A kind of crane drum overspeed protection device and protection method based on photoelectric switch

Abstract

This specification discloses an overspeed protection device and method for crane drums based on photoelectric switches. The overspeed protection device includes: an optically encoded mark disposed on the crane drum and rotating with the crane drum; a photoelectric switch disposed corresponding to the movement trajectory of the optically encoded mark; a brake that can directly act on the crane drum; and an overspeed protection unit electrically connected to the frequency converter, the photoelectric switch, and the brake. The overspeed protection unit includes a processing module and a drive module. The processing module calculates the actual speed of the crane drum based on the pulse generated when the photoelectric switch passes the optically encoded mark. The drive module determines whether overspeeding has occurred based on the operating state of the frequency converter and the actual speed of the crane drum calculated by the processing module. When overspeeding is detected, the drive module drives the brake to mechanically brake the crane drum. This eliminates the blind spot in the overspeed safety protection of the crane drum.

Description

Technical Field

[0001] Several embodiments in this specification relate to the field of industrial automation control technology, specifically to the optimization of overspeed protection functions for crane drums. Background Technology

[0002] Cranes are lifting machines widely used in ports, workshops, construction sites, and other locations. Due to the cyclical and intermittent nature of their operation, their working mechanisms are often in a state of frequent starting, braking, and reversing. To ensure the safety and accuracy of lifting operations, the monitoring and braking control of the motor speed are crucial.

[0003] In conventional applications, an encoder or overspeed switch is usually installed on the motor side to detect the speed of the motor shaft in real time. A brake is installed on the motor shaft. When the speed exceeds a preset threshold, the control system issues a command to activate the brake installed on the motor shaft, thereby achieving deceleration or emergency braking.

[0004] However, a transmission mechanism such as a speed reducer and coupling is usually installed between the motor and the drum. Under the impact of long-term high-speed operation and frequent start-stop cycles, these transmission components may experience fatigue fracture, tooth breakage, and other failure modes. Once a "broken shaft" failure occurs, the brake on the motor side will be unable to effectively control the rotation of the drum, causing the drum to become uncontrollable and resulting in the heavy object falling rapidly. At this time, the overspeed switch's detection signal also depends on the integrity of the transmission chain. Therefore, at the moment of transmission chain failure, it cannot reflect the true state of the drum in a timely and accurate manner, resulting in delayed or even failed braking response and causing a serious safety accident. Summary of the Invention

[0005] This specification provides an embodiment of a crane drum overspeed protection device and method based on a photoelectric switch, which solves the problem that existing crane overspeed protection devices rely on the motor-side transmission chain for detection, resulting in an inability to effectively detect and control the drum state when the transmission chain fails (such as broken shaft or broken teeth), thus creating a safety protection blind spot.

[0006] The technical solution is as follows:

[0007] In a first aspect, the embodiments of this specification provide a crane drum overspeed protection device based on a photoelectric switch. The crane drum adjusts the speed of the drum motor through a frequency converter. The overspeed protection device includes an optical coding mark set on the crane drum and rotating with the crane drum, a photoelectric switch set according to the movement trajectory of the optical coding mark, a brake that can directly act on the crane drum, and an overspeed protection unit electrically connected to the frequency converter, the photoelectric switch and the brake.

[0008] The overspeed protection unit includes a processing module and a drive module;

[0009] The processing module calculates the true speed of the crane drum based on the pulses generated when the photoelectric switch passes through the optically encoded mark.

[0010] The drive module determines whether overspeed is detected based on the operating status of the frequency converter and the actual speed of the crane drum calculated by the processing module. When overspeed is detected, the drive module drives the brake to mechanically brake the crane drum.

[0011] As a preferred embodiment, the optical coding mark includes multiple reflective strips disposed on the end face of the crane drum and evenly distributed around the center of the end face.

[0012] As a preferred embodiment, the number of reflective strips is determined based on the diameter of the light spot emitted by the photoelectric switch, the width of the reflective strips, and the distance between each reflective strip and the center of the end face of the crane drum.

[0013] As a preferred embodiment, the overspeed protection device further includes a rotating component disposed on the end face of the crane drum. The rotating component rotates at a constant speed around the rotation axis of the crane drum, and the rotation direction is opposite to the unwinding rotation direction of the crane drum.

[0014] The photoelectric switch is mounted on the rotating assembly and rotates with the rotating assembly around the shaft of the crane drum.

[0015] As a preferred embodiment, the rotating assembly is electrically connected to the overspeed protection unit;

[0016] The drive module also drives the rotating component to rotate at different speeds based on the operating state of the frequency converter.

[0017] As a preferred embodiment, the processing module determines the faulty reflective strip based on the duty cycle of the pulse generated when the photoelectric switch passes through each reflective strip, corrects the number of pulses counted within a preset time, and calculates the actual speed of the crane drum.

[0018] As a preferred embodiment, the width of each reflective strip is set to gradually change sequentially;

[0019] After determining that there is a failed reflective strip, the processing module feeds back the number of the failed reflective strip based on the change in the duty cycle of the pulse generated when the photoelectric switch passes through each reflective strip.

[0020] Secondly, this specification provides an embodiment of a crane drum overspeed protection method based on a photoelectric switch. The crane drum's motor speed is adjusted by a frequency converter. The crane drum is equipped with an optically encoded mark that rotates with the crane drum and a brake that can directly act on the crane drum. A photoelectric switch is installed corresponding to the movement trajectory of the optically encoded mark. The overspeed protection method includes the following steps:

[0021] Acquire pulses generated when a photoelectric switch passes through an optically encoded mark, as well as the operating status of the frequency converter;

[0022] Count the number of pulses within a preset time and calculate the actual speed of the crane drum;

[0023] Based on the maximum speed corresponding to the current working state of the frequency converter and the actual speed of the crane drum, it is determined whether overspeed is detected. When overspeed is detected, the first drive signal is output to drive the brake to mechanically brake the crane drum.

[0024] As a preferred embodiment, a rotating assembly is provided on the end face of the crane drum. The rotating assembly rotates at a constant speed around the rotation axis of the crane drum, and the rotation direction is opposite to the unwinding rotation direction of the crane drum. The photoelectric switch is provided on the rotating assembly and rotates with the rotating assembly around the rotation axis of the crane drum.

[0025] The overspeed protection method further includes: outputting a second drive signal based on the current operating state of the frequency converter to drive the rotating component to rotate at a preset speed corresponding to the current operating state;

[0026] The process of counting the number of pulses within a preset time period and calculating the actual speed of the crane drum includes:

[0027] Count the number of pulses within a preset time period;

[0028] The actual speed of the crane drum is calculated based on the number of pulses within a preset time and the rotational speed of the rotating components.

[0029] Thirdly, embodiments of this specification provide an electronic device, including a processor and a memory; the processor is connected to the memory; the memory is used to store executable program code; the processor reads the executable program code stored in the memory to run a program corresponding to the executable program code, so as to perform the steps described in the second aspect of the above embodiments.

[0030] Fourthly, embodiments of this specification provide a computer storage medium storing a plurality of instructions adapted for loading by a processor and executing the steps described in the second aspect of the above embodiments.

[0031] The beneficial effects of the technical solutions provided in some embodiments of this specification include at least the following:

[0032] By directly setting optical coding marks and photoelectric switches on the drum body, a drum speed detection circuit independent of the motor and transmission chain is constructed, eliminating the safety protection blind spot caused by transmission chain failure. By setting a rotating component that rotates in the opposite direction to the drum, the relative speed between the photoelectric switch and the reflector is increased under low-speed conditions, improving the measurement accuracy problem caused by sparse pulses at low speeds. The drive module dynamically adjusts the rotation speed of the rotating component according to the inverter's operating status, ensuring the pulse frequency remains within a suitable measurement range at different speeds, balancing low-speed accuracy and high-speed stability. The processing module, based on pulse duty cycle analysis, automatically identifies and corrects pulse counts for failed reflectors, reducing measurement deviations caused by reflector contamination or damage and improving the long-term reliability of the device in harsh environments. By setting the reflector width to gradually change, each pulse's duty cycle carries unique positional information, enabling precise numbering and location of failed reflectors, reducing maintenance and troubleshooting difficulties. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of a crane drum overspeed protection device based on a photoelectric switch, provided in Embodiment 1 of this specification.

[0035] Figure 2 This is a schematic diagram of the overspeed protection unit in a crane drum overspeed protection device based on a photoelectric switch, as provided in Embodiment 1 of this specification.

[0036] Figure 3 This is a schematic diagram of a crane drum overspeed protection device based on a photoelectric switch, provided in Embodiment 2 of this specification.

[0037] Figure 4 This is a flowchart illustrating a crane drum overspeed protection method based on a photoelectric switch, as provided in Embodiment 4 of this specification.

[0038] Figure 5 This is a flowchart illustrating a crane drum overspeed protection method based on a photoelectric switch, as provided in Embodiment 5 of this specification.

[0039] Figure 6 This is a schematic diagram of the structure of an electronic device provided in Embodiment 6 of this specification.

[0040] In the diagram, 1 is the crane drum; 2 is the optical coding mark; 21 is the reflective strip; 3 is the photoelectric switch; 4 is the brake; 5 is the overspeed protection unit; 51 is the processing module; 52 is the drive module; and 6 is the rotating assembly. Detailed Implementation

[0041] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings.

[0042] The terms "first," "second," "third," etc., in the description, claims, and accompanying drawings are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0043] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of this specification. Various processes or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0044] Example 1

[0045] An overspeed protection device for crane drums based on photoelectric switches.

[0046] Reference Figure 1 , Figure 2 As shown, Figure 1 This is a schematic diagram of a crane drum overspeed protection device based on a photoelectric switch, provided in Embodiment 1 of this specification. Figure 2 A schematic diagram of the overspeed protection unit 5 is shown.

[0047] An overspeed protection device for a crane drum based on a photoelectric switch is provided. The crane drum 1 adjusts the speed of the drum motor through a frequency converter. The overspeed protection device includes an optical coding mark 2 set on the crane drum 1 and rotating with the crane drum 1, a photoelectric switch 3 set according to the movement trajectory of the optical coding mark 2, a brake 4 that can directly act on the crane drum 1, and an overspeed protection unit 5 electrically connected to the frequency converter, the photoelectric switch 3 and the brake 4.

[0048] The overspeed protection unit 5 includes a processing module 51 and a drive module 52;

[0049] The processing module 51 calculates the actual speed of the crane drum 1 based on the pulse generated when the photoelectric switch 3 passes the optical coding mark 2.

[0050] The drive module 52 determines whether overspeed is detected based on the working state of the frequency converter and the actual speed of the crane drum 1 calculated by the processing module 51. When overspeed is detected, the drive module 52 drives the brake 4 to mechanically brake the crane drum 1.

[0051] Explanatoryly, in order to solve the safety hazard in the prior art where the motor-side brake 4 and overspeed switch cannot effectively control the drum due to transmission chain failure, thus causing the heavy object to fall uncontrollably, this embodiment provides a crane drum overspeed protection device based on a photoelectric switch.

[0052] The crane drum 1 uses a frequency converter (such as a Schneider ATV930 frequency converter) to adjust the speed of the drum motor, thereby controlling the lifting or lowering speed at different levels. The overspeed protection device of this invention mainly includes an optical coding mark 2, a photoelectric switch 3, a brake 4, and an overspeed protection unit 5. The optical coding mark 2 is installed on the crane drum 1 and rotates with it, used to identify the rotational state of the drum, serving as a physical mark that can be identified by a non-contact sensor. The photoelectric switch 3 (such as an Omron E3Z-R81 photoelectric switch 3) is set to correspond to the movement trajectory of the optical coding mark 2 and can be installed on an external bracket near the drum, ensuring that its detection area covers the path traversed by the optical coding mark 2. When the drum rotates, each time the optical coding mark 2 passes through the detection area of ​​the photoelectric switch 3, the photoelectric switch 3 outputs a pulse signal. Brake 4 is a mechanical braking device that can directly act on the crane drum 1, such as a hydraulic caliper disc brake 4. Its function is to directly apply braking torque to the drum body after receiving a braking command, thereby achieving emergency braking without relying on the brake 4 on the motor or drive shaft side. The overspeed protection unit 5 is electrically connected to the frequency converter, photoelectric switch 3, and brake 4 respectively. The processing module 51 in the overspeed protection unit 5 is used to receive the pulse signal output by the photoelectric switch 3 and calculate the true speed of the crane drum 1 based on the pulse signal. Specifically, the processing module 51 calculates the actual linear speed or angular velocity of the drum by recording the time difference between two pulses generated by the photoelectric switch 3 passing through the optical encoding mark 2 and combining it with the known diameter parameters of the crane drum 1. For example, when a Siemens S7-1500 series PLC is used as the overspeed protection unit 5, its high-speed counter function can be used to accurately count the pulses, and sampling and calculation can be performed at fixed time intervals (such as 1 second) through a cyclic interrupt organization block to achieve real-time monitoring of the drum speed. The drive module 52 in the overspeed protection unit 5 is used to comprehensively determine whether overspeeding has occurred. The determination is based on the current operating state of the frequency converter and the actual drum speed calculated by the processing module 51. The operating state of the frequency converter may include multiple operating gears (such as gears 1 to 4 of the crane remote control or cab operation, corresponding to different operating frequencies from 10Hz to 50Hz) and an inactive state. Based on the operating state of the frequency converter, the drive module 52 determines the allowable safe speed range of the drum under the current operating conditions, and then compares the real-time speed calculated by the processing module 51 with this safe range. When it is determined that the actual drum speed exceeds the allowable range, or the frequency converter is in an inactive state but the drum is still rotating, the drive module 52 immediately outputs a control signal to drive the brake 4 to actuate, directly mechanically braking the crane drum 1.

[0053] Through the above solution, this embodiment directly locks the speed detection and braking execution onto the drum body, forming a safety protection circuit independent of the motor and transmission chain. This ensures that even in extreme cases where transmission components such as the motor shaft or reducer break or fail, the overspeed protection device can still accurately sense the drum's actual movement state and quickly implement effective braking. This fundamentally eliminates safety defects caused by transmission chain failure, significantly improving the safety of crane operations.

[0054] In one embodiment of this specification, the optical coding mark 2 includes a plurality of reflective strips 21 disposed on the end face of the crane drum 1 and evenly distributed around the center of the end face.

[0055] For illustrative purposes, this embodiment features an optimized design for the specific structure of the optical coding mark 2. See also... Figure 1 The optical coding mark 2 specifically includes multiple reflective strips 21 disposed on the end face of the crane drum 1. These reflective strips 21 are evenly distributed around the center of the drum end face, with equal included angles between each reflective strip 21 and the same radius from the center of the end face, thus forming an equally spaced ring array on the drum end face. When the drum rotates, each reflective strip 21 passes sequentially through the detection area of ​​the photoelectric switch 3, causing the photoelectric switch 3 to output a series of continuous pulse signals.

[0056] Explained, since the reflective strips 21 are evenly distributed and the angular interval between adjacent reflective strips 21 is a fixed value, the number of pulses output by the photoelectric switch 3 per unit time directly reflects the rotational speed of the drum. The processing module 51 does not need to wait for the drum to complete a full rotation to calculate the time difference; it only needs to count the total number of pulses within a preset time window (e.g., 1 second) to quickly calculate the real-time rotational speed of the drum. Compared to solutions that require measuring the time of a full rotation, this method has higher time resolution and faster response speed, making it particularly suitable for scenarios requiring rapid judgment of sudden abnormal conditions such as overspeed or shaft breakage. It significantly shortens the speed calculation cycle, improves the sensitivity to and judgment speed of speed changes, thereby enhancing the real-time performance and reliability of the overspeed protection device.

[0057] In one embodiment of this specification, the number of reflective strips 21 is determined based on the diameter of the light spot emitted by the photoelectric switch 3, the width of the reflective strips 21, and the distance between each reflective strip 21 and the center of the end face of the crane drum 1.

[0058] For illustrative purposes, this embodiment limits the method for determining the number of reflective strips 21 in order to balance signal reliability and measurement sensitivity.

[0059] Explanatoryly, the number of reflective strips 21 is not set arbitrarily, but is determined by a combination of three parameters: the diameter of the light spot emitted by the photoelectric switch 3, the width of the reflective strips 21 themselves, and the distance between each reflective strip 21 and the center of the end face of the crane drum 1.

[0060] It is important to note that when determining the number of reflective strips 21, the principle of maximizing density must be followed. That is, the number of reflective strips 21 should be increased as much as possible while ensuring signal quality. On the one hand, if the gap between the reflective strips 21 is too small, less than the diameter of the light spot emitted by the photoelectric switch 3, the light spot may simultaneously cover the end of one reflective strip 21 and the front end of the next reflective strip 21 when the drum rotates. This will prevent the photoelectric switch 3 from generating a clear on / off transition, and the output signal will remain at a high level, thus preventing the processing module 51 from detecting a valid pulse sequence. On the other hand, if the gap between the reflective strips 21 is too large, the number of pulses generated per unit time will be reduced accordingly. When the drum rotates at low speed, this may result in too few pulses within the preset time window, thereby reducing the sensitivity to low-speed overspeed or abnormal conditions, especially when the frequency converter is not running and it is necessary to keenly detect the minute rotations of the drum. The outer edge of the drum end face has a larger circumference, allowing for the placement of more and denser reflective strips 21, thereby improving the pulse resolution per unit angle. Therefore, the distance between the reflective strip 21 and the center of the end face should be as large as possible.

[0061] This embodiment takes into account the above three parameters and rationally selects the number and spacing of reflective strips 21 so that the pulse signal output by photoelectric switch 3 has clear edges and sufficient width under any working condition, thereby ensuring the reliability of the device while taking into account the detection sensitivity of low-speed abnormal conditions.

[0062] For example, when operating at 50Hz, the rated speed of the motor is known to be 1478 r / min, the reduction ratio of the reducer is 1480 / 16.62, and the number of reflective strips per revolution of drum 1 is n. If the size of the drum 1 turntable is 1000mm, the diameter of the corresponding circle of the photoelectric sensor is 488mm, and the size of the photoelectric emission area on site is 25mm, then the spacing between the reflective strips of the photoelectric sensor must be greater than 25mm. Therefore, the rotational speed of drum 1 is 1478 * 16.62 / 1480 = 16.59754 (r / min) = 0.27663 (r / s). When the length and width of the reflective strips are 50 * 10mm, the maximum number of reflective strips can be arranged to ensure signal quality, which means 36 pulses per revolution. The theoretical pulse count per second is calculated to be 36 * 0.27663 ≈ 10. Therefore:

[0063] When the frequency converter is not running, the protection will activate (brake 4 will engage) when photoelectric switch 3 detects two pulses.

[0064] When the frequency converter is running, if the photoelectric switch 3 detects more than or equal to 11 pulses in any position on the remote control within 1 second, the protection will be activated.

[0065] When the gear is in the third gear, the protection will activate when the photoelectric switch 3 detects more than 7 (30hz / 50hz*10) pulses in 1 second.

[0066] When the gear is in the second gear, the protection will activate when the photoelectric switch 3 detects more than 4 (20hz / 50hz*10) pulses in 1 second.

[0067] When the gear is in the second gear, the protection will activate when the photoelectric switch 3 detects more than 2 (10hz / 50hz*10) pulses in 1 second.

[0068] In one embodiment of this specification, the processing module 51 determines the faulty reflective strip 21 based on the duty cycle of the pulse generated when the photoelectric switch 3 passes through each reflective strip 21, corrects the number of pulses counted within a preset time, and calculates the actual speed of the crane drum 1.

[0069] Illustratively, this embodiment addresses the problem that reflective strips 21 may fail to transmit signals due to oil, dust, or physical damage in industrial environments, and provides a failure self-diagnosis and compensation method based on pulse duty cycle analysis.

[0070] Explained in this embodiment, in addition to counting the pulses output by the photoelectric switch 3, the processing module 51 further analyzes the duty cycle of each pulse. The duty cycle refers to the ratio of the duration during which the photoelectric switch 3 detects the reflective strip 21 (i.e., the effective output level) to the entire pulse cycle within one pulse period. When the reflective strips 21 are evenly distributed and have a consistent width, the duty cycle of each pulse should remain essentially consistent when the drum rotates at a constant speed. If a reflective strip 21 experiences a decrease in reflective performance due to contamination, damage, or detachment, its corresponding pulse signal will be distorted, manifesting as abnormal pulse width or amplitude attenuation, thus causing the duty cycle of that pulse to deviate significantly from the normal value. By monitoring the duty cycle of each pulse in real time and comparing it with a preset normal duty cycle range, the processing module 51 can identify potentially faulty reflective strips 21. Once a failed reflective strip 21 is detected, the processing module 51 estimates the pulse count that the failed reflective strip 21 should contribute under normal conditions based on the historical duty cycle characteristics of the failed reflective strip 21 or the pulse interval of adjacent normal reflective strips 21. This compensates for and corrects the total number of pulses counted within a preset time window. Based on the corrected pulse count, the processing module 51 recalculates the actual speed of the crane drum 1 to eliminate measurement deviations caused by the failure of the reflective strip 21. Thus, even with partial failure of the reflective strip 21, accurate measurement of the drum speed is maintained, avoiding protection delays or misjudgments caused by signal loss or anomalies, and improving the long-term operational reliability and safety of the device in harsh industrial environments.

[0071] Example 2

[0072] An overspeed protection device for crane drums based on photoelectric switches.

[0073] The difference between this embodiment and embodiment 1 is that the overspeed protection device further includes a rotating component 6 disposed on the end face of the crane drum 1. The rotating component 6 rotates at a constant speed around the rotating shaft of the crane drum 1, and the rotation direction is opposite to the unwinding rotation direction of the crane drum 1.

[0074] The photoelectric switch 3 is mounted on the rotating assembly 6 and rotates with the rotating assembly 6 around the shaft of the crane drum 1.

[0075] In illustrative terms, this embodiment addresses the problem of slow drum speed and infrequent pulse counts during low-speed operation, leading to insufficient speed calculation accuracy, by providing an optimized detection structure. See also... Figure 3 , Figure 1 This is a schematic diagram of a crane drum overspeed protection device based on a photoelectric switch, provided in Embodiment 2 of this specification.

[0076] Explanatoryly, in this embodiment, the overspeed protection device further includes a rotating assembly 6 disposed at the end face of the crane drum 1. This rotating assembly 6 can rotate uniformly around the axis of rotation of the crane drum 1, and its rotation direction is opposite to the unwinding rotation direction of the crane drum 1. The photoelectric switch 3 is no longer fixedly mounted on the external bracket, but is disposed on the rotating assembly 6 and rotates together with the rotating assembly 6 around the drum axis.

[0077] With the above structure, when the drum operates at a very low speed in a low gear, a large relative speed is generated between the photoelectric switch 3 and the reflective strip 21 on the drum end face due to the uniform rotation of the rotating component 6 in the opposite direction. At this time, the pulse frequency detected by the photoelectric switch 3 is equal to the sum of the drum's own speed and the rotation speed of the rotating component 6 multiplied by the number of reflective strips 21 per unit angle, which is significantly higher than the pulse frequency that can be generated by the drum's own rotation alone. This allows a sufficient number of pulse signals to be obtained within a preset time window even when the drum is almost stationary at low speed, thereby greatly improving the resolution and accuracy of speed calculation, reducing the judgment time at low gears, and improving the response sensitivity and reliability of the overspeed protection device across the entire speed range.

[0078] For example, in a specific implementation, the rotating component 6 can adopt a bearing-supported rotary structure and be equipped with an independent drive motor (such as a small servo motor or stepper motor) to achieve uniform and controllable rotation. The power supply and signal transmission of the photoelectric switch 3 can be achieved through a slip ring device to ensure the stability of the electrical connection during continuous rotation.

[0079] In one embodiment of this specification, the rotating assembly 6 is electrically connected to the overspeed protection unit 5;

[0080] The drive module 52 also drives the rotating component 6 to rotate at different speeds based on the working state of the frequency converter.

[0081] Illustratively, this embodiment optimizes the control method of the rotating component 6, enabling it to adaptively adjust according to actual working conditions, thereby further improving measurement performance across the entire speed range.

[0082] Explained, the drive motor of the rotating component 6 is controlled by the overspeed protection unit 5. In addition to its overspeed detection and braking functions, the drive module 52 further drives the rotating component 6 to rotate at different speeds based on the current operating state of the inverter. The drive module 52 acquires the operating status signal output by the inverter in real time, which reflects the current operating gear of the drum motor. Based on this gear information, the drive module 52 can dynamically adjust the target speed of the rotating component 6. For example, when the inverter is in a low gear (e.g., gear 1, 10Hz), the drum's own speed is extremely slow. At this time, the drive module 52 controls the rotating component 6 to rotate in the opposite direction at a higher speed to significantly increase the relative speed between the photoelectric switch 3 and the reflector strip 21, ensuring a sufficient number of pulses is obtained in a short time, thereby improving the measurement accuracy and response speed at low speeds. When the inverter is in a high gear (e.g., gear 4, 50Hz), the drum's own speed is already fast enough. At this time, the drive module 52 can control the rotating component 6 to reduce its speed or even stop rotating to avoid the pulse frequency exceeding the counting limit of the processing module 51, while reducing unnecessary energy consumption and mechanical wear.

[0083] Through the above-mentioned adaptive control strategy, this embodiment enables the rotational speed of the rotating component 6 to match the actual operating state of the drum. Under different gears, the pulse frequency output by the photoelectric switch 3 can be maintained within an optimal measurement range. This ensures the accuracy of low-speed measurement while taking into account the stability of high-speed operation and the energy consumption of the device, further improving the all-condition adaptability of the overspeed protection device.

[0084] Example 3

[0085] An overspeed protection device for crane drums based on photoelectric switches.

[0086] The difference between this embodiment and embodiment 1 is that the width of each reflective strip 21 is gradually changed in sequence;

[0087] After determining that there is a failed reflective strip 21, the processing module 51 feeds back the number of the failed reflective strip 21 based on the change in the duty cycle of the pulse generated by the photoelectric switch 3 when it passes through each reflective strip 21.

[0088] Illustratively, this embodiment optimizes the arrangement of reflective strips 21, enabling the device to accurately locate failed reflective strips 21.

[0089] Explained in this embodiment, the width of each reflective strip 21 is not fixed, but gradually varies along the circumference of the roll end face. For example, the width of the reflective strip 21 can change cyclically according to an increasing and then decreasing pattern (such as the width sequence of 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.4, 1.3, 1.2, 1.1), so that each reflective strip 21 has a unique width characteristic on the circumference. When the roll rotates at a constant speed, because the width of each reflective strip 21 is different, the pulse width (i.e., duty cycle) generated by the photoelectric switch 3 passing through each reflective strip 21 also shows a regular change. Therefore, under the condition of constant rotation speed, although the total number of pulses per unit time remains unchanged, the duty cycle of each pulse is unique, thereby establishing a correspondence between the pulse duty cycle and the sequence number of the reflective strip 21. The processing module 51 monitors the duty cycle of the pulse generated by the photoelectric switch 3 when passing through each reflective strip 21 in real time and compares it with the preset duty cycle sequence. When a reflective strip 21 deviates abnormally in its pulse duty cycle due to contamination, damage, or detachment, the processing module 51 can accurately output the number of the failed reflective strip 21 by identifying the position of the abnormal duty cycle in the sequence. This provides clear maintenance guidance for on-site maintenance personnel, enabling them to quickly locate, clean, or replace contaminated reflective strips 21, thereby shortening troubleshooting time, reducing maintenance costs, and improving the maintainability and reliability of the overspeed protection device during long-term operation.

[0090] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0091] Example 4

[0092] An overspeed protection method for crane drums based on photoelectric switches.

[0093] Please refer to the following. Figure 4 , Figure 4 A schematic flowchart of a crane drum overspeed protection method based on a photoelectric switch, provided in an embodiment of this specification, is shown.

[0094] A method for overspeed protection of a crane drum based on a photoelectric switch, wherein the crane drum's motor speed is adjusted by a frequency converter, the crane drum is equipped with an optically encoded mark that rotates with the crane drum and a brake that can directly act on the crane drum, and a photoelectric switch is set corresponding to the movement trajectory of the optically encoded mark; the overspeed protection method includes the following steps:

[0095] Step 102: Obtain the pulses generated when the photoelectric switch passes through the optical encoding mark and the operating status of the frequency converter;

[0096] Step 104: Count the number of pulses within the preset time and calculate the actual speed of the crane drum;

[0097] Step 106: Determine whether overspeed is detected based on the maximum speed corresponding to the current working state of the frequency converter and the actual speed of the crane drum. If overspeed is detected, output the first drive signal to drive the brake to mechanically brake the crane drum.

[0098] Working principle:

[0099] The first step is to acquire in real time the pulse signal generated when the photoelectric switch passes through the optically encoded mark, as well as the current operating status signal of the frequency converter. The operating status of the frequency converter reflects the current operating gear of the drum motor or whether it is in a non-operating state.

[0100] The second step is to count the number of pulses within the preset time window, and calculate the actual speed of the crane drum based on the number of pulses, the density of the optical coding marks, and the drum diameter parameter.

[0101] The third step is to determine the maximum safe speed of the drum at the current operating state of the frequency converter. For example, when the frequency converter is running at 10Hz in gear 1, the corresponding maximum safe speed is a lower value; when the frequency converter is running at 50Hz in gear 4, the corresponding maximum safe speed is a higher value. The actual drum speed calculated in the second step is compared with the maximum safe speed corresponding to that gear. If the actual speed exceeds the allowable range, it is considered overspeeding; additionally, if the frequency converter is not running but the drum still has a speed signal, it can also be considered abnormal. Once overspeeding or abnormality is determined, the first drive signal is immediately output to activate the brake, directly mechanically braking the crane drum to achieve emergency braking.

[0102] Even in extreme cases where transmission components such as the motor shaft and reducer break or fail, the method of this embodiment can still accurately sense the actual movement state of the drum and quickly implement effective braking, thereby improving the safety of crane operation.

[0103] Example 5

[0104] An overspeed protection method for crane drums based on photoelectric switches.

[0105] Please refer to the following. Figure 5 , Figure 5 A schematic flowchart of a crane drum overspeed protection method based on a photoelectric switch, provided in an embodiment of this specification, is shown.

[0106] The difference between this embodiment and embodiment 4 is that: a rotating component is provided on the end face of the crane drum, the rotating component rotates at a constant speed around the rotation axis of the crane drum, and the rotation direction is opposite to the unwinding rotation direction of the crane drum; the photoelectric switch is provided on the rotating component and rotates with the rotating component around the rotation axis of the crane drum.

[0107] The overspeed protection method also includes:

[0108] Step 103: Output a second drive signal based on the current operating state of the frequency converter to drive the rotating component to rotate at a preset speed corresponding to the current operating state;

[0109] Step 104: Count the number of pulses within a preset time and calculate the actual speed of the crane drum, including:

[0110] Step 1041: Count the number of pulses within a preset time period;

[0111] Step 1042: Calculate the actual speed of the crane drum based on the number of pulses within a preset time and the rotational speed of the rotating components.

[0112] The method also includes the step of acquiring the current operating state of the frequency converter in real time and outputting a second drive signal based on the operating state to drive the rotating component to rotate at a preset speed corresponding to the current operating state. This ensures that the pulse frequency output by the photoelectric switch is always maintained within a suitable measurement range. In the speed calculation step, since the pulse frequency output by the photoelectric switch is the result of the superposition of the drum's own speed and the rotating component's speed, the total number of pulses within a preset time window must first be counted. Then, based on this total number of pulses and the known current speed of the rotating component, the actual speed of the crane drum is calculated by subtracting the pulse component contributed by the rotating component. For example, if the total number of pulses counted within the preset time is N, and the number of pulses generated by the rotating component within that time period is M (calculated from the rotating component's speed and the optical coding mark density), then the number of pulses contributed by the drum itself is NM, which can then be converted into the actual speed of the drum. This allows the overspeed protection device to maintain high-precision speed measurement capability even when operating at low speeds in low gears, while avoiding the counting pressure caused by excessively high pulse frequencies at high gears, achieving adaptive measurement across the entire speed range and improving the reliability and applicability of the overspeed protection method.

[0113] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the overspeed protection method embodiments are basically similar to the overspeed protection device embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the overspeed protection device embodiments.

[0114] Example 6

[0115] An electronic device.

[0116] Please see Figure 6 The diagram shown is a structural schematic of an electronic device provided in an embodiment of this specification.

[0117] like Figure 6 As shown, the electronic device 600 may include: at least one processor 601, at least one network interface 604, user interface 603, memory 605, and at least one communication bus 602.

[0118] The communication bus 602 can be used to realize the connection and communication of the above components.

[0119] The user interface 603 may include buttons, and the optional user interface may also include a standard wired interface or a wireless interface.

[0120] The network interface 604 may include, but is not limited to, Bluetooth modules, NFC modules, Wi-Fi modules, etc.

[0121] The processor 601 may include one or more processing cores. The processor 601 connects to various parts within the electronic device 600 using various interfaces and lines. It executes various functions and processes data by running or executing instructions, programs, code sets, or instruction sets stored in the memory 605, and by calling data stored in the memory 605. Optionally, the processor 601 may be implemented using at least one hardware form selected from DSP, FPGA, and PLC. The processor 601 may integrate one or more of the following: CPU, GPU, and modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the content required for display; and the modem handles wireless communication. It is understood that the modem may also not be integrated into the processor 601 and may be implemented as a separate chip.

[0122] The memory 605 may include RAM or ROM. Optionally, the memory 605 may include a non-transitory computer-readable medium. The memory 605 may be used to store instructions, programs, code, code sets, or instruction sets. The memory 605 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as touch function, sound playback function, image playback function, etc.), instructions for implementing the above-described method embodiments, etc.; the data storage area may store data involved in the above-described method embodiments, etc. Optionally, the memory 605 may also be at least one storage device located remotely from the aforementioned processor 601. As a computer storage medium, the memory 605 may include an operating system, a network communication module, a user interface module, and an overspeed protection application. The processor 601 may be used to call the overspeed protection application stored in the memory 605 and execute the steps of the overspeed protection method mentioned in the foregoing embodiments.

[0123] Example 7

[0124] A computer-readable storage medium.

[0125] The computer-readable storage medium stores instructions that, when executed on a computer or processor, cause the computer or processor to perform one or more steps in the above-described overspeed protection method embodiments. If the constituent modules of the above-described electronic device are implemented as software functional units and sold or used as independent products, they can be stored in the computer-readable storage medium.

[0126] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this specification are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., Digital Versatile Discs (DVDs)), or semiconductor media (e.g., Solid State Disks (SSDs)).

[0127] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks. Unless otherwise specified, the technical features of this embodiment and its implementation can be combined arbitrarily.

[0128] The embodiments described above are merely preferred embodiments of this specification and are not intended to limit the scope of this specification. Any modifications and improvements made by those skilled in the art to the technical solutions of this specification without departing from the spirit of this specification should fall within the protection scope defined by the claims of this specification.

Claims

1. A crane drum overspeed protection device based on a photoelectric switch, wherein the crane drum adjusts the speed of the drum motor via a frequency converter, characterized in that, The overspeed protection device includes an optical coding mark installed on the crane drum and rotating with the crane drum, a photoelectric switch set according to the movement trajectory of the optical coding mark, a brake that can directly act on the crane drum, and an overspeed protection unit electrically connected to the frequency converter, the photoelectric switch and the brake. The overspeed protection unit includes a processing module and a drive module; The processing module calculates the true speed of the crane drum based on the pulses generated when the photoelectric switch passes through the optically encoded mark. The drive module determines whether overspeed is detected based on the operating status of the frequency converter and the actual speed of the crane drum calculated by the processing module. When overspeed is detected, the drive module drives the brake to mechanically brake the crane drum.

2. The crane drum overspeed protection device based on a photoelectric switch according to claim 1, characterized in that, The optical coding mark includes multiple reflective strips that are set on the end face of the crane drum and are evenly distributed around the center of the end face.

3. The crane drum overspeed protection device based on a photoelectric switch according to claim 2, characterized in that, The number of reflective strips is determined based on the diameter of the light spot emitted by the photoelectric switch, the width of the reflective strips, and the distance between each reflective strip and the center of the end face of the crane drum.

4. The crane drum overspeed protection device based on a photoelectric switch according to claim 3, characterized in that, The overspeed protection device also includes a rotating assembly disposed on the end face of the crane drum. The rotating assembly rotates at a constant speed around the rotation axis of the crane drum, and the rotation direction is opposite to the unwinding rotation direction of the crane drum. The photoelectric switch is mounted on the rotating assembly and rotates with the rotating assembly around the shaft of the crane drum.

5. A crane drum overspeed protection device based on a photoelectric switch according to claim 4, characterized in that, The rotating assembly is electrically connected to the overspeed protection unit; The drive module also drives the rotating component to rotate at different speeds based on the operating state of the frequency converter.

6. A crane drum overspeed protection device based on a photoelectric switch according to claim 2, characterized in that, The processing module determines the faulty reflective strip based on the duty cycle of the pulse generated when the photoelectric switch passes through each reflective strip, corrects the number of pulses counted within a preset time, and calculates the actual speed of the crane drum.

7. A crane drum overspeed protection device based on a photoelectric switch according to claim 6, characterized in that, The width of each reflective strip is set to gradually change sequentially; After determining that there is a failed reflective strip, the processing module feeds back the number of the failed reflective strip based on the change in the duty cycle of the pulse generated when the photoelectric switch passes through each reflective strip.

8. A method for overspeed protection of a crane drum based on a photoelectric switch, wherein the speed of the crane drum motor is adjusted by a frequency converter, characterized in that, The crane drum is equipped with optically coded markers that rotate with the crane drum and a brake that can directly act on the crane drum. A photoelectric switch is installed corresponding to the movement trajectory of the optically coded markers. The overspeed protection method includes the following steps: Acquire pulses generated when a photoelectric switch passes through an optically encoded mark, as well as the operating status of the frequency converter; Count the number of pulses within a preset time and calculate the actual speed of the crane drum; Based on the maximum speed corresponding to the current working state of the frequency converter and the actual speed of the crane drum, it is determined whether overspeed is detected. When overspeed is detected, the first drive signal is output to drive the brake to mechanically brake the crane drum.

9. A method for overspeed protection of a crane drum based on a photoelectric switch according to claim 8, characterized in that, A rotating assembly is provided on the end face of the crane drum. The rotating assembly rotates at a constant speed around the rotation axis of the crane drum, and the rotation direction is opposite to the unwinding rotation direction of the crane drum. The photoelectric switch is provided on the rotating assembly and rotates with the rotating assembly around the rotation axis of the crane drum. The overspeed protection method further includes: outputting a second drive signal based on the current operating state of the frequency converter to drive the rotating component to rotate at a preset speed corresponding to the current operating state; The process of counting the number of pulses within a preset time period and calculating the actual speed of the crane drum includes: Count the number of pulses within a preset time period; The actual speed of the crane drum is calculated based on the number of pulses within a preset time and the rotational speed of the rotating components.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in claim 8 or 9.

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