A weight drop protection system for a vehicle travel limit device

Abstract

This invention discloses a counterweight drop protection system for a crane's upward limit device, comprising an electromagnetic switch, installed in the crane's main control circuit, which is normally closed; a data acquisition module for acquiring the load on the pull rope; a judgment module for judging the counterweight state based on the pull rope load; the counterweight state includes a normal state, an accidental detachment state, and a crane-lifted state; and an execution module for controlling the electromagnetic switch to open and disconnect the crane when the counterweight is in an accidental detachment state. This invention innovatively employs three-dimensional judgment features—load range, instantaneous rate of change, and duration of loss of tension—combined with dynamically calibrated rated load and quantization coefficients to accurately distinguish between the normal state, the accidental detachment state, and the crane-lifted state, and determines a response plan based on the different states of the counterweight. This allows for comprehensive limit-stopping to ensure safety when the counterweight accidentally detaches, while only upper limit-stopping is applied when the counterweight is lifted by the crane to ensure normal operation.

Description

Technical Field

[0001] This invention belongs to the technical field of crane counterweight limit devices, and particularly relates to a counterweight drop protection system for a crane upward limit device. Background Technology

[0002] The counterweight limit switch is a safety protection device in the lifting system of hoisting machinery such as overhead cranes and main hooks. Its working principle is as follows: the counterweight is mechanically connected to the upper limit switch through a steel rope. The counterweight itself generates a continuous tension, keeping the internal contacts of the limit switch closed and ensuring the normal conduction of the hoist main hook lifting circuit. When the hoist main hook exceeds the preset upper limit, the moving pulley of the hoist will lift the counterweight. The tension of the steel rope gradually disappears as the counterweight is lifted. After the limit switch contacts lose tension, they open, thereby cutting off the hoist main hook lifting circuit, realizing overload protection, and avoiding collision between the moving pulley and the fixed pulley, equipment damage, or more serious safety accidents.

[0003] The existing counterweight poses a risk of accidental detachment during use, such as from a broken U-ring or a snapped steel cable. Accidental detachment of the counterweight can cause the limit switch to suddenly lose tension, thus cutting off the crane's ascent circuit. In reality, the impact of a detached counterweight is unpredictable; simply cutting off the ascent circuit does not completely eliminate the hazard. Limiting in both the horizontal and downward directions is also necessary. However, if limiting in other directions is applied when the limit switch should be in place, causing the equipment to malfunction, it will also create numerous inconveniences for operations.

[0004] Chinese patent application CN201621295624.1 discloses a crane counterweight limiting device, which includes a balance bar, a connecting rod, a connecting wire rope, and a counterweight limiting device. The top end of the connecting rod is connected to the crane trolley, and the bottom end is hinged to the front end of the balance bar. The end of the balance bar is connected to the counterweight limiting device through the connecting wire rope. The balance bar is located above the hook, and the connecting wire rope is parallel to the hook wire rope under the adjustment of the balance bar.

[0005] The aforementioned existing technology employs a counterweight limiting device parallel to the wire rope. During operation, no part of the counterweight intersects with the hook wire rope, reducing the safety malfunction of traditional counterweight devices falling off due to entanglement and wear with the hook wire rope. Although this existing technology can reduce the probability of the counterweight falling off, it lacks a mechanism to determine the cause of the limiter losing tension and corresponding countermeasures. Summary of the Invention

[0006] The purpose of this invention is to provide a drop protection system for a crane travel limit device, which partially solves or alleviates the above-mentioned deficiencies in the prior art, and can determine the state of the drop hammer and perform corresponding subsequent processing.

[0007] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A first aspect of the present invention is to provide a counterweight fall protection system for a crane upward limit device, the crane upward limit device including a limiter power-off mechanism and a counterweight connected to the limiter power-off mechanism by a pull rope; when the weight of the counterweight acts on the limiter power-off mechanism, the circuit in the limiter power-off mechanism is closed, allowing the corresponding crane to operate normally; when the limiter power-off mechanism loses the gravity traction of the counterweight, the circuit of the limiter power-off mechanism is disconnected, restricting the upward function of the corresponding crane. The drop protection system for the hammer includes: The electromagnetic switch is installed in the main control circuit of the vehicle and is normally closed. The data acquisition module is used to collect the load on the rope. The judgment module is used to determine the state of the counterweight based on the load on the rope; the state of the counterweight includes normal state, accidental detachment state, and crane-lifted state. The execution module is used to control the electromagnetic switch to disconnect in the event that the counterweight has accidentally fallen off, thereby cutting off the power to the crane.

[0008] Furthermore, the collected rope load data is preprocessed; Based on the preprocessed load data, the normal state, the accidental detachment state and the crane lifting state are distinguished by preset judgment conditions. The final hammer state is confirmed according to the preset priority and anti-shake rules, and the judgment result is output.

[0009] Furthermore, the preprocessing of the collected rope load data includes: The load values ​​are smoothed using a moving average filter. Remove outliers.

[0010] Furthermore, the criteria for determining the normal state are that the following requirements are met simultaneously: The load range is aF0≤F i ≤bF0; instantaneous load change rate k i =(F i F i 1) / T, and |ki|≤cF0 / T; The above two conditions must be met continuously for ≥10 sampling periods; where F0 is the rated load of the hammer, F i The load on the rope is T, the sampling period is k. i Let a be the rate of change, and a, b, and c be coefficients, where a < 1 < b and 0 < c < 0.05.

[0011] Furthermore, the criteria for determining an accidental detachment state are that the following requirements must be met simultaneously: The load value Fi ≤ dF0; The instantaneous load change rate ki ≤ F0 / e; From the moment the pulling rope starts to lose tension until F i ≤ dF0, the duration is less than the threshold time; When F i < fF0, it is determined that the pulling rope starts to lose tension.

[0012] Where d, e, and f are coefficients, and 0 < d < 0.1, 0 < e < 0.3.

[0013] Furthermore, the determination conditions for the vehicle jacking state are that the following requirements are met simultaneously: The cumulative tension loss amplitude ΔF i ≥ 80% × F0; ΔF i = F0 F i ; The instantaneous load change rate F0 / 2 ≤ k i ≤ 0; From the moment the pulling rope starts to lose tension until ΔF i ≥ 80% × F0, the duration is greater than or equal to the threshold time; When F i < fF0, it is determined that the pulling rope starts to lose tension, where f is a coefficient.

[0014] Furthermore, the preset priority is: accidental detachment state > vehicle jacking state > normal state. When the determination conditions for multiple states are met simultaneously, the determination result is output according to the state with a higher priority.

[0015] Furthermore, the anti-jitter rule includes: When switching from the normal state to the accidental detachment state or the vehicle jacking state, the requirements of the verification mechanism for the corresponding state are met; The requirements of the verification mechanism for the accidental detachment state are that the determination conditions are continuously met simultaneously for ≥ n sampling periods; The requirements of the verification mechanism for the vehicle jacking state are that the determination conditions are continuously met simultaneously for ≥ m sampling periods.

[0016] Furthermore, the execution module is electrically connected to the alarm module, and controls the alarm module to give an alarm when the weight is in the accidental detachment state.

[0017] Furthermore, the weight includes a back plate and a roller provided on the top of the back plate. The pulling rope is connected to the weight by passing around the roller; three drums that are spliced into a U-shaped ring are provided on the back plate, and the steel rope of the vehicle passes through the hole between the U-shaped ring and the back plate.

[0018] Beneficial effects: This invention innovatively adopts three-dimensional judgment features of load range, instantaneous change rate, and unload duration, combined with dynamically calibrated rated load and quantification coefficient, to accurately distinguish between normal state, accidental detachment state, and crane-lifted state, and determines the response plan according to the different states of the hammer. Thus, when the hammer accidentally falls, it can limit the movement in all directions to ensure safety, while when the hammer is lifted by the crane, it only limits the movement to ensure normal operation.

[0019] By setting a priority order of accidental detachment status > crane jacking status > normal status, we ensure that fatal faults are responded to as quickly as possible, medium-risk faults are precisely protected according to preset logic, and no-risk conditions affect operation. Attached Figure Description

[0020] 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. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0021] Figure 1 This is a schematic diagram of the overhead crane upward limiting device in this invention; Figure 2 This is a schematic diagram of the structure of the counterweight in this invention.

[0022] Summary of attached labeling and identification: 1-Moving contact, 2-Fixed contact, 3-Spring, 4-Pull rope, 5-Flat weight, 6-Steel rope, 51-Back plate, 52-Roller, 53-Roller. Detailed Implementation

[0023] 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] In this document, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" may be used interchangeably.

[0025] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0028] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0029] Example 1: like Figure 1 As shown, the present invention provides a fall protection system for the weight 5 of a crane upward limit device. The crane upward limit device includes a limiter power-off mechanism and a weight 5 connected to the limiter power-off mechanism by a pull rope 4. When the weight 5 acts on the limiter power-off mechanism, the circuit in the limiter power-off mechanism is closed, allowing the corresponding crane to operate normally. When the limiter power-off mechanism loses the gravity traction of the weight 5, the circuit of the limiter power-off mechanism is disconnected, thus restricting the upward function of the corresponding crane.

[0030] When the weight 5 is continuously pulled by the rope 4, the internal mechanical contacts of the mechanism remain closed, and the crane's lifting circuit is open, allowing it to rise normally. When the traction force disappears, i.e., the weight 5 falls off or is lifted up, the contacts are opened by the internal spring 3, cutting off the lifting circuit and limiting the lifting function to prevent the moving pulley from colliding with the fixed pulley.

[0031] The limiter power-off mechanism includes a fixed contact 2 and a moving contact 1 connected in the ascending circuit, and also includes a spring 3 for pushing the moving contact 1 away from the fixed contact 2. The pulling rope 4 transmits the gravity of the weight 5 to the spring 3, causing the spring 3 to compress, so that the moving contact 1 contacts the fixed contact 2 to conduct the ascending circuit. Once the weight 5 falls off or is lifted, after the traction force of the pulling rope 4 is less than the elastic potential energy of the spring 3, the spring 3 will push the moving contact 1 away from the fixed contact 2, causing the ascending circuit to disconnect.

[0032] Under normal operating conditions, the weight 5 applies a continuous traction force through the pulling rope 4. This force is transmitted along the axis to the upper end face of the spring 3, causing the spring 3 to be compressed against its own elastic potential energy to the working position; during the compression process of the spring 3, the moving contact 1 is driven by the moving contact 1 holder to move towards the fixed contact 2, and finally the two contacts are in close contact; at this time, the ascending circuit of the hoist is conducted, and the main hook can rise normally. The elastic force of the spring 3 and the gravity of the weight 5 form a dynamic balance, and the contacts remain in a stable closed state.

[0033] When the weight 5 accidentally falls off or is lifted by the hoist, the traction force of the pulling rope 4 instantaneously decreases or disappears, and the balance state is broken: if the traction force < the elastic force of the spring 3, the spring 3 starts to reset under the action of the elastic potential energy, pushing the moving contact 1 holder to move away from the fixed contact 2, and the moving contact 1 is completely separated from the fixed contact 2, and the ascending circuit is mechanically cut off; finally, the ascending function of the main hook of the hoist is limited, avoiding safety accidents such as the moving pulley colliding with the fixed pulley and the load getting out of control, and realizing the limit protection.

[0034] As Figure 2 shown, in this embodiment, the weight 5 includes a back plate 51 and a roller 52 provided at the top of the back plate 51. The pulling rope 4 is connected to the weight 5 by passing around the roller 52; three drums 53 that are spliced into a U-shaped ring are provided on the back plate 51, and the steel rope 6 of the hoist passes through the hole between the U-shaped ring and the back plate 51.

[0035] The pulling rope 4 is connected to the weight 5 by passing around the roller 52, changing the direction of the force on the pulling rope 4 from vertically downward to along the tangent direction of the roller 52, avoiding direct friction between the pulling rope 4 and the metal parts of the weight 5; at the same time, the rotational characteristics of the roller 52 convert the sliding friction into rolling friction, reducing the wear rate of the pulling rope 4 and increasing its service life. The three drums 53 of the same specification are spliced in a "pin" shape to form a U-shaped ring structure with an opening facing the steel rope 6 of the hoist. The U-shaped ring drum 53 assembly is fixed in the middle of the back plate 51, and a gap is reserved between the U-shaped ring and the back plate 51. The steel rope 6 of the hoist passes through this gap.

[0036] The U-shaped ring roller 53 assembly limits the lateral offset range of the steel rope 6 through rolling contact and three-point limiting, avoiding rigid collisions or friction between the steel rope 6 and components such as the counterweight 5 back plate 51 and the limiter; at the same time, the rotational characteristics of the roller 53 convert the motion friction of the steel rope 6 into rolling friction, which greatly reduces the wear of the steel rope 6. Especially when the crane is moving up and down, it can avoid localized force concentration caused by the swing of the steel rope 6, thus extending the service life of the steel rope 6.

[0037] The drop protection system of the hammer 5 includes: The electromagnetic switch is installed in the main control circuit of the vehicle and is normally closed.

[0038] The electromagnetic switch is connected in series at the power input terminal of the main control circuit of the vehicle or in the main contactor coil circuit for full circuit power-off control.

[0039] The data acquisition module is used to collect the load of the pull rope 4.

[0040] In this embodiment, the data acquisition module is a tension sensor, which is connected in series at the connection end between the pull rope 4 and the limit switch power-off mechanism. It directly bears the traction force of the pull rope 4, ensuring that the collected load is consistent with the actual tension.

[0041] The judgment module is used to determine the state of the counterweight 5 based on the load on the pull rope 4; the state of the counterweight 5 includes the normal state, the state of accidental detachment, and the state of being lifted by the crane.

[0042] After receiving the data from the data acquisition module, the judgment module performs smoothing filtering and outlier removal on the acquired load data to eliminate high-frequency noise and interference. It calculates three core characteristics in real time: load range, instantaneous rate of change, and duration of load slippage. Based on preset thresholds and logical rules, it outputs three results: normal state, unexpected detachment state, and crane-jacked state.

[0043] The execution module is used to control the electromagnetic switch to disconnect in the event that the counterweight 5 is accidentally detached, thereby cutting off the power to the vehicle.

[0044] The execution module consists of a relay drive circuit and a signal amplification module, and is electrically connected to the judgment module, electromagnetic switch, and limit switch power-off mechanism. After receiving the status signal from the judgment module, it controls the on / off state of the electromagnetic switch coil via an electronic switch to achieve control actions under different states. Under normal conditions, the output is low, the electromagnetic switch coil is not energized and remains normally closed, the crane runs according to the original logic, and the limit switch de-energizing mechanism controls the rising circuit.

[0045] In the event of an accidental detachment, a high-level output is triggered, energizing the electromagnetic switch coil, opening the contacts, de-energizing the main control circuit of the vehicle, and stopping all operations.

[0046] When the crane is in the jacking state, no control signal is output, the electromagnetic switch remains normally closed, and the lifting circuit is disconnected by the limit switch power-off mechanism, while retaining the original protection function.

[0047] In addition, the execution module described in this embodiment is electrically connected to the alarm module, and controls the alarm module to sound an alarm when the hammer 5 is in an accidental fall state.

[0048] More specifically, in this embodiment, the method by which the judgment module determines the state of the counterweight 5 based on the load on the rope 4 includes: S1 preprocesses the collected load data of the pull rope 4.

[0049] The purpose of this step is to eliminate noise interference, remove outlier data, and standardize the data format. Specifically, the preprocessing steps for payload data include: S11 data format standardization.

[0050] The raw load data transmitted by the data acquisition module is format-converted, converting the 4-20mA analog signal output by the sensor into a digital signal via an ADC; a timestamp is added to each data point, aligned with the timestamps of the driving condition data, to facilitate subsequent auxiliary verification of the driving condition. A data cache queue is established for sliding window processing and comparison with historical data.

[0051] S12 smoothing filter.

[0052] The standardized raw data is smoothed by using a moving average filtering method to suppress load fluctuations caused by high-frequency noise from the sensor and vehicle vibration.

[0053] S13 Outlier removal.

[0054] The effective load range is defined as 0~1.5F0 based on the rated load F0 of the hammer 5. If the original data exceeds this range, it is directly judged as an outlier and replaced with the smoothed value of the previous sampling point.

[0055] Calculate the difference between the current raw data and the previous smoothed value. If it exceeds the allowable fluctuation range of the weight 5, it is judged as a sudden abnormal value, and the smoothed value of the previous sampling point is replaced.

[0056] Abnormal data that has been removed is marked. If an abnormal value appears for three consecutive sampling periods, a sensor fault alarm is triggered, and maintenance personnel are notified to carry out repairs.

[0057] S14 starting point mark for pull-out.

[0058] Based on the smoothed load data, it is determined whether the pull rope 4 has started to lose tension, providing a trigger signal for the feature extraction of the module's startup state. A threshold for the start of tension loss is set; when the smoothed load value is less than the threshold, it is marked as the pull rope 4 has started to lose tension. In this embodiment, when F...i When f < F0, it is determined that the pulling rope 4 starts to lose traction, where f is a coefficient. Starting from the marked moment, the duration of traction loss is accumulated, and characteristic parameters such as the load change rate and the accumulated traction loss amplitude are extracted synchronously and pushed to the judgment module for state determination.

[0059] S2 Based on the preprocessed load data, the normal state, accidental detachment state, and vehicle jacking state are distinguished respectively through preset determination conditions.

[0060] Specifically, the determination conditions for the normal state are that the following requirements are satisfied simultaneously: The load range is aF0 ≤ F i ≤ bF0, for example, 0.95F0 ≤ F i ≤ 1.05F0.

[0061] The instantaneous load change rate k i = (F i F i 1) / T, and |ki| ≤ cF0 / T, for example, |ki| ≤ 0.03F0 / T.

[0062] The above two conditions are continuously satisfied for ≥ 10 sampling periods; where F0 is the rated load of the weight 5, F0 = mg (m is the mass of the weight 5, g is the acceleration due to gravity), F i is the load of the pulling rope 4 (data preprocessed through step S1), F i 1 is the load of the pulling rope 4 in the previous period, T is the sampling period, k i is the change rate, and a, b, and c are all coefficients, and a < 1 < b, 0 < c < 0.05.

[0063] Its determination process is as follows: 1. Read the current load F i after preprocessing and the load F i 1 in the previous period; calculate F0 after dynamic calibration; 2. Check whether F i is within the above range. If so, go to the next step; otherwise, it is determined as not satisfied; 3. Calculate the instantaneous change rate ki = (F i F i 1) / 0.1, check whether |F i F i 1| ≤ 0.03F0. If so, go to the next step; otherwise, it is determined as not satisfied; 4. Cumulatively count the number of consecutive periods that meet the above two conditions. If it is ≥ 10, output "Normal state", otherwise continue to accumulate.

[0064] The determination conditions for the accidental detachment state are that the following requirements are met simultaneously: Load value F i ≤ dF0, for example F i ≤ 0.08F0; Instantaneous load change rate k i ≤ F0 / e, for example k i ≤ F0 / 0.25.

[0065] From the moment when the pulling rope 4 starts to lose tension to when F i ≤ 0.08F0, the duration is less than the threshold time. In this embodiment, the threshold time is set to 250 ms.

[0066] When F i < fF0 for example F i < 0.95F0, it is determined that the pulling rope 4 starts to lose tension; Among them, F0 is the rated load of the counterweight 5, and F i is the load of the pulling rope 4, and d, e, f are coefficients, and 0 < d < 0.1, 0 < e < 0.3, 0 < f < 1.

[0067] Its determination process is as follows: 1. Read the preprocessed F i , the load F of the previous period i 1 and the dynamically calibrated F0; 2. Check whether it meets F i [[ID=4�]<0.95F0. If so, start the tension loss timing t0, otherwise it is determined not to be met and the timing is reset; 3. Calculate the instantaneous change rate k i =(F i F i 1) / 0.1, check whether it meets k i ≤ F� / 0.25. If so, proceed to the next step; 4. Check whether it meets F i ≤ 0.08F0. If so, calculate the tension loss duration t t0; [[ID=�� 5. Check t t0 < 250 ms. If the above 4 conditions are met simultaneously and 3 sampling periods are continuously verified, output the accidental detachment state.

[0068] The conditions for determining the jacking state of the crane are that the following requirements are met simultaneously: Cumulative pull-out amplitude ΔF i ≥hF0, for example, ΔF i ≥80%F0; ΔF i =F0 F i ; Instantaneous load change rate F0 / 2≤k i ≤0; From the point where the tension of rope 4 begins to decrease to ΔF i The duration of ≥80%F0 is greater than or equal to the threshold time of 250ms; When the load value F i When the value is less than 80%F0, it is determined that the pull rope 4 has begun to lose tension. Where F0 is the rated load of the hammer 5, F i For the load of rope 4, k i Let ΔF be the rate of change. i For the cumulative pull-out amplitude, F i 1 represents the load of the rope 4 in the previous cycle, f is a coefficient, 75%≤h, 0<f<1.

[0069] The determination process is as follows: 1. Read the preprocessed F i Previous cycle load F i 1 and F0 after dynamic calibration; 2. Check if F is satisfied. i If <0.95F0, then start the pullback timer t0; otherwise, reset the timer and it is determined that the condition is not met. 3. Calculate the cumulative tension loss ΔF i =F0 F i Check if it is ≥80%×F0; if so, proceed to the next step. 4. Calculate the instantaneous rate of change ki = (F i F i 1) / 0.1, check if it meets the requirements. F0 / 2≤k i If ≤0, proceed to the next step; 5. Calculate the duration t of tension loss. t0, check if it is ≥2s. If the above 4 conditions are met at the same time and 5 consecutive sampling cycles are verified, then output the jacking status of the vehicle.

[0070] S3 confirms the final state of the hammer 5 according to the preset priority and outputs the judgment result.

[0071] In this embodiment, the preset priority is: accidental detachment state > vehicle jacking state > normal state. When multiple state determination conditions are met at the same time, the determination result is output according to the state with the higher priority.

[0072] The unexpected detachment state has the highest priority. The judgment conditions are a sudden drop in load, high rate of change, and short duration. It is a sudden, instantaneous fault. Once the judgment conditions are met, other state logic must be overridden immediately.

[0073] The crane lifting state is of medium priority. The judgment conditions are gradual load change, low rate of change, and long time. It belongs to the controllable protection scenario. Even if it partially overlaps with other state conditions, it must be executed after eliminating the risk of falling off.

[0074] The normal state has the lowest priority. The judgment condition is that the load is stable and the rate of change is low. It belongs to the steady state condition and is only output when no higher priority state condition is met.

[0075] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0076] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A drop protection system for a crane travel limit device, characterized in that: The overhead crane upward limit device includes a limit switch power-off mechanism and a counterweight connected to the limit switch power-off mechanism by a pull rope; when the weight of the counterweight acts on the limit switch power-off mechanism, the circuit in the limit switch power-off mechanism is closed, allowing the corresponding overhead crane to operate normally; when the limit switch power-off mechanism loses the traction of the weight of the counterweight, the circuit of the limit switch power-off mechanism is disconnected, thus limiting the upward function of the corresponding overhead crane. The drop protection system for the hammer includes: The electromagnetic switch is installed in the main control circuit of the vehicle and is normally closed. The data acquisition module is used to collect the load on the rope. The judgment module is used to determine the state of the counterweight based on the load on the rope; the state of the counterweight includes normal state, accidental detachment state, and crane-lifted state. The execution module is used to control the electromagnetic switch to disconnect in the event that the counterweight has accidentally fallen off, thereby cutting off the power to the crane.

2. The weight drop protection system for a crane upward limit device according to claim 1, characterized in that... The method by which the judgment module determines the state of the counterweight based on the load on the rope includes: The collected rope load data is preprocessed; Based on the preprocessed load data, the normal state, the accidental detachment state and the crane lifting state are distinguished by preset judgment conditions. The final hammer state is confirmed according to the preset priority, and the judgment result is output.

3. The weight drop protection system for a crane upward limit device according to claim 2, characterized in that... The preprocessing of the collected rope load data includes: The load values ​​are smoothed using a moving average filter. Remove outliers.

4. The weight drop protection system for a crane upward limit device according to claim 2, characterized in that... The criteria for determining a normal state are that the following requirements must be met simultaneously: The load range is aF0≤F i ≤bF0; instantaneous load change rate k i =(F i F i 1) / T, and |ki|≤cF0 / T; The above two conditions must be met continuously for ≥10 sampling periods; where F0 is the rated load of the hammer, F i For the load on the rope, F i 1 represents the cable load in the previous cycle, T represents the sampling period, and k represents the sampling period. i Let a be the rate of change, and a, b, and c be coefficients, where a < 1 < b and 0 < c < 0.

05.

5. The weight drop protection system for a crane upward limit device according to claim 2, characterized in that... The criteria for determining an accidental detachment state are that the following requirements must be met simultaneously: Load value F i ≤dF0; instantaneous load change rate k i ≤ F0 / e; From the moment the rope started to slip to F i The duration of ≤dF0 is less than the threshold time; When F i <fF0, it is determined that the pull rope starts to lose traction; Where F0 is the rated load of the counterweight, F i Let d be the load on the rope, e be the coefficients, and 0 < d < 0.1, 0 < e < 0.3, and 0 < f < 1.

6. The weight drop protection system for a crane upward limit device according to claim 2, characterized in that... The conditions for determining the jacking state of the crane are that the following requirements are met simultaneously: Cumulative pull-out amplitude ΔF i ≥hF0;ΔF i =F0 F i ; Instantaneous load change rate F0 / 2≤k i ≤0; From the moment the rope starts to lose tension to ΔF i The duration of ≥hF0 is greater than or equal to the threshold time; When the load value F i < fF0, it is determined that the guy wire starts to lose tension; Where F0 is the rated load of the counterweight, F i k is the load on the rope. i F is the rate of change. i 1 represents the cable load in the previous cycle, ΔF i The cumulative pull loss is represented by f, where f is a coefficient, 75% ≤ h, and 0 < f < 1.

7. The weight drop protection system for a crane upward limit device according to claim 2, characterized in that... The preset priority is: accidental detachment state > vehicle jacking state > normal state. When multiple state judgment conditions are met at the same time, the judgment result is output according to the state with the higher priority.

8. The weight drop protection system for a crane upward limit device according to claim 1, characterized in that: The execution module is electrically connected to the alarm module, and controls the alarm module to sound an alarm in the event that the hammer is accidentally dropped.

9. The weight drop protection system for a crane upward limit device according to claim 1, characterized in that: The limit switch power-off mechanism includes a fixed contact and a movable contact connected in the rising circuit, and also includes a spring for pushing the movable contact away from the fixed contact; the pull rope transmits the weight of the hammer to the spring, causing the spring to compress, so that the movable contact contacts the fixed contact to conduct the rising circuit; when the hammer falls off or is lifted, the spring pushes the movable contact away from the fixed contact, so that the rising circuit is disconnected.

10. The weight drop protection system for a crane upward limit device according to claim 1, characterized in that: The counterweight includes a back plate and a roller set on top of the back plate. The pull rope is connected to the counterweight by passing around the roller. The back plate is provided with three rollers spliced ​​into a U-shaped ring. The steel rope of the trolley passes through the hole between the U-shaped ring and the back plate.

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