A load detection system for an elevator

Abstract

The application provides a load detection system of an elevator, and relates to the technical field of elevator load detection. The application adopts non-contact displacement sensors arranged in front of and behind the lower beam of a car frame to redundantly detect the displacement of the car, outputs a final load signal through a data fusion algorithm such as weighted average and median value selection, suppresses single-point measurement error, and improves the overall reliability of the system. Meanwhile, the application has the function of detecting unbalanced load, can prompt the unbalanced load state when the signal deviation is too large, is helpful to safety maintenance, can automatically identify the failure of a certain sensor (such as abnormal deviation of the measurement value), and remove it from the fusion calculation, and convert to output using the remaining valid sensor data, so that the system can still operate in degraded mode when some sensors fail, and the availability is improved.

Description

Technical Field

[0001] This invention relates to the field of elevator load detection technology, and more specifically, to an elevator load detection system. Background Technology

[0002] Elevator load detection is a crucial step in ensuring operational safety, improving passenger comfort, and enhancing operational efficiency. Traditional elevators typically use load cells (such as pressure sensors and strain gauges) to directly measure the force on the car. However, these sensors are usually installed at the bottom of the car or at the rope ends, and are subject to long-term impact and vibration, making them prone to zero-point drift, mechanical aging, and even damage. This leads to decreased measurement accuracy and increased maintenance costs. Therefore, we have made improvements and proposed an elevator load detection system. Summary of the Invention

[0003] The present invention provides a load detection system for an elevator, a displacement sensing unit, which is installed at a detection reference position on the elevator car frame to detect the actual distance between the corresponding sensing target on the car and the displacement sensing unit in a non-contact manner, and outputs an original electrical signal corresponding to the actual distance. The signal processing module receives the raw electrical signal output by the displacement sensing unit, performs analog-to-digital conversion, digital filtering and linear correction processing respectively, and then converts the current measured distance value into the corresponding load percentage according to the pre-stored empty load reference distance value and full load reference distance value. Finally, it outputs the final continuous load signal according to the preset fusion rules. The data interface module sends the continuous load signal to the elevator main controller, which uses the continuous load signal to perform control functions including overload detection, starting torque pre-compensation, and full-load direct drive.

[0004] As a preferred technical solution of this application, the displacement sensing unit includes two paths, one of which is installed on the front side of the lower beam of the car frame, and the other is installed on the rear side of the lower beam of the car frame.

[0005] As a preferred technical solution of this application, the preset fusion rules include: taking the weighted average or median value of the load percentage measured by the displacement sensing unit as the final output continuous load signal, and calculating the maximum deviation between the load percentages of each path. When the maximum deviation exceeds the preset off-center load threshold, the signal processing module outputs an off-center load warning sign to the elevator main controller through the data interface module.

[0006] As a preferred technical solution of this application, the preset fusion rules also include: when the signal processing module determines that the measured value of a certain displacement sensing unit deviates from the average value of other sensing units by more than a preset fault threshold, it determines that the sensor is faulty, automatically removes the sensor from the fusion calculation, and uses the average output value of the remaining valid sensors as the continuous load signal, while generating the corresponding sensor fault code for maintenance personnel to refer to.

[0007] As a preferred technical solution of this application, the signal processing module includes a memory that stores a calibration parameter table for the elevator. The calibration parameters include at least the reference distance value measured by each displacement sensing unit under no-load conditions, the reference distance value measured by each displacement sensing unit under full-load conditions, and the specified sensor type and range information. After the signal processing module is powered on, it first reads the calibration parameter table. If it fails to read valid calibration data, it forcibly outputs an uncalibrated alarm signal, and the continuous load signal output by the data interface module is locked to the fault preset value until the valid calibration is completed, at which point the normal load signal output is restored.

[0008] As a preferred technical solution of this application, the signal processing module triggers an automatic calibration process by interacting with the elevator main controller. In the automatic calibration process, the signal processing module first records the measured values ​​of each displacement sensor unit when the elevator is unloaded and stopped at a designated level position as the unloaded reference. Then, it sends a calibration progress prompt to the elevator main controller through the data interface module. The elevator main controller prompts the on-site personnel to load the elevator to the rated load through its human-machine interface or voice prompt device. After the on-site personnel confirm that the loading is completed, the signal processing module records the measured values ​​again as the full load reference and automatically generates a linear or piecewise linear load conversion curve based on these two reference points.

[0009] As a preferred technical solution of this application, the signal processing module further includes a periodic self-test unit. When the elevator is in standby or light load state, the self-test unit compares the difference between the currently measured static distance and the previously successfully calibrated no-load reference distance. If the difference exceeds a preset drift threshold but is still within the allowable safety range, the system is determined to have zero-point drift, and a prompt message indicating that recalibration is required is output to the elevator main controller through the data interface module. During this period, the system continues to output a continuous load signal according to the current measured value. If the difference exceeds a preset emergency threshold, the system is determined to have a serious failure, a fault alarm is forcibly output, and the output of a valid load signal is stopped.

[0010] As a preferred technical solution of this application, the data interface module is configured with at least one analog output channel and one digital communication channel. The analog output channel outputs 0-10V voltage or 4-20mA current, and its output value linearly corresponds to 0% to 120% of the rated load. The digital communication channel adopts Modbus, CAN, RS485 or serial communication protocol, and the output content includes real-time load percentage, original values ​​of each sensor, system status word and fault code.

[0011] As a preferred technical solution of this application, it also includes an overload hard switch interface. The overload hard switch interface is used to connect the signal of an external mechanical overload switch. The contacts of the mechanical overload switch should be connected in series in the elevator's safety circuit. When the signal processing module detects the mechanical overload switch action through the overload hard switch interface, the signal processing module outputs a forced overload flag through the data interface module, which is obtained by the elevator main controller and executes the corresponding prohibition logic. At the same time, the mechanical overload switch itself directly cuts off the safety circuit as redundant protection.

[0012] As a preferred technical solution of this application, the signal processing module uses moving average filtering, median filtering or first-order low-pass filtering algorithm for digital filtering of the original electrical signal. The filtering coefficient is dynamically adjusted according to the elevator's operating status, which is obtained by the signal processing module from the elevator main controller through the data interface module.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This application employs non-contact displacement sensors deployed before and after the lower beam of the car frame, enabling redundant detection of car displacement. The final load signal is output through data fusion algorithms such as weighted averaging and median selection, suppressing single-point measurement errors and improving overall system reliability. Simultaneously, it features off-center load detection; when the signal deviation is too large, it can indicate an off-center load condition, aiding in safe maintenance. This application can automatically identify sensor failures (such as abnormal deviations in measurement values) and remove them from the fusion calculation, switching to the use of remaining valid sensor data. This ensures the system can still operate at a degraded level even with partial sensor failures, improving availability. Attached Figure Description

[0014] Figure 1 A schematic diagram of the load detection system for the elevator provided in this application; Figure 2 A schematic diagram of the preset fusion rules provided for this application; Figure 3 A schematic diagram of the automatic calibration process provided in this application; Figure 4 The flowchart of the periodic self-test unit provided for this application. Detailed Implementation

[0015] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0016] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0017] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0018] For an example, please refer to... Figures 1-4 An elevator load detection system, comprising: The displacement sensing unit is installed at the detection reference position on the elevator car frame. It is used to detect the actual distance between the corresponding sensing target on the car and the displacement sensing unit in a non-contact manner, and outputs the original electrical signal corresponding to the actual distance. The signal processing module receives the raw electrical signal output by the displacement sensing unit, performs analog-to-digital conversion, digital filtering and linear correction processing respectively, and then converts the current measured distance value into the corresponding load percentage according to the pre-stored empty load reference distance value and full load reference distance value. Finally, it outputs the final continuous load signal according to the preset fusion rules. The data interface module sends the continuous load signal to the elevator main controller in the form of analog signals or digital communication messages. The elevator main controller uses the continuous load signal to perform control functions including at least overload judgment, starting torque pre-compensation, and full-load direct drive.

[0019] Overload detection: The main controller has an overload threshold set inside, such as 105% of the rated load. When the received continuous load signal exceeds this threshold, the main controller issues an overload alarm, keeps the door open, prohibits starting, and alerts passengers to the overload through the buzzer and display screen in the car. Starting torque pre-compensation: In traditional elevators, at the moment of startup, before the brake is released, the frequency converter often outputs a fixed initial torque and then relies on the current closed loop for rapid adjustment. If the elevator is in a heavily loaded downward or lightly loaded upward state, this fixed torque may be significantly smaller, causing the elevator to slide backward before moving forward; conversely, it may produce a shock. Using the real-time load information provided by this system, the main controller can pre-calculate the motor torque value that matches the current load at the moment the start command is issued. As soon as the brake is released, the torque is directly output, and the startup process is very smooth with almost no shock. This is especially evident for permanent magnet synchronous gearless traction machines. Full-load direct-drive function: During peak hours in office buildings, hospitals, shopping malls, and other places, elevators often find themselves in situations where the car is nearly full but not overloaded. Without the full-load direct-drive function, the elevator doors would still open after each floor stop, wasting a lot of time. This system allows the main controller to set a full-load threshold, such as 80% of the rated load. When the continuous load signal reaches 80%, the main controller automatically cancels all registered external floor calls (excluding floors already pressed inside the car) and stops responding to new call signals pressed outside the elevator hall. As passengers gradually exit the car and the load drops below 80% (e.g., to 75%), the main controller automatically resumes external call responses.

[0020] Furthermore, the displacement sensing unit includes two paths, one of which is installed on the front side of the lower beam of the car frame, and the other is installed on the rear side of the lower beam of the car frame. The displacement sensing unit can be a laser displacement sensor, an ultrasonic displacement sensor, an eddy current displacement sensor, or a Hall linear sensor. There are two advantages to this approach: first, the measurement error caused by unilateral load imbalance can be offset by averaging the data from both sources; second, if one source fails, the system can continue operating on the other, preventing the elevator from stopping abruptly. After receiving the distance values ​​from the two sensors, the signal processing module first converts each distance value into a corresponding load percentage based on pre-calibrated no-load and full-load references. The conversion formula generally uses linear interpolation. If the sensor's output is non-linear with respect to distance (such as some eddy current sensors), multi-point sampling and piecewise linearization can be performed during calibration. After obtaining the two percentage values, the signal processing module calculates the difference between them. If the difference is small, such as within 5% of the rated load, it can be considered a difference caused by normal off-center loading. The system will take the arithmetic mean of the two values ​​as the final output continuous load signal. If the difference exceeds the preset off-center load threshold, such as 15% of the rated load, the signal processing module will determine that there is a significant off-center load in the car. At this time, the system will still output the average load value (because off-center loading is not the same as overload, and the elevator can still run). However, at the same time, it will send an off-center load warning flag to the elevator main controller through the data interface module. After receiving this flag, the elevator main controller can display "Car off-center load, please adjust the goods" on the operation panel, or send a maintenance reminder through the Internet of Things module if the error does not disappear for a long time.

[0021] Furthermore, the preset fusion rules include: weighting the load percentages measured by the displacement sensing units and selecting the median value as the final output continuous load signal; calculating the maximum deviation between the load percentages of each path; and when the maximum deviation exceeds the preset off-center load threshold, the signal processing module outputs an off-center load warning flag to the elevator main controller through the data interface module. The preset fusion rules also include: when the signal processing module determines that the measured value of a certain displacement sensing unit deviates from the average value of other sensing units by more than the preset fault threshold, it determines that the sensor in that path is faulty, automatically removes the sensor from the fusion calculation, and uses the average output value of the remaining valid sensors as the continuous load signal, while generating the corresponding sensor fault code for maintenance personnel to refer to. The signal processing module continuously monitors whether the output of each sensor is within a reasonable range. For example, the measurement range of a laser displacement sensor is 50mm to 150mm. If the current output value suddenly jumps to 200mm or remains unchanged, clearly exceeding the range, the sensor is determined to be faulty. The judgment logic can also be combined with multi-channel comparison: when the output value of a certain sensor deviates from the average value of other channels by more than the set fault threshold (e.g., more than 30%), and the consistency between other channels is good, the channel that deviates is determined to be faulty. Once a sensor is determined to be faulty, the signal processing module automatically removes that sensor from the fusion calculation and stops it from participating in the averaging calculation. Instead, the output value of the remaining valid sensors is used as the continuous load signal. At the same time, the system generates a corresponding sensor fault code, stores it in the internal non-volatile memory, and reports it to the elevator main controller through the data interface module. Maintenance personnel can quickly locate which sensor is malfunctioning by reading the fault code using debugging tools. During this period, the elevator still maintains its basic load detection function and will not stop due to a single point of failure.

[0022] Furthermore, the signal processing module contains a memory that stores the calibration parameter table for this elevator. The calibration parameters include at least the reference distance values ​​measured by each displacement sensor unit under no-load and full-load conditions, as well as the specified sensor type and range information. Upon power-up, the signal processing module first reads this calibration parameter table. If no valid calibration data is found, it forcibly outputs an uncalibrated alarm signal, and the continuous load signal output by the data interface module is locked to a preset fault value (e.g., 0V or below 4mA for analog channels, or a specific error code for digital communication channels). Normal load signal output is only restored after valid calibration is completed. The calibration process consists of two steps. First, the elevator is confirmed to be unloaded and stopped at a designated leveling position (usually the ground floor leveling position, as changes in the length of the steel cable affect the rope end sensor). At this point, the signal processing module records the distance value measured by each displacement sensor unit as the unloaded baseline and stores it in memory. Second, on-site personnel load the elevator to its rated load. A common practice is to place standard weights or counterweights of known weight into the car. After loading, the elevator is again stopped at the same leveling position. The signal processing module records the distance values ​​at this time as the full-load baseline. With these two baselines (unloaded and full-load), the system automatically establishes a linear relationship between the load percentage and the measured distance. For higher accuracy, sampling can be performed at intermediate points such as 25%, 50%, and 75%. The system automatically fits a piecewise linear curve based on these points, and interpolation is used in subsequent use to calculate the load corresponding to any measured distance. After calibration, the signal processing module will periodically observe the zero-point changes of the sensors during daily operation. For example, during the first run each morning, the system records the measured values ​​of each sensor when the elevator is empty and stopped on the first floor, and compares them with the previously calibrated empty-load reference values. If the deviation is found to exceed, for example, ±3mm, but the deviation is not too large, the system can prompt "recalibration is recommended" through the data interface module. If the deviation is very large, for example, exceeding 10mm, the system will output a forced overload alarm or prohibit the start signal, because at this time the accuracy of the load calculation can no longer be guaranteed. Furthermore, the signal processing module triggers the automatic calibration process by interacting with the elevator main controller. In the automatic calibration process, the signal processing module first records the measured values ​​of each displacement sensor unit when the elevator is unloaded and stopped at a designated level position as the unloaded reference. Then, it sends a calibration progress prompt to the elevator main controller through the data interface module. The elevator main controller prompts the on-site personnel to load the elevator to the rated load through its human-machine interface or voice prompt device. After the on-site personnel confirm that the loading is completed, the signal processing module records the measured values ​​again as the full load reference and automatically generates a linear or piecewise linear load conversion curve based on these two reference points. The signal processing module also includes a periodic self-test unit. When the elevator is in standby or light load condition, the self-test unit compares the difference between the currently measured static distance and the previously successfully calibrated no-load reference distance. If the difference exceeds the preset drift threshold but is still within the allowable safety range, the system is determined to have zero-point drift, and a prompt message indicating that recalibration is required is output to the elevator main controller through the data interface module. During this period, the system continues to output a continuous load signal according to the current measured value. If the difference exceeds the preset emergency threshold, the system is determined to have a serious failure, a fault alarm is forcibly output, and the output of a valid load signal is stopped.

[0023] Furthermore, the data interface module is configured with at least one analog output channel and one digital communication channel. The analog output channel outputs 0-10V voltage or 4-20mA current, and its output value linearly corresponds to 0% to 120% of the rated load. The digital communication channel adopts Modbus, CAN, RS485 or serial communication protocol, and the output content includes real-time load percentage, original values ​​of each sensor, system status word and fault code. The data interface module serves as a bridge between this system and the elevator main controller. Considering that elevator main controllers from different manufacturers and eras have different signal interface requirements, the data interface module in this embodiment is configured with both analog output and digital communication. For analog output, this system provides 0-10V voltage output and 4-20mA current output, both of which can be output simultaneously. Users can select one of them according to the input requirements of the elevator main controller. The output analog value is linearly related to the load percentage. For example, 0V corresponds to 0% of the rated load, and 10V corresponds to 120% of the rated load (leaving a 20% margin for overload situations where the safety circuit has not yet been triggered). Similarly, 4mA corresponds to 0%, and 20mA corresponds to 120%. In terms of digital communication, this system supports Modbus RTU, CAN bus, and ordinary RS485 serial communication. The communication messages contain richer information, including not only the final load percentage, but also the raw distance values ​​of each sensor, the current system status (normal / uncalibrated / off-center load / single-channel fault / needs calibration, etc.), and detailed fault codes. For new elevator main controllers that support digital communication, the digital interface can obtain more complete system status information, making it easier to implement more complex control strategies.

[0024] Furthermore, it also includes an overload hard switch interface, which is used to connect to the signal of an external mechanical overload switch. The contacts of the mechanical overload switch should be connected in series in the elevator's safety circuit. When the signal processing module detects the mechanical overload switch action through the overload hard switch interface, regardless of the value calculated by the continuous load signal, the signal processing module outputs a forced overload flag through the data interface module, which is then obtained by the elevator main controller to execute the corresponding prohibition logic. At the same time, the mechanical overload switch itself directly cuts off the safety circuit as redundant protection. Although this application has provided a continuous load signal for overload detection, elevator safety regulations usually require redundant design for overload protection. Therefore, this embodiment retains an independent overload hard switch interface on the system, which is specifically used to connect an external mechanical overload switch. Mechanical overload switches can be micro switches or direct-acting limit switches, which are directly installed on the lower beam of the car frame. The trigger position is adjusted by the maintenance personnel so that when the car sinks to 105% to 110% of the rated load, it is pressed by the contact plate on the bottom beam of the car. The normally closed contact of the switch is connected in series in the elevator's safety circuit. In this system, the signal from the overload hard switch interface is also acquired by the signal processing module. When the signal processing module detects the mechanical switch's action, regardless of the calculated value of the current continuous load signal (which may be due to sensor drift causing the calculated value to be too low), the signal processing module will send a forced overload flag to the main controller through the data interface module. Upon receiving the flag, the main controller will prioritize the mechanical switch's judgment and prohibit the elevator from starting. The advantage of this is that even if the electronic sensing part completely fails, the mechanical overload switch can still function independently and meet safety regulations. At the same time, the signal processing module can also compare whether the overload judgment calculated electronically is basically consistent with the mechanical switch's action time. If there is a significant difference between the two over a long period of time, it indicates that the electronic part may need to be recalibrated, and the system will provide a prompt.

[0025] Furthermore, the signal processing module employs moving average filtering, median filtering, or first-order low-pass filtering algorithms for digital filtering of the original electrical signal. The filtering coefficient is dynamically adjusted according to the elevator's operating status, which is obtained by the signal processing module from the elevator main controller through the data interface module. When the elevator is in the leveling and door-opening state, the filtering coefficient is smaller to obtain a fast response. When the elevator is in operation, the filtering coefficient is increased to suppress measurement noise caused by vibration. During elevator operation, the car will vibrate and sway to varying degrees. These vibrations will be superimposed on the distance signal measured by the sensor. If not processed, the output load signal will fluctuate, causing the main controller to misjudge. This embodiment implements a variety of digital filtering algorithms in the signal processing module, including moving average filtering, median filtering and first-order low-pass filtering. On-site, the appropriate filtering algorithm and initial coefficients can be selected through debugging tools according to the actual smoothness of elevator operation. A further optimization involves dynamically adjusting the filter coefficient based on the elevator's operating status, rather than keeping it fixed. When the elevator is level and the doors are open, passengers are entering and exiting the car, requiring the system to respond quickly to changes in load. Therefore, a smaller filter coefficient is used (e.g., a time constant of 0.2 seconds for a first-order low-pass filter) to allow the output value to quickly track the actual load. Once the elevator starts and enters a constant-speed operation phase, passengers are stable inside the car, and the load itself will not change significantly. At this point, the main task is to suppress noise caused by operating vibrations, so a larger filter coefficient is used (a time constant of 1 to 2 seconds), resulting in a smoother output. When the elevator approaches the target floor and begins to decelerate, the mechanical braking and guide rail joints may cause impact vibrations, so the filter coefficient can be temporarily restored to a medium level. The implementation of this dynamic adjustment is not complicated. The signal processing module learns the current operating status of the elevator (stop, acceleration, constant speed, deceleration, leveling and door opening, etc.) from the elevator main controller through the data interface module, or determines whether it is in a stable period through its own statistical analysis of sensor signals, and then automatically switches the filtering parameters. During on-site installation, maintenance personnel first need to find a flat location on the lower beam of the car frame that is not easily bumped, and install the sensor's mounting bracket. The bracket should be designed with elongated holes to fine-tune the sensor's installation height, ensuring that the distance between the sensor and the target is in the middle of the sensor's optimal measurement range when unloaded. The target plate is fixed at the corresponding position at the bottom of the car, ensuring that the plane of the target plate is perpendicular to the detection axis of the sensor; All cables run from the sensors along the car frame to the mounting box of the signal processing module. The mounting box can be fixed on the side beam of the car frame or on the wall of the hoistway in a location that is easy to maintain. The power supply can be DC24V from the elevator control cabinet or a backup power supply provided by the main controller. During debugging, first complete the calibration operation, and then verify it: load different weights into the car in sequence, use the debugging tool to read the load percentage output by the system, compare it with the actual percentage of the weights, correct the midpoint deviation in the calibration curve, and put it into use when the error is controlled within 3% in the full range.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Obviously, the embodiments described above are merely some embodiments of the present invention, not all embodiments. The accompanying drawings show preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this invention.

Claims

1. A load detection system for an elevator, characterized in that, include: The displacement sensing unit is installed at the detection reference position on the elevator car frame. It is used to detect the actual distance between the corresponding sensing target on the car and the displacement sensing unit in a non-contact manner, and outputs the original electrical signal corresponding to the actual distance. The signal processing module receives the raw electrical signal output by the displacement sensing unit, performs analog-to-digital conversion, digital filtering and linear correction processing respectively, and then converts the current measured distance value into the corresponding load percentage according to the pre-stored empty load reference distance value and full load reference distance value. Finally, it outputs the final continuous load signal according to the preset fusion rules. The data interface module sends the continuous load signal to the elevator main controller, which uses the continuous load signal to perform control functions including overload detection, starting torque pre-compensation, and full-load direct drive.

2. The elevator load detection system according to claim 1, characterized in that, The displacement sensing unit includes two paths, one of which is installed on the front side of the lower beam of the car frame, and the other is installed on the rear side of the lower beam of the car frame.

3. The elevator load detection system according to claim 2, characterized in that, The preset fusion rules include: weighting the load percentage measured by the displacement sensing unit and selecting the median value as the final output continuous load signal; calculating the maximum deviation between the load percentages of each path; and when the maximum deviation exceeds the preset off-center load threshold, the signal processing module outputs an off-center load warning flag to the elevator main controller through the data interface module.

4. The elevator load detection system according to claim 3, characterized in that, The preset fusion rules also include: when the signal processing module determines that the measured value of a certain displacement sensing unit deviates from the average value of other sensing units by more than the preset fault threshold, it determines that the sensor is faulty, automatically removes the sensor from the fusion calculation, and uses the average output value of the remaining valid sensors as the continuous load signal, while generating the corresponding sensor fault code for maintenance personnel to refer to.

5. The elevator load detection system according to claim 1, characterized in that, The signal processing module contains a memory that stores the calibration parameter table of the elevator. The calibration parameters include at least the reference distance value measured by each displacement sensing unit under no-load conditions, the reference distance value measured by each displacement sensing unit under full-load conditions, and the specified sensor type and range information. After the signal processing module is powered on, it first reads the calibration parameter table. If it fails to read valid calibration data, it forcibly outputs an uncalibrated alarm signal, and the continuous load signal output by the data interface module is locked to the fault preset value until the valid calibration is completed, at which point the normal load signal output is restored.

6. The load detection system for elevators according to claim 5, characterized in that, The signal processing module triggers an automatic calibration process by interacting with the elevator main controller. In the automatic calibration process, the signal processing module first records the measured values ​​of each displacement sensor unit when the elevator is unloaded and stopped at a designated level position as the unloaded reference. Then, it sends a calibration progress prompt to the elevator main controller through the data interface module. The elevator main controller then prompts the on-site personnel to load the elevator to the rated load through its human-machine interface or voice prompt device. After the on-site personnel confirm that the loading is completed, the signal processing module records the measured values ​​again as the full load reference and automatically generates a linear or piecewise linear load conversion curve based on these two reference points.

7. The load detection system for elevators according to claim 1, characterized in that, The signal processing module also includes a periodic self-test unit. When the elevator is in standby or light load condition, the self-test unit compares the difference between the currently measured static distance and the previously successfully calibrated no-load reference distance. If the difference exceeds a preset drift threshold but is still within the allowable safety range, the system is determined to have zero-point drift, and a prompt message indicating that recalibration is required is output to the elevator main controller through the data interface module. During this period, the system continues to output a continuous load signal according to the current measured value. If the difference exceeds a preset emergency threshold, the system is determined to have a serious failure, a fault alarm is forcibly output, and the output of a valid load signal is stopped.

8. The load detection system for elevators according to claim 1, characterized in that, The data interface module is configured with at least one analog output channel and one digital communication channel. The analog output channel outputs 0-10V voltage or 4-20mA current, and its output value linearly corresponds to 0% to 120% of the rated load. The digital communication channel adopts Modbus, CAN, RS485 or serial communication protocol, and the output content includes real-time load percentage, original values ​​of each sensor, system status word and fault code.

9. The load detection system for an elevator according to claim 1, characterized in that, It also includes an overload hard switch interface, which is used to connect the signal of an external mechanical overload switch. The contacts of the mechanical overload switch should be connected in series in the elevator's safety circuit. When the signal processing module detects the mechanical overload switch action through the overload hard switch interface, the signal processing module outputs a forced overload flag through the data interface module, which is then obtained by the elevator main controller to execute the corresponding prohibition logic. At the same time, the mechanical overload switch itself directly cuts off the safety circuit as a redundant protection.

10. The load detection system for an elevator according to claim 1, characterized in that, The signal processing module uses moving average filtering, median filtering, or first-order low-pass filtering algorithms to digitally filter the original electrical signal. The filtering coefficients are dynamically adjusted according to the elevator's operating status, which is obtained by the signal processing module from the elevator main controller through the data interface module.

Images