Elevator safety circuit contact health management method and system

Abstract

The application discloses an elevator safety loop contact health management method and system, and belongs to the technical field of elevator safety control. The method comprises the following steps: collecting the working current and the terminal voltage of the safety loop in real time or periodically; based on the working current and the terminal voltage, determining whether to trigger maintenance through any strategy or a combination of the periodic maintenance strategy and the instant diagnosis strategy; if the maintenance is triggered, controlling the controllable load module to be put into the loop to generate a transient clearing current pulse, and using the Joule heat effect and the electrochemical effect to eliminate the degradation layer of the contact interface of the series safety contact; after the pulse ends, the controllable load module is cut off, and the safety loop returns to the low-power monitoring state. The periodic maintenance strategy triggers the maintenance according to the time interval or the cumulative number of actions in the contact file, and the instant diagnosis strategy identifies the loop impedance anomaly by comparing the terminal voltage deviation. The application can realize the automatic and accurate health management of the safety loop contact, and is helpful to improve the maintenance efficiency and reduce the system power consumption.

Description

Technical Field

[0001] This invention relates to the field of elevator safety control technology, specifically to a method and system for managing the health of elevator safety circuit contacts. Background Technology

[0002] The elevator safety circuit is a crucial component ensuring safe elevator operation. It consists of numerous safety contacts connected in series, such as the hall door lock contacts, car door lock contacts, speed governor switch, and emergency stop switch. The reliability of these contacts directly determines whether the entire safety circuit is functioning correctly, thus affecting the safe operation of the elevator.

[0003] During long-term use of elevators, a deterioration layer gradually forms on the contact interface of the safety contacts. On the one hand, carbon deposits may form due to arcing during frequent switching; on the other hand, insulating compound films may slowly form on the contact surfaces of contacts that remain closed for extended periods with minimal movement. The presence of these deterioration layers leads to increased contact resistance, causing problems such as increased voltage drop in the safety circuit and abnormal signals. In severe cases, it may cause the elevator to malfunction and stop due to a loose connection in the safety circuit, affecting normal operation and increasing maintenance burden.

[0004] Currently, the main solutions to these problems rely on regular manual inspections and cleaning. Maintenance personnel need to check each safety contact individually, assessing the contact condition visually or with instruments, and then wiping or replacing the contacts. This method has significant limitations: firstly, manual maintenance cycles are usually long, making it difficult to detect contact deterioration issues within the interval between maintenance periods; secondly, comprehensive testing of a large number of safety contacts is time-consuming and labor-intensive, resulting in low maintenance efficiency; and thirdly, routine inspections of contacts installed in hard-to-reach locations are particularly difficult.

[0005] Some solutions attempt to suppress contact oxidation by continuously applying a large monitoring current, but this method is energy-intensive, and prolonged energization may cause additional heating and aging effects on the contacts and circuit components. Therefore, there is a need in the industry for a technical solution that can automatically, accurately, and with low power consumption perform health management on safety circuit contacts. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for health management of elevator safety circuit contacts, which can realize automated and precise health management of safety circuit contacts, thereby improving maintenance efficiency and reducing system power consumption.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for managing the health of elevator safety circuit contacts includes: Step 1: Collect the operating current and terminal voltage of the elevator's safety circuit in real time or periodically; Step 2: Based on the collected operating current and terminal voltage, determine whether maintenance should be triggered using any one of the periodic maintenance strategy or the real-time diagnostic strategy, or a combination thereof. Step 3: If maintenance is triggered, the controllable load module is put into operation for a preset short duration to generate an instantaneous clearing current pulse with an amplitude greater than the normal monitoring current. The instantaneous clearing current pulse flows through all safety contacts in series to eliminate the deterioration layer of their contact interface. Step 4: After the instantaneous clear current pulse ends, disconnect the controllable load module to restore the safety circuit to a low-power monitoring state.

[0008] Furthermore, in step 2, the periodic maintenance strategy specifically includes: Maintain a separate file for each safety contact, recording its last maintenance time and the cumulative number of actions since the last maintenance; Maintenance is triggered when the interval between the current time and the last maintenance time of a safety contact reaches a preset time threshold, or when the cumulative number of actions of the safety contact reaches a preset number of actions threshold.

[0009] Furthermore, in the periodic maintenance strategy, for safety contacts that operate frequently, the cumulative number of operations is used as the trigger condition, while for safety contacts that remain closed for a long time with very few operations, the time interval is used as the trigger condition.

[0010] Furthermore, in step 2, the immediate diagnostic strategy specifically includes: Using the elevator's initial installation and commissioning status as a baseline, a baseline calibration process is performed once the elevator installation and commissioning are completed and all safety contacts are confirmed to be in brand new or fully healthy condition: The state value collected once is used as the base value, namely the base end voltage U_end_ref; The real-time end voltage U_end is compared with the base end voltage U_end_ref. If it is greater than the preset ratio, maintenance is triggered.

[0011] Furthermore, in step 3, the duration of the instantaneous clearing current pulse is 100ms-2s.

[0012] This invention also provides an elevator safety circuit contact health management system, applied to the above-mentioned elevator safety circuit contact health management method, comprising: The control unit is used to perform data analysis, logical judgment, and maintenance trigger control. A controllable load module is connected in parallel to the safety circuit in a controlled manner and connected to the control unit. It is used to activate the safety circuit to generate an instantaneous clearing current pulse when it receives an instruction from the control unit. The current monitoring unit and voltage monitoring unit are connected to the control unit and are used to collect the operating current and terminal voltage of the safety circuit in real time, and transmit the collected data to the control unit. The data storage unit is used to store the file, electrical parameter model and historical operating data of each safety contact.

[0013] Furthermore, the controllable load module consists of a safety relay and a power resistor connected in series. The control coil of the safety relay is connected to the control unit through an opto-isolated drive circuit, and the power resistor is connected to the inside of the safety circuit.

[0014] Furthermore, the current monitoring unit is a current sampling resistor, which is connected in series in the safety circuit and connected to the control unit through a differential amplifier circuit.

[0015] Furthermore, the voltage monitoring unit is a resistor voltage divider network, the last safety contact of the safety circuit is connected to the resistor voltage divider network, and the resistor voltage divider network is connected to the control unit.

[0016] In summary, the present invention has at least one of the following beneficial technical effects: First, it automates and intelligentizes contact health management. The system can autonomously perform continuous monitoring, status assessment, and maintenance triggering of safety circuits, responding to potential degradation issues without human intervention. This helps reduce reliance on regular manual inspections and improves the timeliness of maintenance work.

[0017] Secondly, it provides flexibility in two-dimensional decision-making. By combining periodic maintenance strategies and real-time diagnostic strategies, it can perform preventative maintenance on frequently operated contacts based on the number of operations or time cycles, and can also respond instantly to contacts with very few operations or circuit anomalies caused by sudden deterioration, making the decision-making basis more scientific and comprehensive.

[0018] Third, the maintenance method is precise and energy-efficient. A short, instantaneous current pulse is applied to the safety circuit, utilizing concentrated Joule heating and electrochemical effects to remove or break down the degraded layer. The short pulse duration significantly reduces the overall power consumption of the system compared to methods that continuously apply large currents.

[0019] Fourth, it has minimal impact on the normal operation of the elevator. The timing of the maintenance pulse application can be coordinated with the elevator's operating status, such as choosing to execute it during the elevator's idle period or synchronizing it with the door opening and closing actions, thereby reducing interference with elevator service.

[0020] Fifth, it has the ability to assess the maintenance effectiveness. By synchronously acquiring electrical parameters during pulse application, the system can assist in assessing the effectiveness of the maintenance and the current health status of the contacts, providing a reference for subsequent management decisions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system structure of the present invention; Figure 2 This is a schematic diagram of the method flow of the present invention; Figure 3 This is a schematic diagram of the periodic maintenance strategy process; Figure 4 This is a schematic diagram of the real-time diagnostic strategy process. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] This invention provides a method for health management of elevator safety circuit contacts, the logic block diagram of which is shown below. Figure 2 As shown, the specific steps include: Step 1: Collect the operating current and terminal voltage of the elevator's safety circuit in real time or periodically; Step 2: Based on the collected operating current I and end voltage U_end, determine whether maintenance should be triggered by any of the periodic maintenance strategy or the real-time diagnostic strategy, or a combination thereof. Step 3: If maintenance is triggered, the controllable load module is put into operation for a preset short duration to generate an instantaneous clearing current pulse with an amplitude greater than the conventional monitoring current. The instantaneous clearing current pulse flows through all safety contacts in series to eliminate the deterioration layer on their contact interface. The deterioration layer on the contact interface includes a carbon deposit layer caused by insufficient arc switching and an insulating compound film layer formed by long-term closure. The instantaneous clearing current removes or breaks down the contacts through the Joule heating effect and electrochemical effect. Step 4: After the instantaneous clear current pulse ends, disconnect the controllable load module to restore the safety circuit to a low-power monitoring state.

[0024] like Figure 3 As shown, in step 2, the periodic maintenance strategy specifically includes: Maintain a separate file for each safety contact, recording its last maintenance time and the cumulative number of actions since the last maintenance; Maintenance is triggered when the interval between the current time and the last maintenance time of a safety contact reaches a preset time threshold, or when the cumulative number of actions of the safety contact reaches a preset number of actions threshold.

[0025] In the periodic maintenance strategy, for safety contacts that operate frequently, the cumulative number of operations is used as the trigger condition, while for safety contacts that remain closed for a long time with very few operations, the time interval is used as the trigger condition.

[0026] like Figure 4 As shown, in step 2, the instant diagnosis strategy specifically includes: Using the elevator's initial installation and commissioning status as a baseline, a baseline calibration process is performed once the elevator installation and commissioning are completed and all safety contacts are confirmed to be in brand new or fully healthy condition: The state value collected once is used as the base value, namely the base end voltage U_end_ref; The real-time end voltage U_end is compared with the base end voltage U_end_ref, i.e., U_end / U_end_ref. If the ratio is greater than a preset ratio, maintenance is triggered. The preset ratio is set to 120%.

[0027] In step 3, the duration of the instantaneous clearing current pulse is 100ms-2s, and the instantaneous clearing current pulse is 10-50 times the normal monitoring current.

[0028] like Figure 1 As shown, the present invention provides an elevator safety circuit contact health management system, applied to the aforementioned elevator safety circuit contact health management method, comprising: The control unit, used to perform data analysis, logical judgment and maintenance trigger control, is usually the elevator main controller (MCU), and is responsible for executing the core logic algorithm of this invention; A controllable load module is connected in parallel to the safety circuit in a controlled manner and connected to the control unit. It is used to activate the safety circuit to generate an instantaneous clearing current pulse when it receives an instruction from the control unit. The current monitoring unit and voltage monitoring unit are connected to the control unit and are used to collect the operating current and terminal voltage of the safety circuit in real time, and transmit the collected data to the control unit. The data storage unit is used to store the file, electrical parameter model and historical operating data of each safety contact.

[0029] The controllable load module consists of a safety relay K1 and a power resistor R connected in series. The control coil of the safety relay is connected to the control unit through an opto-isolated drive circuit, and the power resistor is connected to the inside of the safety circuit.

[0030] The current monitoring unit is a current sampling resistor RS, which is connected in series in the safety circuit and is connected to the control unit through a differential amplifier circuit.

[0031] The voltage monitoring unit is a resistor voltage divider network, the last safety contact of the safety circuit is connected to the resistor voltage divider network, and the resistor voltage divider network is connected to the control unit.

[0032] Next, the present invention will provide a detailed description of the above system and method in conjunction with specific embodiments: Example 1: like Figure 1 As shown, this embodiment is based on an enhanced elevator safety circuit hardware system. While fully retaining and maintaining compatibility with the original safety circuit (connecting all safety contacts SK1, SK2, ..., SKN in series), this system integrates the following core modules: Controllable load module: This module consists of a safety relay K1 and a power resistor R connected in series and connected in parallel between the power supply terminal and the signal terminal of the safety circuit.

[0033] Parameter design: To generate a clear current pulse of approximately 100mA in a DC110V system, the load resistance is calculated according to Ohm's law: R = V / I = 110V / 0.1A = 1100Ω. In actual selection, the resistor's accuracy, instantaneous power handling capability, and the contact resistance of other contacts in the safety circuit must be considered. For example, a 1000Ω / 50W metal film power resistor can be selected.

[0034] Safety control: The coil of safety relay K1 is controlled by the elevator main control unit (MCU) through an opto-isolated drive circuit to ensure electrical isolation between the high-voltage safety circuit and the control system.

[0035] Current and voltage monitoring unit: Current monitoring channel: A high-precision sampling resistor Rs (e.g., 0.1Ω, 0.1% accuracy) is connected in series in the safety loop. The voltage drop across its terminals is processed by a differential amplifier circuit and then sent to the analog-to-digital converter (ADC) of the MCU to obtain the loop operating current I in real time.

[0036] Voltage monitoring channel: At the far end of the safety circuit (i.e., after the last safety contact), the terminal voltage U_end is safely divided into the ADC range of the MCU for acquisition through a high-impedance, high-precision resistor divider network.

[0037] Control unit and data storage unit: The elevator main controller (MCU) is responsible for running all the algorithm logic of this invention. Its internal non-volatile memory is used to store maintenance records, diagnostic thresholds and historical data of each contact.

[0038] Example 2: like Figure 2 As shown, this invention is a continuously running "monitor-judgment-execution-recovery" closed loop executed by an MCU. S1 (Monitoring Step): Real-time or periodic acquisition of the operating current and terminal voltage of the safety circuit.

[0039] The system performs this step at a fixed period (e.g., 10 times per second) or when triggered by a specific event (e.g., elevator leveling, door lock action): The MCU synchronously initiates the ADC conversion of the current and voltage monitoring channels.

[0040] After reading and filtering, the current operating current value I and the terminal voltage value U_end are obtained.

[0041] This real-time data is used for subsequent judgments and can optionally be recorded to form historical trend curves.

[0042] S2 (Judgment Step): Based on the collected data, determine whether maintenance is triggered through periodic maintenance or real-time diagnostic strategies.

[0043] Executed by the MCU's logic decision unit, the periodic maintenance strategy is as follows: Figure 3 As shown, the real-time diagnostic strategy is as follows: Figure 4 As shown: Periodic maintenance strategy: Data maintenance: The system maintains an independent file for each safety contact. For example, frequently activated contacts (such as hall door lock contacts) record the last maintenance time T_last and the cumulative number of actions N since the last maintenance; infrequently activated contacts (such as speed limiter switches) only record T_last.

[0044] Threshold comparison: Preset time threshold T_max (e.g., 10 days) and action threshold N_max (e.g., 500 times). When the elevator reaches a certain floor, the system reads the file of the corresponding door lock contact.

[0045] Logical judgment: If (current time - T_last ≥ T_max) or (N ≥ N_max) is true, then it is determined that maintenance needs to be triggered for this contact point.

[0046] Real-time diagnostic strategy: Model Calculation: Based on the real-time acquired I and U_end, combined with the known power supply voltage V_supply (110V), the system calculates the real-time dynamic impedance or voltage drop of the circuit. For example, it calculates the percentage decrease of U_end relative to V_supply.

[0047] Anomaly Diagnosis: Compare the calculated results with preset health thresholds (e.g., U_end should not be lower than 107V). If U_end is found to be consistently abnormally low or impedance is significantly increased, it is determined that there is a risk of contact deterioration in the entire safety circuit, and maintenance is immediately triggered.

[0048] S3 (Execution Step): Once triggered, the controllable load module is engaged for a predetermined short duration to generate an instantaneous clearing current pulse.

[0049] Once step S2 determines that maintenance is required, the system proceeds to this execution step: Timing Synchronization: If the object being maintained is a door lock contact, the MCU will precisely synchronize this operation with the elevator's normal door opening and closing actions. The MCU will issue the execution command 200ms before outputting the door opening command.

[0050] Pulse application: The execution command closes the safety relay K1 via the drive circuit, connecting the load resistor R into the circuit. The duration of the connection is strictly controlled within a predetermined short duration T_pulse (set to 1500 milliseconds in this embodiment).

[0051] Current generation: Within T_pulse, a DC110V voltage drives the generation of a transient clearing current pulse with an amplitude of approximately 100mA (significantly greater than the conventional 30mA monitoring current). This pulse flows through all series-connected safety contacts, utilizing the Joule heating effect to concentrate and remove carbon deposits from the contact surfaces or break down the insulating film.

[0052] S4 (Recovery Step): The load is immediately disconnected after the pulse ends, and the system returns to the low-power monitoring state.

[0053] Load cut-off: When the T_pulse timer ends, the MCU immediately cuts off the control signal to K1, and the load resistor R is completely removed from the safety circuit.

[0054] State recovery: The safety loop is restored to a state where only the original monitoring circuit is working, the current is restored to the milliampere level, and the system as a whole returns to a low-power monitoring state, waiting for the next S1 step acquisition cycle or event trigger.

[0055] Status Update: For maintenance triggered by the periodic maintenance strategy, the system will update the corresponding contact file after this step (setting T_last to the current time and clearing N to zero). The system can also collect pulse current and voltage data during S3 to evaluate the improvement of contact resistance and generate a maintenance log.

[0056] Example 3: Assume that an elevator executes 10 maintenance pulses of 0.5 seconds each per day on average: Pulse energy consumption: E_pulse = 110V × 0.1A × 0.5s × 10 = 55J (watt-second); Total daily energy consumption: E_day = 55J × 10 ≈ 0.0153Wh; Total annual energy consumption: E_year = 0.0153Wh × 365 ≈ 5.58Wh; Compared to the continuous current solution, which consumes approximately 96.36 kWh per year (110V×0.1A×24h×365d), the energy-saving efficiency is as high as 99.994%, meeting the green elevator standard.

[0057] Embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0058] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0059] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0060] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0061] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A method for managing the health of elevator safety circuit contacts, characterized in that, include: Step 1: Collect the operating current and terminal voltage of the elevator's safety circuit in real time or periodically; Step 2: Based on the collected operating current and terminal voltage, determine whether maintenance should be triggered using either a periodic maintenance strategy or an immediate diagnostic strategy, or a combination thereof. Specifically, the periodic maintenance strategy is as follows: Maintain a separate file for each safety contact, recording its last maintenance time and the cumulative number of actions since the last maintenance; Maintenance is triggered when the interval between the current time and the last maintenance time of a safety contact reaches a preset time threshold, or when the cumulative number of actions of the safety contact reaches a preset number of actions threshold. In the periodic maintenance strategy, for safety contacts that move frequently, the cumulative number of moves is used as the trigger condition, while for safety contacts that remain closed for a long time and move very few moves, the time interval is used as the trigger condition. The specific instant diagnostic strategy is as follows: Using the elevator's initial installation and commissioning status as a baseline, a baseline calibration process is performed once the elevator installation and commissioning are completed and all safety contacts are confirmed to be in brand new or fully healthy condition: The state is collected once as the base value, namely the base end voltage U_end_ref; The real-time end voltage U_end is compared with the base end voltage U_end_ref. If it is greater than a preset ratio, maintenance is triggered. Step 3: If maintenance is triggered, the controllable load module is put into operation for a preset short duration to generate an instantaneous clear current pulse with an amplitude greater than the normal monitoring current. The instantaneous clear current pulse flows through all safety contacts in series to eliminate the deterioration layer of their contact interface. Step 4: After the instantaneous clear current pulse ends, disconnect the controllable load module to restore the safety circuit to a low-power monitoring state.

2. The elevator safety circuit contact health management method according to claim 1, characterized in that, In step 3, the duration of the instantaneous clearing current pulse is 100ms-2s.

3. An elevator safety circuit contact health management system, applied to the elevator safety circuit contact health management method according to claim 1 or 2, characterized in that, include: The control unit is used to perform data analysis, logical judgment, and maintenance trigger control. A controllable load module is connected in parallel to the safety circuit in a controlled manner and connected to the control unit. It is used to activate the safety circuit to generate an instantaneous clearing current pulse when it receives an instruction from the control unit. The current monitoring unit and voltage monitoring unit are connected to the control unit and are used to collect the operating current and terminal voltage of the safety circuit in real time, and transmit the collected data to the control unit. The data storage unit is used to store the file, electrical parameter model and historical operating data of each safety contact.

4. The elevator safety circuit contact health management system according to claim 3, characterized in that, The controllable load module consists of a safety relay and a power resistor connected in series. The control coil of the safety relay is connected to the control unit through an opto-isolated drive circuit, and the power resistor is connected to the inside of the safety circuit.

5. The elevator safety circuit contact health management system according to claim 3, characterized in that, The current monitoring unit is a current sampling resistor, which is connected in series in the safety circuit and is connected to the control unit through a differential amplifier circuit.

6. The elevator safety circuit contact health management system according to claim 3, characterized in that, The voltage monitoring unit is a resistor voltage divider network, the last safety contact of the safety circuit is connected to the resistor voltage divider network, and the resistor voltage divider network is connected to the control unit.

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