Circuit breaker with adjustable effective length of bimetallic strip

Abstract

The present invention relates to the technical field of circuit breakers, and in particular discloses a circuit breaker with an adjustable effective length of a bimetallic strip, which includes a base and a thermal tripping device arranged on the base. The thermal tripping device includes a connecting plate and a bimetallic strip. One end of the bimetallic strip is connected to the connecting plate, and an adjusting screw is arranged at the other end. One side of the bimetallic strip abuts against the connecting plate, and an adjusting block is pressed against the other side. The adjusting block can move along the length direction of the bimetallic strip to adjust the distance between the adjusting block and the adjusting screw. With the above structure, a structure with an adjustable effective length of a bimetallic strip is provided, which can use bimetallic strips of the same type and the same size to achieve tripping that meets the requirements of the standard under different fault currents.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers, in particular to a circuit breaker with an adjustable effective length of a bimetal sheet. Background Art

[0002] In the prior art, under one case frame of a molded case circuit breaker, there are products with multiple current specifications. Their external dimensions are exactly the same, and the vast majority of parts are common. Specifically for the thermal tripping function module, for a purely mechanical thermal tripping device, in order to ensure that circuit breakers with different rated currents under the same case frame can work when encountering corresponding thermal overload faults, an adjusting screw is usually provided on the bimetal sheet. The stroke can be adjusted by adjusting the distance between the adjusting screw installed on the bimetal sheet and the traction rod. However, when facing a small current, there will be a situation of insufficient heating. Sometimes, the stroke adjustment of the bimetal sheet is extremely limited. In addition, there is also a problem of insufficient thrust of the bimetal sheet, which cannot be solved only by the adjusting screw on the bimetal sheet; in order to ensure that all can meet the tripping requirements, generally different heating materials are adopted. The methods are nothing more than using different materials for the bimetal sheet or the heating element with heat conduction, or materials with different thicknesses. In this way, a lot of spare materials are added, or the number of molds is increased, increasing the production cost and the material control cost.

[0003] In order to improve the versatility of the parts of the molded case circuit breaker and reduce the types of materials, it is imperative to introduce a universal thermal tripping device. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a structure with an adjustable effective length of a bimetal sheet that can use the same type and the same size of bimetal sheet to achieve tripping that meets the requirements specified by the standard under different fault currents.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a circuit breaker with an adjustable effective length of a bimetal sheet, including a base and a thermal tripping device provided on the base. The thermal tripping device includes a connecting plate and a bimetal sheet. One end of the bimetal sheet is connected to the connecting plate, and an adjusting screw is provided at the other end. One side of the bimetal sheet abuts against the connecting plate, and an adjusting block is pressed against the other side. The adjusting block can move along the length direction of the bimetal sheet to adjust the distance between the adjusting block and the adjusting screw.

[0006] In the above technical solution, the bimetal sheet is riveted or welded to the connecting plate, but the riveting point or welding point is not the starting position where bending occurs when heated. Instead, an adjusting block is used to adjust the starting position where the bimetal sheet bends when heated, so as to make the effective length of the bimetal sheet adjustable. That is, the distance between the adjusting screw and the adjusting block is the effective length of the bimetal sheet. Therefore, the highest point where the adjusting block abuts against the bimetal sheet is higher than the riveting point or welding point. By adjusting the effective length of the bimetal sheet, it is possible to achieve tripping under standard conditions for thermal overload faults of different current specifications, reducing materials, reducing molds, and improving the versatility of parts.

[0007] As a further setting of the present invention, an adjusting screw is connected to the adjusting block. One end of the adjusting screw is connected to the adjusting block, and the other end passes through the base to form a driving end. The adjusting screw can be telescoped on the base to realize the movement of the adjusting block.

[0008] In the above technical solution, the driving end is located outside the base, which is convenient for operation and adjustment. The adjusting screw telescopes along its own axial direction, and this telescoping direction is consistent with the moving direction of the adjusting block. In addition, in order to ensure that the adjusting screw does not affect the magnetic circuit and is heat-resistant, its material is stainless steel.

[0009] As a further setting of the present invention, a positioning block is provided on the base, and there is a guiding structure between the positioning block and the adjusting block to guide the movement of the adjusting block.

[0010] In the above technical solution, the setting of the positioning block mainly provides a guiding function, avoiding the shaking of the adjusting block and making the movement adjustment more accurate.

[0011] As a further setting of the present invention, the guiding structure includes a concave cavity provided on the adjusting block and an embedding portion provided on the positioning block. The embedding portion is placed in the concave cavity to form a guiding setting.

[0012] In the above technical solution, the positioning of the adjusting block in the y direction is realized by the auxiliary limiting of the adjusting block and the adjusting screw, and the positioning block and the adjusting block. The lowest position of the adjusting block in the z direction is determined by the limit between the adjusting block and the positioning block. The positioning block has a certain height compared with the inner side surface of the base and can form a guiding fit with the adjusting block. The adjusting block is equivalent to being sleeved on the positioning block, with reliable cooperation and stable guiding.

[0013] As a further setting of the present invention, a limiting shoulder is also provided on the positioning block. The limiting shoulder is arranged opposite to the bimetal sheet to limit the adjusting block between the limiting shoulder and the bimetal sheet.

[0014] In the above technical solution, the positioning of the adjusting block in the x direction is realized through the transition fit of the limiting shoulder and the bimetal sheet, so that the adjusting block can closely adhere to the bimetal sheet to ensure the effective length of the bimetal sheet bending. Preferably, the limiting shoulders are arranged on the corresponding two sides of the positioning block to improve the positioning strength.

[0015] As a further arrangement of the present invention, the adjusting screw passes through the positioning block and is connected to the adjusting block. A concave portion is provided at the end of the adjusting screw, and a clamping groove adapted to the concave portion is provided on the adjusting block. The end of the adjusting screw is snapped into the clamping groove to form a clamping linkage arrangement.

[0016] In the above technical solution, since the adjusting screw needs to be linked with the adjusting block and the adjusting screw also needs to drive the adjusting block to move by rotation, it cannot be fixedly connected. The opposite sides of the clamping groove are embedded in the concave portion to form a clamping limit in the z direction, and the rotation of the adjusting screw is not restricted. The clamping groove is a kidney-shaped groove with an opening at one end, which is convenient for the adjusting screw to be snapped in. The structure is simple and the installation is convenient.

[0017] As a further arrangement of the present invention, a first convex block and a second convex block are provided between the connecting plate and the adjusting block to form a limiting fit. A strip-shaped groove is provided on the abutting surface of the adjusting block against the bimetal sheet, and the strip-shaped groove is distributed along the moving direction of the adjusting block.

[0018] In the above technical solution, the highest position of the adjusting block in the z direction is determined by the limit between the first convex block and the second convex block. The strip-shaped groove is provided for the rivet head or welding point on the bimetal sheet to be embedded, so that it can be guided to move along the length direction of the strip-shaped groove, and the adjusting block can also be closely attached to the bimetal sheet. In addition, in order to ensure that the adjusting block will not interfere with the position of the armature in the rotation area no matter which position it is adjusted to, the adjusting block is designed in a shape similar to a chair, and the strip-shaped groove is provided on the back of the chair, and the layout is reasonable.

[0019] As a further arrangement of the present invention, the adjusting screw is cylindrical, and the through hole on the base for the adjusting screw to pass through is at least two-stage, and its diameter gradually increases from the inner side to the outer side of the base. The diameter of the inner section of the through hole is larger than the diameter of the adjusting screw, and an insert nut threadedly connected to the adjusting screw is embedded in the outer section of the through hole, and the insert nut is in interference fit with the outer section through hole.

[0020] In the above technical solution, the diameter of the inner section is slightly larger than the diameter of the adjusting screw. In this way, during installation, the adjusting screw can pass through quickly. The adjusting block is adjusted in the z direction through the screw pair of the adjusting screw and the insert nut. Preferably, the insert nut is fixed in the through hole, and the adjusting screw realizes telescoping by rotation. The structure is simple and the operation is convenient.

[0021] As a further arrangement of the present invention, a locking nut is threadedly connected to the end of the adjusting screw outside the insert nut, and a driving hole is provided on the end surface of the end of the adjusting screw.

[0022] In the above technical solution, the adjusting block is finally locked and positioned by a lock nut. During adjustment, the adjusting screw can be rotated by driving through the driving hole. The driving hole can be a groove in the shape of a straight slot, a cross slot, an internal hexagon, etc., which makes the adjustment more efficient.

[0023] As a further setting of the present invention, the through hole is in a three-section form. The insert nut is located in the middle section of the through hole. The outer diameter of the lock nut is larger than the diameter of the middle section, and the diameter of the outer section of the through hole is larger than the outer diameter of the lock nut.

[0024] In the above technical solution, the lock nut is placed inside the through hole to avoid protruding from the outer side of the base and affecting the use of the product.

[0025] The present invention will be further described below with reference to the accompanying drawings. Description of the Drawings

[0026] Attached Figure 1 is a sectional perspective view of the bimetallic strip at the maximum effective length in a specific embodiment of the present invention;

[0027] Attached Figure 2 is a sectional perspective view of the bimetallic strip at the minimum effective length in a specific embodiment of the present invention;

[0028] Attached Figure 3 is a sectional structure view of the bimetallic strip at the maximum effective length in a specific embodiment of the present invention;

[0029] Attached Figure 4 is a sectional structure view of the bimetallic strip at the minimum effective length in a specific embodiment of the present invention;

[0030] Attached Figure 5 is a structure view of the base in a specific embodiment of the present invention;

[0031] Attached Figure 6 is the A-A sectional view of Attached Figure 5 ;

[0032] Attached Figure 7 is a structure view of the adjusting block in a specific embodiment of the present invention;

[0033] Attached Figure 8 is a structure view of the adjusting block in a specific embodiment of the present invention;

[0034] Attached Figure 9 is a structure view of the bimetallic strip in a specific embodiment of the present invention;

[0035] Attached Figure 10 is a structure view of the adjusting screw in a specific embodiment of the present invention;

[0036] Attached Figure 11 is a structure view of the lock nut in a specific embodiment of the present invention;

[0037] Appendix Figure 12 It is the structure diagram of the connecting plate in the specific embodiment of the present invention. Specific Embodiment

[0038] The specific embodiment of the present invention is as Figures 1-12 shown. A circuit breaker with adjustable effective length of a bimetallic strip includes a base 1 and a thermal tripping device arranged on the base 1. The thermal tripping device includes a connecting plate 2 and a bimetallic strip 4. One end 41 of the bimetallic strip 4 is connected to the connecting plate 2, and an adjusting screw C is arranged on the other end 42. One side of the bimetallic strip 4 abuts against the connecting plate 2, and an adjusting block 3 is pressed against the other side. The adjusting block 3 can move along the length direction of the bimetallic strip 4 to adjust the distance between the adjusting block 3 and the adjusting screw C. The bimetallic strip 4 is riveted or welded to the connecting plate 2, but the riveting point or welding point is not the starting position where it bends when heated. Instead, an adjusting block 3 is used to adjust the starting position where the bimetallic strip 4 bends when heated, so as to realize the adjustable effective length of the bimetallic strip 4. That is, the distance between the adjusting screw C and the adjusting block 3 is the effective length of the bimetallic strip 4. Therefore, the highest point where the adjusting block 3 abuts against the bimetallic strip 4 should be higher than the riveting point or welding point. By adjusting the effective length of the bimetallic strip 4, it can be ensured that the thermal overload faults under different current specifications can trip under standard-compliant conditions, reducing materials, reducing molds, and improving the versatility of parts.

[0039] An adjusting screw rod 5 is connected to the above-mentioned adjusting block 3. One end of the adjusting screw rod 5 is connected to the adjusting block 3, and the other end passes through the base 1 to form a driving end 52. The adjusting screw rod 5 can stretch on the base 1 to realize the movement of the adjusting block 3. The driving end 52 is located outside the base 1, which is convenient for operation and adjustment. The adjusting screw rod 5 stretches along its own axial direction, and this stretching direction is consistent with the moving direction of the adjusting block 3. In addition, in order to ensure that the adjusting screw rod 5 does not affect the magnetic circuit and is heat-resistant, its material is stainless steel.

[0040] A positioning block 11 is arranged on the above-mentioned base 1. There is a guiding structure between the positioning block 11 and the adjusting block 3 to guide the movement of the adjusting block 3. The setting of the positioning block 11 mainly provides a guiding function to prevent the adjusting block 3 from shaking and make the movement adjustment more accurate.

[0041] The above-mentioned guiding structure includes a concave cavity 31 arranged on the adjusting block 3 and an embedding part 111 arranged on the positioning block 11. The embedding part 111 is placed in the concave cavity 31 to form a guiding setting. The positioning of the adjusting block 3 in the y direction is realized by the auxiliary limiting between the adjusting block 3 and the adjusting screw rod 5, and between the positioning block 11 and the adjusting block 3. The lowest position of the adjusting block 3 in the z direction is determined by the limit between the adjusting block 3 and the positioning block 11. The positioning block 11 has a certain height compared with the inner side surface of the base 1 and can form a guiding fit with the adjusting block 3. The adjusting block 3 is equivalent to being sleeved on the positioning block 11, with reliable cooperation and stable guiding.

[0042] A limiting shoulder 112 is further provided on the above-mentioned positioning block 11. The limiting shoulder 112 is arranged opposite to the bimetal sheet 4 to limit the adjusting block 3 between the limiting shoulder 112 and the bimetal sheet 4. The adjusting block 3 is positioned in the x direction through the transitional fit of the limiting shoulder 112 and the bimetal sheet 4, so that the adjusting block 3 can closely adhere to the bimetal sheet 4, ensuring the effective length of the bending of the bimetal sheet 4. Preferably, the limiting shoulders 112 are arranged on the corresponding two sides of the positioning block 11 to improve the positioning strength.

[0043] The above-mentioned adjusting screw 5 passes through the positioning block 11 and is connected to the adjusting block 3. A concave portion 511 is provided at the end 51 of the adjusting screw 5, and a clamping groove 32 adapted to the concave portion 511 is provided on the adjusting block 3. The end 51 of the adjusting screw 5 is snapped into the clamping groove 32 to form a clamping linkage arrangement. Since the adjusting screw 5 needs to be linked with the adjusting block 3, and the adjusting screw 5 also needs to drive the adjusting block 3 to move by rotation, it cannot be fixedly connected. The opposite sides of the clamping groove 32 are embedded in the concave portion 511 to form a clamping limit in the z direction, and the rotation of the adjusting screw 5 is not restricted. The clamping groove 32 is a kidney-shaped groove with an opening at one end, which is convenient for the adjusting screw 5 to be snapped in, and the structure is simple and the installation is convenient.

[0044] A first convex block 21 and a second convex block 34 that form a limiting fit are provided between the above-mentioned connecting plate 2 and the adjusting block 3. A strip-shaped groove 33 is provided on the abutting surface of the adjusting block 3 abutting against the bimetal sheet 4, and the strip-shaped groove 33 is distributed along the moving direction of the adjusting block 3. The highest position of the adjusting block 3 in the z direction is determined by the limit between the first convex block 21 and the second convex block 34. The strip-shaped groove 33 is provided for the rivet head B or the welding point on the bimetal sheet 4 to be embedded, so that it can be guided to move along the length direction of the strip-shaped groove 33, and also enables the adjusting block 3 to closely adhere to the bimetal sheet 4. In addition, in order to ensure that the adjusting block 3 will not interfere with the position of the armature in the rotation area no matter which position it is adjusted to, the adjusting block 3 is designed in a shape similar to a chair, and the strip-shaped groove 33 is provided on the back of the chair, and the layout is reasonable.

[0045] The above-mentioned adjusting screw 5 is cylindrical. The through hole 12 on the base 1 through which the adjusting screw 5 passes is of a three-section type, and its diameter gradually increases from the inner side to the outer side of the base 1. The diameter of the inner section 121 of the through hole 12 is larger than the diameter of the adjusting screw 5. An insert nut 13 threadedly connected to the adjusting screw 5 is embedded in the middle section 122 of the through hole 12, and the insert nut 13 is in interference fit with the through hole 12 of the middle section 122. The diameter of the inner section 121 is slightly larger than the diameter of the adjusting screw 5, so that during installation, the adjusting screw 5 can pass through quickly. The adjusting block 3 is adjusted in the z direction through the screw pair of the adjusting screw 5 and the insert nut 13. Preferably, there is an insert nut 13 on the base 1, and the adjusting screw 5 is in threaded cooperation with it. The concave portion 511 on the adjusting screw 5 is stuck in the card slot 32 of the adjusting block 3. Since the insert nut 13 is fixed in the base 1, when the locking nut 6 locks the adjusting screw 5, the offset amount of the adjusting block 3 in the y direction is also determined, and the inner walls 381 and 382 of the adjusting block 3 are in contact with the side walls 161 and 162 of the positioning block 11, playing an auxiliary positioning role. In this way, the adjusting block 3 can be positioned in the y direction.

[0046] A locking nut 6 is threadedly connected to the end of the adjusting screw 5 located outside the insert nut 13, and a driving hole 521 is provided on the end face of the end of the adjusting screw 5. The adjusting block 3 is finally locked and positioned by the locking nut 6. During adjustment, the adjusting screw 5 can be driven to rotate for adjustment through the driving hole 521. The driving hole 521 can be a groove in the shape of a straight slot, a cross slot, an internal hexagon, etc., and the adjustment is more efficient.

[0047] The outer diameter of the locking nut 6 is larger than the diameter of the middle section 122, and the diameter of the outer section 123 of the through hole 12 is larger than the outer diameter of the locking nut 6. The locking nut 6 is placed in the through hole 12 to avoid protruding from the outer side face of the base 1 and affecting the use of the product.

[0048] During installation, first insert the insert nut 13 into the base 1, then screw the adjusting screw 5 into the insert nut 13. After screwing to a certain distance, place the adjusting block 3 on the positioning block 11 of the base 1. The upper surface 391 of the adjusting block 3 contacts the upper surface 113 of the positioning block 11. Pass the slot 32 of the adjusting block 3 through the recess 511 of the adjusting screw 5, so that the surfaces 5111 and 5112 of the recess 511 contact or have a small gap with the surfaces 392 and 391 of the adjusting block 3 respectively, and push the adjusting block 3 in the x direction to the end so that the surfaces 351 and 352 of the adjusting block 3 contact the surfaces 141 and 142 of the limit shoulder 112 respectively; at this time, install the thermal magnetic release on the base 1 so that one end 41 of the bimetal 4 is closely attached to the surface 36 of the adjusting block 3. At this time, fix the connecting plate 2 on the thermal magnetic release to the base 1 with screws. At this time, there is only a small gap in the x direction for the adjusting block 3, and this gap can ensure that the adjusting block 3 is driven by the adjusting screw 5 to move freely in the z direction. If the lock nut 6 is tightened at this position so that the upper surface 61 of the lock nut 6 contacts the surface 1231 of the through hole 12, the position of the adjusting block 3 is locked.

[0049] At this time, the distance from the adjusting screw C on the bimetal 4 to the upper surface 341 of the adjusting block 3 in the z direction is the effective length of the bimetal 4, and at this time the effective length is at the maximum value within the adjustment range. The bending starting line of the bimetal 4 is at the position of the edge 342 of the adjusting block 3; note that the driving end 52 of the adjusting screw 5 should exceed the surface 124 of the base 1 in the positive z-axis direction at this time.

[0050] Next, loosen the lock nut 6 and continue to screw the adjusting screw 5. The surface 5112 on the recess 511 drives the surface 391 of the adjusting block 3 to move in the positive z direction. As the adjusting block 3 continuously moves in the positive z direction, the distance from the adjusting screw C on the bimetal 4 to the upper surface 341 of the adjusting block 3 continuously decreases, that is, the effective length of the bimetal 4 continuously decreases. If the lock nut 6 locks the adjusting screw 5 at this time, then a value between the minimum effective length and the maximum effective length is obtained.

[0051] Of course, the adjusting block 3 can continue to move in the positive z direction until the surfaces 343 and 344 of the adjusting block 3 contact the surfaces 211 and 212 on the connecting plate 2. At this time, the adjusting block 3 has reached the limit position in the z direction. If the lock nut 6 locks the adjusting screw 5 at this time, the distance from the adjusting screw C of the bimetal 4 to the upper surface 341 of the adjusting block 3 is the minimum value, that is, the minimum effective length of the bimetal 4 is reached. Note that any part of the adjusting screw 5 should not interfere with the armature 7 whether it is in the attracted state or in the moving process, and sufficient clearance should be ensured.

[0052] If the effective length of the bimetallic strip 4 needs to be lengthened, turn the adjusting screw C to move in the negative direction of z. In this way, according to different current levels, the effective length of the required effective bimetallic strip 4 can be adjusted.

[0053] According to the calculation formula of the well-known bimetallic element, the displacement of the bimetallic strip 4 is proportional to the square of the effective length of the bimetallic strip 4; the thrust generated by the bimetallic strip 4 is inversely proportional to the effective length; the maximum load (stress) of the bimetallic strip 4 is proportional to the effective length. For example, under the same frame size, when the circuit breaker is for the overload current of large current, the displacement is larger within the same time, and at this time, the effective length of the bimetallic strip 4 should be adjusted to a smaller length; when the circuit breaker is for the overload current of small current, the effective length of the bimetallic strip 4 should be adjusted to a longer length.

[0054] It can be seen that by adjusting the effective length of the bimetallic strip 4 within a suitable range, it is possible to meet the requirement of tripping in accordance with the standard regulations for different fault currents using the bimetallic strip 4 of the same type and the same size.

[0055] The present invention is not limited to the above specific embodiments. Those of ordinary skill in the art can implement the present invention in other various specific embodiments according to the content disclosed in the present invention, or those that adopt the design structure and idea of the present invention and make simple changes or modifications all fall within the protection scope of the present invention.

Claims

1. A circuit breaker with adjustable effective length of a bimetal strip, comprising a base and a thermal tripping device arranged on the base. The thermal tripping device includes a connecting plate and a bimetal strip. One end of the bimetal strip is connected to the connecting plate, and an adjusting screw is arranged at the other end. It is characterized in that: One side of the bimetal strip abuts against the connecting plate, and an adjusting block is pressed against the other side. The adjusting block can move along the length direction of the bimetal strip to adjust the distance between the adjusting block and the adjusting screw; an adjusting screw is connected to the adjusting block. One end of the adjusting screw is connected to the adjusting block, and the other end passes through the base to form a driving end. The adjusting screw can stretch on the base to realize the movement of the adjusting block; a positioning block is arranged on the base, and there is a guiding structure for guiding the movement of the adjusting block between the positioning block and the adjusting block; the guiding structure includes a concave cavity arranged on the adjusting block and an embedding part arranged on the positioning block. The embedding part is placed in the concave cavity to form a guiding setting; a limiting shoulder is also arranged on the positioning block. The limiting shoulder is arranged opposite to the bimetal strip to limit the adjusting block between the limiting shoulder and the bimetal strip; the adjusting screw passes through the positioning block and is connected to the adjusting block. A concave part is arranged at the end of the adjusting screw, and a clamping groove adapted to the concave part is arranged on the adjusting block. The end of the adjusting screw is clamped into the clamping groove to form a clamping linkage setting.

2. The circuit breaker with adjustable effective length of a bimetal strip according to claim 1, It is characterized in that: A first convex block and a second convex block forming a limiting fit are arranged between the connecting plate and the adjusting block. A strip-shaped groove is arranged on the abutting surface of the adjusting block against the bimetal strip, and the strip-shaped groove is distributed along the moving direction of the adjusting block.

3. The circuit breaker with adjustable effective length of a bimetal strip according to claim 1, It is characterized in that: The adjusting screw is cylindrical. The through hole on the base for the adjusting screw to pass through is at least two-stage, and its diameter gradually becomes larger from the inner side to the outer side of the base. The diameter of the inner section of the through hole is larger than the diameter of the adjusting screw. An insert nut threadedly connected to the adjusting screw is embedded in the outer section of the through hole, and the insert nut is in interference fit with the outer section through hole.

4. The circuit breaker with adjustable effective length of a bimetal strip according to claim 3, It is characterized in that: A locking nut is threadedly connected to the end of the adjusting screw outside the insert nut, and a driving hole is arranged on the end face of the end of the adjusting screw.

5. The circuit breaker with adjustable effective length of a bimetal strip according to claim 4, It is characterized in that: The through hole is three-stage. The insert nut is located in the middle section of the through hole. The outer diameter of the locking nut is larger than the diameter of the middle section, and the diameter of the outer section of the through hole is larger than the outer diameter of the locking nut.

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