Low voltage shunt release

Abstract

The application discloses a low-voltage split excitation tripping device, which solves the problem of failing to realize tripping at low voltage. The electromagnetic device comprises an electromagnet mechanism and a swing support, the electromagnet mechanism is electrically connected with an input end; the swing support comprises an attraction end, a pressing end and a fulcrum, the fulcrum of the swing support is closer to the pressing end, the swing support is rotatably connected to a shell body around the fulcrum of the middle frame body, the attraction end is in attraction cooperation with the electromagnet mechanism, and the pressing end is in pressing cooperation with a tripping support. The electromagnet mechanism attracts the swing support through electromagnetic force, the attraction end of the swing support is close to or contacts the electromagnet mechanism, the pressing end presses on the tripping support to make the tripping support displace, and the tripping device is tripped; since the fulcrum of the swing support is closer to the pressing end, the electromagnetic attraction force required by the electromagnet mechanism can be smaller to cause the attraction reaction, low-voltage tripping can be realized below 70% of a rated control power voltage, and the safety protection performance of the product is greatly improved.

Description

Technical Field

[0001] This invention relates to shunt trip units, and more particularly to a low-voltage shunt trip unit. Background Technology

[0002] A shunt trip unit is used to control or remotely control the tripping of a circuit breaker. When the power supply voltage is maintained between 70% and 110% of the rated control power supply voltage, the shunt trip unit should be able to disconnect the electrical appliance under all operating conditions. A prior art Chinese invention patent, CN100561629C, discloses a shunt trip unit with an indicating function, which discloses a base with a cover, a main shaft, a tripping device, and an electromagnetic system located within the base. The main shaft is located in a hole on the upper right side of the base, and the tripping device is rotatably located on the main shaft. The electromagnetic system is located in a fixed groove on the upper left side of the base. In the electromagnetic system, a coil frame is located within a magnetic yoke, and a coil winding is located on the coil frame. A left and right iron core are fixed to the magnetic yoke within the coil frame. Movable push rods are located within the left and right iron cores, and a second spring is located between the step on the push rod and the iron core. The left-side iron core, acted upon by electromagnetic force, overcomes the reaction force of the second spring, pushing the push rod from left to right, thereby pressing against the tripping device to achieve tripping. In practical use, due to the size limitations of the tripping device itself, the electromagnetic system of the tripping device cannot be made infinitely large. Therefore, the electromagnetic force that can be provided is basically a fixed value, and the tripping function can only be achieved within a certain range. However, in some applications with high safety requirements, tripping must be achieved below 70% of the rated control power supply voltage. The electromagnetic force of the existing electromagnetic system cannot achieve tripping at low voltages, thus limiting the safety protection performance of the tripping device. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art by providing a low-voltage shunt trip device, which solves the problem of inability to trip under low voltage.

[0004] The technical solution of the present invention includes a tripping bracket, a housing, and an input end. An electromagnetic device is provided inside the housing. The electromagnetic device includes an electromagnet mechanism and a swing bracket. The electromagnet mechanism is electrically connected to the input end. The swing bracket includes a pull-in end, a pressing end, and a fulcrum located in the middle. The fulcrum of the swing bracket is closer to the pressing end. The swing bracket is rotatably connected to the housing around the fulcrum of its middle frame. The pull-in end engages with the electromagnet mechanism to drive the swing bracket to swing. The pressing end presses against the tripping bracket.

[0005] Using the above technical solution, the electromagnet mechanism attracts the swing bracket with electromagnetic force, causing the attraction end of the swing bracket to approach or contact the electromagnet mechanism. The pressure end then applies pressure to the trip bracket, causing the trip bracket to shift and thus driving the trip unit to trip. Because the fulcrum of the swing bracket is closer to the pressure end, the electromagnetic attraction force required by the electromagnet mechanism can be smaller to achieve the attraction reaction. Therefore, low-voltage tripping can be achieved at less than 70% of the rated control power supply voltage, greatly improving the safety protection performance of the product.

[0006] In one possible design, the electromagnet mechanism includes a coil frame with a coil wound around it. A movable iron core is fitted inside the coil frame. The movable iron core includes an inner engaging part, an outer engaging part, and a connecting part that fixes the two together. The inner engaging part moves through the coil frame and its end forms a first engaging point with the engaging end of the swing bracket. The outer engaging part is located outside the coil frame and its end forms a second engaging point with the engaging end of the swing bracket.

[0007] With the above design, the movable iron core extends outward to form two attraction points, one inside and one outside. Compared with the existing technology which only has one attraction point, the electromagnetic attraction force can be increased and the required voltage can be reduced.

[0008] In one possible design, the movable iron core is in the shape of an "n", with the inner and outer suction parts arranged in parallel and the connecting part arranged perpendicular to the inner suction part.

[0009] The above design can generate electromagnetic forces acting in the same direction, effectively transmitting electromagnetic attraction.

[0010] In one possible design, the swing bracket includes a plastic outer layer and a metal block, with the metal block embedded and fixed in the plastic outer layer, and the metal block is arranged opposite to the inner suction part and the outer suction part respectively.

[0011] By adopting the above design, it is equivalent to setting metal blocks at the positions where the inner and outer attraction parts need to be attracted, reducing external interference, making the magnetic attraction more concentrated, and improving the magnetic attraction effect of the electromagnet mechanism.

[0012] In one possible design, a reset spring is also provided inside the housing, with its two ends hooked onto the top pressure end and the housing, respectively.

[0013] With the above design, when the trip unit needs to be reset, the electromagnetic device is not energized, and the swing bracket is reset by the reset spring.

[0014] In one possible design, a limiting protrusion is fixed inside the housing, located on the side where the top pressure end shifts.

[0015] The above design is used to limit the swinging motion of the swing bracket and prevent excessive movement from causing the trip unit to operate normally. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure before the tripping action of the present invention;

[0017] Figure 2 This is a schematic diagram of the structure after the tripping action of the present invention;

[0018] Figure 3 This is an exploded view of the electromagnetic device of the present invention;

[0019] Among them, 1. Tripping bracket; 2. Housing; 3. Input end; 4. Electromagnetic device; 41. Electromagnetic mechanism; 42. Swing bracket; 421. Pull-in end; 422. Top pressure end; 423. Fulcrum; 411. Coil frame; 412. Coil; 413. Moving iron core; 414. Inner pull-in part; 415. Outer pull-in part; 416. Connecting part; 424. Plastic outer layer; 425. Metal block; 21. Reset tension spring; 22. Limiting protrusion. Detailed Implementation

[0020] like Figure 1-3 The low-voltage shunt trip unit shown includes a trip bracket 1, a housing 2, and an input terminal 3. An electromagnetic device 4 is housed within the housing 2, comprising an electromagnet mechanism 41 and a swing bracket 42. The electromagnet mechanism 41 is electrically connected to the input terminal 3. The swing bracket 42 includes an engaging end 421, a pressing end 422, and a fulcrum 423 approximately midway between the engaging end 421 and the pressing end 422. The fulcrum 423 is closer to the pressing end 422 than the engaging end 421. The swing bracket 42 is rotatably connected to the housing 2 around its fulcrum 423. The engaging end 421 engages with the electromagnet mechanism 41 to drive the swing bracket 42 to swing, and the pressing end 422 presses against the trip bracket 1. The trip bracket 1 is prior art; its function is to apply pressure and cause the trip unit handle to swing, thus tripping. Further details are omitted here. When tripping is required, the electromagnet mechanism 41 is energized to generate an electromagnetic field and attracts the attraction end 421 of the swing bracket 42 through electromagnetic force. The swing bracket 42 rotates around the fulcrum 423, and the top pressure end 422 is displaced and applies pressure to the tripping bracket 1. The tripping bracket 1 then actuates to trip the tripping device.

[0021] The electromagnet mechanism 41 includes a coil frame 411, with a coil 412 wound around it. A movable iron core 413 is fitted inside the coil frame 411. The movable iron core 413 includes an inner engaging part 414, an outer engaging part 415, and a connecting part 416 that integrally connects the two. The inner engaging part 414 extends movably through the coil frame 411, and its end forms a first engaging point with the engaging end 421 of the swing bracket 42. The outer engaging part 415 is located outside the coil frame 411, and its end forms a second engaging point with the engaging end 421 of the swing bracket 42. This creates two engaging points, increasing the electromagnetic attraction and requiring a lower voltage. According to experimental results, taking a rated voltage of 12V as an example, the required tripping voltage is around 5V, which is about 40% of the rated control power supply voltage, achieving low-voltage tripping.

[0022] The movable iron core 413 is in the shape of an "n", with the inner attracting part 414 and the outer attracting part 415 arranged in parallel, and the connecting part 416 arranged perpendicular to the inner attracting part 414. The parallel inner attracting part 414 and the outer attracting part 415 can form an electromagnetic force acting in the same direction, effectively transmitting the electromagnetic attraction force.

[0023] The swing bracket 42 includes a plastic outer layer 424 and a metal block 425. The metal block 425 is embedded and fixed in the plastic outer layer 424, and is arranged directly opposite the inner attraction part 414 and the outer attraction part 415. Essentially, the metal block 425 is placed at the positions where the inner attraction part 414 and the outer attraction part 415 need to be attracted. Compared to the swing bracket 42 being made entirely of metal, this arrangement reduces interference from non-directly aligned positions, making the magnetic attraction more concentrated and improving the magnetic attraction effect of the electromagnet mechanism 41. Of course, for ease of manufacturing, the swing bracket 42 can also be made entirely of metal.

[0024] A reset spring 21 is also provided inside the housing 2, with its two ends hooked onto the top pressure end 422 and the housing 2, respectively. When the trip unit needs to be reset, the electromagnetic device 4 is not energized, and the top pressure end 422 of the swing bracket 42 is swung back to its original position by the elastic force of the reset spring 21.

[0025] A limiting protrusion 22 is integrally fixed inside the housing 2. The limiting protrusion 22 is located on the side where the top pressure end 422 moves. When the swing bracket 42 swings, the top pressure end 422 presses against the trip bracket 1 and then abuts against the limiting protrusion 22. The swing bracket 42 reaches its limit of movement, which can prevent excessive movement from causing the trip device to operate normally.

Claims

1. A low-voltage shunt trip unit, comprising a tripping bracket, a housing, and an input terminal, wherein an electromagnetic device is disposed within the housing, characterized in that: The electromagnetic device includes an electromagnet mechanism and a swing bracket. The electromagnet mechanism is electrically connected to the input end. The swing bracket includes an engaging end, a pressing end, and a fulcrum located in the middle. The fulcrum of the swing bracket is closer to the pressing end. The swing bracket is rotatably connected to the housing around the fulcrum of the middle frame. The engaging end engages with the electromagnet mechanism to drive the swing bracket to swing. The pressing end presses against the tripping bracket. The electromagnet mechanism includes a coil frame with a coil wound around it. A movable iron core is adapted to be installed inside the coil frame. The movable iron core includes an inner attracting part, an outer attracting part, and a connecting part that fixes the two together. The inner attracting part moves through the coil frame and its end forms a first attracting point with the attracting end of the swing bracket. The outer attracting part is located outside the coil frame and its end forms a second attracting point with the attracting end of the swing bracket.

2. The low-voltage shunt trip unit according to claim 1, characterized in that: The movable iron core is in the shape of an "n", the inner suction part and the outer suction part are arranged in parallel, and the connecting part is arranged perpendicular to the inner suction part.

3. The low-voltage shunt trip unit according to claim 1, characterized in that: The swing bracket includes a plastic outer layer and a metal block. The metal block is embedded and fixed in the plastic outer layer, and the metal block is arranged opposite to the inner suction part and the outer suction part, respectively.

4. The low-voltage shunt trip unit according to claim 1, characterized in that: The housing is also equipped with a reset spring, the two ends of which are hooked to the top pressure end and the housing, respectively.

5. The low-voltage shunt trip unit according to claim 1, characterized in that: A limiting protrusion is fixed inside the housing, and the limiting protrusion is located on the side where the top pressure end shifts.

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