end of the rotating armature is provided with a buffer pad on the side facing the release mechanism.

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