Mechanical structure and control method of double-break linkage arc-extinguishing dc circuit breaker

Abstract

The application relates to a double-breakpoint linkage arc-extinguishing type direct-current circuit breaker mechanical structure and a control method, and belongs to the technical field of direct-current circuit breakers. The mechanical structure comprises a mechanism frame, a handle, a rocker arm and a double-breakpoint movable contact assembly, the double-breakpoint movable contact assembly comprises a movable contact support which is rotationally connected to the mechanism frame and is connected with the rocker arm through a contact spring, and a side wall of the movable contact support is provided with a guide sliding groove; a movable contact body is rotationally connected to the movable contact support, and a side wall of the movable contact body is provided with a compensation sliding groove; an adjusting assembly comprises a sliding block which is slidably arranged in the guide sliding groove, and a driving column which is fixed to the sliding block and extends into the compensation sliding groove; the compensation sliding groove and the guide sliding groove are arranged in a non-parallel mode, so that, in the opening process, the sliding block is converted into the angular displacement of the movable contact body relative to the movable contact support for compensation through the cooperation of the driving column and the compensation sliding groove. Through the application, the problems of service life reduction and safety hazards caused by contact thinning in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the mechanical structure and control method of a double-break linkage arc-extinguishing DC circuit breaker, belonging to the technical field of DC circuit breakers. Background Technology

[0002] DC circuit breakers, as core protection components in DC power distribution systems, are widely used in new energy power generation, rail transit, industrial DC speed regulation, and household DC power supply. Their core function is to connect normal load current and quickly disconnect current in the event of overload, short circuit, or other faults, cutting off the faulty circuit and ensuring personal safety and equipment stability. Structurally, a DC circuit breaker mainly includes a frame, operating mechanism, contact system, arc extinguishing system, and trip unit. The operating mechanism is responsible for driving the closing and opening of the contacts, and its core consists of a handle, torsion spring, and locking assembly. The contact system is the core of current conduction and interruption, divided into moving contact assembly and stationary contacts. The contact reliability of the moving contact assembly directly determines its conductivity. The arc extinguishing system is used to quickly extinguish the arc generated during interruption, reducing arc erosion of the contacts. The trip unit includes an electromagnetic trip unit (responding to short-circuit faults) and a thermal trip unit (responding to overload faults), achieving fault interruption through mechanical triggering.

[0003] Compared to AC circuits, DC circuits lack a natural zero-crossing point. When a short-circuit fault occurs, extinguishing the arc is more difficult, placing higher demands on the breaking capacity, contact corrosion resistance, and stability of the operating mechanism of the circuit breaker. However, most miniature circuit breakers in the current-use technology adopt a single-break breaking structure, which achieves current switching through the cooperation of a single moving contact and its corresponding stationary contact. This structure has significant drawbacks in practical applications: firstly, the single-break structure has poor current-limiting performance, resulting in high peak current during short circuits and insufficiently timely contact switching, leading to prolonged arc duration and severe contact burn-out; secondly, the single-break design has slow opening and closing speeds and limited breaking capacity, failing to meet the requirements of DC circuits for rapid arc extinguishing and low contact wear, thus shortening the overall service life of the circuit breaker.

[0004] To address the aforementioned issues, targeted structural improvements have emerged in related technical fields. For example, the "Double-Breakpoint Miniature Circuit Breaker Operating Mechanism" (patent publication number CN107946148A) achieves high breaking capacity and stable performance through optimized operating mechanism design, employing a double-breakpoint moving contact assembly and a linkage locking structure. The core design of this patent includes: a handle, a locking assembly, and a double-breakpoint moving contact assembly linked on the mechanism frame. The locking assembly uses multiple pins to cooperate with a rocker arm for precise linkage. The double-breakpoint moving contact assembly features two C-shaped contact portions with silver moving contacts spot-welded into the grooves, and a contact spring adjusts the fit. The L-shaped limiting portion of the upper stop and the spoon-shaped body of the lower stop form a limiting fit, ensuring instantaneous contact of the moving contact during closing and reducing electrical wear. This structure, through its double-breakpoint design, facilitates rapid arc transfer, enhancing breaking capacity and providing an important reference for the structural optimization of DC circuit breakers.

[0005] In practical use, especially in scenarios with frequent short-circuit faults, the thickness of the moving and stationary contacts gradually decreases. The core reason for this is the arc erosion and material loss during fault breaking: When a short circuit occurs, the short-circuit current can reach tens of kiloamperes, generating a high-temperature arc of 3,000-10,000°C between the contacts. This high temperature causes the metal materials on the contact surface (such as silver-based alloys, pure silver, etc.) to melt and evaporate instantly, forming metal vapor loss, resulting in ablation and pitting on the contact surface, and a gradual reduction in thickness. At the same time, the scouring effect of the arc will exacerbate the material peeling off the contact surface. Combined with the repeated hot and cold cycles caused by frequent short circuits, this will lead to plastic deformation and thermal fatigue damage in the contacts, further accelerating the thickness reduction. In addition, the low-melting-point components in the contact material preferentially evaporate at high temperatures, leading to component segregation, which will also indirectly accelerate the wear and thinning of the contacts.

[0006] Thinning of the moving and stationary contacts directly leads to abnormal changes in the final contact pressure, which is a key parameter for ensuring the conductivity reliability of a circuit breaker. Final pressure refers to the contact pressure between the moving and stationary contacts when the circuit breaker is closed. Its core function is to reduce contact resistance and prevent localized overheating when current flows. According to the national standard GB10963.1 "Circuit Breakers for Household and Similar Purposes," the contact resistance of the circuit breaker contacts when closed must be controlled within specified limits, and the temperature rise during normal operation must not exceed the standard specifications (e.g., casing temperature rise ≤ 60K). When the contacts become thinner, the spring compression during contact closure will be insufficient. Simultaneously, high-temperature conduction will cause the contact spring to temper, reducing its elastic modulus and ultimately resulting in a significant drop in final pressure. If localized melting or deformation occurs in the contacts, it will also lead to uneven distribution of final pressure and a reduction in the actual contact area. Insufficient or uneven final pressure will cause a sharp increase in contact resistance. When current passes through, the temperature rise of the contact will exceed the national standard limit. This will not only affect the conductivity, but also accelerate the further erosion of the contact material, forming a vicious cycle of "decreased final pressure - increased contact resistance - overheating of the contact - increased wear".

[0007] In particular, short-circuit faults are frequent in the following special scenarios, further amplifying the above problems: In damp environments such as bathrooms and kitchens, steam or water accumulation can easily damage the insulation of wiring, leading to short circuits; old appliances with a service life exceeding 8 years may have oxidized internal terminals and cracked power cord insulation, easily triggering internal short circuits; haphazardly connected, substandard power strips frequently cause short-circuit faults due to overload, compression, or water ingress. In these scenarios, the circuit breaker must repeatedly withstand the arc impact of short-circuit breaking, accelerating the thinning of the moving and stationary contacts, ultimately resulting in more pronounced abnormal pressure changes. This not only significantly reduces the circuit breaker's lifespan (far below the designed 1000 breaking cycles) but may also cause faults such as overheating during closing, false tripping, and failure to trip. Furthermore, the inability of the contacts to effectively break the arc can even induce fire hazards.

[0008] Therefore, in order to meet the needs of DC circuit breakers in frequent short-circuit scenarios, it is urgent to further optimize the mechanical structure design based on the existing double-break structure, improve the arc erosion resistance and final pressure stability of the contact system, so as to solve the problems of reduced lifespan and safety hazards caused by thinner contacts, and meet the requirements of DC power distribution systems for high reliability and long lifespan of circuit breakers. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a mechanical structure for a double-break linkage arc-extinguishing DC circuit breaker, which solves the problems of reduced lifespan and safety hazards caused by thinner contacts in the prior art.

[0010] The technical problem to be solved by this invention is achieved by the following technical solution:

[0011] A mechanical structure for a double-break linkage arc-extinguishing DC circuit breaker includes a frame, a handle, a rocker arm, and a double-break moving contact assembly, wherein the double-break moving contact assembly includes:

[0012] The moving contact support is rotatably connected to the mechanism frame and connected to the rocker arm via a contact spring. The side wall of the moving contact support is provided with a guide groove.

[0013] The moving contact body is rotatably connected to the moving contact support, and a compensation groove is provided on its side wall.

[0014] The adjustment assembly includes a slider that is slidably disposed in the guide groove and a drive column that is fixed to the slider and extends into the compensation groove;

[0015] The compensation groove and the guide groove are not parallel, so that the slider moves along the guide groove under the centrifugal force obtained by inertia during the opening process, and is converted into the angular displacement of the moving contact body relative to the moving contact support for compensation through the cooperation of the driving column and the compensation groove.

[0016] The present invention is further configured to include a lead screw that is drivenly connected to the slider, and a one-way locking mechanism composed of the lead screw and the slider;

[0017] The one-way locking mechanism includes a ratchet thread on the lead screw, a connecting hole in the slider, and a plurality of ratchet blocks on the inner wall of the connecting hole.

[0018] Each of the ratchet blocks is connected to the inner wall of the connecting hole by an elastic element and engages with the ratchet thread to restrict the movement of the slider in the direction that reduces the angular displacement;

[0019] The plurality of ratchet blocks are distributed circumferentially in the connecting hole. Each ratchet block has ratchet teeth arranged at equal intervals along the axial direction of the connecting hole. The plurality of ratchet blocks are staggered in the axial direction of the connecting hole, such that the stagger distance of the ratchet teeth is less than the tooth pitch, so as to form the minimum step distance of the slider.

[0020] The invention is further configured such that: a support spring is also provided in the guide groove, one end of the support spring is connected to the slider, and the other end is connected to the end of the guide groove, for providing damping for the compensating displacement of the slider and establishing force balance.

[0021] The present invention is further configured such that the center line of the compensation chute is constructed as a preset continuous curve;

[0022] The compensation chute is configured such that, during the process of the slider moving from the initial position to the maximum compensation position, the angle θ between the tangent at any point on the center line of the compensation chute and the guide chute changes continuously, and the change law of the angle θ, θ=f(s), is determined by comprehensive optimization based on the wear characteristic model of the moving contact, the force balance model of the transmission mechanism, and the preset final pressure target curve.

[0023] Where s is the displacement of the slider from its initial position;

[0024] The wear characteristic model defines the correspondence between the electrical wear of the contact and the angular displacement. The force balance model includes the elastic force of the support spring, the frictional force between the slider and the guide groove, and the interaction force between the drive column and the compensation groove.

[0025] The preset final pressure target curve defines the functional relationship between the desired final pressure and the cumulative wear of the contact.

[0026] A control method for the mechanical structure of a double-break interlocking arc-extinguishing DC circuit breaker includes the following steps:

[0027] After each opening operation is completed, the maximum instantaneous angular velocity of the moving contact support during the opening process is detected and recorded;

[0028] Obtain the steady-state current value in the line before this tripping event;

[0029] The tripping event type is determined based on the steady-state current value, wherein the tripping event type includes short-circuit tripping, overload tripping, and normal tripping.

[0030] Based on the type of tripping event and the maximum instantaneous angular velocity, assess the final contact pressure state;

[0031] Based on the final pressure state of the contact, the control indicator device issues a corresponding visual warning signal to prompt the user to perform maintenance operations.

[0032] The present invention is further configured such that: the determination of the tripping event type based on the steady-state current value specifically includes:

[0033] When the steady-state current value is greater than the first current threshold, the tripping event type is short-circuit tripping;

[0034] When the steady-state current value is greater than the rated current but less than or equal to the first current threshold, the tripping event type is overload tripping;

[0035] When the steady-state current value is less than or equal to the rated current, the tripping event type is normal tripping;

[0036] The first current threshold is set based on the rated short-circuit current of the circuit breaker.

[0037] The present invention is further configured such that: the evaluation of the final pressure state of the contact specifically includes:

[0038] Maintain a wear index, with an initial value of 0;

[0039] After each tripping event, update the wear index according to the tripping event type:

[0040] For short-circuit tripping, the wear index increases by the first increment value;

[0041] For overload tripping, the wear index increases by a second increment, which is less than the first increment.

[0042] For normal tripping, the wear index remains unchanged;

[0043] Based on the maximum instantaneous angular velocity and wear index, the final pressure state of the contact is evaluated, wherein:

[0044] When the maximum instantaneous angular velocity is continuously higher than the first velocity threshold, it is determined that the final contact pressure is too high.

[0045] When the maximum instantaneous angular velocity continuously remains lower than the second speed threshold, it is determined that the final contact pressure is too small;

[0046] Among them, the first speed threshold is greater than the second speed threshold.

[0047] The present invention is further configured to: sending corresponding visual warning signals according to the state of the final contact pressure, specifically including:

[0048] When the wear index is greater than the first threshold S1 and the maximum instantaneous angular velocity is within the normal range, trigger the L1 warning, and control the indicating light to be in the off state;

[0049] When the wear index is greater than the second threshold S2 and the maximum instantaneous angular velocity continuously remains lower than the second speed threshold, trigger the L2 warning, and control the indicating light to flash at the first frequency, prompting the user to check for wear or adjust the slider forward;

[0050] When the maximum instantaneous angular velocity continuously remains higher than the first speed threshold, trigger the L2 warning, and control the indicating light to flash at the second frequency, prompting the user to adjust the slider backward to reduce the compensation amount;

[0051] When the wear index is greater than the third threshold S3 or the maximum instantaneous angular velocity continuously remains lower than the third speed threshold, trigger the L3 warning, and control the indicating light to be in the on state, prompting to replace the contact;

[0052] Among them, S1 < S2 < S3, and the third speed threshold is less than the first speed threshold.

[0053] The present invention is further configured to: further include a dynamic threshold adjustment step:

[0054] Based on the historical data of the type of opening event, adaptively adjust the speed threshold for health assessment;

[0055] Record the proportion of short - circuit opening events. When this proportion continuously remains high, increase the value of the second speed threshold to enhance the monitoring sensitivity for insufficient final contact pressure;

[0056] Record the proportion of overload opening events, and combine with the cumulative trend of the wear index S. When over - compensation is suspected, reduce the value of the first speed threshold to enhance the monitoring sensitivity for excessive final contact pressure.

[0057] The present invention is further configured to: after sending the L2 warning, further include a maintenance guidance step:

[0058] During the user's adjustment operation, continuously monitor the maximum instantaneous angular velocity in several subsequent opening operations;

[0059] When the maximum instantaneous angular velocity recovers to the normal range between the first velocity threshold and the second velocity threshold, the signal of the indicator device is automatically switched to an off state indicating a healthy condition.

[0060] The beneficial effects of this invention are:

[0061] A mechanical compensation mechanism consisting of a slider, drive column, and specially curved groove can automatically trigger compensation action using the inertial force during the opening process. This compensation is optimized based on a preset final pressure target curve and wear model. It can dynamically and precisely adjust the contact angle of the moving contact according to the cumulative wear level, ensuring that the final contact pressure is stabilized within the optimal range throughout the entire lifespan. This effectively slows down the performance degradation process, allowing the electrical life of the circuit breaker to approach its mechanical life, thus extending its service life.

[0062] The health status of the contacts is diagnosed by monitoring the maximum instantaneous angular velocity of the moving contact support during reset. This angular velocity is directly related to the energy stored in the contact spring; sufficient final pressure results in a high velocity, while insufficient final pressure results in a low velocity. By combining current information to classify and weight tripping events, the system can eliminate interference and accurately assess the final pressure change caused solely by effective wear, thereby improving the reliability of the power supply system.

[0063] By setting up a multi-level visual warning system, Level L1 indicates normal monitoring; Level L2 clearly distinguishes between two opposing adjustment directions—one requiring increased compensation and the other requiring decreased compensation—through two different frequencies; and Level L3 forcibly prompts for replacement to prevent operation with defects. This presents the complex internal status to the user in an extremely intuitive way that requires no professional knowledge, significantly reducing the risk of misjudgment and misoperation, and guiding the user to perform the correct maintenance operations.

[0064] The system adaptively adjusts the sensitivity of the speed criterion based on the distribution of historical tripping event types. This allows the diagnostic system to adapt to the different usage habits and operating conditions of various users, avoiding false alarms and missed alarms, maintaining high accuracy in judgment across different application scenarios, and exhibiting better robustness. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the overall structure of the structural part in this invention.

[0066] Figure 2 yes Figure 1 A magnified view of part A in the middle.

[0067] Figure 3 This is a structural schematic diagram of the double-breakpoint moving contact assembly in the structural part of the present invention.

[0068] Figure 4 This is a schematic diagram of the guide groove part in this invention.

[0069] Figure 5 This is a schematic diagram of the structure of the compensation groove in this invention.

[0070] Figure 6 This is a cross-sectional view of the adjustment component in this invention.

[0071] Figure 7 yes Figure 6 A magnified view of part B in the middle section.

[0072] Figure 8 This is a schematic diagram of the system framework of the present invention.

[0073] Figure 9 This is an overall flowchart of the method in this invention.

[0074] Figure 10 This is an overall flowchart of the steps for maintaining the wear index in this invention.

[0075] Figure 11 This is an overall flowchart of the steps for evaluating the final pressure state of the contact in this invention.

[0076] Figure 12 This is an overall flowchart of the step of issuing a warning signal in this invention.

[0077] Figure 13 This is an overall flowchart of the maintenance and guidance steps in this invention.

[0078] In the diagram: 1. Mechanism frame; 2. Handle; 3. Rocker arm; 4. Moving contact support; 5. Moving contact body; 6. Adjustment assembly; 7. Contact spring; 8. Guide groove; 9. Compensation groove; 10. Slider; 11. Drive column; 12. Support spring; 13. One-way locking mechanism; 14. Rattle thread; 15. Connecting hole; 16. Rattle block; 17. Elastic element; 18. Hall sensor; 19. Main control unit; 20. Indicator light; 21. Stationary contact; 22. Lead screw. Detailed Implementation

[0079] To facilitate a clear understanding of the technical means, creative features, objectives, and effects of this invention, the invention will be further described below in conjunction with specific illustrations.

[0080] like Figures 1-7 As shown, a mechanical structure of a double-break linkage arc-extinguishing DC circuit breaker includes a frame 1, a handle 2, a rocker arm 3, and a double-break moving contact assembly. The handle 2 and the rocker arm 3 are rotatably connected to the frame 1, and the handle 2 and the rocker arm 3 are connected by an operating mechanism. The operating mechanism is a conventional technology and will not be described in detail here. There is one rocker arm 3 on each side of the frame 1. The double-break moving contact assembly includes two sets of moving contact supports 4, moving contact bodies 5, and adjustment components 6 symmetrically arranged on the rocker arms 3.

[0081] The moving contact support 4 is rotatably connected to the mechanism frame 1 and is connected to the rocker arm 3 through the contact spring 7. The contact spring 7 is a torsion spring, one end of which is connected to the side wall of the moving contact support 4 and the other end is engaged with the rocker arm 3. One end of the rocker arm 3 is connected to the operating mechanism and the other end abuts against the side surface of the moving contact support 4 near the stationary contact 21.

[0082] The moving contact body 5 is rotatably connected to the moving contact support 4. When the rocker arm 3 rotates away from the stationary contact 21, it drives the moving contact support 4 and the moving contact body 5 away from the stationary contact 21 through its end. When the rocker arm 3 rotates towards the stationary contact 21, it is driven by the contact spring 7. When the moving contact body 5 contacts the stationary contact 21, it continues to rotate over the stroke, thereby compressing the contact spring 7 to store energy and form the final pressure.

[0083] To adjust the final pressure, the side wall of the moving contact support 4 is provided with a guide groove 8, and the side wall of the moving contact body 5 is provided with a compensation groove 9. The adjustment assembly 6 includes a slider 10 slidably disposed in the guide groove 8 and a drive column 11 fixed to the slider 10 and extending into the compensation groove 9. A support spring 12 is also provided in the guide groove 8, one end of which is connected to the slider 10 and the other end is connected to the end of the guide groove 8, which is used to provide damping for the compensatory displacement of the slider 10 and to establish force balance.

[0084] The compensation groove 9 and the guide groove 8 are not parallel, so that the slider 10 is displaced along the guide groove 8 under the centrifugal force obtained by inertia during the opening process. Through the cooperation of the drive column 11 and the compensation groove 9, it is converted into the angular displacement of the moving contact body 5 relative to the moving contact support 4 for compensation. The guide groove 8 is provided with a lead screw 22 for the transmission connection of the slider 10. One end of the lead screw 22 extends to the surface of the moving contact support 4 and is provided with an internal hexagon head to facilitate the rotation of the lead screw 22.

[0085] To prevent the slider 10 from moving back, a one-way locking mechanism 13 is formed between the lead screw 22 and the slider 10. The one-way locking mechanism 13 includes a ratchet thread 14 provided on the lead screw 22, a connecting hole 15 opened in the slider 10, and a plurality of ratchet blocks 16 provided on the inner wall of the connecting hole 15.

[0086] Each ratchet block 16 is connected to the inner wall of the connecting hole 15 via an elastic element 17. The elastic element 17 can be made of a spring or an elastic block and engages with the ratchet thread 14 to restrict the slider 10 from moving in the direction of reducing angular displacement. Several ratchet blocks 16 are distributed circumferentially in the connecting hole 15. Each ratchet block 16 has ratches that are equally spaced along the axial direction of the connecting hole 15. Several ratchet blocks 16 are staggered in the axial direction of the connecting hole 15 so that the stagger distance of the ratches is less than the tooth pitch, so as to form the minimum step distance of the slider 10.

[0087] To facilitate monitoring of the angular velocity of the rocker arm 3 during closing, a Hall sensor 18 is provided on the inner wall of the mechanism frame 1. The Hall sensor 18 is located on one side of the rocker arm 3, and a permanent magnet is installed at the pivot of the rocker arm 3. When installing the Hall sensor 18, it is necessary to align it with the movement trajectory of the permanent magnet, and the spacing is controlled within 2-3mm to ensure signal strength and avoid mechanical interference.

[0088] A main control unit 19 and an LED indicator light 20 are provided inside the frame 1 or on the external control board of the circuit breaker. The input terminal is electrically connected to the Hall sensor 18 and the current transformer, and the output terminal is electrically connected to the indicating device such as the LED indicator light 20. The main control unit 19 has a built-in microprocessor and non-volatile memory.

[0089] The centerline of the compensation groove 9 is constructed as a preset continuous curve to achieve precise matching between contact wear and dynamic compensation of final pressure. The compensation groove 9 is configured such that, as the slider 10 moves from its initial position to its maximum compensation position, the angle θ between the tangent at any point on the centerline of the compensation groove 9 and the guide groove 8 changes continuously. The variation law of this angle θ, θ=f(s), is determined through comprehensive optimization based on the wear characteristic model of the moving contact, the force balance model of the transmission mechanism, and the preset final pressure target curve. Here, s is the displacement of the slider 10 from its initial position.

[0090] The wear characteristic model defines the relationship between contact electrical wear and angular displacement. Basic data is obtained through accelerated life testing, in which the circuit breaker is repeatedly subjected to a specified number of short-circuit and overload breaking operations in a laboratory setting, with the actual wear of the contacts measured periodically during this process. Simultaneously, high-precision sensors record the compensating angular displacement of the moving contact body 5 required to maintain the standard final pressure at different wear stages. By fitting these data, a wear characteristic model describing the relationship between contact electrical wear and compensating angular displacement can be established.

[0091] The force balance model includes the elastic force of the supporting spring 12, the frictional force between the slider 10 and the guide groove 8, and the interaction force between the drive column 11 and the compensation groove 9. This ensures that the entire mechanism achieves a stable force balance state under a given slider 10 displacement, allowing the moving contact body 5 to accurately remain at the expected compensation angle. The model establishes the system's force balance equations and torque balance equations through force analysis of the slider 10, drive column 11, and moving contact body 5. The equations must include the elastic force of the supporting spring 12, which is related to the displacement of the slider 10; the sliding frictional force between the slider 10 and the guide groove 8, the magnitude of which can be obtained through material pairing experiments; and the normal contact force and tangential component force generated by the interaction of the drive column 11 and the curved surface of the compensation groove 9, which involves contact mechanics. The purpose of this model is to accurately calculate the resistance that the slider 10 needs to overcome and its own required displacement to produce a specific compensation angular displacement.

[0092] After obtaining the above input model, the curve optimization solution stage can begin. This stage uses the wear characteristic model, force balance model, and final pressure target curve as input and constraint conditions. The optimization objective is set as follows: to find a compensating groove 9 curve such that when the slider 10 moves from its initial position to any position s, the actual angular displacement generated allows the final pressure of the system to be closest to the expected value of the target curve under that cumulative wear. This optimization process is typically completed in a computer using a numerical iterative algorithm. By adjusting the preset curve parameters, simulation calculations are repeatedly performed until the optimal θ=f(s) function relationship is found.

[0093] The preset final pressure target curve defines the ideal functional relationship between the desired final contact pressure and the cumulative wear over the entire contact lifespan. This target curve aims to ensure that the final closing pressure is maintained within an optimal range that guarantees low contact resistance without causing mechanical jamming or excessive wear, from the contact's new state to its wear limit state.

[0094] like Figures 8-13 As shown, a control method for the mechanical structure of a double-break linkage arc-extinguishing DC circuit breaker includes the following steps:

[0095] S1. After each opening operation is completed, detect and record the maximum instantaneous angular velocity of the moving contact support 4 during the opening process.

[0096] Since the final pressure is the contact pressure when the moving and stationary contacts close, its magnitude will change the rotation speed when the circuit is opened: when the final pressure is larger, the restoring force on the moving contact support 4 is stronger, and the maximum instantaneous angular velocity is higher. When the final pressure is smaller, the contact resistance is smaller, and the angular velocity is lower.

[0097] The Hall sensor 18 preferably uses a linear Hall element AH3503 with a response frequency of up to 1MHz, which can accurately capture rapidly changing magnetic field signals. When installing, it needs to be aligned with the movement trajectory of the magnetic element, and the distance should be controlled within 2-3mm to ensure signal strength and avoid mechanical interference.

[0098] When the circuit breaker is opened, the moving contact support 4 rotates, causing the magnetic element to rotate. The Hall sensor 18 outputs periodic induced voltage pulses. The peak value of the pulse is proportional to the instantaneous angular velocity. The faster the angular velocity, the higher the rate of change of the magnetic field and the larger the peak value. Therefore, the maximum instantaneous angular velocity can be obtained by extracting the peak value.

[0099] S2. Obtain the steady-state current value in the line before the current tripping occurs. The current intensity corresponding to different tripping types is significantly different: the current increases sharply during a short-circuit fault, the current exceeds the rated value but does not reach the short-circuit level during an overload, and the current is within the rated range during normal tripping.

[0100] S3. Determine the tripping event type based on the steady-state current value, where the tripping event types include short-circuit tripping, overload tripping, and normal tripping.

[0101] When the steady-state current value exceeds the first current threshold, it is determined to be a short-circuit trip, at which point the arc intensity is at its maximum and contact wear is most severe. When the steady-state current value exceeds the rated current but is less than or equal to the first current threshold, it is determined to be an overload trip, with the arc intensity being slightly lower and wear less. When the steady-state current value is less than or equal to the rated current, it is determined to be a normal trip, with almost no arc generation and negligible wear. The first current threshold is set based on the circuit breaker's rated short-circuit current.

[0102] S4. Evaluate the final pressure state of the contacts based on the type of tripping event and the maximum instantaneous angular velocity.

[0103] The final pressure condition of the contact is assessed, specifically by maintaining a wear index with an initial value of 0.

[0104] After each tripping event, the wear index is updated according to the type of tripping event. The update logic is based on the difference in arc erosion intensity for different tripping types: the arc temperature of short-circuit tripping reaches 3000-10000℃, the metal material melts and evaporates violently, and the wear is the most severe, so the wear index increases by the first increment value of 0.8; the arc intensity of overload tripping is the second, and the wear index increases by the second increment value of 0.3; there is no obvious wear in normal tripping, and the index remains unchanged. The cumulative wear of the contacts can be quantified by accumulating the index.

[0105] For short-circuit tripping, the wear index increases by a first increment; for overload tripping, the wear index increases by a second increment, which is less than the first increment; for normal tripping, the wear index remains unchanged.

[0106] Evaluate the final contact pressure state based on the maximum instantaneous angular velocity and wear index, where:

[0107] When the maximum instantaneous angular velocity continuously exceeds the first speed threshold, it is determined that the final contact pressure is too large; when the maximum instantaneous angular velocity continuously falls below the second speed threshold, it is determined that the final contact pressure is too small; where the first speed threshold is greater than the second speed threshold.

[0108] For example, in the normal final pressure state, the angular velocity range is 100 - 150 rad / s. Therefore, if the first speed threshold is set to 160 rad / s, it is determined that the final pressure is too large; if the second speed threshold is set to 90 rad / s, it is determined that the final pressure is too small. To avoid misjudgment due to accidental factors, "continuously" is defined as satisfying the condition for 3 consecutive breaker operations. Through multiple detections, ensure that the evaluation result reflects the stable abnormal state of the final pressure, rather than the fluctuations caused by single interference.

[0109] S5. According to the final contact pressure state, control the indicating device to emit corresponding visual warning signals to prompt the user to perform maintenance operations.

[0110] Emitting corresponding visual warning signals according to the final contact pressure state specifically includes:

[0111] When the wear index is greater than the first threshold S1 and the maximum instantaneous angular velocity is within the normal range, trigger the L1 warning, and control the indicating light 20 to be in the off state.

[0112] When the wear index is greater than the second threshold S2 and the maximum instantaneous angular velocity continuously falls below the second speed threshold, trigger the L2 warning, and control the indicating light 20 to flash at the first frequency to prompt the user to check for wear or adjust the slider 10 forward; when the maximum instantaneous angular velocity continuously exceeds the first speed threshold, trigger the L2 warning, and control the indicating light 20 to flash at the second frequency to prompt the user to adjust the slider 10 backward to reduce the compensation amount.

[0113] When the wear index is greater than the third threshold S3 or the maximum instantaneous angular velocity continuously falls below the third speed threshold, trigger the L3 warning, and control the indicating light 20 to be in the on state to prompt replacement of the contact.

[0114] Where S1 < S2 < S3, and the thresholds S1, S2, and S3 are set according to the designed life of the contact. And the third speed threshold is less than the first speed threshold.

[0115] After issuing an L2 warning and the user performs the adjustment operation, the effect needs to be verified through subsequent tripping data. Ideally, this should be achieved by monitoring the maximum instantaneous angular velocity during three consecutive trips. These three measurements cover different operating states, ensuring adjustment stability. When the angular velocity returns to the normal range between the first and second velocity thresholds, it indicates that the final pressure has returned to a reasonable range. The indicator automatically switches to an off state, providing clear feedback to the user and preventing over-adjustment or repeated operations, thus forming a complete maintenance closed loop.

[0116] S6. Based on historical data of circuit breaker event types, adaptively adjust the speed threshold used for health assessment.

[0117] Record the proportion of short-circuit tripping events. When the proportion of short-circuit tripping exceeds 50% in 10 consecutive tripping events, it indicates that the contacts are facing frequent arc erosion, the wear rate is accelerated, and the risk of insufficient final pressure is increased. At this time, the second speed threshold is increased (e.g., adjusted from 90 rad / s to 95 rad / s), the judgment criteria for insufficient final pressure are tightened, and the monitoring sensitivity is enhanced.

[0118] Record the overload tripping ratio. When the wear index increases by more than 2.0 after 5 consecutive overload trips, and overcompensation is suspected, reduce the first speed threshold (e.g., adjust from 160 rad / s to 155 rad / s) to enhance the monitoring sensitivity to excessive final pressure, promptly remind the circuit breaker to adjust in reverse, avoid aggravated wear or tripping jamming, and ensure that the circuit breaker can accurately monitor the final pressure status in different scenarios.

[0119] The implementation principle of this invention is as follows:

[0120] When the circuit breaker trips due to a fault or manual operation, the moving contact support 4 rotates rapidly under the drive of the contact spring 7. During this process, the centrifugal force gained by the slider 10 due to inertia overcomes the tension of the support spring 12, resulting in a small displacement along the guide groove 8. This linear displacement is precisely converted into a compensating angular displacement of the moving contact body 5 relative to the moving contact support 4 through the cooperation of the drive column 11 and the specially designed compensating groove 9. Crucially, the compensating groove 9 is pre-designed as an optimized continuous curve, the shape of which is determined by the contact wear model, the mechanism force balance model, and the desired final pressure target curve. This ensures that every displacement s of the slider 10 corresponds to an optimal compensation angle θ. The effect is that during the next closing operation, the moving contact body 5 will contact the stationary contact 21 at a pre-adjusted, better angle, automatically compensating for the spring compression lost due to contact wear and thinning, thereby maintaining the final pressure within the target range.

[0121] Simultaneously, the maximum instantaneous angular velocity of the moving contact support 4 is accurately detected by the Hall sensor 18 during each trip, and combined with the steady-state current value before tripping to distinguish the type of tripping event. The system maintains a virtual "wear index," which is accumulated only for events such as short circuits and overloads that cause actual wear.

[0122] By analyzing the correlation between the dynamic parameter "angular velocity" and the historical record "wear index", the system can diagnose whether the current state is "normal final pressure", "insufficient final pressure" or "overcompensation", and issue clear and graded maintenance guidance to the user through three-level warning indicator lights.

[0123] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A mechanical structure for a double-break linkage arc-extinguishing DC circuit breaker, comprising a frame, a handle, a rocker arm, and a double-break moving contact assembly, characterized in that, The dual-break moving contact assembly includes: The moving contact support is rotatably connected to the mechanism frame and connected to the rocker arm via a contact spring. The side wall of the moving contact support is provided with a guide groove. The moving contact body is rotatably connected to the moving contact support, and a compensation groove is provided on its side wall. The adjustment assembly includes a slider that is slidably disposed in the guide groove and a drive column that is fixed to the slider and extends into the compensation groove; The compensation groove and the guide groove are not parallel, so that the slider moves along the guide groove under the centrifugal force obtained by inertia during the opening process, and is converted into the angular displacement of the moving contact body relative to the moving contact support for compensation through the cooperation of the driving column and the compensation groove.

2. The mechanical structure of the double-break linkage arc-extinguishing DC circuit breaker according to claim 1, characterized in that: It also includes a lead screw that is drivenly connected to the slider, and a one-way locking mechanism consisting of the lead screw and the slider; The one-way locking mechanism includes a ratchet thread on the lead screw, a connecting hole in the slider, and a plurality of ratchet blocks on the inner wall of the connecting hole. Each of the ratchet blocks is connected to the inner wall of the connecting hole by an elastic element and engages with the ratchet thread to restrict the movement of the slider in the direction that reduces the angular displacement; The plurality of ratchet blocks are distributed circumferentially in the connecting hole. Each ratchet block has ratchet teeth arranged at equal intervals along the axial direction of the connecting hole. The plurality of ratchet blocks are staggered in the axial direction of the connecting hole, such that the stagger distance of the ratchet teeth is less than the tooth pitch, so as to form the minimum step distance of the slider.

3. The mechanical structure of the double-break linkage arc-extinguishing DC circuit breaker according to claim 2, characterized in that: A support spring is also provided inside the guide groove. One end of the support spring is connected to the slider, and the other end is connected to the end of the guide groove. It is used to provide damping for the compensating displacement of the slider and to establish force balance.

4. The mechanical structure of the double-break linkage arc-extinguishing DC circuit breaker according to claim 3, characterized in that: The centerline of the compensation chute is constructed as a preset continuous curve. The compensation chute is configured such that, during the process of the slider moving from the initial position to the maximum compensation position, the angle θ between the tangent at any point on the center line of the compensation chute and the guide chute changes continuously, and the variation law of the angle θ, θ=f, is determined by comprehensive optimization based on the wear characteristic model of the moving contact, the force balance model of the transmission mechanism, and the preset final pressure target curve. Where s is the displacement of the slider from its initial position; The wear characteristic model defines the correspondence between the electrical wear of the contact and the angular displacement. The force balance model includes the elastic force of the support spring, the frictional force between the slider and the guide groove, and the interaction force between the drive column and the compensation groove. The preset final pressure target curve defines the functional relationship between the desired final pressure and the cumulative wear of the contact.

5. A control method for the mechanical structure of a double-break linkage arc-extinguishing DC circuit breaker as described in any one of claims 1-4, characterized in that, Includes the following steps: After each opening operation is completed, the maximum instantaneous angular velocity of the moving contact support during the opening process is detected and recorded; Obtain the steady-state current value in the line before this tripping event; The tripping event type is determined based on the steady-state current value, wherein the tripping event type includes short-circuit tripping, overload tripping, and normal tripping. Based on the type of tripping event and the maximum instantaneous angular velocity, assess the final contact pressure state; According to the final contact pressure state, control the indicating device to emit corresponding visual warning signals to prompt the user to perform maintenance operations.

6. The method according to claim 5, characterized in that, Determining the type of opening event based on the steady-state current value specifically includes: When the steady-state current value is greater than the first current threshold, the type of opening event is a short-circuit opening; When the steady-state current value is greater than the rated current but less than or equal to the first current threshold, the type of opening event is an overload opening; When the steady-state current value is less than or equal to the rated current, the type of opening event is a normal opening; Wherein, the first current threshold is set based on the rated short-circuit current of the circuit breaker.

7. The method according to claim 5, characterized in that, Evaluating the final contact pressure state specifically includes: Maintain a wear index, the initial value of which is 0; After each opening event, update the wear index according to the type of opening event: For a short-circuit opening, the wear index increases by a first increment value; For an overload opening, the wear index increases by a second increment value, and the second increment value is less than the first increment value; For a normal opening, the wear index remains unchanged; Based on the maximum instantaneous angular velocity and the wear index, evaluate the final contact pressure state, wherein: When the maximum instantaneous angular velocity continuously exceeds the first speed threshold, it is determined that the final contact pressure is too large; When the maximum instantaneous angular velocity continuously is lower than the second speed threshold, it is determined that the final contact pressure is too small; Wherein, the first speed threshold is greater than the second speed threshold.

8. The method according to claim 7, characterized in that, Emitting corresponding visual warning signals according to the final contact pressure state specifically includes: When the wear index is greater than the first threshold S1 and the maximum instantaneous angular velocity is in the normal range, trigger the L1 warning, and control the indicating light to be in the off state; When the wear index is greater than the second threshold S2 and the maximum instantaneous angular velocity continuously is lower than the second speed threshold, trigger the L2 warning, and control the indicating light to flash at a first frequency, prompting the user to check for wear or adjust the slider forward; When the maximum instantaneous angular velocity continuously exceeds the first speed threshold, trigger the L2 warning, and control the indicating light to flash at a second frequency, prompting the user to adjust the slider backward to reduce the compensation amount; When the wear index is greater than the third threshold S3 or the maximum instantaneous angular velocity continuously is lower than the third speed threshold, trigger the L3 warning, and control the indicating light to be in the on state, prompting to replace the contact; Wherein, S1 < S2 < S3, and the third speed threshold is less than the first speed threshold.

9. The method according to claim 6, characterized in that, It further includes a dynamic threshold adjustment step: Based on the historical data of the type of opening event, adaptively adjust the speed threshold for health assessment; Record the proportion of short-circuit opening events. When this proportion continuously is on the high side, increase the value of the second speed threshold to enhance the monitoring sensitivity to insufficient final contact pressure; Record the proportion of overload opening events, and in combination with the cumulative trend of the wear index S, when overcompensation is suspected, reduce the value of the first speed threshold to enhance the monitoring sensitivity to excessive final contact pressure.

10. The method according to claim 8, characterized in that, After the L2 warning is issued, it further includes a maintenance guidance step: During the user's adjustment operation, continuously monitor the maximum instantaneous angular velocity in several subsequent opening operations; When the maximum instantaneous angular velocity recovers to the normal range between the first velocity threshold and the second velocity threshold, the signal of the indicator device is automatically switched to an off state indicating a healthy condition.

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