A speed control method of a hoist system, a hoist system, and a crane

Abstract

The application discloses a speed control method of a hoist system, the hoist system and a crane. The speed control method comprises the following steps: obtaining a load ratio and a control current of a proportional pressure reducing valve, wherein the load ratio represents a ratio of a current load to a full load; obtaining a control pressure signal of a control handle; and calculating a limit current of the proportional pressure reducing valve when the load ratio is greater than a preset proportional threshold, and performing secondary adjustment on the control pressure of the handle, adjusting an opening degree of a main valve and limiting a rotating speed of a hoist motor. That is, the weight ratio of the load is obtained in real time during the operation of the hoist system. If the load is large, the limit current of the proportional pressure reducing valve is calculated, the output pressure of the handle is secondarily adjusted, and the actual rotating speed of the hoist motor is controlled, so that the large load is at a low rotating speed, and the small load is at a high rotating speed. Therefore, the safety during the operation is improved, the operation comfort is improved, and the operation efficiency is also improved as much as possible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cranes, in particular to a speed control method of a hoist system, a hoist system and a crane. BACKGROUND

[0002] Most of the hoist lifting mechanisms of conventional small-tonnage cranes adopt constant torque motors, that is, the output torque of the motor is constant, and the constant torque motor has no high-low speed switching function, that is, the motor speed is controlled according to the control signal input by the handle. That is, the motor speed is manually controlled by the operator, and the speed of the motor and the lifting speed of the hoist system are determined by the operator. In the control process, if the operation is not skilled, it is easy to cause a sense of stagnation, and if the operation is improper, it may cause safety accidents. Therefore, this operation method may have certain safety hazards for operators who are not skilled in operation, and it is difficult to ensure the operation comfort. SUMMARY

[0003] In order to solve the above technical problems, the present application is proposed. The embodiments of the present application provide a speed control method of a hoist system, a hoist system and a crane, which solve the above technical problems.

[0004] According to one aspect of the present application, a speed control method of a hoist system is provided, the hoist system comprising a hoist motor, a proportional pressure reducing valve and a control handle connected in sequence; the speed control method comprising: obtaining a load ratio; wherein the load ratio represents the ratio of the current load to the full load; obtaining a control signal of the control handle; wherein the control signal represents the expected speed of the operator; when the load ratio is greater than a preset ratio threshold, calculating a limit current of the proportional pressure reducing valve; wherein the limit current limits the maximum value of the output pressure of the control handle; and controlling the speed of the hoist motor according to the control signal and the limit current; wherein the limit current corresponds to the highest speed of the hoist motor.

[0005] In an embodiment, the ratio threshold comprises a first ratio threshold; wherein the when the load ratio is greater than a preset ratio threshold, calculating the limit current of the proportional pressure reducing valve comprises:

[0006] When the load ratio is greater than the first ratio threshold, a first limit current of the proportional pressure reducing valve is calculated according to the load ratio and the first ratio threshold.

[0007] In an embodiment, the when the load ratio is greater than the first ratio threshold, calculating the first limit current of the proportional pressure reducing valve according to the load ratio and the first ratio threshold comprises:

[0008] calculating a first limit current of the proportional pressure reducing valve when the hoisting system is in the ascending state and the load ratio is greater than the first ratio threshold.

[0009] In an embodiment, the calculating the first limit current of the proportional pressure reducing valve comprises:

[0010]

[0011] wherein I1 is the first limit current of the proportional pressure reducing valve, N is the load ratio, I m is a full load target current of the proportional pressure reducing valve corresponding to a full load, N1 is the first ratio threshold, I m1 is a first target current of the proportional pressure reducing valve corresponding to the first ratio threshold.

[0012] In an embodiment, the ratio threshold comprises a second ratio threshold, and the first ratio threshold is less than the second ratio threshold; wherein after calculating the first limit current of the proportional pressure reducing valve according to the load ratio and the first ratio threshold, the speed control method further comprises:

[0013] when the load ratio is less than the second ratio threshold, releasing the current limit of the proportional pressure reducing valve.

[0014] In an embodiment, the speed control method further comprises:

[0015] when the load ratio is greater than or equal to the second ratio threshold, calculating a second limit current of the proportional pressure reducing valve according to the load ratio and the second ratio threshold.

[0016] In an embodiment, the calculating the second limit current of the proportional pressure reducing valve according to the load ratio and the second ratio threshold when the load ratio is greater than or equal to the second ratio threshold comprises:

[0017] when the hoisting system is in the descending state and the load ratio is greater than or equal to the second ratio threshold, calculating the second limit current of the proportional pressure reducing valve.

[0018] In an embodiment, the calculating the second limit current of the proportional pressure reducing valve comprises:

[0019]

[0020] wherein I2 is the second limit current of the proportional pressure reducing valve, N is the load ratio, I m is a full load target current of the proportional pressure reducing valve corresponding to a full load, N2 is the second ratio threshold, I m2 is a second target current of the proportional pressure reducing valve corresponding to the second ratio threshold.

[0021] According to another aspect of the present application, there is provided a hoist system, comprising: a hoist motor; a proportional pressure reducing valve; a control handle; wherein the hoist motor, the proportional pressure reducing valve and the control handle are connected in sequence; and a controller configured to perform the speed control method according to any one of the above.

[0022] According to another aspect of the present application, there is provided a crane, comprising: a crane body; and a hoist system according to the above.

[0023] The speed control method of a hoist system, the hoist system and the crane provided by the present application can obtain the load ratio in real time during the operation of the hoist system, and if the load is large, the limit current of the proportional pressure reducing valve (i.e. the maximum speed of the hoist motor) is calculated, and the output pressure of the handle is secondarily adjusted, so as to control the actual speed of the hoist motor, thereby ensuring the large load at low speed and the small load at high speed, improving the safety during the operation, improving the operation comfort, and improving the operation efficiency as much as possible. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description of embodiments of the present application taken in conjunction with the accompanying drawings. The drawings provided herein are for illustrative purposes only and, therefore, are not to be construed as being to scale. The same reference numerals in different drawings represent the same element or the same concept. In the drawings:

[0025] Figure 1 is a flowchart of a speed control method of a hoist system according to an exemplary embodiment of the present application.

[0026] Figure 2 is a flowchart of a speed control method of a hoist system according to another exemplary embodiment of the present application.

[0027] Figure 3 is a flowchart of a speed control method of a hoist system according to another exemplary embodiment of the present application.

[0028] Figure 4is a flowchart of a speed control method of a hoist system according to an example embodiment of the present application.

[0029] Figure 5 is a flowchart of a speed control method of a hoist system according to an example embodiment of the present application.

[0030] Figure 6 is a flowchart of a speed control method of a hoist system according to an example embodiment of the present application.

[0031] Figure 7 is a structural diagram of a hoist system according to an example embodiment of the present application.

[0032] Figure 8 is a structural diagram of a hoist system according to an example embodiment of the present application.

[0033] Figure 9 is a structural diagram of a hoist system according to an example embodiment of the present application.

[0034] As shown by the reference signs: hoist motor 1, hoist balance valve 2, proportional reversing valve 3, proportional pressure reducing valve 4, control handle 5, controller 6, first proportional pressure reducing valve 41, second proportional pressure reducing valve 42. DETAILED DESCRIPTION

[0035] Hereinafter, example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein.

[0036] Figure 1 is a flowchart of a speed control method of a hoist system according to an example embodiment of the present application. The hoist system includes a hoist motor, a proportional pressure reducing valve and a control handle connected in sequence; as shown in Figure 1 The speed control method includes the following steps:

[0037] Step 100: obtaining a load ratio.

[0038] The load ratio represents the ratio of the current load to the full load. That is, the current load accounts for the proportion of the full load, and by obtaining the weight of the current load, it can be determined whether the current load is heavy or light, so that the lifting speed of the hoist system can be adaptively adjusted.

[0039] Step 200: obtaining a control signal of the control handle.

[0040] The control signal represents the desired speed of the operator. The operator inputs the control signal through the control handle to input the desired speed of the operator, i.e., the operator controls the lifting speed of the hoisting system through the control handle.

[0041] Step 300: When the load ratio is greater than the preset ratio threshold, the limiting current of the proportional pressure reducing valve is calculated.

[0042] The limiting current limits the maximum value of the output pressure of the control handle, i.e., the maximum opening of the main valve. If the current load ratio is greater than the ratio threshold, i.e., the current load is large, the limiting current (corresponding to the opening of the proportional pressure reducing valve) of the proportional pressure reducing valve is calculated, and the rotational speed of the hoisting motor is limited according to the limiting current, thereby realizing slow speed under heavy load.

[0043] Step 400: The rotational speed of the hoisting motor is controlled according to the control signal and the limiting current.

[0044] The limiting current corresponds to the highest rotational speed of the hoisting motor. After the limiting current of the proportional pressure reducing valve is calculated, the opening of the proportional pressure reducing valve is limited according to the limiting current (i.e., the maximum opening of the proportional pressure reducing valve). Specifically, the maximum opening of the proportional pressure reducing valve is determined according to the ratio of the limiting current to the no-load current (the maximum current of the proportional pressure reducing valve in the no-load state), and the rotational speed of the hoisting motor is controlled in combination with the control signal of the operator. For example, if the ratio of the limiting current to the no-load current is 80% calculated according to the current load, it is determined that the opening limitation of the proportional pressure reducing valve is 80%, and the highest rotational speed of the hoisting motor is 80% of the highest rotational speed of the hoisting motor in the no-load state. In combination with the control signal input by the operator, the current rotational speed of the hoisting motor is calculated. Specifically, the current rotational speed of the hoisting motor is calculated according to the control signal input by the operator (the input pressure value of the control handle) and the opening limitation of the proportional pressure reducing valve, wherein the current rotational speed of the hoisting motor = the motor rotational speed corresponding to the input pressure value of the control handle * the opening limitation of the proportional pressure reducing valve.

[0045] The application provides a speed control method of a hoist system. The method comprises the following steps: obtaining a load ratio, wherein the load ratio represents a ratio of a current load to a full load; obtaining a control signal (a control pressure signal) of a control handle, wherein the control signal represents an expected speed of an operator; and calculating a limiting current of a proportional pressure-reducing valve when the load ratio is greater than a preset ratio threshold, and performing secondary adjustment on a control pressure of the handle, adjusting an opening degree of a main valve, and limiting a rotating speed of a hoist motor. In other words, the weight ratio of the load is obtained in real time during the operation of the hoist system. If the load is large, the limiting current of the proportional pressure-reducing valve (i.e., the maximum rotating speed of the hoist motor) is calculated, and the output pressure of the handle is secondarily adjusted to control the actual rotating speed of the hoist motor, so that the large load is at a low rotating speed and the small load is at a high rotating speed, thereby improving the safety during the operation, improving the operation comfort, and improving the operation efficiency as much as possible.

[0046] Figure 2 is a flowchart of a speed control method of a hoist system according to another example embodiment of the application. The ratio threshold comprises a first ratio threshold. As shown in Figure 2 the step 300 can comprise the following steps:

[0047] Step 310: When the load ratio is greater than the first ratio threshold, a first limiting current of the proportional pressure-reducing valve is calculated according to the load ratio and the first ratio threshold.

[0048] If the load ratio is greater than the first ratio threshold, it indicates that the current load is heavy at this time. At this time, the first limiting current of the proportional pressure-reducing valve is calculated according to the load ratio and the first ratio threshold. In other words, the first limiting current is related to the current load and the first ratio threshold. Specifically, the greater the current load, the smaller the first limiting current.

[0049] Figure 3 is a flowchart of a speed control method of a hoist system according to another example embodiment of the application. As shown in Figure 3 the step 310 can comprise the following steps:

[0050] Step 311: When the hoist system is in an ascending state and the load ratio is greater than the first ratio threshold, a first limiting current of the proportional pressure-reducing valve is calculated.

[0051] Specifically, the calculation method of the first limiting current of the proportional pressure-reducing valve can be as follows:

[0052]

[0053] wherein I1 is the first limiting current of the proportional pressure-reducing valve, N is the load ratio, I m is a full-load target current of the proportional pressure-reducing valve corresponding to a full load, N1 is the first ratio threshold, and I m1The first target current of the proportional pressure reducing valve corresponding to the first proportion threshold.

[0054] If the hoisting system is in the lifting state and the current load proportion is greater than the first proportion threshold, in order to ensure the safety of the hoisting system in the lifting process, the first limit current of the proportional pressure reducing valve is calculated by the above formula, and the maximum speed of the hoisting motor is limited according to the first limit current, so that the improper operation of the operator can be avoided to cause the hoisting motor to rotate too fast, and the heavy load can be prevented from rotating too fast in the lifting process to cause inertia to be too large, thereby improving the operation safety. It should be understood that the hoisting system in the present application can also calculate the limit current of the proportional pressure reducing valve when the load proportion is greater than the first proportion threshold in the descending process to avoid descending too fast, wherein the calculation of the limit current of the hoisting system in the descending process can also use the above formula.

[0055] Figure 4 is a flowchart of a speed control method of a hoisting system provided by another exemplary embodiment of the present application. The proportion threshold includes a second proportion threshold, and the first proportion threshold is less than the second proportion threshold; as shown in Figure 4 After step 310, the above speed control method can further include:

[0056] Step 500: When the load proportion is less than the second proportion threshold, the current limit of the proportional pressure reducing valve is released.

[0057] Since the hoisting system is likely to cause the real-time acquired load proportion to fluctuate due to shaking and the like during the lifting and descending processes, if only one proportion threshold is set, it is likely to frequently switch between exceeding the proportion threshold and being lower than the proportion threshold, which is not conducive to the comfort of control. Therefore, the present application sets a second proportion threshold, if the acquired load proportion is greater than the first proportion threshold, it is possible that it is caused by temporary shaking, and if the acquired load proportion is less than the second proportion threshold, the current limit of the proportional pressure reducing valve can be released, that is, the maximum speed of the hoisting motor is not limited. If the acquired load proportion is greater than or equal to the second proportion threshold, the current limit of the proportional pressure reducing valve is continued, specifically, the first limit current can be used to limit the current of the proportional pressure reducing valve to reduce the calculation amount, of course, the acquired load proportion and the second proportion threshold can also be used to calculate a new limit current to limit the current of the proportional pressure reducing valve to improve the accuracy.

[0058] Figure 5 is a flowchart of a speed control method of a hoisting system provided by another exemplary embodiment of the present application. As shown in Figure 5 The above speed control method can further include:

[0059] Step 600: When the load ratio is greater than or equal to the second ratio threshold, a second limit current of the proportional pressure reducing valve is calculated according to the load ratio and the second ratio threshold.

[0060] If the load ratio is greater than the second ratio threshold, it indicates that the current load is heavy at this time, and the second limit current of the proportional pressure reducing valve is calculated according to the load ratio and the second ratio threshold, that is, the second limit current is related to the current load and the second ratio threshold. Specifically, the greater the current load, the smaller the second limit current.

[0061] Figure 6 is a flowchart of a speed control method of a hoisting system according to another example embodiment of the present application. As shown in Figure 6 , the above step 600 can include:

[0062] Step 610: When the hoisting system is in a descending state and the load ratio is greater than or equal to the second ratio threshold, a second limit current of the proportional pressure reducing valve is calculated.

[0063] Specifically, the calculation method of the second limit current of the proportional pressure reducing valve can be:

[0064]

[0065] wherein I2 is the second limit current of the proportional pressure reducing valve, N is the load ratio, I m is a full load target current of the proportional pressure reducing valve corresponding to the full load, N2 is the second ratio threshold, and I m2 is a second target current of the proportional pressure reducing valve corresponding to the second ratio threshold.

[0066] If the hoisting system is in a descending state and the current load ratio is greater than the second ratio threshold, in order to ensure the safety of the hoisting system during the descending process, the second limit current of the proportional pressure reducing valve is calculated by the above formula, and the maximum speed of the hoisting motor is limited according to the second limit current, so that the improper operation of the operator can be avoided to cause the hoisting motor to rotate too fast, and thus the heavy load can be prevented from rotating too fast during the descending process to cause excessive inertia, thereby improving the operation safety. It should be understood that the hoisting system in the present application can also calculate the limit current of the proportional pressure reducing valve when the load ratio is greater than the second ratio threshold during the ascending process to avoid ascending too fast, and the calculation of the limit current of the hoisting system during the ascending process can also use the above formula.

[0067] Figure 7 is a structural diagram of a hoisting system according to an example embodiment of the present application. As shown in Figure 7As shown, the hoist system comprises: a hoist motor 1, a proportional pressure reducing valve 4, a control handle 5, and a controller 6; wherein the hoist motor 1, the proportional pressure reducing valve 4 and the control handle 5 are connected in sequence, the controller 6 is connected with the proportional pressure reducing valve 4 and the control handle 5, and the controller 6 is used to execute the speed control method of any one of the above. Preferably, the ascending hoist system can further comprise: a hoist balance valve 2 and a proportional reversing valve 3, and the proportional pressure reducing valve 4 can comprise a first proportional pressure reducing valve 41 and a second proportional pressure reducing valve 42, and the first proportional pressure reducing valve 41 and the second proportional pressure reducing valve 42 are connected with the control handle 5 (for example, a pilot handle) respectively.

[0068] The specific working mode of the hoist system provided by the present application is as follows:

[0069] The descending process: first, control the control handle 5 to send a driving signal to the right side of the proportional reversing valve 3 (for example, provide pilot oil to the right side of the proportional reversing valve 3), at the same time, obtain the load ratio of the load, and calculate the limiting current of the first proportional pressure reducing valve 41 in combination with the load ratio, correct the pilot pressure by using the first proportional pressure reducing valve 41, control the proportional reversing valve 3 to work at the left position, and the corrected pilot pressure determines the spool opening of the proportional reversing valve 3, the pressure oil at the P port passes through the proportional reversing valve 3 to the right side of the hoist motor 1, and passes through the X port of the hoist balance valve 2, so that the hoist balance valve 2 is opened, the pressure oil at the left side of the hoist motor 1 returns to the T port through the balance valve 2 and the proportional reversing valve 3, and the descending is realized.

[0070] The ascending process: first, control the control handle 5 to send a driving signal to the left side of the proportional reversing valve 3 (for example, provide pilot oil to the left side of the proportional reversing valve 3), at the same time, obtain the load ratio of the load, and calculate the limiting current of the second proportional pressure reducing valve 42 in combination with the load ratio, correct the pilot pressure by using the second proportional pressure reducing valve 42, control the proportional reversing valve 3 to work at the right position, and the corrected pilot pressure determines the spool opening of the proportional reversing valve 3, the pressure oil at the P port passes through the proportional reversing valve 3 and the A port of the hoist balance valve 2 to the left side of the hoist motor 1, and the pressure oil at the right side of the hoist motor 1 returns to the T port through the proportional reversing valve 3, and the ascending is realized.

[0071] The application provides a winding system, which acquires a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquires a control signal (a control pressure signal) of a control handle; wherein the control signal represents an expected speed of an operator; when the load ratio is greater than a preset ratio threshold, a limiting current of a proportional pressure reducing valve is calculated, a control pressure of the handle is secondarily adjusted, an opening degree of a main valve is adjusted, and a rotating speed of a winding motor is limited; that is, a weight ratio of the load is acquired in real time during a working process of the winding system, if the load is large, the limiting current of the proportional pressure reducing valve (that is, a highest rotating speed of the winding motor) is calculated, and the output pressure of the handle is secondarily adjusted, so that the actual rotating speed of the winding motor is controlled, thereby ensuring a large load with a low rotating speed and a small load with a high rotating speed, improving the safety during the working process, improving the operation comfort, and improving the working efficiency as much as possible.

[0072] Figure 8 is a structural schematic diagram of a winding system provided by another exemplary embodiment of the application. As shown in the figure, the control handle 5 is an electric control handle, the electric control handle is connected with a controller 6, the operator directly inputs an electric control signal to the controller 6 through the electric control handle, the controller 6 calculates a limiting current of a proportional pressure reducing valve according to the electric control signal and the load ratio, and controls the rotating speed of the winding motor. Figure 8

[0073] The application further provides a crane, which comprises a crane body and the winding system as above.

[0074] The application provides a crane, which acquires a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquires a control signal (a control pressure signal) of a control handle; wherein the control signal represents an expected speed of an operator; when the load ratio is greater than a preset ratio threshold, a limiting current of a proportional pressure reducing valve is calculated, a control pressure of the handle is secondarily adjusted, an opening degree of a main valve is adjusted, and a rotating speed of a winding motor is limited; that is, a weight ratio of the load is acquired in real time during a working process of the winding system, if the load is large, the limiting current of the proportional pressure reducing valve (that is, a highest rotating speed of the winding motor) is calculated, and the output pressure of the handle is secondarily adjusted, so that the actual rotating speed of the winding motor is controlled, thereby ensuring a large load with a low rotating speed and a small load with a high rotating speed, improving the safety during the working process, improving the operation comfort, and improving the working efficiency as much as possible.

[0075] Hereinafter, an electronic device according to an embodiment of the application will be described with reference to Figure 9 The electronic device can be either or both of the first device and the second device, or a single device independent of them, which can communicate with the first device and the second device to receive the acquired input signals therefrom.

[0076] ​Figure 9 Fig. 1 illustrates a block diagram of an electronic device according to an embodiment of the present application.

[0077] As shown in Fig. 1, the electronic device 10 includes one or more processors 11 and a memory 12. Figure 9

[0078] The processor 11 can be a central processing unit (CPU) or other form of processing unit having data processing and / or instruction execution capabilities, and can control other components in the electronic device 10 to perform desired functions.

[0079] The memory 12 can include one or more computer program products that can include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory, for example, can include random access memory (RAM), cache memory, and / or the like. The non-volatile memory, for example, can include read-only memory (ROM), hard disk, flash memory, and / or the like. One or more computer program instructions can be stored on the computer-readable storage media, which the processor 11 can execute to implement the methods of the various embodiments of the present application described above and / or other desired functions. Various contents such as input signals, signal components, noise components, and the like can also be stored in the computer-readable storage media.

[0080] In one example, the electronic device 10 can further include an input device 13 and an output device 14, which are interconnected through a bus system and / or other forms of connection mechanisms (not shown).

[0081] When the electronic device is a stand-alone device, the input device 13 can be a communication network connector for receiving acquired input signals from the first device and the second device.

[0082] In addition, the input device 13 can further include, for example, a keyboard, a mouse, and the like.

[0083] The output device 14 can output various information including determined distance information, direction information, and the like to the outside. The output device 14 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto, and the like.

[0084] Of course, in order to simplify, Figure 9 In Fig. 1, only some of the components in the electronic device 10 related to the present application are shown, and components such as buses, input / output interfaces, and the like are omitted. In addition to this, the electronic device 10 can further include any other appropriate components according to specific application cases.

[0085] ​The computer program product can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, C++, or the like, and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computing device, partly on the user's computing device, as a stand-alone software package, partly on the user's computing device and partly on a remote computing device or entirely on the remote computing device or server. The embodiments of methods

[0086] The computer readable storage medium can be a combination of one or more types of computer readable storage media. The computer readable storage medium can be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium can include, for example, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any suitable combination of the above. More specific examples (a non-exhaustive list) of the computer readable storage medium include an electrical connection having one or more wires, a portable disc, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0087] The above description is given for illustrative and descriptive purposes. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although several example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations of the above.

Claims

1. A speed control method of a hoisting system, characterized by, The winding system comprises a winding motor, a proportional pressure reducing valve and a control handle connected in sequence; the speed control method comprises: obtaining a load ratio; wherein the load ratio represents a ratio of a current load to a full load; obtaining a control signal of the control handle; when the load ratio is greater than a preset ratio threshold, calculating a limit current of the proportional pressure reducing valve according to the load ratio and the ratio threshold; wherein the limit current limits a maximum value of an output pressure of the control handle; and controlling a rotating speed of the winding motor according to the control signal and the limit current; wherein the limit current corresponds to a highest rotating speed of the winding motor.

2. The speed control method of a hoist system according to claim 1, characterized by, The ratio threshold comprises a first ratio threshold; wherein the calculation of the limit current of the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold comprises: when the load ratio is greater than the first ratio threshold, calculating a first limit current of the proportional pressure reducing valve according to the load ratio and the first ratio threshold.

3. The speed control method of a hoist system according to claim 2, characterized by, The calculation of the first limit current of the proportional pressure reducing valve when the load ratio is greater than the first ratio threshold comprises: when the winding system is in an ascending state and the load ratio is greater than the first ratio threshold, calculating the first limit current of the proportional pressure reducing valve.

4. The speed control method of a hoist system according to claim 3, characterized by, The calculation of the first limit current of the proportional pressure reducing valve comprises: ； wherein, I 1 is a first limit current of the proportional pressure reducing valve for the ratio, N is the load ratio, I m is a full load target current of the proportional pressure reducing valve for the full load, N 1 is the first proportional threshold, I m1 is a first target current of the proportional pressure reducing valve for the first proportional threshold.

5. The speed control method of a hoist system according to claim 2, characterized by, The ratio threshold comprises a second ratio threshold, and the first ratio threshold is less than the second ratio threshold; wherein after the calculation of the first limit current of the proportional pressure reducing valve according to the load ratio and the first ratio threshold, the speed control method further comprises: when the load ratio is less than the second ratio threshold, releasing the current limit of the proportional pressure reducing valve.

6. The speed control method of a hoist system according to claim 5, characterized by, The speed control method further comprises: when the load ratio is greater than or equal to the second ratio threshold, calculating a second limit current of the proportional pressure reducing valve according to the load ratio and the second ratio threshold.

7. The speed control method of a hoist system according to claim 6, characterized by, The calculation of the second limit current of the proportional pressure reducing valve when the load ratio is greater than or equal to the second ratio threshold comprises: when the winding system is in a descending state and the load ratio is greater than or equal to the second ratio threshold, calculating the second limit current of the proportional pressure reducing valve.

8. The speed control method of a hoist system according to claim 7, characterized by, The calculation of the second limit current of the proportional pressure reducing valve comprises: ； wherein, I 2 is a second limit current of the proportional pressure reducing valve for the ratio, N is the load ratio, I m is a full load target current of the proportional pressure reducing valve for the full load, N 2 is the second ratio threshold, I m2 is a second target current of the proportional pressure reducing valve for the second ratio threshold.

9. A hoist system characterized by, comprises: a winding motor; a proportional pressure reducing valve; a control handle; wherein the winding motor, the proportional pressure reducing valve and the control handle are connected in sequence; and a controller configured to execute the speed control method according to any one of claims 1-8.

10. A crane, characterized in that comprises: a crane body; and the winding system according to claim 9.

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