Speed control method for winch system, winch system, and crane

Abstract

A speed control method for a winch system, a winch system, and a crane. The method comprises: acquiring a load ratio and presetting a control current of a proportional pressure reducing valve, wherein the load ratio represents a ratio of a current load to a full load; acquiring a signal of a control pressure of a control handle; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold; and performing secondary adjustment on the control pressure of the control handle so as to adjust an opening degree of a main valve, thereby limiting a rotational speed of a winch motor.

Description

RELATED APPLICATIONS

[0001] The present application claims priority to Chinese Patent Application No. 202310098588.8, filed to the China National Intellectual Property Administration (CNIPA) on January 31, 2023, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present application relates to the technical field of cranes, and in particular relates to a speed control method for a winch system, a winch system, and a crane.BACKGROUND

[0003] Most of winch hoisting mechanisms of existing conventional cranes with small tonnage adopt a constant displacement motor, i.e. an output torque of the motor is constant, and the constant displacement motor does not have a function of switching between high speed and low speed, i.e., a function wherein a control signal is inputted from a handle and then a rotational speed of the motor is controlled according to the control signal. In other words, the rotational speed of the motor is controlled manually by an operator, and thus the speed of the motor and the lifting speed of the winch system are all determined by the operator. During a process of manipulation, if the manipulation is not well skilled, it is easy to cause pause and disruption, and if the manipulation is not proper, it may probably lead to a safety accident. Therefore, this way of manipulation has a certain potential safety hazard for an operator without high proficiency, and it is also difficult to ensure comfort of manipulation.SUMMARY OF THE INVENTION Technical solution

[0004] In order to solve the above technical problem, the present application is provided. Embodiments of the present application provide a speed control method for a winch system, a winch system, and a crane to solve the above technical problem.

[0005] According to one aspect of the present application, a speed control method for a winch system is provided. The winch system comprises a winch motor, a proportional pressure reducing valve and a control handle connected in sequence, and the speed control method comprises: acquiring a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquiring a control signal of the control handle, wherein the control signal represents a speed desired by an operator; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold, wherein the limiting current limits a maximum value of an output pressure of the control handle; and controlling a rotational speed of the winch motor according to the control signal and the limiting current, wherein the limiting current corresponds to a maximum rotational speed of the winch motor.

[0006] In an embodiment, the ratio threshold comprises a first ratio threshold, and the step of calculating the limiting current for the proportional pressure reducing valve when the load ratio is greater than the preset ratio threshold comprises: calculating a first limiting current for the proportional pressure reducing valve based on the load ratio and the first ratio threshold when the load ratio is greater than the first ratio threshold.

[0007] In an embodiment, the step of calculating the first limiting current for the proportional pressure reducing valve based on the load ratio and the first ratio threshold when the load ratio is greater than the first ratio threshold comprises: calculating the first limiting current for the proportional pressure reducing valve when the winch system is in a lifting state and the load ratio is greater than the first ratio threshold.

[0008] In an embodiment, the step of calculating the first limiting current for the proportional pressure reducing valve comprises: I 1 = 100 ∗ I m − I m 1 100 − N 1 ∗ N + 100 ∗ I m 1 − I m ∗ N 1 100 − N 1 ; wherein I 1 is the first limiting current for 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, N 1 is the first ratio threshold, and I m1 is a first target current of the proportional pressure reducing valve corresponding to the first ratio threshold.

[0009] 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 limiting current for the proportional pressure reducing valve based on the load ratio and the first ratio threshold, the speed control method further comprises: cancelling the limiting on the current of the proportional pressure reducing valve when the load ratio is less than the second ratio threshold.

[0010] In an embodiment, the speed control method further comprises: calculating a second limiting current for the proportional pressure reducing valve based on the load ratio and the second ratio threshold when the load ratio is greater than or equal to the second ratio threshold.

[0011] In an embodiment, the step of calculating the second limiting current for the proportional pressure reducing valve based on the load ratio and the second ratio threshold when the load ratio is greater than or equal to the second ratio threshold comprises: calculating the second limiting current for the proportional pressure reducing valve when the winch system is in a descending state and the load ratio is greater than or equal to the second ratio threshold.

[0012] In an embodiment, the step of calculating the second limiting current for the proportional pressure reducing valve comprises: I 2 = 100 ∗ I m − I m 2 100 − N 2 ∗ N + 100 ∗ I m 2 − I m ∗ N 2 100 − N 2 ; wherein I 2 is the second limiting current for 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, N 2 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.

[0013] According to another aspect of the present application, a winch system is provided. The winch system comprises: a winch motor; a proportional pressure reducing valve; a control handle, wherein the winch motor, the proportional pressure reducing valve and the control handle are connected in sequence; and a controller, configured to perform the speed control method as described above.

[0014] According to another aspect of the present application, a crane is provided. The crane comprises: a crane body; and a winch system as described above.

[0015] The present application provides a speed control method for a winch system, a winch system, and a crane. The speed control method comprises: acquiring a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquiring a control signal (a control pressure signal) of the control handle, wherein the control signal represents a speed desired by an operator; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold, wherein the limiting current limits a maximum value of an output pressure of the control handle; and performing secondary adjustment on the control pressure of the control handle according to the control signal and the limiting current so as to adjust an opening degree of a main valve, thereby limiting a rotational speed of a winch motor. In other words, during an operation process of the winch system, a weight ratio of the load is acquired in real time, the limiting current for the proportional pressure reducing valve is calculated and obtained (i.e. limiting the maximum rotational speed of the winch motor) if the load is relatively large, and secondary adjustment is performed on the output pressure of the control handle to control an actual rotational speed of the winch motor, thereby ensuring a low rotational speed for a large load and a high rotational speed for a small load, which not only improves the safety in the operation process, but also improves the comfort of the control, and at the same time increases the operation efficiency as much as possible.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other purposes, features and advantages of the present application will become more apparent by providing a more detailed description of the embodiments of the present application with reference to the drawings. The drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification, are used in combination with the embodiments of the present application to explain the present application, and do not constitute a limitation to the present application. In the drawings, the same reference sign generally represent the same part or step. FIG 1 is a flow chart of a speed control method for a winch system provided by an exemplary embodiment of the present application. FIG 2 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. FIG 3 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. FIG 4 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. FIG 5 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. FIG 6 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. FIG 7 is a schematic structural diagram of a winch system provided by an exemplary embodiment of the present application. FIG 8 is a schematic structural diagram of a winch system provided by another exemplary embodiment of the present application. FIG 9 is a schematic structural diagram of an electronic device provided by an exemplary embodiment of the present application.

[0017] Reference signs: winch motor 1, winch balance value 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

[0018] In the following, exemplary embodiments according to the present application will be described in detail with reference to the drawings. Apparently, the described embodiments only represent a part of the embodiments of the present application and not all the embodiments of the present application. It should be understood that the present application is not limited by the exemplary embodiments described herein.

[0019] FIG 1 is a flow chart of a speed control method for a winch system provided by an exemplary embodiment of the present application. The winch system comprises a winch motor, a proportional pressure reducing valve and a control handle connected in sequence. As shown in FIG 1, the speed control method comprises the following steps: Step 100: a load ratio is acquired.

[0020] Wherein the load ratio represents a ratio of a current load to a full load, e.g., a proportion value of the current load to the full load. A weight value of the current load is acquired to determine whether the current load is relatively heavier or relatively lighter, so that a lifting and descending speed of the winch system can be adjusted accordingly.

[0021] Step 200: a control signal of the control handle is acquired.

[0022] Wherein, the control signal represents a speed desired by an operator. The operator inputs the control signal by using the control handle so as to input the speed desired by the operator, i.e., the operator controls the lifting and descending speed of the winch system by using the control handle.

[0023] Step 300: a limiting current for the proportional pressure reducing valve is calculated when the load ratio is greater than a preset ratio threshold.

[0024] Wherein, the limiting current limits a maximum value of an output pressure of the control handle, e.g., a maximum opening degree of a main value. If the current load ratio is greater than the preset ratio threshold, i.e., if the current load is relatively larger, the limiting current for the proportional pressure reducing valve (corresponding to an opening degree of the proportional pressure reducing valve) is calculated and a rotational speed of the winch motor is limited according to the calculated limiting current, so as to achieve a low rotational speed for a large load.

[0025] Step 400: a rotational speed of the winch motor is controlled according to the control signal and the limiting current.

[0026] Wherein, the limiting current corresponds to a maximum rotational speed of the winch motor. After calculating and obtaining the limiting current for the proportional pressure reducing valve, the opening degree of the proportional pressure reducing valve is limited according to the limiting current (i.e., the maximum opening degree of the proportional pressure reducing valve). Specifically, the maximum opening degree of the proportional pressure reducing valve is determined according to a ratio of the limiting current to a no-load current (e.g., the maximum current of the proportional pressure reducing valve in the no-load state), and in combination with the control signal of the operator, the rotational speed of the winch motor is controlled. For example, if the ratio of the limiting current to the no-load current is calculated to be 80% according to the current load, then it is determined that the opening degree of the proportional pressure reducing valve is limited to be 80%, then the rotational speed of the winch motor is set to have a maximum value of 80% of the maximum rotational speed of the winch motor when it is in the no-load state, and in combination with the control signal inputted by the operator, the current rotational speed of the winch motor is calculated. Specifically, the current rotational speed of the winch motor is calculated according to the control signal inputted by the operator (a input pressure value of the control handle) and the limited opening degree of the proportional pressure reducing valve, wherein the current rotational speed of the winch motor=the rotational speed of the motor corresponding to the input pressure value of the control handle * the limited opening degree of the proportional pressure reducing valve.

[0027] The present application provides a speed control method for a winch system, which comprises: acquiring a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquiring a control signal (a control pressure signal) of the control handle, wherein the control signal represents a speed desired by an operator; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold; and performing secondary adjustment on the control pressure of the control handle so as to adjust an opening degree of a main valve, thereby limiting a rotational speed of a winch motor. In other words, during an operation process of the winch system, a weight ratio of the load is acquired in real time, the limiting current for the proportional pressure reducing valve is calculated and obtained (i.e. limiting the maximum rotational speed of the winch motor) if the load is relatively large, and secondary adjustment is performed on the output pressure of the control handle to control an actual rotational speed of the winch motor, thereby ensuring a low rotational speed for a large load and a high rotational speed for a small load, which not only improves the safety in the operation process, but also improves the comfort of the control, and at the same time increases the operation efficiency as much as possible.

[0028] FIG 2 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. The ratio threshold comprises a first ratio threshold. As shown in FIG 2, the Step 300 may comprise: Step 310: a first limiting current for the proportional pressure reducing valve is calculated based on the load ratio and the first ratio threshold when the load ratio is greater than the first ratio threshold.

[0029] If the load ratio is greater than the first ratio threshold, it means that the current load is relatively heavier at this time. And at this time, the first limiting current for the proportional pressure reducing valve is calculated based on the load ratio and the first ratio threshold, that is to say, the first limiting current is related to the current load and the first ratio threshold, and, specifically, the heavier the current load is, the smaller the first limiting current is.

[0030] FIG 3 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. As shown in FIG 3, the Step 310 may comprise: Step 311: the first limiting current for the proportional pressure reducing valve is calculated when the winch system is in a lifting state and the load ratio is greater than the first ratio threshold.

[0031] Specifically, the first limiting current for the proportional pressure reducing valve may be calculated in the following way: I 1 = 100 ∗ I m − I m 1 100 − N 1 ∗ N + 100 ∗ I m 1 − I m ∗ N 1 100 − N 1 ; wherein I 1 is the first limiting current for 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, N 1 is the first ratio threshold, and I m1 is a first target current of the proportional pressure reducing valve corresponding to the first ratio threshold.

[0032] If the winch system is in the lifting state and the current load ratio is greater than the first ratio threshold, in order to ensure the safety of the winch system in the lifting process, the first limiting current of the proportional pressure reducing valve is calculated and obtained by using the above formula, and the maximum rotational speed of the winch motor is limited according to the first limiting current, so as to prevent improper operation of the operator that may cause the rotational speed of the winch motor to be too fast, and thus prevent an excessive inertia from being generated because of the rotational speed being too fast during the lifting process of a relatively heavy load, thereby improving the safety of the operation. It should be understood that, when the load ratio is greater than the first ratio threshold during a descending process of the winch system, a limiting current for the proportional pressure reducing valve may also be calculated for preventing too fast descent, wherein the limiting current during the descending process of the winch system can also be calculated by using the above-mentioned formula.

[0033] FIG 4 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. The ratio threshold comprises a second ratio threshold, and the first ratio threshold is less than the second ratio threshold. As shown in FIG 4, after the Step 310, the speed control method further comprises: Step 500: the limiting on the current of the proportional pressure reducing valve is cancelled when the load ratio is less than the second ratio threshold.

[0034] Since it is likely that the real-time acquired load ratio fluctuates during the lifting and descending process of the winch system due to jitter and other conditions, if only one ratio threshold is set, it is likely that frequent switching back and forth between a condition of exceeding the ratio threshold and a condition of falling below the ratio threshold occurs, which is not conducive to the comfort of the control. Therefore, a second ratio threshold is set in the present application, so that if the acquired load ratio is greater than the first ratio threshold, it may be caused by temporary jitter, and if the load ratio acquired again is less than the second ratio threshold, the limiting on the current of the proportional reducing valve can be cancelled, i.e. the maximum rotational speed of the winch motor is not being restricted. If the load ratio acquired again is greater than or equal to the second ratio threshold, the limiting on the current of the proportional pressure reducing valve is continued, and specifically, it may continue to use the first limiting current to limit the current of the proportional pressure reducing valve in order to reduce the computation amount, and of course, the load ratio acquired again and the second ratio threshold may also be used to calculate a new limiting current to perform the limiting on the current of the proportional pressure reducing valve, so as to improve the control accuracy.

[0035] FIG 5 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. As shown in FIG 5, the above speed control method further comprises: Step 600: a second limiting current for the proportional pressure reducing valve is calculated based on the load ratio and the second ratio threshold when the load ratio is greater than or equal to the second ratio threshold.

[0036] If the load ratio is greater than the second ratio threshold, it means that the current load is relatively heavier at this time. And at this time, the second limiting current for the proportional pressure reducing valve is calculated based on the load ratio and the second ratio threshold, that is to say, the second limiting current is related to the current load and the second ratio threshold, and, specifically, the heavier the current load is, the smaller the second limiting current is.

[0037] FIG 6 is a flow chart of a speed control method for a winch system provided by another exemplary embodiment of the present application. As shown in FIG.6, the Step 600 may comprise: Step 610: the second limiting current for the proportional pressure reducing valve is calculated when the winch system is in a descending state and the load ratio is greater than or equal to the second ratio threshold.

[0038] Specifically, the second limiting current for the proportional pressure reducing valve may be calculated in the following way: I 2 = 100 ∗ I m − I m 2 100 − N 2 ∗ N + 100 ∗ I m 2 − I m ∗ N 2 100 − N 2 ; wherein I 2 is the second limiting current for 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, N 2 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.

[0039] If the winch system is in the descending state, and the current load ratio is greater than the second ratio threshold, in order to ensure the safety of the winch system in the descending process, the second limiting current of the proportional pressure reducing valve is calculated and obtained by using the above formula, and the maximum rotational speed of the winch motor is limited according to the second limiting current, so as to prevent improper operation of the operator that may cause the rotational speed of the winch motor to be too fast, and thus prevent an excessive inertia from being generated because of the rotational speed being too fast during the descending process of a relatively heavy load, thereby improving the safety of the operation. It should be understood that, when the load ratio is greater than the second ratio threshold during the lifting process of the winch system, a limiting current for the proportional pressure reducing valve may also be calculated for preventing too fast lift, wherein the limiting current during the lifting process of the winch system can also be calculated by using the above-mentioned formula.

[0040] FIG 7 is a schematic structural diagram of a winch system provided by an exemplary embodiment of the present application. As shown in FIG 7, the winch system comprises a winch motor 1, a proportional pressure reducing valve 4, a control handle 5, and a controller 6; wherein the winch motor 1, the proportional pressure reducing valve 4 and the control handle 5 are connected in sequence, the controller 6 is connected to the proportional pressure reducing valve 4 and the control handle 5, and is configured to perform the speed control method as described in any one of the above embodiments. Preferably, the lifting winch system may also comprise: a winch balance valve 2 and a proportional reversing valve 3, and the proportional pressure reducing valve 4 may comprise a first proportional pressure reducing valve 41 and a second proportional pressure reducing valve 42, which are separately connected to the control handle 5 (e.g., a pilot handle).

[0041] The specific operation modes of the winch system provided by the present application are as follows: The descending process: firstly, the control handle 5 is controlled to send a driving signal to the right side of the proportional reversing valve 3 (e.g., to provide pilot oil to the right side of the proportional reversing valve 3), and at the same time, the load ratio of the load is acquired, and in combination with the load ratio, the limiting current for the first proportional reducing valve 41 is calculated, and the first proportional reducing valve 41 is used to correct the pilot pressure, and the proportional reversing valve 3 is controlled to be operated in the left position, the corrected pilot pressure determines the opening degree of a valve spool of the proportional reversing valve 3, and pressure oil from port P reaches the right side of the winch motor 1 after passing through the proportional reversing valve 3, and at the same time passes through port X of the winch balance valve 2, so that the winch balance valve 2 opens, and the pressure oil from the left side of the winch motor 1 returns to port T after passing through the winch balance valve 2 and the proportional reversing valve 3, thereby achieving the descent.

[0042] The lifting process: firstly, the control handle 5 is controlled to send a driving signal to the left side of the proportional reversing valve 3 (e.g., to provide pilot oil to the left side of the proportional reversing valve 3), and at the same time, the load ratio of the load is acquired, and in combination with the load ratio, the limiting current for the second proportional reducing valve 42 is calculated, and the second proportional reducing valve 41 is used to correct the pilot pressure, and the proportional reversing valve 3 is controlled to be operated in the right position, the corrected pilot pressure determines the opening degree of the valve spool of the proportional reversing valve 3, and pressure oil from port P reaches the left side of the winch motor 1 after passing through the proportional reversing valve 3 and port A of the winch balance valve 2, and the pressure oil from the right side of the winch motor 1 returns to port T after passing through the proportional reversing valve 3, thereby achieving the lift.

[0043] The winch system provided by the present application may perform: acquiring a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquiring a control signal (a control pressure signal) of the control handle, wherein the control signal represents a speed desired by an operator; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold; and performing secondary adjustment on the control pressure of the control handle so as to adjust an opening degree of a main valve, thereby limiting a rotational speed of a winch motor. In other words, during an operation process of the winch system, a weight ratio of the load is acquired in real time, the limiting current for the proportional pressure reducing valve is calculated and obtained (i.e. limiting the maximum rotational speed of the winch motor) if the load is relatively large, and secondary adjustment is performed on the output pressure of the control handle to control an actual rotational speed of the winch motor, thereby ensuring a low rotational speed for a large load and a high rotational speed for a small load, which not only improves the safety in the operation process, but also improves the comfort of the control, and at the same time increases the operation efficiency as much as possible.

[0044] FIG 8 is a schematic structural diagram of a winch system provided by another exemplary embodiment of the present application. As shown in FIG 8, the control handle 5 is an electronically controlled handle, which is connected to the controller 6. An electronically controlled signal is directly input to the controller 6 by the operator using the electronically controlled handle, and the controller 6 calculates the limiting current of the proportional pressure reducing valve according to the electronically controlled signal and the load ratio, so as to control the rotational speed of the winch motor.

[0045] The present application provides a crane, which comprises a crane body and a winch system as described above.

[0046] The crane provided by the present application may perform: acquiring a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquiring a control signal (a control pressure signal) of the control handle, wherein the control signal represents a speed desired by an operator; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold; and performing secondary adjustment on the control pressure of the control handle so as to adjust an opening degree of a main valve, thereby limiting a rotational speed of a winch motor. In other words, during an operation process of the winch system, a weight ratio of the load is acquired in real time, the limiting current for the proportional pressure reducing valve is calculated and obtained (i.e. limiting the maximum rotational speed of the winch motor) if the load is relatively large, and secondary adjustment is performed on the output pressure of the control handle to control an actual rotational speed of the winch motor, thereby ensuring a low rotational speed for a large load and a high rotational speed for a small load, which not only improves the safety in the operation process, but also improves the comfort of the control, and at the same time increases the operation efficiency as much as possible.

[0047] In the following, an electronic device according to an embodiment of the present application is described with reference to FIG 9. The electronic device may be either or both of a first device and a second device, or a stand-alone device independent of them, which may be in communication with the first device and the second device to receive the collected input signals from them.

[0048] FIG 9 is a schematic structural diagram of an electronic device provided by an exemplary embodiment of the present application.

[0049] As shown in Figure 9, the electronic device 10 includes one or more processors 11 and a memory 12.

[0050] The processor 11 may be a central processing unit (CPU) or other forms of processing unit having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device 10 to perform desired functions.

[0051] The memory 12 may contain one or more computer program products, which may comprise various forms of computer readable storage medium, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, comprise random access memory (RAM) and / or cache memory (cache) and the like. The non-volatile memory may, for example, comprise a read-only memory (ROM), a hard disc, a flash memory and the like. One or more computer program instructions may be stored in the computer-readable storage medium, and the processor 11 may run the program instructions 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 may also be stored in the computer-readable storage medium.

[0052] In one example, the electronic device 10 may also include: an input device 13 and an output device 14, and these components are interconnected via a bus system and / or other forms of connecting mechanism (not shown).

[0053] When the electronic device is a stand-alone device, the input device 13 may be a communication network connector, configured to receive the collected input signals from the first device and the second device.

[0054] In addition, the input device 13 may also include, for example, a keyboard, a mouse, and the like.

[0055] The output device 14 may output various information to an outside party, including determined distance information, direction information, and the like. The output device 14 may include, for example, a display, a speaker, a printer, and a communication network and remote output devices connected thereto, and the like.

[0056] Of course, for simplicity, only some of the components of the electronic device 10 related to the present application are shown in FIG 9, and components such as buses, input / output interfaces, and the like are omitted. In addition, the electronic device 10 may include any other appropriate components based on specific application scenarios.

[0057] The computer program product may comprise program codes for performing the operations of embodiments of the present application that are written in any combination of one or more programming languages, wherein the programming languages include object-oriented programming languages such as Java, C++, etc., and also include conventional procedural programming languages such as the 'C' language or similar programming languages. The program codes may be executed entirely on a user computing device, partially on a user device, as a stand-alone software package, partially on a user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0058] The computer-readable storage medium may employ any combination of one or more types of readable medium. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may, for example, include, but is not limited to, a system, apparatus or device that is electrical, magnetic, optical, electromagnetic, infrared, or semiconductor-based, or any combination of the above. More specific examples of readable storage medium (a non-exhaustive list) include: an electrical connection having one or more wires, a portable disc, a hard disc, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optic fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0059] The above specification has been given for purposes of illustration and description. Moreover, this specification is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a plurality of exemplary aspects and embodiments have been discussed above, a persona skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A speed control method for a winch system, wherein the winch system comprises a winch motor, a proportional pressure reducing valve and a control handle connected in sequence, and the speed control method comprises: acquiring a load ratio, wherein the load ratio represents a ratio of a current load to a full load; acquiring a control signal of the control handle; calculating a limiting current for the proportional pressure reducing valve when the load ratio is greater than a preset ratio threshold, wherein the limiting current limits a maximum value of an output pressure of the control handle; and controlling a rotational speed of the winch motor according to the control signal and the limiting current, wherein the limiting current corresponds to a maximum rotational speed of the winch motor.

2. The speed control method for the winch system according to claim 1, wherein the ratio threshold comprises a first ratio threshold, and the step of calculating the limiting current for the proportional pressure reducing valve when the load ratio is greater than the preset ratio threshold comprises: calculating a first limiting current for the proportional pressure reducing valve based on the load ratio and the first ratio threshold when the load ratio is greater than the first ratio threshold.

3. The speed control method for the winch system according to claim 2, wherein the step of calculating the first limiting current for the proportional pressure reducing valve based on the load ratio and the first ratio threshold when the load ratio is greater than the first ratio threshold comprises: calculating the first limiting current for the proportional pressure reducing valve when the winch system is in a lifting state and the load ratio is greater than the first ratio threshold.

4. The speed control method for the winch system according to claim 3, wherein the step of calculating the first limiting current for the proportional pressure reducing valve comprises: I 1 = 100 ∗ I m − I m 1 100 − N 1 ∗ N + 100 ∗ I m 1 − I m ∗ N 1 100 − N 1 ; wherein I1 is the first limiting current for the proportional pressure reducing valve, N is the load ratio, Im is a full load target current of the proportional pressure reducing valve corresponding to the full load, N1 is the first ratio threshold, and Im1 is a first target current of the proportional pressure reducing valve corresponding to the first ratio threshold.

5. The speed control method for the winch system according to claim 2, wherein 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 limiting current for the proportional pressure reducing valve based on the load ratio and the first ratio threshold, the speed control method further comprises: cancelling the limiting on the current of the proportional pressure reducing valve when the load ratio is less than the second ratio threshold.

6. The speed control method for the winch system according to claim 5, wherein the speed control method further comprises: calculating a second limiting current for the proportional pressure reducing valve based on the load ratio and the second ratio threshold when the load ratio is greater than or equal to the second ratio threshold.

7. The speed control method for the winch system according to claim 6, wherein the step of calculating the second limiting current for the proportional pressure reducing valve based on the load ratio and the second ratio threshold when the load ratio is greater than or equal to the second ratio threshold comprises: calculating the second limiting current for the proportional pressure reducing valve when the winch system is in a descending state and the load ratio is greater than or equal to the second ratio threshold.

8. The speed control method for the winch system according to claim 7, wherein the step of calculating the second limiting current for the proportional pressure reducing valve comprises: I 2 = 100 ∗ I m − I m 2 100 − N 2 ∗ N + 100 ∗ I m 2 − I m ∗ N 2 100 − N 2 ; wherein I2 is the second limiting current for the proportional pressure reducing valve, N is the load ratio, Im is a full load target current of the proportional pressure reducing valve corresponding to the full load, N2 is the second ratio threshold, and Im2 is a second target current of the proportional pressure reducing valve corresponding to the second ratio threshold.

9. A winch system comprising: a winch motor; a proportional pressure reducing valve; a control handle; wherein the winch 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 claims 1-8.

10. A crane, comprising: a crane body; and a winch system according to claim 9.

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