Electric four-drive synchronous control method and system for double-lifting-point crane

Abstract

The invention relates to the technical field of hoisting operation, and discloses an electric four-drive synchronous control method and system for a double-hoisting-point crane, and the method comprises the following steps: S1, firstly electrifying the whole crane, operating a running mechanism selection button on a crane operation table, selecting a hoisting point operation mode, and operating a hoisting point operation mode; the system judges whether lifting point synchronous detection is started or not according to the lifting point operation mode; s2, the system generates different frequency converter speed words according to the selected hoisting point operation mode and sends signals to frequency converters of the corresponding hoisting mechanisms through signal cables, the frequency converters control hoisting motors of the hoisting mechanisms according to the different speed words after receiving instructions, and the crane operates according to the preset hoisting point operation mode; and S3, the system judges whether deviation rectification control is started or not according to the synchronous detection result, and electric synchronous control of the crane in different lifting point operation modes is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of lifting operations, and in particular to an electrical four-drive synchronous control method and system for a double-lifting-point crane. Background Art

[0002] With the increase in the capacity of lifting equipment, the four-drive lifting structure design is becoming more and more common. Each lifting point includes multiple sets of independent lifting mechanisms. In order to ensure the force balance between the lifting mechanisms, all lifting mechanisms are required to adopt electrical synchronization control technology and take into account multiple electrical synchronization methods, including: electrical synchronization control of four lifting mechanisms, linkage control of two lifting mechanisms and single-action control of a single lifting mechanism.

[0003] When multiple lifting mechanisms operate independently, it is impossible to guarantee the height and load errors between lifting points. The force on the lifting device is easily uneven, causing instability during the lifting process and posing a safety hazard. Summary of the invention

[0004] In order to solve the problems and deficiencies in the above-mentioned prior art, the present invention specifically proposes a method and system for electrical four-drive synchronous control of a double-hanging-point crane. Based on the selected hanging-point operation mode, the present invention dynamically judges the deviation between the running lifting mechanism and the synchronous reference point, intelligently distinguishes the deviation type and corrects the deviation according to the preset type. If the deviation exceeds the alarm value, the correction fault and shutdown command are output, and the system stops running immediately. The present invention can well perform electrical synchronous control on the four lifting mechanisms of the crane, realize lifting balance under different hanging-point operation modes, and meet the hanging-point balance requirements in hoisting.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: A method for synchronously controlling an electrical four-drive system of a double-lifting-point crane, the method comprising the following steps: Step S1. First, power on the entire crane, operate the operating mechanism selection button on the crane operating console, select the lifting point operation mode, and the system determines whether to start the lifting point synchronization detection according to the selected lifting point operation mode; Step S2. The system generates different inverter speed words according to the selected lifting point operation mode and sends the signal to the inverter of the corresponding lifting mechanism through the signal cable. After receiving the command, the inverter controls the lifting motor of the lifting mechanism, and the crane starts to operate according to the preset lifting point operation mode. During the crane operation, the system obtains the height and load of the operating lifting mechanism in real time; Step S3. The system obtains the synchronous detection result and determines whether to start the correction control according to whether the synchronous detection is performed, as well as the height and load of the hoisting mechanism of the operation, so as to realize the electrical synchronous control of the crane in different lifting point operation modes.

[0006] Preferably, the lifting point operation mode includes single-action control of a single lifting mechanism of a single lifting point, linkage control of two lifting mechanisms of a single lifting point, linkage control of two lifting mechanisms of double lifting points, and electrical synchronization control of four lifting mechanisms of double lifting points.

[0007] Preferably, when the lifting point operation mode is single-lifting point single-action control, the system does not start synchronous detection; the system first generates the inverter operation speed word of the lifting mechanism of the selected operation, and then sends the signal instruction to the inverter of the lifting mechanism, and the inverter outputs the operation frequency according to the operation speed word, controls the lifting motor action, and drives the corresponding lifting mechanism to operate; at the same time, the system generates the inverter stop speed word of the remaining lifting mechanisms, and the inverter sets the output frequency to zero according to the stop speed word, and brakes the remaining three lifting mechanisms; During the operation of the crane, the system obtains the load value of the operating lifting mechanism in real time. When the load value of the lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a shutdown command, and the operating lifting mechanism stops running immediately.

[0008] Preferably, when the lifting point operation mode is single lifting point double lifting mechanism linkage control or double lifting point two lifting mechanism linkage control, the two selected lifting mechanisms work, and the system starts the lifting point synchronization detection; Initially, the system generates the inverter running speed words of the two selected lifting mechanisms, and sends the running speed words to the inverters of the corresponding lifting mechanisms. The inverter outputs the running frequency according to the running speed words, controls the action of the lifting motor, and drives the corresponding lifting mechanism to operate. At the same time, the system generates the inverter stop speed words of the remaining two lifting mechanisms, and sends the stop speed words to the inverters of the lifting mechanisms. The inverter sets the output frequency to zero according to the stop speed words, and brakes the remaining two lifting mechanisms. During the operation of the lifting mechanism, the system obtains the load value and height value of each operating lifting mechanism in real time, and calculates the load deviation and height deviation between each operating lifting mechanism and the synchronous reference point; When the load value of any operating lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a stop command, and all lifting mechanisms stop running immediately; When the sum of the load values ​​of the two operating lifting mechanisms is greater than the second load alarm value, the system outputs a load deviation alarm signal and a stop command, and all the operating lifting mechanisms stop running immediately; When the absolute value of the load deviation between any operating lifting mechanism and the synchronous reference point is greater than the load deviation alarm value, the system outputs a load deviation alarm signal; When the absolute value of the height deviation between any running lifting mechanism and the synchronous reference point exceeds the correction alarm value, the system outputs a correction alarm signal and a stop command, and all running lifting mechanisms stop running immediately; When the absolute value of the height deviation between the running lifting mechanism and the synchronous reference point is greater than or equal to the correction input value, the system starts the correction control and corrects the lifting mechanism according to the preset correction coefficient.

[0009] Preferably, when the lifting point operation mode is the electrical synchronous control of two lifting points and four lifting mechanisms, all four lifting mechanisms on the crane work, and the system starts the synchronous detection of the lifting points; Initially, the system generates the inverter operating speed words of the four lifting mechanisms and sends the operating speed words to the inverters of the corresponding lifting mechanisms. The inverters output the operating frequency according to the operating speed words, control the action of the lifting motor, and drive the four lifting mechanisms to operate. During the operation of the lifting mechanism, the system obtains the load value and height value of each operating lifting mechanism in real time, and calculates the load deviation and height deviation between each operating lifting mechanism and the synchronous reference point; When the load value of any operating lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a stop command, and all lifting mechanisms stop running immediately; When the sum of the load values ​​of the four lifting mechanisms is greater than the third load alarm value, the system outputs a load deviation alarm signal and a shutdown command, and all the running lifting mechanisms stop running immediately; When the absolute value of the load deviation between any operating lifting mechanism and the synchronous reference point is greater than the load deviation alarm value, the system outputs a load deviation alarm signal; When the absolute value of the height deviation between any running lifting mechanism and the synchronous reference point exceeds the correction alarm value, the system outputs a correction alarm signal and a stop command, and the lifting mechanism stops running immediately; When the absolute value of the height deviation between the running lifting mechanism and the synchronous reference point is greater than or equal to the correction input value, the system starts the correction control and corrects the lifting mechanism according to the preset correction coefficient.

[0010] Preferably, when the height of the synchronous reference point minus the height of the lifting mechanism for correction is ≥ 0 and the lifting mechanism is in the ascending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1 + correction coefficient) × input speed; When the height of the synchronous reference point minus the height of the lifting mechanism for correction is ≥ 0 and the lifting mechanism is in the descending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1-correction coefficient) × input speed; When the height of the synchronous reference point minus the height of the lifting mechanism for correction is less than 0 and the lifting mechanism is in the ascending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1-correction coefficient) × input speed; When the height of the synchronous reference point minus the height of the lifting mechanism for correction is less than 0 and the lifting mechanism is in the descending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1 + correction coefficient) × input speed.

[0011] Preferably, the height of the lifting mechanism is the distance from the lifting mechanism to the reference horizontal plane. The height of the synchronization reference point is the distance from the synchronization reference point to the reference horizontal plane.

[0012] Preferably, the synchronization reference point is a calibrated reference point, or any one of the operating lifting mechanisms is selected as the synchronization reference point.

[0013] Preferably, when the synchronization reference point is a calibrated reference point, the height of the synchronization reference point is the average value of the sum of heights of all operating lifting mechanisms; the load of the synchronization reference point is the average value of the sum of loads of all operating lifting mechanisms.

[0014] Based on the same inventive concept, on the other hand, the present invention also proposes an electrical four-drive synchronous control system for a double-lifting-point crane, the system being used to implement the electrical synchronous control method described above, the system comprising: a No. 1 lifting mechanism, a No. 2 lifting mechanism, a No. 3 lifting mechanism, a No. 4 lifting mechanism, a PLC controller and an operating mechanism button, the operating mechanism button being connected to the PLC controller via a signal cable, each lifting mechanism being provided with a position sensor and a load sensor, the position sensor and the load sensor being connected to the PLC controller via a signal cable, and each lifting mechanism comprising a power mechanism consisting of a lifting motor and a frequency converter, the lifting motor being connected to the lifting mechanism and to the frequency converter via a power cable, the frequency converter being connected to the PLC controller via a signal cable.

[0015] Beneficial effects of the present invention: The present invention first selects the crane's lifting point operation mode, and then based on the selected lifting point operation mode, dynamically determines the deviation between the running lifting mechanism and the synchronization reference point, intelligently identifies the deviation type and performs deviation correction according to the preset type. If the deviation exceeds the alarm value, a correction fault and a shutdown command are output, and the running lifting mechanism stops running immediately. The present invention can well perform electrical synchronous control on the four lifting mechanisms of the crane, achieve lifting balance under different lifting point operation modes, and meet the lifting point balance requirements in hoisting. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing and following detailed description of the present invention will become more apparent when read in conjunction with the following drawings, in which: Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 It is a schematic diagram of the layout structure of the lifting mechanism of the present invention. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions for achieving the purpose of the present invention will be further described below through several specific embodiments. It should be noted that the technical solutions claimed for protection in the present invention include but are not limited to the following embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0018] As the most basic implementation mode of the present invention, this embodiment first discloses a method for synchronously controlling the electric four-drive of a double-hanging-point crane. Figure 1 , the method mainly comprises the following steps: Step S1. First, power on the crane and the entire system. The operator operates the operating mechanism selection button on the crane operating console to select the lifting point operation mode. The PLC controller determines whether to start the lifting point synchronization detection according to the selected lifting point operation mode.

[0019] In the embodiment described in the present invention, the lifting point operation mode includes single-point single-lifting mechanism single-action control, single-point double-lifting mechanism linkage control, double-point two-lifting mechanism linkage control and double-point four-lifting mechanism electrical synchronization control. It should be noted that the entire crane corresponds to two hooks, that is, two lifting points, each lifting point includes two independent lifting mechanisms, and the entire lifting system includes four independent lifting mechanisms. Figure 2 As shown in the figure, the No. 1 and No. 2 lifting mechanisms correspond to one lifting point of the crane, and the No. 3 and No. 4 lifting mechanisms correspond to another lifting point of the crane. For the single-lifting point single-lifting mechanism single-action control, any one of the four lifting mechanisms is in operation; the single-lifting point double-lifting mechanism linkage control is generally the linkage control of the No. 1 lifting mechanism and the No. 2 lifting mechanism or the linkage control of the No. 3 lifting mechanism and the No. 4 lifting mechanism; the double-lifting point four-lifting mechanism electrical synchronous control, that is, all four lifting mechanisms are in operation.

[0020] In particular, when a lifting mechanism at one lifting point fails, but two lifting mechanisms are required to work together, dual lifting point two lifting mechanism linkage control will be used, that is, one lifting mechanism is selected from the two lifting mechanisms at each lifting point for combined use.

[0021] In general, the linkage control of two lifting mechanisms at a single lifting point is to select two lifting mechanisms for one hook; while the linkage control of two lifting mechanisms at two lifting points is to select one of the two lifting mechanisms corresponding to the two hooks according to the actual working conditions and the lifting mechanism conditions, and use them in combination. The combination scheme can be linkage control of the No. 1 lifting mechanism and the No. 3 lifting mechanism, linkage control of the No. 1 lifting mechanism and the No. 4 lifting mechanism, linkage control of the No. 2 lifting mechanism and the No. 3 lifting mechanism, or linkage control of the No. 2 lifting mechanism and the No. 4 lifting mechanism.

[0022] It can be understood that when the selected operating mode is single-point single-lifting mechanism single-action control, the system will not start the lifting point synchronization detection; when the selected operating mode is single-point two-lifting mechanism linkage control or double-point four-lifting mechanism electrical synchronization control, the system will synchronously start the synchronization detection program to detect the synchronization between each operating lifting mechanism in real time during operation.

[0023] Step S2. Initially, the PLC controller controls the operation of the corresponding lifting mechanism according to the selected lifting point operation mode, and the crane starts operating according to the preset lifting point operation mode.

[0024] In the embodiment described in the present invention, when the lifting point operation mode is single lifting point single lifting mechanism single action control, in the initial stage, the single action control of the first lifting mechanism is taken as an example to illustrate the work flow, which is as follows: The PLC controller generates the initial operating speed word of the inverter of the No. 1 lifting mechanism, and then sends the initial operating speed word to the inverter of the No. 1 lifting mechanism through the signal cable. The inverter outputs the operating frequency according to the initial operating speed word, and connects to the lifting motor of the No. 1 lifting mechanism through the power cable, and finally drives the No. 1 lifting mechanism to operate. At the same time, the PLC controller generates the inverter stop speed word of the No. 2 lifting mechanism, the No. 3 lifting mechanism, and the No. 4 lifting mechanism, and sends the stop speed word signal to the inverter of the corresponding lifting mechanism through the signal cable. The inverter sets the output frequency to zero according to the stop speed word, and brakes the No. 2 lifting mechanism, the No. 3 lifting mechanism, and the No. 4 lifting mechanism respectively, so as to realize the single-action operation of the No. 1 lifting mechanism; During the operation of the crane, the PLC controller will obtain the load value of the running No. 1 lifting mechanism in real time. When the load value of the No. 1 lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a shutdown command, and the No. 1 lifting mechanism stops running immediately.

[0025] The working process of the single-action control of the single lifting mechanism corresponding to the No. 2 lifting mechanism, the No. 3 lifting mechanism and the No. 4 lifting mechanism refers to the above-mentioned single-action control of the No. 1 lifting mechanism, and will not be elaborated in detail here.

[0026] In the embodiment described in the present invention, when the lifting point operation mode is the linkage control of the two lifting mechanisms of a single lifting point, in the initial stage, the linkage control of the first lifting mechanism and the second lifting mechanism is taken as an example to illustrate the work flow, which is as follows: In the initial stage, the PLC controller generates the initial operating speed word of the inverter for the No. 1 and No. 2 lifting mechanisms, and then sends it to the corresponding lifting mechanism inverter through the signal cable. The inverter outputs the operating frequency according to the initial operating speed word, controls the corresponding lifting motor action, and finally drives the No. 1 and No. 2 lifting mechanisms to operate together. At the same time, the PLC controller generates the inverter stop speed word for the No. 3 and No. 4 lifting mechanisms, and sends it to the corresponding inverter through the signal cable. The inverter sets the output frequency to zero according to the stop speed word, and finally brakes the No. 3 and No. 4 lifting mechanisms.

[0027] The working process of the linkage control of the No. 3 lifting mechanism and the No. 4 lifting mechanism refers to the linkage control of the No. 1 lifting mechanism and the No. 2 lifting mechanism mentioned above, and will not be elaborated in detail here.

[0028] Furthermore, for the workflow of the linkage control of the two lifting mechanisms at double lifting points, reference can be made to the linkage control of the two lifting mechanisms at single lifting points, which will not be elaborated in detail here.

[0029] In the embodiment described in the present invention, when the lifting point operation mode is the electrical synchronous control of the double lifting point and four lifting mechanisms, the working process of the system in the initial stage is as follows: The PLC controller generates the initial operating speed words of the inverters of the four lifting mechanisms, and sends them to the inverters of the corresponding lifting mechanisms through signal cables. The inverters output the operating frequency according to the initial operating speed words, and drive the corresponding lifting motors to work through the power cables, and finally drive the various lifting mechanisms to run synchronously.

[0030] Therefore, it can be understood that when the selected operating mode is single-action control of a single lifting mechanism, the selected lifting mechanism is working, while the remaining lifting mechanisms are in a shutdown state and do not participate in the lifting work; when the selected operating mode is linkage control of two lifting mechanisms, the selected two lifting mechanisms are working, and the remaining lifting mechanisms are not working; in the operating mode of electrical synchronous control of four lifting mechanisms, the four lifting mechanisms corresponding to the crane must all work.

[0031] Step S3. During the operation of the crane, for the operation modes of linkage control of two lifting mechanisms and electrical synchronous control of four lifting mechanisms, the PLC controller detects the synchronization between each operating lifting mechanism and the synchronization reference point in real time, and determines whether to start the correction control based on the synchronization detection result, so as to realize the electrical synchronous control of the crane in different lifting point operation modes.

[0032] After the crane starts to operate, the system will start the synchronization detection program for the two operation modes of linkage control of two lifting mechanisms and electrical synchronization control of four lifting mechanisms. The process of the synchronization detection program is the same. Each lifting mechanism is equipped with a position sensor and a load sensor to detect the height and load of the lifting mechanism respectively. The PLC controller calculates the load deviation and height deviation between each operating lifting mechanism and the synchronization reference point in real time based on the data received from the position sensor and load sensor. For the synchronous detection of height deviation: When the absolute value of the height deviation between the running lifting mechanism and the synchronous reference point is less than the correction input value, the correction control program for the lifting mechanism system is not started; When the absolute value of the height deviation between the running lifting mechanism and the synchronous reference point is greater than or equal to the correction input value, the system starts the correction control program for the lifting mechanism, and the PLC controller corrects the lifting mechanism according to the preset correction coefficient. At this time, the lifting mechanism is a correction lifting mechanism; when the correction stop value is reached, the correction control is exited; When the absolute value of the height deviation between any running lifting mechanism and the synchronous reference point exceeds the correction alarm value, the PLC controller outputs a correction alarm signal and a stop command, and the lifting mechanism stops running immediately.

[0033] Each operating lifting mechanism is compared with the synchronous reference point and independently performs deviation correction control, so as to achieve electrical synchronous operation control between two lifting mechanisms or four lifting mechanisms.

[0034] In the embodiment described in the invention, when the deviation correction control program is started, the PLC controller will correct the deviation of the lifting mechanism in combination with the running direction, height and other data of the lifting mechanism. The specific deviation correction process is as follows: 1) When the deviation correction control program is started, when |the height of the lifting mechanism to be corrected - the height of the synchronous reference point| is less than the deviation correction input value, the deviation correction control program is not activated. At this time, the output speed of the PLC controller = the input speed (the output speed is the current operating speed of the lifting mechanism, and the input speed is the initial operating speed given by the PLC controller when the lifting mechanism starts to operate); 2) When the deviation correction control program is started, when |the height of the lifting mechanism to be corrected - the height of the synchronous reference point|≥the deviation correction input value, the deviation correction control program is activated; 3) When the height of the synchronous reference point - the height of the lifting mechanism for correction is ≥0 and the lifting mechanism is running in the ascending direction, the speed of the lifting mechanism for correction is slow and needs to be increased. The output speed of the PLC controller = (1 + correction coefficient) × input speed; when the height of the synchronous reference point - the height of the lifting mechanism for correction is ≥0 and the lifting mechanism is running in the descending direction, the speed of the lifting mechanism for correction is fast and needs to be reduced. The output speed of the PLC controller = (1-correction coefficient) × input speed; when the height of the synchronous reference point - the height of the lifting mechanism for correction is <0 and the lifting mechanism is running in the ascending direction, the speed of the lifting mechanism for correction is fast and needs to be reduced. The output speed of the PLC controller = (1-correction coefficient) × input speed; when the height of the synchronous reference point - the height of the lifting mechanism for correction is <0 and the lifting mechanism is running in the ascending direction, the speed of the lifting mechanism for correction is slow and needs to be increased. The output speed of the PLC controller = (1 + correction coefficient) × input speed; 4) After the deviation correction control program is activated, after a period of deviation correction, when |synchronous reference point height - lifting mechanism height for deviation correction| < deviation correction stop value appears, the deviation correction control program is released, and the output speed of the lifting mechanism output by the PLC controller = input speed.

[0035] For load testing: a) Linkage control of two lifting mechanisms During the operation of the lifting mechanism, when the load value of any operating lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a stop command, and all lifting mechanisms stop operating immediately; When the sum of the load values ​​of the two operating lifting mechanisms is greater than the second load alarm value, the system outputs a load deviation alarm signal and a stop command, and all the operating lifting mechanisms stop running immediately; When the absolute value of the load deviation between any operating lifting mechanism and the synchronous reference point is greater than the load deviation alarm value, the system outputs a load deviation alarm signal; b) Electrical synchronization control of four lifting mechanisms During the operation of the lifting mechanism, when the load value of any operating lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a stop command, and all lifting mechanisms stop operating immediately; When the sum of the load values ​​of the four lifting mechanisms is greater than the third load alarm value, the system outputs a load deviation alarm signal and a shutdown command, and all the running lifting mechanisms stop running immediately; When the absolute value of the load deviation between any operating lifting mechanism and the synchronous reference point is greater than the load deviation alarm value, the system outputs a load deviation alarm signal.

[0036] In all the embodiments described in the present invention, the height of the lifting mechanism is the distance from the lifting mechanism to the base reference horizontal plane; the height of the synchronization reference point is the distance from the synchronization reference point to the base reference horizontal plane.

[0037] In all embodiments described in the present invention, the reference level is set as follows: Y=kx+b, x is the original code value data of the height encoder, Y is the calibrated lifting mechanism height, k and b are the coefficients of the linear function; The highest limit point and the lowest limit point of the lifting mechanism are selected as calibration points. The lowest limit point can be calibrated with a relative height of 0m or the actual altitude. The highest limit point is linearly calibrated with a distance of +0m or altitude relative to the lowest limit point. Through calibration, the values ​​of k and b are calculated. When the lifting mechanism is running, the PLC controller will bring the value of the position sensor read into the above linear function in real time to obtain the height of the lifting mechanism.

[0038] Similarly, the load of the lifting mechanism can also be calibrated using the above method. After the calibration is completed, when the lifting mechanism is running, the PLC controller will read the value of the load sensor into the linear function in real time to obtain the load of the lifting mechanism.

[0039] It is understandable that for the two operation modes of linkage control of two lifting mechanisms and electrical synchronous control of four lifting mechanisms, the selection of synchronization reference points is the same. For example, the synchronization reference point can be any one of the operating lifting mechanisms selected as the synchronization reference point, and the remaining lifting mechanisms refer to the lifting mechanism for synchronization detection and deviation correction during operation. The synchronization reference point can also be a calibrated reference point.

[0040] It can be understood that when a certain lifting mechanism is selected as the synchronization reference point, the height and load of the synchronization reference point are the height value and load value corresponding to the lifting mechanism.

[0041] It can be understood that when the synchronization reference point is the calibrated reference reference point, the position of the reference reference point is the arithmetic mean of the sum of the heights of the hoisting mechanisms of all working operations of the crane, and the calculation formula is as follows: When the two lifting mechanisms are in linkage control mode: The reference point position = (height of the first lifting mechanism + height of the second lifting mechanism) / 2; or, The position of the reference point = (height of the third lifting mechanism + height of the fourth lifting mechanism) / 2; When the four lifting mechanisms are in electrical synchronous control mode: The position of the benchmark reference point = (height of the No. 1 lifting mechanism + height of the No. 2 lifting mechanism + height of the No. 3 lifting mechanism + height of the No. 4 lifting mechanism) / 4.

[0042] When the synchronous reference point is the calibrated reference point, the load at the reference point is the arithmetic mean of the sum of the loads of the hoisting mechanisms of all working operations of the crane. The calculation formula is as follows: When the two lifting mechanisms are in linkage control mode: The reference point position = (load of the first lifting mechanism + load of the second lifting mechanism) / 2; or, The position of the reference point = (load of the third lifting mechanism + load of the fourth lifting mechanism) / 2; When the four lifting mechanisms are in electrical synchronous control mode: The position of the datum reference point = (load of lifting mechanism No. 1 + load of lifting mechanism No. 2 + load of lifting mechanism No. 3 + load of lifting mechanism No. 4) / 4.

[0043] Therefore, it can be further understood that when the synchronization reference point is a calibrated reference reference point, its distance to the reference horizontal plane does not need to be calculated again, and the position obtained by the above calculation formula is the height of the synchronization reference point; and the load of the synchronization reference point at this time is also the value obtained by the above calculation formula.

[0044] In all the embodiments described in the present invention, it should be noted that the first load value is 1.1 times the rated load value of a single lifting mechanism, the second load value is 1.1 times the sum of the rated load values ​​of two operating lifting mechanisms, and the third load value is 1.1 times the sum of the rated load values ​​of four operating lifting mechanisms.

[0045] Based on the same inventive concept, the embodiment of the present invention also discloses an electrical four-drive synchronous control system for a double-lifting-point crane. Since the principle of solving the problem by the system is similar to the electrical synchronous control method for the four lifting mechanisms of the crane, the implementation of the system can refer to the implementation of the method, and the repeated parts will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable. Figure 2 A schematic diagram of the layout structure of an electrical four-drive synchronous control system for a double-hanging-point crane provided by an embodiment of the present invention is shown in FIG. Figure 2As shown, the system mainly consists of a No. 1 lifting mechanism, a No. 2 lifting mechanism, a No. 3 lifting mechanism, a No. 4 lifting mechanism, a signal cable, a power cable, a PLC controller, an operating mechanism selection button, a frequency converter, a lifting motor, a position sensor, a load sensor, etc. Among them, the operating mechanism selection button is connected to the PLC controller through a signal cable, the frequency converter and the lifting motor form a power mechanism, and the above four lifting mechanisms each include a set of power mechanisms composed of a frequency converter and a lifting motor; the PLC controller is connected to the frequency converter of each lifting mechanism through a signal cable, and the frequency converter is connected to the corresponding lifting motor through a power cable, and the lifting motor is connected to the corresponding lifting mechanism through a mechanical connection shaft, and the position sensor and the load sensor are both installed on the lifting mechanism and connected to the PLC through a signal cable. The position sensor is used to detect the distance from the lifting mechanism to the reference horizontal plane, and the load sensor is used to detect the corresponding load of the lifting mechanism.

[0046] After the system is powered on, the operator selects the lifting point operation mode through the operating mechanism selection button on the operating console, and transmits the selected operation mode to the PLC controller; among them, the lifting point operation mode includes electrical synchronous control of four lifting mechanisms, linkage control of No. 1 and No. 2 lifting mechanisms, linkage control of No. 3 and No. 4 lifting mechanisms, linkage control of No. 1 and No. 3 lifting mechanisms, linkage control of No. 1 and No. 4 lifting mechanisms, linkage control of No. 2 and No. 3, linkage control of No. 2 and No. 4, single-action control of No. 1 lifting mechanism, single-action control of No. 2 lifting mechanism, single-action control of No. 3 lifting mechanism and single-action control of No. 4 lifting mechanism.

[0047] After the PLC controller has judged the operation mode instruction internally, it determines whether to start the synchronous detection of the lifting mechanism; then the PLC controller generates different inverter speed words according to the selected lifting point operation mode and sends the signal to the inverter of the corresponding lifting mechanism through the signal cable. After receiving the instruction, the inverter controls the lifting motor of the corresponding lifting mechanism according to the different speed words, and the crane starts to operate according to the preset lifting point operation mode; during the operation of the crane, the PLC obtains the height and load of each running lifting mechanism in real time, and then detects the height deviation and load deviation between each running lifting mechanism and the synchronous reference point according to the synchronous detection control, and determines whether to start the correction control or output the alarm signal according to the synchronous detection result, so as to finally realize the electrical synchronous control of the crane under different lifting point operation modes.

[0048] It should be noted that the systems, devices, models or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, in this specification, the above devices are described in various units according to their functions. Of course, when implementing the present invention, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0049] Furthermore, in the present specification, adjectives such as first and second may be used merely to distinguish one element or action from another, without necessarily or implying any actual such relationship or order.

[0050] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware.

[0051] The above description is only a preferred embodiment of the present invention and does not constitute any form of hindrance to the present invention. Any simple modification or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for synchronous control of electrical four-drive of a double-lifting-point crane, characterized in that: The method comprises the following steps: Step S1. First, power on the entire crane, operate the operating mechanism selection button on the crane operating console, select the lifting point operation mode, and the system determines whether to start the lifting point synchronization detection according to the selected lifting point operation mode; Step S2. The system generates different inverter speed words according to the selected lifting point operation mode and sends the signal to the inverter of the corresponding lifting mechanism. After receiving the command, the inverter controls the lifting motor of the lifting mechanism, and the crane starts to operate according to the preset lifting point operation mode; Step S3. During the crane operation, the system determines whether to start the deviation correction control according to the synchronization detection result, so as to realize the electrical synchronization control of the crane in different lifting point operation modes.

2. The electrical four-drive synchronous control method of a double-lifting-point crane according to claim 1 is characterized in that: The lifting point operation modes include single-lifting mechanism single-action control of a single lifting point, linkage control of two lifting mechanisms of a single lifting point, linkage control of two lifting mechanisms of a double lifting point, and electrical synchronization control of four lifting mechanisms of a double lifting point.

3. The electrical four-drive synchronous control method of a double-lifting-point crane according to claim 2 is characterized in that: When the lifting point operation mode is single lifting point single lifting mechanism single action control, the selected lifting mechanism works, the system generates the inverter running speed word of the lifting mechanism, and then sends the signal instruction to the inverter of the lifting mechanism. The inverter outputs the running frequency according to the running speed word, controls the lifting motor action, and drives the corresponding lifting mechanism to operate; at the same time, the system generates the inverter stop speed word of the remaining lifting mechanisms, and the inverter sets the output frequency to zero according to the stop speed word, and brakes the remaining three lifting mechanisms; During the operation of the crane, the system obtains the load value of the operating lifting mechanism in real time. When the load value of the lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a shutdown command, and the lifting mechanism stops running immediately.

4. The electrical four-drive synchronous control method of a double-lifting-point crane according to claim 2 is characterized in that: When the lifting point operation mode is single lifting point two lifting mechanism linkage control or double lifting point two lifting mechanism linkage control, the selected two lifting mechanisms work, and the system starts the lifting point synchronization detection; Initially, the system generates the inverter running speed words of the two selected lifting mechanisms, and sends the running speed words to the inverters of the corresponding lifting mechanisms. The inverter outputs the running frequency according to the running speed words, controls the action of the lifting motor, and drives the corresponding lifting mechanism to operate. At the same time, the system generates the inverter stop speed words of the remaining two lifting mechanisms, and sends the stop speed words to the inverters of the lifting mechanisms. The inverter sets the output frequency to zero according to the stop speed words, and brakes the remaining two lifting mechanisms. During the operation of the lifting mechanism, the system obtains the load value and height value of each operating lifting mechanism in real time, and calculates the load deviation and height deviation between each operating lifting mechanism and the synchronous reference point; When the load value of any operating lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a stop command, and all lifting mechanisms stop running immediately; When the sum of the load values ​​of the two operating lifting mechanisms is greater than the second load alarm value, the system outputs a load deviation alarm signal and a stop command, and all the operating lifting mechanisms stop running immediately; When the absolute value of the load deviation between any operating lifting mechanism and the synchronous reference point is greater than the load deviation alarm value, the system outputs a load deviation alarm signal; When the absolute value of the height deviation between any running lifting mechanism and the synchronous reference point exceeds the correction alarm value, the system outputs a correction alarm signal and a stop command, and all running lifting mechanisms stop running immediately; When the absolute value of the height deviation between the running lifting mechanism and the synchronous reference point is greater than or equal to the correction input value, the system starts the correction control and corrects the lifting mechanism according to the preset correction coefficient.

5. The electrical four-drive synchronous control method of a double-lifting-point crane according to claim 2, characterized in that: When the lifting point operation mode is the electrical synchronous control of two lifting points and four lifting mechanisms, all four lifting mechanisms on the crane work, and the system starts the synchronous detection of lifting points; Initially, the system generates the inverter operating speed words of the four lifting mechanisms and sends the operating speed words to the inverters of the corresponding lifting mechanisms. The inverters output the operating frequency according to the operating speed words, control the action of the lifting motor, and drive the four lifting mechanisms to operate. During the operation of the lifting mechanism, the system obtains the load value and height value of each operating lifting mechanism in real time, and calculates the load deviation and height deviation between each operating lifting mechanism and the synchronous reference point; When the load value of any operating lifting mechanism is greater than the first load alarm value, the system outputs a load deviation alarm signal and a stop command, and all lifting mechanisms stop running immediately; When the sum of the load values ​​of the four lifting mechanisms is greater than the third load alarm value, the system outputs a load deviation alarm signal and a shutdown command, and all the running lifting mechanisms stop running immediately; When the absolute value of the load deviation between any operating lifting mechanism and the synchronous reference point is greater than the load deviation alarm value, the system outputs a load deviation alarm signal; When the absolute value of the height deviation between any running lifting mechanism and the synchronous reference point exceeds the correction alarm value, the system outputs a correction alarm signal and a stop command, and the lifting mechanism stops running immediately; When the absolute value of the height deviation between the running lifting mechanism and the synchronous reference point is greater than or equal to the correction input value, the system starts the correction control and corrects the lifting mechanism according to the preset correction coefficient.

6. The method for electrical synchronous control of four hoisting mechanisms of a crane according to claim 4 or 5, characterized in that: When the height of the synchronous reference point minus the height of the lifting mechanism to be corrected is ≥ 0 and the lifting mechanism is in the ascending direction, the system outputs the inverter speed word of the lifting mechanism to be corrected, and the output speed = (1 + correction coefficient) × input speed; When the height of the synchronous reference point minus the height of the lifting mechanism for correction is ≥ 0 and the lifting mechanism is in the descending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1-correction coefficient) × input speed; When the height of the synchronous reference point minus the height of the lifting mechanism for correction is less than 0 and the lifting mechanism is in the ascending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1-correction coefficient) × input speed; When the height of the synchronous reference point minus the height of the lifting mechanism for correction is less than 0 and the lifting mechanism is in the descending direction, the system outputs the inverter speed word of the lifting mechanism for correction, and the output speed = (1 + correction coefficient) × input speed.

7. A method for synchronously controlling electrical four-drive systems of a double-hanging-point crane according to any one of claims 4 or 5, characterized in that: The height of the lifting mechanism is the distance from the lifting mechanism to the reference horizontal plane.

8. The height of the synchronization reference point is the distance from the synchronization reference point to the reference horizontal plane; The electrical four-drive synchronous control method for a double-hanging-point crane according to any one of claims 4 or 5 is characterized in that: The synchronization reference point is a calibrated reference point, or is arbitrarily selected as a synchronization reference point in the operating lifting mechanism.

9. The electrical four-drive synchronous control method of a double-lifting-point crane according to claim 8, characterized in that: When the synchronous reference point is a calibrated reference point, the height of the synchronous reference point is the average value of the sum of the heights of all operating lifting mechanisms; the load of the synchronous reference point is the average value of the sum of the loads of all operating lifting mechanisms.

10. An electrical four-drive synchronous control system for a double-lifting-point crane, the system being used to implement the electrical synchronous control method according to any one of claims 1 to 9, characterized in that: include: Lifting mechanism No. 1, lifting mechanism No. 2, lifting mechanism No. 3, lifting mechanism No. 4, PLC controller and operating mechanism button, the operating mechanism button is connected to the PLC controller through a signal cable, each lifting mechanism is provided with a position sensor and a load sensor, the position sensor and the load sensor are connected to the PLC controller through a signal cable, and each lifting mechanism includes a power mechanism consisting of a lifting motor and a frequency converter, the lifting motor is connected to the lifting mechanism and connected to the frequency converter through a power cable, and the frequency converter is connected to the PLC controller through a signal cable.

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