Crane start-up safety control self-checking system and method

Abstract

The application discloses a kind of hoisting machinery startup safety control self-checking system and method, belong to hoisting machinery technical field, the self-checking system includes PLC controller, end limit box self-checking module, ascending weight limit self-checking module, hoisting mechanism rotation self-checking module and hoisting weight limiter self-checking module, PLC controller receives and judges according to preset logic sequence, generates pass instruction when all self-checking items pass, generates corresponding fault coding instruction when any self-checking item does not pass, also discloses a kind of hoisting machinery startup safety control self-checking method.The application integrates four independent self-checking circuits in PLC control framework, and automatically executes according to preset logic sequence, realizes the comprehensive coverage and standardization of self-checking process, completely changes the dispersed mode of each detection in traditional scheme, relies on manual operation item by item.

Description

Technical Field

[0001] This invention belongs to the field of lifting machinery technology, and in particular relates to a self-testing system and method for safety control of lifting machinery startup. Background Technology

[0002] Lifting machinery (such as tower cranes and bridge cranes) is an indispensable key equipment in modern industry and construction, and its operational safety is directly related to personal and property safety. To ensure that lifting machinery is in a safe condition before each start-up, current national standards and industry specifications generally require that the functions of its key safety devices (such as limit switches, lifting capacity limiters, brakes, etc.) be checked before the equipment is put into formal operation.

[0003] However, existing power-on security checks mainly rely on manual, item-by-item testing, which has the following shortcomings: (1) Inefficient: Operators need to manually trigger each limit switch and simulate overload signals in sequence, which takes a long time, especially in multiple equipment or large construction sites, which seriously affects the efficiency of operation.

[0004] (2) Easy to miss or misjudge: Manual inspection is prone to missing some items due to negligence, fatigue or experience differences, or inaccurate judgment of fault phenomena, leaving potential safety hazards.

[0005] (3) Lack of automatic recording and diagnosis: Traditional inspection methods cannot automatically record inspection results and fault codes. Once an accident occurs, it is difficult to trace the safety status at the time of startup.

[0006] (4) Lack of physical interlock mechanism: In manual inspection mode, operators may forcibly start the equipment when the inspection is not completed or has not passed.

[0007] Therefore, there is an urgent need to design a self-testing system and method for the safety control of lifting machinery at startup to solve the problems mentioned above. Summary of the Invention

[0008] The purpose of this invention is to provide a self-testing system and method for safety control of crane startup, which has the advantages of automatically, efficiently and reliably completing the safety test of crane startup, and can automatically control the on / off of the operating system and output fault codes according to the test results, thus solving the problems mentioned in the background art.

[0009] To achieve the above objectives, the specific technical solution of the self-test system and method for safety control of lifting machinery startup according to the present invention is as follows: A self-test system for safety control during startup of lifting machinery includes: PLC controller; The end limit box self-test module is used to trigger the end limit switch contacts and send the first signal back to the PLC controller; The rising counterweight limit self-test module is used to trigger the rising limit contact and send a second signal back to the PLC controller. The hoisting mechanism rotation self-test module is used to drive the drum to rotate forward and backward, detect the actual rotation status of the drum, and send the third and fourth signals back to the PLC controller. The lifting capacity limiter self-test module is used to input an analog-to-digital conversion signal corresponding to a preset percentage of the rated load to the encoder of the lifting capacity limiter, so that the lifting capacity limiter issues an alarm and sends a fifth signal back to the PLC controller. The PLC controller receives and judges the first, second, third, fourth and fifth signals according to a preset logical sequence. When all self-test items pass, a pass instruction is generated, and when any self-test item fails, a corresponding fault code instruction is generated. The access control module is connected to the PLC controller and is used to automatically activate the lifting machinery control system when a pass command is received. The fault code output module, which is connected to the PLC controller, is used to output the code signal corresponding to the self-test failure item when the fault code instruction is received.

[0010] Furthermore, the end limit box self-test module and the rising counterweight limit self-test module respectively include an electromagnetic spring mechanism and a self-test iron column; After the equipment is powered on, the electromagnetic spring mechanism drives the self-test iron column to move, so as to strike the corresponding end limit switch contact or the upper limit contact.

[0011] Furthermore, the lifting mechanism rotation self-test module includes an induction iron block mounted on the drum and / or a rotary encoder mounted on the drive shaft; The PLC controller is used to briefly output forward and reverse signals of the motor in the control system, and to receive third and fourth signals from the induction block and / or rotary encoder, respectively.

[0012] Furthermore, the preset percentage of the rated load is 91%.

[0013] Furthermore, the fault coding output module includes a first output port, a second output port, and a third output port; When the end limit box fails the self-test, the first output port, the second output port and the third output port output the code 001; When the self-test of the rising counterweight limit fails, the code output by the first output port, the second output port and the third output port is 010; When the lifting capacity limiter fails the self-test, the first output port, the second output port, and the third output port output the code 011. When the self-test of the hoisting mechanism fails, the code output by the first output port, the second output port and the third output port is 100.

[0014] Furthermore, the access control module includes a start-stop circuit. After the equipment is powered on and before all self-tests pass, the start-stop circuit keeps the self-test loop connected and the operating system loop disconnected. After the PLC controller generates a pass command, the start-stop circuit switches to disconnect the self-test loop and connect the operating system loop.

[0015] Furthermore, the start-stop circuit includes a logic relay and a first time-delay relay; The coil of the logic relay is connected in series with the start signal output by the PLC, and the normally open contact of the logic relay is connected in parallel with the start signal output by the PLC to form a self-locking circuit. The coil of the first time-delay relay is controlled by the PLC controller. The normally closed contact of the first time-delay relay is connected in series in the self-locking circuit of the logic relay to disconnect the self-locking after the self-test is completed.

[0016] Furthermore, it also includes a cleaning control module. When the cleaning control module is triggered, it controls the electromagnetic spring mechanism of the end limit box self-test module and / or the rising counterweight limit self-test module to repeatedly operate, so as to clean the dust or rust from the end limit switch contacts and / or the rising limit contacts by impact.

[0017] On the other hand, this application also proposes a self-test method for the safety control of lifting machinery at startup, applied to the aforementioned self-test system for the safety control of lifting machinery at startup, comprising the following steps: S1. After the equipment is powered on, the PLC controller starts the self-test window timing and disconnects the crane operation system circuit, keeping only the self-test circuit connected. S2, the PLC controller executes multiple self-test items in a preset logical order, and collects the corresponding feedback signal in real time after each self-test item is executed; After all self-test items are completed, the S3 and PLC controllers make a comprehensive judgment on all the collected feedback signals. If all self-test items pass, the PLC controller generates a pass command and controls the access control module to switch the self-test loop to the operating system loop; If any self-test item fails, the PLC controller generates a corresponding fault code instruction and controls the fault code output module to output the code signal corresponding to the failed self-test item, while keeping the operating system loop disconnected. S4. If the PLC controller has not completed the pass judgment of all self-test items when the self-test window timer reaches the preset time, the current self-test process will be forcibly terminated, the control system loop will be kept open, and a timeout fault code will be output through the fault code output module.

[0018] Furthermore, in S2, several self-check items include: The end limit box self-test module triggers the end limit switch contact and collects the first signal; The rising counterweight limit self-test module triggers the rising limit contact and collects the second signal; The hoisting mechanism rotation self-test module drives the drum to rotate forward and backward, and collects the third and fourth signals of the actual rotation status of the drum; The lifting capacity limiter self-test module sends an analog-to-digital conversion signal corresponding to a preset percentage of the rated load to the encoder of the lifting capacity limiter, and collects the fifth signal generated by the lifting capacity limiter alarm.

[0019] The present invention has the following advantages: by integrating four independent safety detection functions—end limit box self-inspection, rising counterweight limit self-inspection, lifting mechanism rotation self-inspection, and lifting weight limiter self-inspection—into a unified PLC control framework, and automatically executing them according to a preset logical sequence, the self-inspection process is fully covered and standardized, completely changing the decentralized mode in the traditional solution where each detection is independent and relies on manual operation item by item. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the self-testing system of the present invention; Figure 2 This is a schematic diagram of the end-positioning box self-testing module of the present invention; Figure 3 This is a schematic diagram of the structure of the self-test module for limiting the rising counterweight of the present invention; Figure 4 This is a schematic diagram of the lifting mechanism rotation self-test module of the present invention; Figure 5 This is a schematic diagram of the PLC control program for the PLC controller of the present invention. Figure 1 ; Figure 6 This is a schematic diagram of the PLC control program for the PLC controller of the present invention. Figure 2 ; The markings in the diagram are as follows: 1. End limit box self-test module; 11. Electromagnetic spring mechanism; 12. Self-test iron column; 2. End limit switch; 21. End limit switch contact; 3. Rising counterweight limit self-test module; 4. Upper limit box; 41. Rising limit contact; 5. Lifting mechanism rotation self-test module; 51. Rotary encoder; 52. Rotary switch; 53. Induction iron block; 6. Drum. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0023] The following is a reference to the appendix. Figure 1 To be continued Figure 6 This invention describes a self-testing system and method for safety control during startup of lifting machinery.

[0024] A self-testing system for safety control of lifting machinery includes a PLC controller, an end limit box self-testing module 1, a lifting counterweight limit self-testing module 3, a lifting mechanism rotation self-testing module 5, a lifting capacity limiter self-testing module, an access control module, and a fault code output module.

[0025] As the core control unit of the system, the PLC controller has multiple digital input ports (X ports) and digital output ports (Y ports) to receive feedback signals from various detection modules and send control commands to each execution component according to a preset logic program. In this embodiment, the PLC controller is a programmable logic controller, and its model can be selected according to the actual application scenario, as long as it has sufficient I / O points to meet the requirements.

[0026] Each self-test module is responsible for verifying the functionality of different key safety devices on the lifting machinery. The PLC controller triggers each module to perform self-tests in a pre-set logical sequence, and collects the corresponding feedback signal in real time after each self-test is completed. When all self-test items pass, the PLC controller generates a pass instruction and sends it to the access control module; when any self-test item fails, the PLC controller generates a corresponding fault code instruction and sends it to the fault code output module.

[0027] The access control module is connected to the output port (e.g., port Y023) of the PLC controller to automatically connect the hoisting machinery control system circuit when a pass command is received, so that the operator can operate the equipment normally.

[0028] The fault code output module is connected to three output ports of the PLC controller (e.g., Y001, Y002, Y003 ports) to output a three-bit binary code signal when a fault code command is received, so that maintenance personnel can quickly locate the fault type.

[0029] Fault code commands are displayed on the display module, which can be equipped with indicator lights, PLC programming software monitoring, external display screens, etc.

[0030] The end limit box self-test module 1 is used to trigger the end limit switch contact 21 and send back the first signal to the PLC controller. Specifically, the end limit box self-test module 1 includes an electromagnetic spring mechanism 11 and a self-test iron column 12. The electromagnetic spring mechanism 11 is composed of a coil. The front end of the self-test iron column 12 faces the end limit switch contact 21. After the equipment is powered on, the PLC controller sends a high-level start signal to the coil of the electromagnetic spring mechanism 11 through the output port Y011. The coil is energized and generates electromagnetic force, which drives the self-test iron column 12 to pop outward along the movement direction, hit the end limit switch contact 21, and force the end limit switch 2 to act.

[0031] After the end limit switch 2 is activated, its normally open contact closes, generating a high-level signal as the first signal, which is transmitted back to the PLC controller through the input port X001. When the PLC controller detects that the input port X001 is at a high level, it determines that the end limit box self-test has passed. If the input port X001 does not receive a high-level signal within a predetermined time (i.e., the input port X001 is at a low level), it determines that the end limit box self-test has failed.

[0032] The purpose of the end limit box self-test is to verify whether the mechanical action of the end limit switch 2 is flexible and whether the electrical contacts are reliable. In practical applications, the end limit switch 2 is usually installed at both ends of the trolley or carriage track of the crane to prevent the equipment from running beyond the limit position. Through the automatic detection of this end limit box self-test module 1, it can be ensured that the safety device is in normal working condition before each start-up.

[0033] The rising counterweight limit self-test module 3 is used to trigger the rising limit contact 41 and send a second signal back to the PLC controller. Specifically, the rising counterweight limit self-test module 3 is the same as the end limit box self-test module 1, which also includes an electromagnetic spring mechanism 11 and a self-test iron column 12. After the equipment is powered on, the PLC controller sends a high-level start signal to the coil of the electromagnetic spring mechanism 11 through the output port Y012. The coil is energized and generates electromagnetic force, which drives the self-test iron column 12 to pop outward along the movement direction, hit the rising limit contact 41, and force the limit switch inside the upper limit box 4 to act.

[0034] After the limit switch inside the upper limit box 4 is activated, its normally open contact closes, generating a high-level signal as a second signal, which is transmitted back to the PLC controller through input port X002. When the PLC controller detects that input port X002 is at a high level, it determines that the self-test of the rising counterweight limit switch has passed; if input port X002 does not receive a high-level signal within a preset time (i.e., input port X002 is at a low level), it determines that the self-test of the rising counterweight limit switch has failed.

[0035] The lifting counterweight limiter is used to prevent the hook or lifting device of the lifting machinery from rising above the maximum allowable position. It is a key safety device to prevent top-overhead accidents. This lifting counterweight limiter self-test module 3 ensures that the device is in good working order before each start-up by automatic detection.

[0036] The hoisting mechanism rotation self-test module 5 is used to drive the drum 6 to rotate forward and backward, detect the actual rotation status of the drum 6, and send back the third and fourth signals to the PLC controller. Specifically, the hoisting mechanism rotation self-test module 5 includes an induction iron block 53 set on the drum 6 and / or a rotary encoder 51 set on the drive shaft. The induction iron block 53 rotates with the drum 6. When the induction iron block 53 passes the rotary switch 52, the rotary switch 52 generates a pulse signal. The rotary encoder 51 is mounted on the drive shaft and is used to accurately detect the rotation direction and number of revolutions of the shaft.

[0037] The inductive iron block 53 and the rotary encoder 51 can be set either one or both.

[0038] During the self-test process, the PLC controller first briefly outputs a forward rotation signal to the motor through output port Y014, driving the hoisting mechanism motor to rotate forward, which in turn drives the drum 6 to rotate forward. When the drum 6 rotates forward, the sensing iron block 53 passes through the rotary switch 52, generating a pulse signal as the third signal, which is transmitted back to the PLC controller through input port X004. Subsequently, the PLC controller briefly outputs a reverse rotation signal to the motor through output port Y015, driving the hoisting mechanism motor to rotate in the opposite direction, which in turn drives the drum 6 to rotate in the reverse direction. When the drum 6 rotates in the reverse direction, the sensing iron block 53 again passes through the rotary switch 52, generating another pulse signal as the fourth signal, which is transmitted back to the PLC controller through input port X005.

[0039] When the PLC controller detects that both input ports X004 and X005 receive high-level pulse signals within a preset time, it determines that the hoisting mechanism rotation self-test has passed. If either input port X004 or input port X005 does not receive a signal (i.e., it is low-level), it determines that the hoisting mechanism rotation self-test has failed.

[0040] It should be noted that the self-test of the hoisting mechanism not only verifies whether the forward and reverse control circuit of the motor is normal, but also indirectly verifies the operational flexibility of mechanical transmission components such as drum 6, wire rope, and reducer. In addition, since the forward and reverse signals of the motor are output briefly (usually lasting 0.5s to 1s), drum 6 only rotates a very small angle, which will not cause substantial changes to the actual position of the hoisting machinery, nor will it cause a safety accident.

[0041] The lifting capacity limiter self-test module is used to input an analog-to-digital conversion signal corresponding to a preset percentage of the rated load to the encoder of the lifting capacity limiter, so that the lifting capacity limiter issues an alarm and sends a fifth signal back to the PLC controller. Specifically, the PLC controller sends an analog-to-digital conversion signal to the encoder of the lifting capacity limiter via output port Y013. The amplitude of this signal corresponds to 91% of the rated load. In this embodiment, the lifting capacity limiter uses a 24-bit A / D converter for load measurement. When the crane is empty (load is 0 tons), the A / D reading is 1,000,000 (decimal, i.e., hexadecimal 0x0F4240); when fully loaded (load is 10 tons), the A / D reading is 15,000,000 (decimal, i.e., hexadecimal 0xE4E1C0). The A / D reading corresponding to 91% of the rated load is 13,740,000 (decimal, i.e., hexadecimal 0xD1A5E0), which, when converted to a 24-bit binary number, is 110100011010010111100000.

[0042] When the lifting capacity limiter receives the simulated load signal, its internal processor determines that the current load has reached 91% of the rated load, exceeding the set alarm threshold. Therefore, it triggers an overload alarm. The alarm signal generates a high-level signal through the alarm output contact of the lifting capacity limiter, which serves as the fifth signal and is transmitted back to the PLC controller through the input port X003.

[0043] The typical alarm threshold for a lifting capacity limiter is 90% of the rated load. This invention injects an analog signal corresponding to 91% load into the encoder. The purpose is to verify whether the overload alarm function of the limiter can be reliably triggered above the 90% alarm threshold. The 91% value is sufficient to activate the alarm (above 90%) while leaving a safety margin (not reaching 100% full load), avoiding the mechanical overload risk that may occur when testing at the actual full load threshold. This value was determined based on a full balance between detection reliability and safety redundancy.

[0044] The aforementioned 91% is an optimal value determined based on the conventional 90% alarm threshold of the lifting capacity limiter, combined with safety redundancy requirements. In other embodiments, depending on the type of lifting capacity limiter and its alarm threshold settings, this preset percentage can also be slightly adjusted, as long as it ensures that an overload alarm is triggered above the lifting capacity limiter alarm threshold.

[0045] When the PLC controller detects that the input port X003 receives a high-level signal within a preset time, it determines that the lifting capacity limiter self-test has passed; if the input port X003 does not receive a high-level signal within the preset time (i.e., the input port X003 is at a low level), it determines that the lifting capacity limiter self-test has failed.

[0046] By injecting simulated load signals, this module can fully verify the signal acquisition, data processing, threshold judgment, and alarm output functions of the lifting capacity limiter without actually lifting heavy objects. This ensures the comprehensiveness of the detection while avoiding the safety risks associated with actual loading.

[0047] The PLC controller executes the above four self-test items sequentially according to a preset logical order. In this embodiment, the preset logical order is: end limit box self-test, rising counterweight limit self-test, lifting capacity limiter self-test, and lifting mechanism rotation self-test. In other embodiments of the present invention, this order can be adjusted according to actual needs, but the priority of the preset logical order remains unchanged, that is, the priority setting is determined according to the importance of each safety device.

[0048] The PLC controller collects the corresponding feedback signal in real time after each self-test item is executed, and performs a comprehensive judgment on all feedback signals. The specific judgment logic is as follows: When the first signal of the end limit box self-test module 1 is high (i.e., the input port X001 is high), it is determined that the end limit box self-test has passed, and the corresponding internal flag bit M1 is set to high; otherwise, M1 is low.

[0049] When the second signal of the rising counterweight limit self-test module 3 is high (i.e., the input port X002 is high), it is determined that the rising counterweight limit self-test has passed, and the corresponding internal flag M2 is set to high; otherwise, M2 is low.

[0050] When the fifth signal of the lifting capacity limiter self-test module is high (i.e., input port X003 is high), the lifting capacity limiter self-test is considered to have passed, and the corresponding internal flag M3 is set to high; otherwise, M3 is low.

[0051] When the third and fourth signals of the hoisting mechanism rotation self-test module 5 are both high (i.e., input ports X004 and X005 are high), the hoisting mechanism rotation self-test is deemed to have passed, and the corresponding internal flag M4 is set to high; otherwise, M4 is low.

[0052] When M1, M2, M3, and M4 are all at high level, it indicates that all self-test items have passed. The PLC controller sets the internal flag M10 to high level and outputs a high-level signal through the output port Y023 as a pass instruction, which is then sent to the access control module.

[0053] When any one of M1, M2, M3, or M4 is at a low level, it indicates that the corresponding self-test item has failed. The PLC controller generates a corresponding fault code instruction based on the failed item and outputs a three-bit binary code signal through output ports Y001, Y002, and Y003.

[0054] The fault coding output module includes a first output port Y001, a second output port Y002, and a third output port Y003. These three output ports together form a three-bit binary coding output channel, used to indicate different fault types. The specific coding rules are as follows: When the end limit box fails the self-test, the first output port Y001, the second output port Y002 and the third output port Y003 output the code 001, that is, the first output port Y001 is low level, the second output port Y002 is low level and the third output port Y003 is high level. When the self-test of the rising counterweight limit fails, the code output by the first output port Y001, the second output port Y002 and the third output port Y003 is 010, that is, the first output port Y001 is low level, the second output port Y002 is high level and the third output port Y003 is low level. When the lifting capacity limiter fails the self-test, the code output by the first output port Y001, the second output port Y002 and the third output port Y003 is 011, that is, the first output port Y001 is low level, the second output port Y002 is high level and the third output port Y003 is high level. When the self-test of the hoisting mechanism rotation fails, the code output by the first output port Y001, the second output port Y002 and the third output port Y003 is 100, that is, the first output port Y001 is high level, the second output port Y002 is low level and the third output port Y003 is low level.

[0055] With the aforementioned three-bit binary code, maintenance personnel can quickly determine the fault type simply by observing the status of the indicator lights on the three output ports, without needing a display screen or a complex fault code table, thus significantly shortening the troubleshooting time.

[0056] It should be noted that when multiple self-test items fail simultaneously, this embodiment prioritizes outputting the fault code with the highest priority. For example, if both the end limit box self-test and the lifting capacity limiter self-test fail, the code 001 corresponding to the end limit box self-test will be output first. Of course, in other embodiments, it can also be designed to display multiple fault codes in a sequential loop, or to achieve simultaneous display by increasing the number of output ports.

[0057] The access control module is connected to the PLC controller and is used to automatically turn on the crane operation system when a pass command is received. Specifically, the access control module includes a start-stop circuit, which is used to realize the on-off control of the operation system circuit. The start-stop circuit includes a logic relay M8 and a first time delay relay T11K25.

[0058] The coil of logic relay M8 is connected in series with the start signal output by the PLC controller (the start button signal connected to input port X011). When the operator presses the start button, X011 becomes high, the coil of logic relay M8 is energized, and its normally open contact closes. This normally open contact is connected in parallel with the start signal to form a self-locking circuit, so that even if the operator releases the start button, logic relay M8 can remain energized.

[0059] The coil of the first time-delay relay T11K25 is controlled by the PLC controller. Its normally closed contact is connected in series in the self-locking circuit of the logic relay M8. After the equipment is powered on, the PLC controller immediately starts the self-test window timing and simultaneously energizes the coil of the first time-delay relay T11K25. Its normally closed contact remains closed, allowing the self-locking circuit to remain conductive. When the self-test window timing reaches the preset time (e.g., 2.5s), if the PLC controller has completed the pass judgment of all self-test items, it controls the coil of the first time-delay relay T11K25 to be de-energized, its normally closed contact opens, cuts off the self-locking circuit of the logic relay M8, de-energizes the coil of the logic relay M8, and its normally open contact opens, thereby cutting off the self-test circuit.

[0060] After the equipment is powered on and before all self-tests pass, the start-stop circuit keeps the self-test circuit connected and the control system circuit disconnected. At this time, the operator's control commands cannot be transmitted to the hoisting mechanism, traveling mechanism and other actuators, thus forcibly ensuring that operation can only be carried out after the self-test passes.

[0061] The self-test circuit consists of the control signal output path and feedback signal acquisition path between the PLC controller and the end limit box self-test module 1, the lifting counterweight limit self-test module 3, the lifting mechanism rotation self-test module 5, and the lifting weight limiter self-test module.

[0062] When the PLC controller generates a pass instruction (Y023 outputs a high level), this signal controls an intermediate relay to activate, connecting the control system circuit. At this time, the operator can normally operate the crane to perform operations.

[0063] By designing a start-stop circuit, this invention achieves integrated closed-loop control of self-testing and operation system access, completely eliminating manual intervention and fundamentally avoiding the safety risks of skipping self-testing and directly starting the equipment due to operator forgetting to switch, operational errors, or wishful thinking.

[0064] The system also includes a cleaning control module. When the cleaning control module is triggered, it controls the electromagnetic spring mechanism 11 of the end limit box self-test module 1 and / or the rising counterweight limit self-test module 3 to repeatedly operate, so as to clean the dust or rust of the end limit switch contact 21 and / or the rising limit contact 41 by impact.

[0065] Specifically, the cleaning control module includes a cleaning button X022 and a second time-delay relay T22. When the operator continuously presses the cleaning button X022, the PLC controller controls the output ports Y011 and Y012 to alternately output high-level signals through the second time-delay relay T22, causing the electromagnetic spring mechanism 11 of the end limit box self-test module 1 and the rising counterweight limit self-test module 3 to repeatedly operate. During the repeated popping and retraction process, the iron column of the electromagnetic spring mechanism 11 generates continuous impact and vibration on the limit switch contacts, thereby shaking off dust, rust, or other foreign objects attached to the contacts to restore the conductivity of the internal contactor and the mechanical flexibility of the contacts.

[0066] The cleaning control module solves the problem of poor contact caused by dust accumulation or oxidation of limit switch contacts during long-term use, extending the service life of the equipment and reducing maintenance workload. This function is especially suitable for construction environments with high dust levels (such as construction sites, mine docks, etc.).

[0067] On the other hand, this application also proposes a self-test method for the safety control of lifting machinery at startup, applied to the aforementioned self-test system for the safety control of lifting machinery at startup, comprising the following steps: S1. After the equipment is powered on, the PLC controller starts the self-test window timing and disconnects the crane operation system circuit, keeping only the self-test circuit connected. When the operator turns on the main power switch of the equipment, the PLC controller powers on and initializes. The PLC controller immediately starts an internal timer as a self-test window timer, with a preset duration of 8 seconds. At the same time, the PLC controller controls the logic relay M8 to remain energized through the start-stop circuit, keeping the self-test circuit connected while the operating system circuit is disconnected. At this time, the operator cannot control any movement of the crane machinery using the control handle or remote control.

[0068] The PLC controller starts an internal timer as the total timer for the self-test process, with a preset total duration of 8 seconds, to monitor whether the entire self-test process is completed within a reasonable time. Simultaneously, the PLC controller establishes a 2.5-second self-test execution window through the first delay relay T11K25 in the start-stop circuit. This window serves as the timeout protection threshold for the execution of self-test items and feedback acquisition. If the PLC fails to complete the pass judgment for all four self-test items within 2.5 seconds after the self-test starts, it will be forcibly terminated to prevent the system from freezing.

[0069] S2, the PLC controller executes multiple self-test items in a preset logical order, and collects the corresponding feedback signal in real time after each self-test item is executed; Specifically, the self-inspection items include: End limit box self-test: The PLC controller sends a high-level signal to the electromagnetic spring mechanism 11 of the end limit box self-test module 1 through the output port Y011, driving the self-test iron column 12 to strike the end limit switch contact 21, and collects the first signal through the input port X001. Rising counterweight limit self-test: The PLC controller sends a high-level signal to the electromagnetic spring mechanism 11 of the rising counterweight limit self-test module 3 through the output port Y012, driving the self-test iron column 12 to strike the rising limit contact 41, and collects the second signal through the input port X002. Self-test of hoisting mechanism rotation: The PLC controller briefly outputs a forward rotation signal of the motor through output port Y014 to drive the drum 6 to rotate forward, and collects the third signal through input port X004; then it briefly outputs a reverse rotation signal of the motor through output port Y015 to drive the drum 6 to rotate in reverse, and collects the fourth signal through input port X005. Self-test of lifting capacity limiter: The PLC controller sends an analog-to-digital conversion signal corresponding to 91% of the rated load to the encoder of the lifting capacity limiter through the output port Y013, and collects the fifth signal through the input port X003; The above self-check items are executed sequentially according to a preset logical order. The execution time of each self-check is approximately 0.5s-1s, and the total duration of the entire self-check process is controlled within 8s.

[0070] In actual engineering, the physical execution time of each individual self-test is usually much less than 1 second, and the total time of the four self-tests generally does not exceed 1.5 seconds. Therefore, the 2.5-second window has sufficient redundancy. The execution time of each self-test recorded in the manual as 0.5-1 seconds is the maximum allowable time for each module's action and is used for system configuration reference. It is not the actual running time of each self-test.

[0071] After all self-test items are completed, the S3 and PLC controllers make a comprehensive judgment on all the collected feedback signals. If all self-test items pass (i.e., input ports X001, X002, and X003 are all at high level, and input ports X004 and X005 both receive high-level pulse signals within their respective detection windows), the PLC controller generates a pass instruction and outputs a high-level signal through output port Y023, controlling the access control module to switch the self-test loop to the operating system loop, enabling the operator to operate the equipment normally; If any self-test item fails (i.e., a low level exists in input ports X001, X002, X003, X004, and X005), the PLC controller generates a corresponding fault code instruction and outputs a three-bit binary code signal corresponding to the failed self-test item through the first output port Y001, the second output port Y002, and the third output port Y003. At the same time, the control system loop is kept disconnected to prevent the equipment from entering the operating state. S4. If the PLC controller has not completed the pass judgment of all self-test items when the self-test window timer reaches the preset time, the current self-test process will be forcibly terminated, the control system loop will be kept open, and a timeout fault code will be output through the fault code output module.

[0072] Specifically, the timeout fault code can be a preset special code (e.g., 111) to prompt maintenance personnel that the self-test process has timed out, which may indicate a serious system failure or communication anomaly. This mechanism ensures that even in extreme cases, the system will not wait indefinitely or erroneously allow the device to start, further enhancing security.

[0073] This invention integrates four independent safety detection functions—end limit box self-test, rising counterweight limit self-test, hoisting mechanism rotation self-test, and lifting capacity limiter self-test—into a unified PLC control framework. These functions are automatically executed according to a preset logical sequence, achieving comprehensive coverage and standardization of the self-test process. This completely changes the fragmented approach of traditional solutions where each test is independent and relies on manual operation. Furthermore, this invention establishes an integrated closed-loop control system for self-testing and the control system via a start-stop circuit. After the equipment is powered on, the PLC automatically takes over all self-test processes, automatically connecting the control system only after all tests have passed. If the self-test fails or exceeds the timeout (2.5s), the control system remains physically disconnected, fundamentally eliminating manual intervention and completely avoiding the safety risks of operators skipping self-tests and directly starting the equipment due to forgetting to switch, operational errors, or wishful thinking.

[0074] This invention establishes a three-bit binary fault coding system (001 / 010 / 011 / 100), which allows for quick fault identification using three indicator lights without the need for a display screen, greatly reducing the troubleshooting time for maintenance personnel.

[0075] This self-inspection system can complete the entire self-inspection process in just 8 seconds, which is more than 100 times more efficient than the 15 to 30 minutes required for traditional manual inspection. It has achieved a leap from manual intervention and decentralized inspection to unmanned, integrated, and intelligent inspection, significantly reducing the accident rate of lifting machinery and ensuring production safety and personnel safety.

[0076] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A self-test system for safety control during startup of lifting machinery, characterized in that, include: PLC controller; The end limit box self-test module is used to trigger the end limit switch contacts and send the first signal back to the PLC controller; The rising counterweight limit self-test module is used to trigger the rising limit contact and send a second signal back to the PLC controller. The hoisting mechanism rotation self-test module is used to drive the drum to rotate forward and backward, detect the actual rotation status of the drum, and send the third and fourth signals back to the PLC controller. The lifting capacity limiter self-test module is used to input an analog-to-digital conversion signal corresponding to a preset percentage of the rated load to the encoder of the lifting capacity limiter, so that the lifting capacity limiter issues an alarm and sends a fifth signal back to the PLC controller. The PLC controller receives and judges the first, second, third, fourth and fifth signals according to a preset logical sequence. When all self-test items pass, a pass instruction is generated, and when any self-test item fails, a corresponding fault code instruction is generated. The access control module is connected to the PLC controller and is used to automatically activate the lifting machinery control system when a pass command is received. The fault code output module, which is connected to the PLC controller, is used to output the code signal corresponding to the self-test failure item when the fault code instruction is received.

2. The self-test system for safety control of lifting machinery startup according to claim 1, characterized in that, The end limit box self-test module and the rising counterweight limit self-test module respectively include an electromagnetic spring mechanism and a self-test iron column; After the equipment is powered on, the electromagnetic spring mechanism drives the self-test iron column to move, so as to strike the corresponding end limit switch contact or the upper limit contact.

3. The self-test system for safety control of lifting machinery startup according to claim 1, characterized in that, The hoisting mechanism rotation self-test module includes an induction iron block mounted on the drum and / or a rotary encoder mounted on the drive shaft; The PLC controller is used to briefly output forward and reverse signals of the motor in the control system, and to receive third and fourth signals from the induction block and / or rotary encoder, respectively.

4. The self-test system for safety control of lifting machinery startup according to claim 1, characterized in that, The preset percentage of rated load is 91%.

5. The self-test system for safety control of lifting machinery startup according to claim 1, characterized in that, The fault code output module includes a first output port, a second output port, and a third output port; When the end limit box fails the self-test, the first output port, the second output port and the third output port output the code 001; When the self-test of the rising counterweight limit fails, the code output by the first output port, the second output port and the third output port is 010; When the lifting capacity limiter fails the self-test, the first output port, the second output port, and the third output port output the code 011. When the self-test of the hoisting mechanism rotation fails, the code output by the first output port, the second output port and the third output port is 100.

6. The self-test system for safety control of lifting machinery startup according to claim 1, characterized in that, The access control module includes a start-stop circuit. After the equipment is powered on and before all self-tests pass, the start-stop circuit keeps the self-test loop connected and the operating system loop disconnected. After the PLC controller generates a pass command, the start-stop circuit switches to disconnect the self-test loop and connect the operating system loop.

7. The self-test system for safety control of lifting machinery startup according to claim 6, characterized in that, The start-stop circuit includes a logic relay and a first time-delay relay; The coil of the logic relay is connected in series with the start signal output by the PLC, and the normally open contact of the logic relay is connected in parallel with the start signal output by the PLC to form a self-locking circuit. The coil of the first time-delay relay is controlled by the PLC controller. The normally closed contact of the first time-delay relay is connected in series in the self-locking circuit of the logic relay to disconnect the self-locking after the self-test is completed.

8. The self-test system for safety control of lifting machinery startup according to claim 2, characterized in that, It also includes a cleaning control module. When the cleaning control module is triggered, it controls the electromagnetic spring mechanism of the end limit box self-test module and / or the rising counterweight limit self-test module to repeatedly operate, so as to clean the dust or rust on the end limit switch contacts and / or the rising limit contacts by impact.

9. A self-test method for safety control of lifting machinery during startup, characterized in that, The self-test system for safety control of lifting machinery as described in any one of claims 1-8 includes the following steps: S1. After the equipment is powered on, the PLC controller starts the self-test window timing and disconnects the crane operation system circuit, keeping only the self-test circuit connected. S2, the PLC controller executes multiple self-test items in a preset logical order, and collects the corresponding feedback signal in real time after each self-test item is executed; After all self-test items are completed, the S3 and PLC controllers make a comprehensive judgment on all the collected feedback signals. If all self-test items pass, the PLC controller generates a pass command and controls the access control module to switch the self-test loop to the operating system loop; If any self-test item fails, the PLC controller generates a corresponding fault code instruction and controls the fault code output module to output the code signal corresponding to the failed self-test item, while keeping the operating system loop disconnected. S4. If the PLC controller has not completed the pass judgment of all self-test items when the self-test window timer reaches the preset time, the current self-test process will be forcibly terminated, the control system loop will be kept open, and a timeout fault code will be output through the fault code output module.

10. The self-test method for safety control of lifting machinery upon startup according to claim 9, characterized in that, In S2, several self-check items include: The end limit box self-test module triggers the end limit switch contact and collects the first signal; The rising counterweight limit self-test module triggers the rising limit contact and collects the second signal; The hoisting mechanism rotation self-test module drives the drum to rotate forward and backward, and collects the third and fourth signals of the actual rotation status of the drum; The lifting capacity limiter self-test module sends an analog-to-digital conversion signal corresponding to a preset percentage of the rated load to the encoder of the lifting capacity limiter, and collects the fifth signal generated by the lifting capacity limiter alarm.

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