A magnetic trip system for a miniature circuit breaker

Abstract

The application discloses a magnetic tripping system of a small circuit breaker, which is installed in a shell of the small circuit breaker and comprises a wiring terminal plate, a current detection component and a coil component. The current detection component is arranged on the wiring terminal plate. The coil component comprises a winding coil, a core component, a magnetic yoke and a static contact. The winding coil is wound around the periphery of the core component. The core component is arranged in the magnetic yoke. One end of the winding coil is welded with the wiring terminal plate, and the other end is spot-welded with one end of the static contact on the magnetic yoke, so that the wiring terminal plate, the winding coil and the static contact form a current passage. The magnetic tripping system has only one spot-welding point between the wiring terminal plate and the coil, the sectional area of the current detection component is relatively large, the temperature rise of the product can meet the requirements, and the magnetic tripping system is small in size and can realize the miniaturization requirement of the small circuit breaker.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and in particular to a magnetic tripping system for a miniature circuit breaker. Background Technology

[0002] Miniature circuit breakers (MCBs) are the most widely used terminal protection devices in electrical distribution systems. MCBs have a basically fixed shape, size, and wiring method, and are typically used at the very end of a power distribution line, installed on multiple branches to protect and control electrical equipment. With the development and demands of Internet of Things (IoT) technology, it is necessary to install current sensing components on MCBs to collect their current readings, but it is desirable that the size of the MCBs not increase significantly.

[0003] The patent with publication number CN110444447A discloses "a miniature circuit breaker" which has a current detection device and a thermomagnetic trip unit installed inside the housing. It occupies a large amount of usable space and is not suitable for small circuit breakers in small spaces. Summary of the Invention

[0004] The purpose of this invention is to provide a magnetic tripping system for miniature circuit breakers, enabling installation in small spaces and passing temperature rise tests. To achieve the above objective, this invention adopts the following technical solution:

[0005] A magnetic tripping system for a miniature circuit breaker is installed inside the casing of the miniature circuit breaker. It includes a terminal block, a current detection assembly, and a coil assembly. The current detection assembly is disposed on the terminal block. The coil assembly includes a wound coil, an iron core assembly, a magnetic yoke, and a stationary contact. The wound coil is wound around the outer periphery of the iron core assembly, which is disposed inside the magnetic yoke. One end of the wound coil is welded to the terminal block, and the other end is spot-welded together with one end of the stationary contact to the magnetic yoke, so that the terminal block, the wound coil, and the stationary contact form a current path.

[0006] In one embodiment, the current detection component is a current transformer, the terminal block is a bent plate made of conductive material, and the current transformer passes through the terminal block and is disposed on the outer ring of the bent plate.

[0007] Preferably, the bent plate includes a first straight section, a vertical section and a second straight section, the vertical section connects the first straight section and the second straight section, the first straight section is located at the edge of the housing, a vertical baffle is provided inside the housing, the vertical baffle is partially broken to form an accommodating space, the vertical section is arranged in the accommodating space and is arranged on the same plane as the vertical baffle, and the current transformer is fitted around the outer ring of the second straight section.

[0008] Preferably, the edge of the bent plate is chamfered.

[0009] In another embodiment, the current detection component includes a manganese copper sampling resistor and two sets of current sampling terminals. The manganese copper sampling resistor is embedded in the terminal block, and the current sampling terminals are located on both sides of the manganese copper sampling resistor. The current sampling terminals are connected to the circuit board of the miniature circuit breaker.

[0010] Furthermore, the terminal block is also provided with a voltage sampling terminal, which is connected to the circuit board of the miniature circuit breaker.

[0011] The magnetic yoke includes a front magnetic yoke plate disposed at the front end of the core assembly, a rear magnetic yoke plate disposed at the rear end of the core assembly, and a connecting magnetic yoke plate connecting the front magnetic yoke plate and the rear magnetic yoke plate. The front magnetic yoke plate or the rear magnetic yoke plate is provided with mounting holes for the core assembly to pass through.

[0012] The core assembly includes a core sleeve, a moving core, a stationary core, a reset spring, and a push rod installed inside the core sleeve. The stationary core is fixed at the end of the core assembly. The inner end of the stationary core has a groove. One end of the reset spring is installed in the groove, and the other end abuts against the push rod. One end of the push rod is located inside the core sleeve and compresses the reset spring under the action of the moving core. The other end passes through the stationary core and extends out of the core sleeve.

[0013] Furthermore, it also includes a gasket made of magnetically conductive material, the gasket having a locking hole for inserting the end of the stationary iron core, the gasket being installed at the rear end of the front magnetic yoke.

[0014] Preferably, the iron core sleeve has a recess for rotation at its rear end, a raised rib for securing it to the inner side of the rear magnetic yoke on its outer wall, and a notch groove on the mounting hole of the rear magnetic yoke.

[0015] Due to the adoption of the above structure, the present invention has the following beneficial effects:

[0016] 1. This invention employs a terminal block and a wound coil spot-welded together, requiring only one spot weld point, making welding convenient. Because the terminal block is plate-shaped and a rigid conductor, and the terminal block has a large cross-sectional area, the product's temperature rise meets requirements. The current detection component is placed at the terminal block, facilitating current detection and occupying minimal space. The overall structure of this invention is compact, meeting the miniaturization requirements of miniature circuit breakers. The structure of this invention allows for a relatively symmetrical spatial design of the miniature circuit breaker's housing, enabling inverted wiring.

[0017] 2. The current detection component uses a current transformer. The current transformer passes through the terminal block and is placed on its outer ring. In three-phase products, the current transformer is connected to the circuit board, and there is electrical isolation between the three phases, which is beneficial to the design of the circuit board.

[0018] 3. The terminal block is a bent plate with a vertical section in the middle. The vertical section is set on the same plane as the vertical retaining wall of the housing, forming part of the retaining wall. This can minimize the space occupied by the terminal block and shorten the length of the MCB as much as possible.

[0019] 4. The bend plate has chamfered edges, which increases the surface area of ​​the plate, which helps to enhance the magnetic circuit and facilitates the passage of the current transformer.

[0020] 5. Shims are used to fix the iron core assembly. After being installed in the housing, the iron core assembly can be prevented from falling out, thus solving the process problems of welding and assembly of the product. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of Embodiment 1.

[0022] Figure 2 This is a front view schematic diagram of Embodiment 1.

[0023] Figure 3 yes Figure 2 BB cross-sectional diagram.

[0024] Figure 4 This is a schematic diagram of the current transformer installed on the outer ring of the terminal block in Embodiment 1.

[0025] Figure 5 This is a schematic diagram of the structure of Embodiment 1 of the present invention installed on the housing of a miniature circuit breaker. The iron core assembly has not yet been installed in the figure.

[0026] Figure 6 yes Figure 5 A schematic diagram of the three-dimensional structure.

[0027] Figure 7 yes Figure 3 The diagram shows the C-axis direction, with the current transformer omitted.

[0028] Figure 8 This is a schematic diagram of the structure of Embodiment 2.

[0029] Explanation of key symbols:

[0030] 1: Terminal block; 11: Vertical section; 12: First straight section; 13: Second straight section; 14: Chamfer; 2: Winding coil; 3: Current transformer; 4: Core assembly; 41: Core bushing; 411: Rib; 412: Recess; 42: Moving core; 43: Stationary core; 44: Push rod; 45: Reset spring; 46: Groove; 5: Magnetic yoke; 51: Front yoke piece; 52: Rear yoke piece; 521: Notch; 53: Connecting yoke piece; 54: Mounting hole; 55: Fixing hole; 6: Gasket; 61: Locking hole; 7: Housing; 71: Vertical retaining wall; 8: Stationary contact; 91: Manganese copper sampling resistor; 92: Current sampling terminal; 93: Voltage sampling terminal. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] like Figures 1-3 As shown, this embodiment discloses a magnetic tripping system for a miniature circuit breaker, including a terminal block 1, a coil assembly, and a current transformer 3. The coil assembly includes a wound coil 2, an iron core assembly 4, a magnetic yoke 5, a stationary contact 8, and a gasket 6.

[0034] The current transformer 3 passes through the terminal block 1 and is located on the outer ring of the terminal block 1. The wound coil 2 is wound around the outer periphery of the iron core assembly 4, which is located inside the magnetic yoke 5. One end of the wound coil 2 is welded to the terminal block 1, and the other end is spot-welded to the magnetic yoke 5 together with one end of the stationary contact 8. Figure 1 Point A is the spot welding location. By welding at two points, the terminal block 1, the wound coil 2, and the stationary contact 8 form a current path.

[0035] Combination Figure 3 As shown, the terminal block 1 is a bent plate made of conductive material. The bent plate includes a first straight section 12, a vertical section 11, and a second straight section 13, with the vertical section 11 connecting the first straight section 12 and the second straight section 13. Figure 5 As shown, a vertical retaining wall 71 is provided inside the miniature circuit breaker housing 7. The vertical retaining wall 71 is partially broken to form an accommodating space. A vertical section 11 is arranged in the accommodating space and is on the same plane as the vertical retaining wall 71. The first straight section 12 is located at the edge of the housing 7, and the current transformer 3 is fitted around the outer ring of the second straight section 13.

[0036] Combination Figure 4 As shown, the edge of the bent plate is chamfered 14. The current transformer 3 passes through the bent plate with chamfered 14 and is located on the outer ring of the second straight section 13. The current transformer 3 is a zero-sequence current transformer.

[0037] The magnetic yoke 5 includes a front magnetic yoke plate 51, a rear magnetic yoke plate 52, and a connecting magnetic yoke plate 53. The front magnetic yoke plate 51 is located at the front end of the iron core assembly 4, and has a mounting hole 54 for the iron core assembly 4 to pass through. The rear magnetic yoke plate 52 is located at the rear end of the iron core assembly 4, and the connecting magnetic yoke plate 53 connects the front magnetic yoke plate 51 and the rear magnetic yoke plate 52. The gasket 6 has a locking hole 61 for the end of the stationary iron core 43 to be inserted, and the gasket 6 is installed at the rear end of the front magnetic yoke plate 51. The gasket 6 is made of a magnetically conductive material.

[0038] The core assembly 4 includes a core sleeve 41, a moving core 42, a stationary core 43, a return spring 45, and a push rod 44, all installed within the core sleeve 41. The stationary core 43 is fixed to the end of the core assembly 4. A groove 46 is provided inside the stationary core 43. One end of the return spring 45 is installed in the groove 46, and the other end abuts against the push rod 44. One end of the push rod 44 is located inside the core sleeve 41, and the other end passes through the stationary core 43 and extends outside the core sleeve 41. Figure 7 , Figure 3 As shown, the rear end of the iron core sleeve 41 is provided with a recess 412 for rotation, and the outer wall of the iron core sleeve 41 is provided with a raised rib 411. The mounting hole 54 of the rear magnetic yoke 52 is provided with a notch 521. The recess 412 can be in the shape of a straight line, a cross, etc. When energized, under the action of the magnetic field of the wound coil 2, the moving iron core 42 moves and pushes the push rod 44. The push rod 44 compresses the reset spring 45 and moves outward. The reset spring 45 stores elastic potential energy. When de-energized, the reset spring 45 releases the elastic potential energy, causing the push rod 44 to reset.

[0039] Conclusion Figure 5 , Figure 6 As shown, the installation steps in this embodiment are as follows:

[0040] (1) Fit the current transformer 3 onto the terminal block 1. The magnetic yoke 5 is mounted on the housing 7.

[0041] (2) Weld the terminal block 1 to one end of the winding coil 2, and spot weld the other end of the winding coil 2 and one end of the stationary contact 8 together to the connecting magnetic yoke 53.

[0042] (3) Since the current transformer blocks the rear end of the yoke, the core assembly 4 is inserted into the mounting hole 54 of the front yoke plate 51 and installed from front to back, so that the core assembly 4 is located between the front yoke plate 51 and the rear yoke plate 52. The protruding rib 411 is inserted into the notch 521, and the core sleeve 41 is rotated by inserting a tool into the recess 412, so that the protruding rib 411 is rotated to the inner end of the rear yoke plate 52 and locked.

[0043] (4) Install the iron core assembly 4 into the locking hole 61 of the gasket 6 and fix the gasket 6 into the cavity of the housing 7.

[0044] In this embodiment, the current transformer and terminal block are connected to the circuit board of the miniature circuit breaker. The current transformer detects the current. When leakage occurs, the current transformer detects the abnormal current and feeds the signal back to the circuit board. The winding coil 4 is energized. Under the action of the magnetic field generated by the winding coil, the moving iron core 42 moves along the direction of the stationary iron core 43, driving the push rod 44 to move outward. The pad 6 is made of magnetic material. The pad 6 and the magnetic yoke 5 together enhance the magnetic circuit, so that the moving iron core 42 quickly drives the push rod 44 to strike the free trip module inside the miniature circuit breaker, realizing the tripping.

[0045] Example 2

[0046] like Figure 8 As shown, this embodiment discloses a magnetic tripping system for a miniature circuit breaker, including a terminal block 1, a coil assembly, a manganin sampling resistor 91, a current sampling terminal 92, and a voltage sampling terminal 93. The coil assembly includes a wound coil 2, an iron core assembly 4, a magnetic yoke 5, and a stationary contact 8.

[0047] A manganin sampling resistor 91 is embedded in a terminal block 1, which is a bent plate made of conductive material. The bent plate includes a first straight section 12, a vertical section 11, and a second straight section 13, with the vertical section 11 connecting the first straight section 12 and the second straight section 13. The two ends of the manganin sampling resistor 91 are soldered to the vertical section 11 of the terminal block 1. A current sampling terminal 92 is located on both sides of the manganin sampling resistor 91, and a voltage sampling terminal 93 is located at any point on the terminal block 1. Both the current sampling terminal 92 and the voltage sampling terminal 93 are connected to the circuit board of the miniature circuit breaker.

[0048] The magnetic yoke 5 includes a front magnetic yoke plate 51, a rear magnetic yoke plate 52, and a connecting magnetic yoke plate 53. The front magnetic yoke plate 51 is located at the front end of the iron core assembly 4 and has a fixing hole 55. The rear magnetic yoke plate 52 is located at the rear end of the iron core assembly 4, and the connecting magnetic yoke plate 53 connects the front magnetic yoke plate 51 and the rear magnetic yoke plate 52. The rear magnetic yoke plate 52 has a mounting hole 54 for the iron core assembly 4 to pass through.

[0049] In this embodiment, the structure of the iron core assembly 4 is the same as that in Embodiment 1.

[0050] The installation steps in this embodiment are as follows:

[0051] (1) The manganin sampling resistor 91 is embedded in the terminal block 1, and the terminal block 1 is provided with a current sampling terminal 92 and a voltage sampling terminal 93. The current sampling terminal 92 and the voltage sampling terminal 39 and the terminal block 1 are connected to the circuit board of the miniature circuit breaker. The magnetic yoke 5 is installed on the housing 7 of the miniature circuit breaker.

[0052] (2) Weld the terminal block 1 to one end of the winding coil 2, and spot weld the other end of the winding coil 2 and one end of the stationary contact 8 together to the connecting magnetic yoke 53.

[0053] (3) Insert the iron core assembly 4 into the mounting hole 54 of the rear yoke 51 and install it from back to front, so that the iron core assembly 4 is located between the front yoke 51 and the rear yoke 52. The end of the stationary iron core 43 at the front end of the iron core assembly is engaged in the fixing hole 55 of the front yoke 51.

[0054] In this embodiment, the current sampling terminal 92 and the voltage sampling terminal 93 test the current and voltage. When leakage occurs, the current sampling terminal 92 and the voltage sampling terminal 93 detect the abnormal current and voltage and feed the signal back to the circuit board. The winding coil 4 is energized. Under the action of the magnetic field generated by the winding coil 2, the moving iron core 42 moves along the direction of the stationary iron core 43, which drives the push rod 44 to move outward and hit the free trip module in the miniature circuit breaker to achieve tripping.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A magnetic tripping system for a miniature circuit breaker, installed inside the housing of the miniature circuit breaker, characterized in that: It includes a terminal block, a current detection component, and a coil assembly, wherein the current detection component is mounted on the terminal block. The coil assembly includes a wound coil, an iron core assembly, a magnetic yoke, and a stationary contact. The wound coil is wound around the outer periphery of the iron core assembly, which is located inside the magnetic yoke. One end of the wound coil is welded to a terminal block, and the other end is spot-welded to the magnetic yoke along with one end of the stationary contact, so that the terminal block, the wound coil, and the stationary contact form a current path. The magnetic yoke includes a front magnetic yoke plate disposed at the front end of the core assembly, a rear magnetic yoke plate disposed at the rear end of the core assembly, and a connecting magnetic yoke plate connecting the front magnetic yoke plate and the rear magnetic yoke plate. The front magnetic yoke plate and the rear magnetic yoke plate are provided with mounting holes for the core assembly to pass through. The core assembly includes a core sleeve, a moving core, a stationary core, a reset spring, and a push rod installed inside the core sleeve. The stationary core is fixed to the end of the core assembly. The inner end of the stationary core has a groove. One end of the reset spring is installed in the groove, and the other end abuts against the push rod. One end of the push rod is located inside the core sleeve and compresses the reset spring under the action of the moving core. The other end passes through the stationary core and extends out of the core sleeve. The rear end of the core sleeve has a recess for rotation. The outer wall of the core sleeve has a rib for securing to the inner side of the rear yoke. The mounting hole of the rear yoke has a notch. The installation steps of the core assembly are as follows: insert the core assembly into the mounting hole of the front yoke and install it from front to back, so that the core assembly is located between the front yoke and the rear yoke. Insert the rib into the notch and use a tool to insert into the recess and rotate the core sleeve so that the rib rotates to the inner end of the rear yoke and is secured. It also includes a gasket made of magnetically conductive material, the gasket having a locking hole for inserting the end of the stationary iron core, the gasket being installed at the rear end of the front magnetic yoke; The current detection component is a current transformer, and the terminal block is a bent plate made of conductive material. The current transformer passes through the terminal block and is located on the outer ring of the terminal block. The bent plate includes a first straight section, a vertical section, and a second straight section. The vertical section connects the first straight section and the second straight section. The first straight section is located at the edge of the housing. A vertical baffle is provided inside the housing. The vertical baffle is partially broken to form an accommodating space. The vertical section is located in the accommodating space and is on the same plane as the vertical baffle. The current transformer is fitted around the outer ring of the second straight section. The current detection component includes a manganese copper sampling resistor and two sets of current sampling terminals. The manganese copper sampling resistor is embedded in the terminal block, and the current sampling terminals are located on both sides of the manganese copper sampling resistor. The current sampling terminals are connected to the circuit board of the miniature circuit breaker.

2. The magnetic tripping system for a miniature circuit breaker as described in claim 1, characterized in that: The edges of the bent plate are chamfered.

3. The magnetic tripping system for a miniature circuit breaker as described in claim 1, characterized in that: The terminal block is also equipped with a voltage sampling terminal, which is connected to the circuit board of the miniature circuit breaker.

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