A motor circuit breaker with adjustable trip

Abstract

The utility model relates to a motor circuit breaker with adjustable tripping stroke, which comprises a shell, a tripping device and a bimetallic strip installed in the shell, an adjusting assembly installed in the shell, an adjusting knob, a fine adjustment screw, a knob holder and a secondary piece support, the adjusting knob is provided with a worm-shaped convex involute part, one end of the knob holder is connected with the shell, the other end is connected with the fine adjustment screw through screw threads, the fine adjustment screw is in contact with the involute part, the secondary piece support is connected with the knob holder to form a seesaw structure, one end of the secondary piece support is provided with a driving element connected with the bimetallic strip, the driving element is in a seesaw state, and the secondary piece support can extrude the tripping device in the direction of the knob holder through the other end push plate to trigger; the rotation of the fine adjustment screw can change the stroke interval between the push plate and the tripping device, the bimetallic strip only needs to be bent with a smaller amplitude to drive the push plate to extrude the tripping device, and the position of the bimetallic strip does not need to be changed by disassembling the shell during the process, so the operation is simple and convenient.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and more particularly to an adjustable tripping stroke motor circuit breaker. Background Technology

[0002] A circuit breaker is a switching device capable of closing, carrying, and interrupting current under normal circuit conditions, and capable of closing, carrying, and interrupting current under abnormal circuit conditions (including short-circuit conditions) within a specified time. Currently, circuit breakers on the market consist of a circuit breaker housing, within which short-circuit protection devices and overload protection devices are installed. Because the short-circuit and overload protection devices are housed within the confined space of the circuit breaker housing, and these devices have numerous components, assembly is relatively inconvenient and the assembly efficiency is lower.

[0003] When a circuit breaker is used for thermal overload protection, it works by utilizing the thermal bending characteristics of bimetallic strips. Bimetallic strips are composite materials composed of two or more metals or other materials with suitable properties. Due to the different thermal expansion coefficients of the constituent layers, when the temperature changes, the deformation of the active layer is greater than that of the passive layer. As a result, the entire bimetallic strip will bend towards the passive layer, pushing and triggering the tripping device to cut off the circuit and protect the equipment from damage caused by excessive current.

[0004] According to patent number "201720640806.6", a circuit breaker switching device is disclosed, which includes a housing and a switch electrode assembly, a mechanical locking unit, a magnetic / thermal unit, a baffle element and a terminal element disposed in the housing. The housing includes a switch base and a switch housing that is detachably fitted to the switch base. The switch base and the switch housing are pre-positioned by a snap-fit ​​assembly. The switch electrode assembly is disposed in the receiving groove of the switch base, and the other components are disposed in the receiving cavity of the switch housing. The assembly is simple and efficient.

[0005] However, overload protection is tested at the factory to determine if the bimetallic strip's bending stroke during protection is appropriate, and to confirm whether the circuit breaker will trip prematurely and whether it can return to its original position normally. Existing circuit breaker switching devices enclose the thermal overload protection mechanism inside the circuit breaker by passing screws through the first connection hole in the switch base and the second connection hole in the switch housing. If the bimetallic strip's protection stroke is inappropriate, the screws must be removed to separate the switch housing from the switch base, and the bimetallic strip's bending stroke to the tripping device must be readjusted.

[0006] Therefore, designing an adjustable tripping stroke motor circuit breaker that allows for convenient adjustment of the bimetallic strip stroke without disassembling the housing has become an urgent technical problem to be solved. Summary of the Invention

[0007] To solve the above problems, the present invention provides a motor circuit breaker with adjustable tripping stroke.

[0008] The present invention provides a motor circuit breaker with adjustable tripping stroke, comprising a housing, and a switching electrode assembly, a mechanical locking unit, a magnetic / thermal unit, terminal elements, an arc-extinguishing chamber, a tripping device, and a bimetallic strip installed within the housing. The housing includes a top cover, a base, and fasteners. The fasteners pass through a first connecting hole in the top cover and a second connecting hole in the base for fixed connection. An adjustment assembly is also installed inside the housing, comprising an adjustment knob, a fine-tuning screw, a knob holder, and a secondary plate support. The adjustment knob is rotatably connected to the housing and located between the knob holder and the secondary plate support. The circumferential surface of the adjustment knob has an involute portion with vortex-shaped protrusions. One end of the knob holder is axially connected to the housing to form a fixed end, and the other end forms a movable end. The fine-tuning screw is threaded onto the movable end, with its tip abutting against the involute section. A pivot is located in the middle of the sub-plate support, which is connected to the knob frame to form a rocker structure. One end of the sub-plate support is connected to a push plate, and the other end is connected to a rotatable drive component. The push plate is aligned with the tripping device and has a travel interval. The drive component is connected to a bimetallic strip for coordinated operation. The passive layer of the bimetallic strip is oriented in the same direction as the drive component's tilting motion on the sub-plate support. When the drive component is tilted, the sub-plate support can be triggered by the push plate pressing against the knob frame. The spiral pitch of the involute section is greater than the thread pitch of the fine-tuning screw. The top cover has through holes for the end of the adjustment knob and the tail end of the fine-tuning screw to extend.

[0009] With the above structure, a push plate is set at one end of the sub-plate bracket, which is aligned with the tripping device and has a travel interval. The other end is connected to a drive component, which in turn indirectly connects to the bimetallic strip. One end of the knob bracket is shaft-connected to the housing to form a fixed end, and the other end forms a movable end. The fine-adjustment screw is threaded onto the movable end, and the tip of the fine-adjustment screw abuts against the involute portion. The sub-plate bracket is shaft-connected to the knob bracket in the middle to form a rocker structure. The fixed end is marked as point A, the movable end as point B, the shaft as point C, the push plate as point D, and the sub-plate bracket connected to the drive component as point E. When the circuit breaker just starts working, the bimetallic strip does not bend. The drive component is connected to the bimetallic strip 3 for linkage. Points E and B are fixed points. Due to the travel interval, points A, B, and C are movable points. The adjustment component is in a loose state to prevent the push plate from accidentally triggering the tripping device due to vibration.

[0010] When the circuit breaker enters overload protection mode, the passive layer of the bimetallic strip aligns with the direction in which the drive component tilts on the secondary support. The bimetallic strip heats up and bends towards the side where the passive layer is located. Point E tilts upward away from the knob bracket, connecting the secondary support to the knob bracket via point C. Pulling the knob bracket causes it to rotate around point A. The fine-tuning screw at point B abuts against the involute section, preventing the knob bracket from rotating further. Subsequently, the secondary support rotates around point C, and the push plate at point D passes through the travel interval and engages with the tripping device. At this point, the adjusting assembly is in a taut state. As the bimetallic strip bends further, the push plate presses against the tripping device to trigger it, completing the tripping operation. When the overload protection ends, the bimetallic strip cools down and returns to its original state, causing the secondary support and knob bracket to return to their original positions. The adjusting assembly becomes loose again, and the tripping device is reset via a motor.

[0011] By setting an involute with volute-like protrusions on the circumference of the adjustment knob, the degree of protrusion of the involute at different positions varies. Rotating the adjustment knob in the direction of increasing protrusion of the involute aligns the involutes of different protrusions with the fine-tuning screw, squeezing the fine-tuning screw, and thus pushing the movable end, causing point B to rotate around point A. This pulls point C towards the knob holder. Point E, due to the bimetallic strip connecting the drive component, forms a fixed point. Point C pulls the secondary plate support, causing it to rotate around point E. The push plate at point D moves closer to the tripping device, shortening the travel interval. In this case, the bimetallic strip only needs to bend less to drive the push plate through the travel interval and push the tripping device. By aligning the pointing marks on the adjustment knob with different scales on the housing, coarse adjustment is achieved. The circuit breaker's overload protection setting is achieved by using a spiral section with a pitch greater than that of the fine-tuning screw. The fine-tuning screw is threadedly connected to the movable end. Rotating the fine-tuning screw moves it on the movable end, increasing the length of the screw extending from the movable end and abutting the adjustment knob, thus achieving the same function as the spiral section. This pulls point C towards the knob holder. Compared to rotating the adjustment knob to move point C, this allows for more precise adjustment of the bimetallic strip and push plate's stroke, fine-tuning to match the overload protection setting without altering the positions of the bimetallic strip and tripping device. The upper cover has through holes for the end of the adjustment knob and the tail end of the fine-tuning screw to extend from, allowing for rotation by grasping the end extending from the through hole without removing the upper cover, making overload protection adjustment during circuit breaker calibration easier.

[0012] As a further improvement of this utility model, a pair of sliding grooves are provided inside the housing. The sliding grooves are arranged sequentially on both sides of the bimetallic sheet along the length direction of the sub-plate support. According to the distance from the sub-plate support from near to far, an upper traction rod and a lower traction rod are correspondingly connected for sliding engagement. The length direction of the sliding groove matches the bending direction of the bimetallic sheet. The upper traction rod is provided with a first clamping block and a first driving column, and the lower traction rod is provided with a second clamping block and a second driving column. The first clamping block and the second clamping block respectively abut against the passive layer and the active layer of the bimetallic sheet. The sub-plate support is provided with a sub-plate bent towards the knob frame at one end connected to the driving component. The driving component is a lever. The lever is provided with an elliptical hole, an insertion hole, and a hook portion for hooking the sub-plate. The first driving column is inserted into the elliptical hole, and the second driving column is inserted into the insertion hole and axially connected to the driving component. The major axis direction of the elliptical hole matches the line direction connecting the first driving column and the second driving column.

[0013] With the above structure, a secondary plate is provided at one end of the connecting lever via a secondary plate bracket, bending towards the knob frame. The secondary plate is hooked by the hook on the lever, connecting the two and allowing them to rotate relative to each other. Corresponding to point E, the first drive post is inserted into the elliptical hole, which is point F, and the second drive post is inserted into the insertion hole, which is point G. Slides are arranged sequentially on both sides of the bimetallic strip along the length direction of the secondary plate bracket. The length direction of the slides matches the bending direction of the bimetallic strip. When the bimetallic strip is about to bend, the first clamping block will be pushed first, causing the upper traction rod to slide on the slide and move towards the direction of the tilting point E. At this time, the push plate will generate resistance due to the pressure of the release device, keeping the transmission component from rotating around point C. Point E is temporarily fixed. The first drive post of the upper traction rod will press against the side wall of the elliptical hole, pushing the lever to tend to rotate around point E. If points F and G rotate around point E, since the distance from point G to point E is greater than the distance from point F to point E, the rotation angle is the same. In this situation, point G, with a larger radius of rotation, will move a greater distance than point F. At point G, the lever uses the wall of the insertion hole to press the second drive column, causing the lower traction rod and the upper traction rod to slide in the same direction. Because the bimetallic strip is blocked between the first and second clamping blocks, the lower traction rod cannot move a greater distance than the upper traction rod. This manifests as the bimetallic strip bending, and due to the resistance generated by pushing the release device, the first and second clamping blocks will always press against the bimetallic strip from the passive and active layers. Points F and G will move synchronously. The position of the lever is determined by points F and G, preventing the lever from rotating. Instead, it causes point E to become a moving point and tilt up, causing the sub-plate bracket to rotate. The push plate at point D pushes the release device to trigger. By matching the length direction of the elliptical hole with the line connecting the first and second drive columns, when the lever tends to rotate around point E, a margin is created at point F for the first drive column to move, preventing the lever from jamming.

[0014] As a further improvement of this utility model, the end of the adjustment knob and the tail end of the fine-tuning screw are provided with a groove that matches the screwdriver, and the groove is a slotted groove or a cross groove.

[0015] With the above structure, the end of the adjustment knob and the tail of the fine-tuning screw are provided with a slotted or Phillips head that matches the screwdriver. By inserting a tool such as a slotted or Phillips head screwdriver into the slot, the adjustment knob or fine-tuning screw can be turned more easily.

[0016] As a further improvement of this utility model, the first end of the fine-tuning screw is provided with a raised circular surface, and the end face of the movable end is flared, with the flared arc surface corresponding to the position of the involute portion.

[0017] With the above structure, the fine-adjusting screw has a raised circular surface at its head, and the movable end has a flared end face with the flared arc surface corresponding to the position of the involute. The involute has cross-sections at both ends of the raised part. The cross-sections press against the circular surface at the head of the fine-adjusting screw and the flared end face of the movable end. The fine-adjusting screw indirectly or directly pushes the movable end, causing it to move away from the sub-plate support, creating space for the maximum protrusion of the involute to pass through. This allows the adjusting knob to continuously rotate in the direction of decreasing protrusion of the involute, thus coarsely adjusting the overload protection setting of the circuit breaker. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic diagram of the structure of this utility model.

[0019] Figure 2 The diagram shows the operation of the adjustment component mechanism.

[0020] Figure 3 The diagram shown is a schematic of the adjustment component structure.

[0021] Figure 4 The diagram shown is a cross-sectional view of the Z-section adjustment knob and fine-tuning screw.

[0022] 2-Disengagement device, 3-Bimetallic strip, 4-Upper cover, 5-Base, 6-Adjustment knob, 7-Fine adjustment screw, 8-Knob bracket, 9-Sub-plate bracket, 10-Involute section, 11-Fixed end, 12-Moving end, 13-Rotating shaft, 14-Push plate, 15-Lever, 16-Upper traction rod, 17-Lower traction rod, 18-First clamping block, 19-First drive column, 20-Second clamping block, 21-Second drive column, 22-Sub-plate, 23-Oval hole, 24-Hook section, 25-Circular surface. Detailed Implementation

[0023] like Figures 1-4The circuit breaker with adjustable bimetallic strip 3 overload protection stroke is shown. It includes a housing, and a switching electrode assembly, a mechanical locking unit, a magnetic / thermal unit, terminal elements, an arc-extinguishing chamber 1, a tripping device 2, and a bimetallic strip 3 installed within the housing. The housing includes a top cover 4, a base 5, and fasteners. The fasteners pass through a first connecting hole in the top cover 4 and a second connecting hole in the base 5 for fixed connection. An adjustment assembly is also installed inside the housing, including an adjustment knob 6, a fine-tuning screw 7, a knob holder 8, and a secondary strip support 9. The adjustment knob 6 is rotatably connected to the housing and located between the knob holder 8 and the secondary strip support 9. The circumferential surface of the adjustment knob 6 has a spirally protruding involute portion 10. One end of the knob holder 8 is axially connected to the housing to form a fixed end 11, and the other end forms a movable end 12. The fine-tuning screw 7 is screwed... The involute is connected to the movable end 12, and the head of the fine-tuning screw 7 abuts against the involute portion 10. The middle of the sub-plate bracket 9 is provided with a rotating shaft 13, which is connected to the knob frame 8 to form a rocker structure. One end of the sub-plate bracket 9 is connected to a push plate 14, and the other end is connected to a drive component that can rotate relative to it. The push plate 14 is aligned with the tripping device 2 and has a stroke interval. The drive component is connected to the bimetallic strip 3 for linkage. The passive layer of the bimetallic strip 3 is oriented to match the direction in which the drive component is rocked on the sub-plate bracket 9. When the drive component is in the rocked state, the sub-plate bracket 9 can be triggered by the push plate 14 pressing the tripping device 2 towards the knob frame 8. The spiral pitch of the involute portion 10 is greater than the thread pitch of the fine-tuning screw 7. The upper cover 4 is provided with a through hole for the end of the adjusting knob 6 and the tail end of the fine-tuning screw 7 to extend.

[0024] A push plate 14 is installed at one end of the sub-plate bracket 9, which is aligned with the tripping device 2 and has a travel interval. The other end is connected to a drive component, which in turn indirectly connects to the bimetallic strip 3. One end of the knob bracket 8 is shaft-connected to the housing to form a fixed end 11, and the other end forms a movable end 12. The fine-tuning screw 7 is threaded onto the movable end 12, and the tip of the fine-tuning screw 7 abuts against the involute portion 10. The sub-plate bracket 9 is shaft-connected to the knob bracket 8 via the central pivot 13, forming a rocker. Structure: Fixed end 11 is designated as point A, movable end 12 as point B, rotating shaft 13 as point C, push plate 14 as point D, and sub-plate bracket 9 connected to the drive component as point E. When the circuit breaker just starts working, the bimetallic strip 3 does not bend, and the drive component connects to the bimetallic strip 3 for linkage. Points E and B are fixed points. Due to the stroke interval, points A, B, and C are movable points. The adjustment component is in a loose state to prevent the push plate 14 from accidentally triggering the tripping device 2 due to vibration.

[0025] When the circuit breaker enters overload protection mode, the passive layer of the bimetallic strip 3 is aligned with the direction in which the drive component tilts on the sub-plate bracket 9. The bimetallic strip 3 heats up and bends towards the side where the passive layer is located. Point E tilts upward away from the knob bracket 8, connecting the sub-plate bracket 9 and the knob bracket 8 through point C. The knob bracket 8 is pulled to rotate around point A. The fine-tuning screw 7 at point B abuts against the involute portion 10, preventing the knob bracket 8 from rotating further. Subsequently, the sub-plate bracket 9 rotates around point C, and the push plate 14 at point D passes through the travel interval and engages with the tripping device 2. At this time, the adjusting component is in a taut state. As the bimetallic strip 3 bends further, the push plate 14 presses against the tripping device 2 to trigger it, completing the tripping operation. When the overload protection ends, the bimetallic strip 3 cools down and returns to its original state, causing the sub-plate bracket 9 and the knob bracket 8 to return to their original state. The adjusting component becomes loose again, and the tripping device 2 is reset by the motor.

[0026] By setting a spiral-shaped involute portion 10 on the circumferential surface of the adjusting knob 6, the degree of protrusion of the involute portion 10 at different positions is different. Rotating the adjusting knob 6 in the direction of increasing protrusion of the involute portion 10, the involute portion 10 with different degrees of protrusion is aligned with the fine-tuning screw 7. Squeezing the fine-tuning screw 7 pushes the movable end 12, causing point B to rotate around point A, thereby pulling point C to move in the direction of the knob bracket 8. Point E is fixed due to the bimetallic strip 3 connected to the driving component. Point C pulls the secondary plate bracket 9, causing it to rotate around point E. The push plate at point D moves closer to the tripping device 2, shortening the stroke interval. In this case, the bimetallic strip 3 only needs to bend less to drive the push plate 14 through the stroke interval and push the tripping device 2. By aligning the pointing marks on the adjusting knob 6 with different scales on the housing, the circuit break is coarsely adjusted. The circuit breaker has an overload protection setting. The spiral pitch of the involute 10 is greater than the thread pitch of the fine-adjustment screw 7. The fine-adjustment screw 7 is threadedly connected to the movable end 12. Rotating the fine-adjustment screw 7 moves it on the movable end 12, increasing the length of the fine-adjustment screw 7 that extends from the movable end 12 and abuts against the adjustment knob 6. This has the same effect as the involute 10, pulling point C towards the direction of the knob bracket 8. Compared to rotating the adjustment knob 6 to move point C, this allows for more precise adjustment of the stroke changes of the bimetallic strip 3 and the push plate 14, fine-tuning it to match the overload protection setting without changing the position of the bimetallic strip 3 and the tripping device 2. The upper cover 4 has through holes for the end of the adjustment knob 6 and the tail end of the fine-adjustment screw 7 to extend out. This allows for rotation by grasping the end of both extending out of the through holes without removing the upper cover 4, making the overload protection adjustment during circuit breaker calibration easier.

[0027] The housing contains a pair of sliding grooves arranged sequentially along the length of the sub-plate support 9 on both sides of the bimetallic strip 3. The grooves are connected to an upper traction rod 16 and a lower traction rod 17 in a sliding engagement, with the grooves aligned with the bending direction of the bimetallic strip 3. The upper traction rod 16 has a first clamping block 18 and a first driving column 19, while the lower traction rod 17 has a second clamping block 20 and a second driving column 21. 0 respectively abuts against the passive layer and active layer of the bimetallic strip 3; the sub-plate bracket 9 has a sub-plate 22 bent towards the knob frame 8 at one end connected to the drive component, the drive component is a lever 15, the lever 15 has an elliptical hole 23, an insertion hole, and a hook part 24 that hooks the sub-plate 22, the first drive column 19 is inserted into the elliptical hole 23, the second drive column 21 is inserted into the insertion hole and is axially connected to the drive component, and the major axis direction of the elliptical hole 23 matches the line direction connecting the first drive column 19 and the second drive column 21.

[0028] A secondary plate 22, bent towards the knob holder 8, is provided at one end of the connecting lever 15 via the secondary plate bracket 9. The secondary plate 22 is hooked by the hook portion 24 on the lever 15, enabling the two to be connected and rotate relative to each other. Corresponding to point E, the first drive post 19 is inserted into the elliptical hole 23, which is point F, and the second drive post 21 is inserted into the insertion hole, which is point G. Slides are arranged sequentially on both sides of the bimetallic strip 3 along the length direction of the secondary plate bracket 9. The length direction of the slides matches the bending direction of the bimetallic strip 3. When the bimetallic strip 3 is about to bend, First, the first clamping block 18 will be pushed, causing the upper traction rod 16 to slide on the groove and move towards the direction where point E is raised. At this time, the push plate 14 will generate resistance due to the pressure of the release device 2, keeping the transmission component from rotating around point C. Point E is temporarily fixed. The first drive column 19 of the upper traction rod 16 will press against the side wall of the elliptical hole 23, pushing the lever 15 to tend to rotate around point E. If points F and G rotate around point E, since the distance from point G to point E is greater than the distance from point F to point E, the rotation radius is larger when the rotation angle is the same. At point G, the movement distance of the lower traction rod 17 is greater than that of point F. At point G, lever 15 uses the wall of the insertion hole to press against the second drive column 21, causing the lower traction rod 17 and the upper traction rod 16 to slide in the same direction. However, because the bimetallic strip 3 is blocked between the first clamping block 18 and the second clamping block 20, the movement distance of the lower traction rod 17 cannot be greater than that of the upper traction rod 16. This manifests as the bimetallic strip 3 bending during the process, due to the resistance generated by pushing the release device 2, the first clamping block 18 and the second clamping block 20 will always resist the bimetallic strip from the passive layer and the active layer. Piece 3, points F and G will move synchronously. The position of lever 15 is determined by points F and G, so that lever 15 will not rotate, but will drive point E to become a moving point and tilt up. Sub-piece bracket 9 will rotate, and push plate 14 at point D will push release device 2 to trigger. By matching the length direction of elliptical hole 23 with the line direction connecting the first drive column 19 and the second drive column 21, when lever 15 tends to rotate around point E, a margin is generated at point F for the first drive column 19 to move, so as to prevent lever 15 from jamming.

[0029] The end of the adjustment knob 6 and the tail end of the fine-tuning screw 7 are provided with a slot that matches the screwdriver. The slot is a slotted groove or a cross-shaped groove.

[0030] The adjustment knob 6 and the fine-tuning screw 7 are provided with slots or Phillips head slots that match the screwdriver. By inserting a tool such as a slotted screwdriver into the slot, the adjustment knob 6 or the fine-tuning screw 7 can be turned more easily.

[0031] The fine-tuning screw 7 has a raised circular surface 25 at its head end, and the end face of the movable end 12 is flared, with the flared arc surface corresponding to the position of the involute portion 10.

[0032] The fine-adjusting screw 7 has a raised circular surface 25 at its head end, and the end face of the movable end 12 is flared, with the flared arc surface corresponding to the position of the involute 10. The involute 10 has cross-sections at both ends of its protrusion. These cross-sections press against the circular surface 25 at the head end of the fine-adjusting screw 7 and the flared end face of the movable end 12. The fine-adjusting screw 7 indirectly pushes the movable end 12, or directly pushes the movable end 12, causing it to move away from the sub-plate support 9. This creates space for the maximum protrusion of the involute 10 to pass through, allowing the adjusting knob 6 to rotate continuously in the direction of decreasing protrusion of the involute 10, thus coarsely adjusting the overload protection setting of the circuit breaker.

Claims

1. An adjustable tripping stroke motor circuit breaker, comprising a housing, and a switching electrode assembly, a mechanical locking unit, a magnetic / thermal unit, terminal elements, an arc-extinguishing chamber, a tripping device, and a bimetallic strip installed within the housing, the housing comprising a top cover, a base, and fasteners, the fasteners being fixedly connected by passing through a first connecting hole in the top cover and a second connecting hole in the base, characterized in that: An adjustment assembly is also installed inside the housing. This assembly includes an adjustment knob, a fine-tuning screw, a knob holder, and a secondary plate support. The adjustment knob is rotatably connected to the housing and located between the knob holder and the secondary plate support. The circumferential surface of the adjustment knob has a spirally convex involute portion. One end of the knob holder is axially connected to the housing to form a fixed end, and the other end forms a movable end. The fine-tuning screw is threaded onto the movable end, with its tip abutting against the involute portion. The secondary plate support has a pivot in the middle, which is axially connected to the knob holder to form a rocker structure. One end of the sub-plate bracket is connected to a push plate, and the other end is connected to a drive component that can rotate relative to it. The push plate is aligned with the tripping device and has a stroke interval. The drive component is connected to a bimetallic strip for linkage. The passive layer of the bimetallic strip is oriented in the same direction as the drive component tilting on the sub-plate bracket. When the drive component is tilted, the sub-plate bracket can be triggered by the push plate pressing the tripping device towards the knob frame. The pitch of the spiral line of the involute is greater than the thread pitch of the fine-tuning screw. The upper cover has through holes for the end of the adjustment knob and the tail end of the fine-tuning screw to extend out.

2. The adjustable tripping stroke motor circuit breaker according to claim 1, characterized in that: The housing contains a pair of sliding grooves arranged sequentially along the length of the sub-plate support on both sides of the bimetallic strip. The grooves are connected to an upper traction rod and a lower traction rod in sliding engagement, arranged from closest to furthest from the sub-plate support. The length of the grooves matches the bending direction of the bimetallic strip. The upper traction rod has a first clamping block and a first driving column, while the lower traction rod has a second clamping block and a second driving column. The first and second clamping blocks respectively abut against the passive and active layers of the bimetallic strip. The sub-plate support has a sub-plate bent towards the knob frame at one end connected to the driving component. The driving component is a lever with an elliptical hole, an insertion hole, and a hook portion for engaging the sub-plate. The first driving column is inserted into the elliptical hole, and the second driving column is inserted into the insertion hole and axially connected to the driving component. The major axis of the elliptical hole matches the direction of the line connecting the first and second driving columns.

3. The adjustable tripping stroke motor circuit breaker according to claim 1, characterized in that: The end of the adjustment knob and the tail end of the fine-tuning screw are provided with a slot that matches the screwdriver. The slot is a slotted groove or a cross-shaped groove.

4. The adjustable tripping stroke motor circuit breaker according to claim 1, characterized in that: The fine-tuning screw has a raised circular surface at its head end, and the end face of the movable end is flared, with the flared arc surface corresponding to the position of the involute portion.

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