Overload protection system

Abstract

The invention provides an overload protection system, the overload protection system is arranged on a crane and drives a winch to act, the overload protection system comprises an oil tank, a pilot overflow valve, a first switch valve, a first control valve group, a second control valve group, a detection part and a motor, a hydraulic pump is arranged on the oil tank, and the hydraulic pump is connected with a first port of the motor through an oil inlet pipeline; a second port of the motor is connected with the oil tank through an oil return pipeline, a pilot-operated overflow valve is arranged between the oil inlet pipeline and the oil return pipeline, the oil inlet end of the pilot-operated overflow valve is connected with the oil inlet pipeline, and the oil outlet end of the pilot-operated overflow valve is connected with the oil return pipeline; the first control valve group comprises a first control switch valve, a first control reversing valve and a first control overflow valve; according to the structure, under the emergency condition, the pressure of the overflow valve can be adjusted, so that it is guaranteed that a hydraulic oil way can be kept stable, and under the emergency condition, a winch is controlled to quickly loosen a steel wire rope to achieve emergency rope abandoning.

Description

Technical Field

[0001] The invention relates to the technical field of winch control systems, and in particular to an overload protection system. Background Art

[0002] The hydraulic winch is mainly composed of a hydraulic motor (low-speed or high-speed motor), a hydraulic normally closed multi-disc brake, a planetary gearbox, a clutch (optional), a drum, a support shaft, a frame, a rope presser (optional), etc. The hydraulic motor has high mechanical efficiency and large starting torque. It can be equipped with different distributors according to the working conditions. The valve group can also be designed and integrated directly on the motor distributor according to the needs, such as a valve group with a balance valve, an overload valve, a high-pressure shuttle valve, a speed regulating reversing valve or other performance. The brake, planetary gearbox, etc. are directly installed in the drum. The drum, support shaft, and frame are designed according to mechanical requirements. The overall structure is simple and reasonable and has sufficient strength and rigidity. The general principle is to drive the drum to rotate through the hydraulic motor, and the wire rope is wound around the drum through the rotation of the drum for retraction.

[0003] In the patent document with Chinese patent application number 202311396506.4 and publication date 2024.04.16, a method for overload protection of a hydraulic oil circuit is disclosed, which records the full load oil pressure value of the winch system running at full load under different openings of the throttle valve; in this way, the oil pressure value of more than 1.1 times the overload can be calculated under the current full load oil pressure value, and the calculation is accurate; the throttle valve amplifies the oil pressure of the oil inlet pipeline in the oil pump and multi-way valve group area, so that the difference between the full load oil pressure value and the overload oil pressure value increases, and then the pressure switch can accurately detect the numerical difference between the full load oil pressure value and the overload oil pressure value; thus, the pressure switch can accurately detect whether the winch system is overloaded.

[0004] This document will open the pressure relief valve when an overload is detected. However, like the prior art of this document, the regulating pressure of the pressure relief valve is generally pre-set, and the pressure relief valve will be opened when an overload is detected. In this way, if the regulating pressure of the pressure relief valve is at a relatively high level, a relatively high hydraulic oil pressure is required to open the pressure relief valve. If the pressure of the pressure relief valve is to be adjusted, the machine needs to be shut down first, which is likely to waste working time and reduce efficiency. In addition, it is only adjusted through the pressure relief valve. When a problem occurs with the pressure relief valve, the pressure cannot be quickly relieved manually, and the rope cannot be abandoned in an emergency. Summary of the invention

[0005] The present invention provides an overload protection system, which can adjust the pressure of a relief valve manually or automatically, thereby ensuring that a hydraulic oil circuit can remain stable and ensuring the stability of a rope abandonment process.

[0006] To achieve the above-mentioned purpose, the technical solution of the present invention is: an overload protection system, which is arranged on a crane and drives the winch to move, including an oil tank, a pilot overflow valve, a first switch valve, a first control valve group, a second control valve group, a detection component and a motor, a hydraulic pump is provided on the oil tank, the hydraulic pump is connected to the first port of the motor through an oil inlet pipe, the second port of the motor is connected to the oil tank through an oil return pipe, a pilot overflow valve is provided between the oil inlet pipe and the oil return pipe, the oil inlet end of the pilot overflow valve is connected to the oil inlet pipe, and the oil outlet end of the pilot overflow valve is connected to the oil return pipe; a first switch valve is provided on the oil return pipe.

[0007] The first control valve group includes a first control switch valve, a first control reversing valve and a first control overflow valve, the P end and T end of the first control reversing valve are connected to the oil tank, the A end of the first control reversing valve is connected to the control end of the first control switch valve, the first port of the first control switch valve is connected to the oil tank through the first control overflow valve, the second port of the first control switch valve is connected to the control oil circuit of the pilot overflow valve, and the overflow pressure of the first control overflow valve is less than the control pressure of the control oil circuit of the pilot overflow valve.

[0008] The second control valve group includes a second control switch valve, a second control reversing valve and a second control overflow valve. The P end and T end of the second control reversing valve are connected to the oil tank, the A end of the second control reversing valve is connected to the control end of the second control switch valve, the first port of the second control switch valve is connected to the oil tank through the second control overflow valve, the second port of the second control switch valve is connected to the control oil circuit of the pilot overflow valve, the overflow pressure of the second control overflow valve is less than the control pressure of the control oil circuit of the pilot overflow valve; the oil leakage pressure of the first control overflow valve is less than the oil leakage pressure of the second control overflow valve.

[0009] The detection component is communicatively connected with the second control reversing valve, and the detection component includes an inclination sensor arranged on the crane and a force sensor arranged on the winch. The inclination sensor and the force sensor are connected to the control end of the second control reversing valve through a terminal processor; a pressure regulator is also provided at the control end of the second control overflow valve, and the pressure regulator is communicatively connected with the terminal processor.

[0010] The second control end of the first switch valve is connected to the A end of the first control reversing valve and the A end of the second control reversing valve through the first shuttle valve, the first port of the first switch valve is connected to the second port of the motor through the return oil pipeline, the second port of the first switch valve is connected to the oil tank through the return oil pipeline, the first control end of the first switch valve connects the first port and the second port of the first switch valve, the second control end of the first switch valve is also connected to the oil tank through the first shuttle valve, the first control end of the first switch valve controls the first port and the second port of the first switch valve to be connected, and the second control end of the first switch valve controls the first port and the second port of the first switch valve to be disconnected.

[0011] In the above structure, when the rope is being retracted, the oil tank outputs hydraulic oil into the oil inlet pipe and then passes through the motor and the oil return pipe and enters the oil tank for circulation to realize the rope retracting operation. At the same time, a first switch valve is provided on the oil return pipe. When the motor rotates normally, the oil tank delivers hydraulic oil to the motor through the oil inlet pipe and flows into the oil return pipe through the motor. The hydraulic oil in the oil return pipe flows to the first control end of the first switch valve, thereby driving the first switch valve to switch and connect the first port and the second port, so that the oil return pipe is connected with the oil tank, and the hydraulic oil can flow back to the oil tank to realize circulation. When the operation is to lift the heavy object, it is in the rope retracting state. The inclination sensor detects the working radius of the crane, and the force sensor detects the tension of the wire rope in the rope retracting state. The current working radius of the crane is compared with the preset working radius, and the current wire rope tension is compared with the preset wire rope tension. When the wire rope tension is too large under the working radius of the crane, the terminal processor drives the second control valve to switch and connect the A end with the P end. The oil tank outputs hydraulic oil to the control end of the second control switch valve through the second control reversing valve, so that the second control switch valve switches and connects the first port and the second port of the second control switch valve, thereby making the control hydraulic oil of the control oil circuit of the pilot relief valve flow back to the oil tank through the second control relief valve to relieve pressure, thereby making the regulating pressure of the pilot relief valve lower. At the same time, the terminal processor controls the pressure regulator in real time according to the overturning moment of the crane, thereby driving the second The relief pressure of the control relief valve is adjusted to ensure that the oil pressure of the hydraulic oil is neither too large nor too small, and the overturning moment of the crane can be within a safe range, so that the internal circulation oil circuit can be quickly formed, ensuring that the rope is automatically and quickly released while also ensuring the stability of the hydraulic oil circuit; if the hook is hooked to an object that cannot be unhooked when the rope is collected, the first control reversing valve is manually turned on, the first control reversing valve is switched to connect the A end with the P end, and the oil tank outputs hydraulic oil to the control end of the first control switch valve through the first control reversing valve, so that the first control switch valve is switched and connected to the first port and the second port of the first control switch valve, thereby allowing the control hydraulic oil of the control oil circuit of the pilot relief valve to be depressurized through the first control relief valve and flow back to the oil tank. Therefore, the regulating pressure of the pilot relief valve becomes lower, and since the oil pressure in the oil inlet pipe is greater than the regulating pressure of the pilot relief valve, the pilot relief valve is driven to open, so that the hydraulic oil in the oil inlet pipe is released to the return oil pipe through the pilot relief valve, thereby increasing the oil pressure on the return oil pipe and making the oil pressure at the end of the motor connected to the return oil pipe greater than the oil pressure at the end of the motor connected to the oil inlet pipe. Due to the overflow effect of the pilot relief valve, a circulation loop is formed between the oil inlet pipe, the return oil pipe and the motor through the pilot relief valve, and the oil tank continues to output hydraulic oil to the oil inlet pipe, thereby increasing the hydraulic oil in the circulation loop, thereby increasing the pressure difference at both ends of the motor, and then increasing the speed of the motor to achieve rapid rope release.

[0012] Furthermore, the inclination sensor and the force sensor are connected to the control end of the second control reversing valve through the terminal processor; a pressure regulator is also provided at the control end of the second control overflow valve, and the pressure regulator is communicatively connected to the terminal processor.

[0013] The above arrangement can facilitate pressure regulation of the second control relief valve by providing a pressure regulator.

[0014] Furthermore, a second switch valve is provided between the oil inlet end of the pilot relief valve and the oil inlet pipeline, a first port of the second switch valve is connected to the oil inlet pipeline, and a second port of the second switch valve is connected to the oil inlet end of the pilot relief valve.

[0015] The above arrangement, by providing the second switch valve, allows the oil circuit between the oil inlet pipeline and the pilot-operated relief valve to be opened only when the pilot-operated relief valve is needed, thereby facilitating control of the hydraulic system.

[0016] Furthermore, a balancing valve group is provided on the oil inlet pipeline, and the balancing valve group includes a balancing overflow valve and a balancing check valve. The oil inlet end of the balancing overflow valve is connected to the first port of the motor through the oil inlet pipeline, and the oil outlet end of the balancing overflow valve is connected to the hydraulic pump through the oil inlet pipeline. The oil inlet end of the balancing check valve is connected to the oil outlet end of the balancing overflow valve, and the oil outlet end of the balancing check valve is connected to the oil inlet end of the balancing overflow valve.

[0017] The above arrangement, by setting a balancing valve group, makes the hydraulic oil output of the oil inlet pipeline stable.

[0018] Furthermore, a brake valve is provided on the motor, and the control end of the brake valve is connected to the oil inlet pipeline and the oil outlet pipeline through the brake reversing valve, the P end of the brake reversing valve is connected to the oil tank, the A end of the brake reversing valve is connected to the control end of the brake valve, and the control end of the brake reversing valve is connected to the oil inlet pipeline and the oil outlet pipeline.

[0019] The above arrangement connects the oil inlet pipeline and the oil outlet pipeline through the control end of the brake valve reversing valve. When the winch is to be started, the hydraulic oil in the oil inlet pipeline and the oil outlet pipeline flows to the control end of the brake reversing valve and controls the reversal of the brake reversing valve so that the A end is connected to the P end, so that the hydraulic oil output by the oil tank flows to the control end of the brake valve, thereby driving the brake valve to open, facilitating the rotation of the motor.

[0020] Furthermore, a spring is provided on the second control end of the first switch valve, and the hydraulic oil pressure at the second control end plus the pressure of the spring is greater than the hydraulic oil pressure at the first control end of the first switch valve.

[0021] The above arrangement, by setting a spring, ensures that when the first switch valve is to be closed, the hydraulic oil pressure flowing from the oil tank to the second control end of the first switch valve plus the elastic force of the spring overcomes the hydraulic oil pressure at the first control end of the first switch valve, thereby driving the first switch valve to close, so that the hydraulic oil cannot flow back to the oil tank through the return oil pipe.

[0022] Furthermore, the first port of the first shuttle valve is connected to the A end of the first control reversing valve and the A end of the second control reversing valve, the second port of the first shuttle valve is connected to the oil tank, and the third port of the first shuttle valve is connected to the second control end of the first switch valve.

[0023] In the above arrangement, by arranging the first shuttle valve between the second control end of the first switch valve and the A end of the first control reversing valve and the A end of the second control reversing valve, the hydraulic oil flowing to the second control end of the first switch valve through the second control reversing valve and the hydraulic oil flowing from the oil tank to the second control end of the first switch valve will not conflict with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the hydraulic system of the present invention.

[0025] Figure 2 for Figure 1 Connection diagram of hydraulic circuit in A.

[0026] Figure 3 for Figure 1 Enlarged view of point B in the middle. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1-Figure 3As shown, an overload protection system is arranged on a crane and drives a winch to move, comprising an oil tank 1, a pilot relief valve 2, a first switch valve 3, a motor 4, a detection component (not shown in the figure), a first control valve group and a second control valve group. A hydraulic pump (not shown in the figure) is arranged on the oil tank 1, the hydraulic pump is connected to a first port 41 of the motor 4 through an oil inlet pipeline 11, and a second port 42 of the motor 4 is connected to the oil tank 1 through an oil return pipeline 12. A pilot relief valve 2 is arranged between the oil inlet pipeline 11 and the oil return pipeline 12, the oil inlet end of the pilot relief valve 2 is connected to the oil inlet pipeline 11, and the pilot relief valve 2 is connected to the oil return pipeline 12. The oil outlet is connected to the oil return pipeline 12; a first switch valve 3 is provided on the oil return pipeline 12, a first port of the first switch valve 3 is connected to the second port 42 of the motor 4 through the oil return pipeline 12, a second port of the first switch valve 3 is connected to the oil tank 1 through the oil return pipeline 12, a first control end 31 of the first switch valve 3 is connected to the first port and the second port of the first switch valve 3, a second control end 32 of the first switch valve 3 is connected to the oil tank, the first control end 31 of the first switch valve 3 controls the first port and the second port of the first switch valve 3 to be connected, and the second control end 32 of the first switch valve 3 controls the first port and the second port of the first switch valve 3 to be disconnected.

[0029] The first control valve group includes a first control switch valve 81, a first control reversing valve 82 and a first control relief valve 83. The P end and the T end of the first control reversing valve 82 are connected to the oil tank 1, the A end of the first control reversing valve 82 is connected to the control end 811 of the first control switch valve 81, the first port of the first control switch valve 81 is connected to the oil tank 1 through the first control relief valve 83, and the second port of the first control switch valve 81 is connected to the control oil circuit 20 of the pilot relief valve 2. The relief pressure of the first control relief valve 83 is less than the control pressure of the control oil circuit 20 of the pilot relief valve 2. In this embodiment, the control end 821 of the first control reversing valve is connected to the control button (not shown in the figure) of the crane cab through an external circuit. When encountering an emergency, the staff in the cab presses the control button to drive the first control reversing valve to achieve reversal.

[0030] The second control valve group includes a second control switch valve 91, a second control reversing valve 92, and a second control relief valve 93. The P end and the T end of the second control reversing valve 92 are connected to the oil tank 1, and the A end of the second control reversing valve 92 is connected to the control end 911 of the second control switch valve 91. The first port of the second control switch valve 91 is connected to the oil tank 1 through the second control relief valve 93, and the second port of the second control switch valve 91 is connected to the control oil circuit 20 of the pilot relief valve 2. The relief pressure of the second control relief valve 93 is less than the control pressure of the control oil circuit 20 of the pilot relief valve 2. The oil leakage pressure of the first control relief valve is less than the oil leakage pressure of the second control relief valve.

[0031] The detection component is connected to the second control reversing valve 92 in communication, and the detection component includes an inclination sensor arranged on the crane and a force sensor arranged on the winch, and the inclination sensor and the force sensor are connected to the control end of the second control reversing valve 92 through a terminal processor; a pressure regulator 931 is also provided at the control end of the second control relief valve 93, and the pressure regulator 931 is connected to the terminal processor in communication. In this embodiment, the terminal processor is a device for processing information such as a PLC or a CPU, which is specifically a prior art and will not be described here.

[0032] A first shuttle valve 84 is provided between the second control end 32 of the first switch valve 3 and the A end of the first control reversing valve 82 and the A end of the second control reversing valve 92, the first port 841 of the first shuttle valve 84 is connected to the A end of the second control reversing valve 92, the second port 842 of the first shuttle valve 84 is connected to the oil tank 1, and the third port 843 of the first shuttle valve 84 is connected to the second control end 32 of the first switch valve 3.

[0033] The first shuttle valve 84 is arranged between the second control end 32 of the first switch valve 3 and the A end of the second control reversing valve 92. When the rope is collected in the normal state, the hydraulic oil of the control oil tank 1 enters the second port 842 of the first shuttle valve 84, and the first port 841 of the first shuttle valve 84 cannot be supplied with oil because the second control switch valve 92 is in the closed state, so that the hydraulic oil in the oil tank 1 enters the second control end 32 of the first switch valve 3 through the second port 842, so that the first switch valve 3 is closed, so that the rope collection operation can be closed when the rope is collected. When emergency rope collection is required, since the second control switch valve 92 is in the conducting state, the hydraulic oil of the oil tank 1 enters the first port 841 of the first shuttle valve 84 through the second control switch valve 92 and then flows into the control end of the first switch valve 3, so that the first switch valve 3 is closed, so that the emergency rope collection is realized. And the hydraulic oil flowing to the second control end 32 of the first switch valve 3 through the second control reversing valve 92 and the hydraulic oil flowing to the second control end 32 of the first switch valve 3 from the oil tank 1 will not conflict with each other.

[0034] A second switch valve 21 is provided between the oil inlet end of the pilot relief valve 2 and the oil inlet pipeline, wherein a first port of the second switch valve 21 is connected to the oil inlet pipeline 11, and a second port of the second switch valve 21 is connected to the oil inlet end of the pilot relief valve 2. By providing the second switch valve 21, the oil circuit between the oil inlet pipeline 11 and the pilot relief valve 2 is opened only when the pilot relief valve 2 is needed, thereby facilitating control of the hydraulic system.

[0035] A balancing valve group 5 is provided on the oil inlet pipeline 11, and the balancing valve group 5 includes a balancing relief valve 51 and a balancing check valve 52. The oil inlet end of the balancing relief valve 51 is connected to the first port 41 of the motor 4 through the oil inlet pipeline 11, and the oil outlet end of the balancing relief valve 51 is connected to the hydraulic pump through the oil inlet pipeline 11. The oil inlet end of the balancing check valve 52 is connected to the oil outlet end of the balancing relief valve 51, and the oil outlet end of the balancing check valve 52 is connected to the oil inlet end of the balancing relief valve 51. By providing the balancing valve group 5, the hydraulic oil output of the oil inlet pipeline 11 is stable.

[0036] like Figure 1 As shown, a brake valve 43 is also provided on the motor 4, and the control end of the brake valve 43 is connected to the oil inlet pipeline and the oil outlet pipeline through a brake reversing valve 44, the P end of the brake reversing valve 44 is connected to the oil tank, the A end of the brake reversing valve is connected to the control end of the brake valve, and the control end K of the brake reversing valve 44 is connected to the oil inlet pipeline 11 and the oil outlet pipeline 12. The control end K of the brake valve reversing valve 44 is connected to the oil inlet pipeline 11 and the oil outlet pipeline 12. When the winch is to be started, the hydraulic oil in the oil inlet pipeline 11 and the oil outlet pipeline 12 flows to the control end of the brake reversing valve 44 and controls the brake reversing valve 44 to reverse so that the A end is connected to the P end, so that the oil tank 1 outputs the hydraulic oil to flow to the control end of the brake valve 43, thereby driving the brake valve 43 to open, so that the motor 4 rotates.

[0037] like Figure 2 As shown, a spring 33 is further provided on the second control end 32 of the first switch valve 3, and the hydraulic oil pressure at the second control end 32 plus the pressure of the spring 33 is greater than the hydraulic oil pressure at the first control end 31 of the first switch valve 3. By providing the spring 33, when the first switch valve 3 is to be closed, the hydraulic oil pressure flowing from the oil tank 1 to the second control end 32 of the first switch valve 3 plus the elastic force of the spring 33 overcomes the hydraulic oil pressure at the first control end 31 of the first switch valve 3, thereby driving the first switch valve 3 to close, so that the hydraulic oil cannot flow back to the oil tank through the return oil pipeline 12.

[0038] The working principle of the present invention is as follows: when the rope is being reeled in, the hydraulic oil output from the oil tank 1 enters the oil inlet pipe 11 through the balanced one-way valve 52, then passes through the motor 4 and enters the oil tank 1 through the oil return pipe 12 to circulate and realize the rope reeling operation. At the same time, a first switch valve 3 is provided on the oil return pipe 12. When the motor 4 rotates normally, the oil tank 1 delivers the hydraulic oil to the motor 4 through the oil inlet pipe 11 and flows into the oil return pipe 12 through the motor 4. The hydraulic oil in the oil return pipe 12 flows to the first control end 31 of the first switch valve 3, thereby driving the first switch valve 3 to reverse and connect the first port and the second port, thereby connecting the oil return pipe 12 with the oil tank, and the hydraulic oil can flow back to the oil tank 1 to realize circulation. When the crane is operating to lift a heavy object, the crane is in the rope-retracting state. The inclination sensor detects the working radius of the crane, and the force sensor detects the tension of the wire rope in the rope-retracting state. By comparing the current working radius of the crane with the preset working radius, and the current wire rope tension with the preset wire rope tension, when the wire rope tension is too large under the working radius of the crane, the terminal processor drives the second control valve to switch and connect the A end with the P end, and the oil tank outputs hydraulic oil to the control end 911 of the second control switch valve 91 through the second control reversing valve 92, so that the second control switch valve 91 switches and connects the first port and the second end of the second control switch valve 91. The second control relief valve 93 is used to release the pressure of the first control reversing valve 91, and the second control reversing valve 93 is used to release the pressure of the second control reversing valve 91. A control reversing valve 82 is switched so that the A end is connected to the P end, and the oil tank outputs hydraulic oil to the control end 811 of the first control switch valve 81 through the first control reversing valve 82, so that the first control switch valve 81 is switched and connected to the first port and the second port of the first control switch valve 81, thereby making the control hydraulic oil of the control oil circuit 20 of the pilot relief valve 2 flow back to the oil tank through the first control relief valve 83 to release pressure, thereby making the regulating pressure of the pilot relief valve 2 lower. Since the oil relief pressure of the first control relief valve is lower than the oil relief pressure of the second control relief valve, the regulating pressure of the pilot relief valve can be reduced to a greater extent, thereby making the oil leakage speed of the hydraulic oil circuit faster;Since the oil pressure of the oil inlet pipeline 11 is greater than the regulating pressure of the pilot relief valve 2, the pilot relief valve 2 is driven to open, so that the hydraulic oil in the oil inlet pipeline 11 is released to the return oil pipeline 12 through the pilot relief valve 2, thereby increasing the oil pressure on the return oil pipeline 12, and making the oil pressure at the end of the motor 4 connected to the return oil pipeline 12 greater than the oil pressure at the end of the motor connected to the oil inlet pipeline 11, and due to the overflow effect of the pilot relief valve 2, a circulation loop is formed between the oil inlet pipeline, the return oil pipeline and the motor through the pilot relief valve, and the oil tank continues to output hydraulic oil to the oil inlet pipeline, thereby increasing the hydraulic oil in the circulation loop, thereby increasing the pressure difference at both ends of the motor 4, and then increasing the speed of the motor 4 to achieve rapid rope release. ;

Claims

1. An overload protection system, which is arranged on a crane and drives a winch to operate, characterized in that: It includes an oil tank, a pilot relief valve, a first switch valve, a first control valve group, a second control valve group, a detection component and a motor. A hydraulic pump is provided on the oil tank. The hydraulic pump is connected to a first port of the motor through an oil inlet pipeline. The second port of the motor is connected to the oil tank through an oil return pipeline. A pilot relief valve is provided between the oil inlet pipeline and the oil return pipeline. The oil inlet end of the pilot relief valve is connected to the oil inlet pipeline, and the oil outlet end of the pilot relief valve is connected to the oil return pipeline. A first switch valve is provided on the oil return pipeline. The first control valve group includes a first control switch valve, a first control reversing valve and a first control relief valve, the P end and the T end of the first control reversing valve are connected to the oil tank, the A end of the first control reversing valve is connected to the control end of the first control switch valve, the first port of the first control switch valve is connected to the oil tank through the first control relief valve, the second port of the first control switch valve is connected to the control oil circuit of the pilot relief valve, and the relief pressure of the first control relief valve is less than the control pressure of the control oil circuit of the pilot relief valve; The second control valve group includes a second control switch valve, a second control reversing valve and a second control relief valve, the P end and the T end of the second control reversing valve are connected to the oil tank, the A end of the second control reversing valve is connected to the control end of the second control switch valve, the first port of the second control switch valve is connected to the oil tank through the second control relief valve, the second port of the second control switch valve is connected to the control oil circuit of the pilot relief valve, the relief pressure of the second control relief valve is less than the control pressure of the control oil circuit of the pilot relief valve; the oil leakage pressure of the first control relief valve is less than the oil leakage pressure of the second control relief valve; The detection component is in communication connection with the second control reversing valve, and the detection component includes an inclination sensor arranged on the crane and a force sensor arranged on the winch. The second control end of the first switch valve is connected to the A end of the first control reversing valve and the A end of the second control reversing valve through the first shuttle valve, the first port of the first switch valve is connected to the second port of the motor through the return oil pipeline, the second port of the first switch valve is connected to the oil tank through the return oil pipeline, the first control end of the first switch valve connects the first port and the second port of the first switch valve, the second control end of the first switch valve is also connected to the oil tank through the first shuttle valve, the first control end of the first switch valve controls the first port and the second port of the first switch valve to be connected, and the second control end of the first switch valve controls the first port and the second port of the first switch valve to be disconnected.

2. An overload protection system according to claim 1, characterized in that: The inclination sensor and the force sensor are connected to the control end of the second control reversing valve through the terminal processor; a pressure regulator is also provided at the control end of the second control relief valve, and the pressure regulator is communicatively connected with the terminal processor.

3. An overload protection system according to claim 1, characterized in that: A second switch valve is provided between the oil inlet end of the pilot relief valve and the oil inlet pipeline, a first port of the second switch valve is connected to the oil inlet pipeline, and a second port of the second switch valve is connected to the oil inlet end of the pilot relief valve.

4. An overload protection system according to claim 1, characterized in that: A balancing valve group is provided on the oil inlet pipeline, and the balancing valve group includes a balancing overflow valve and a balancing check valve. The oil inlet end of the balancing overflow valve is connected to the first port of the motor through the oil inlet pipeline, and the oil outlet end of the balancing overflow valve is connected to the hydraulic pump through the oil inlet pipeline. The oil inlet end of the balancing check valve is connected to the oil outlet end of the balancing overflow valve, and the oil outlet end of the balancing check valve is connected to the oil inlet end of the balancing overflow valve.

5. An overload protection system according to claim 1, characterized in that: A brake valve is also provided on the motor, and the control end of the brake valve is connected to the oil inlet pipeline and the oil outlet pipeline through the brake reversing valve. The P end of the brake reversing valve is connected to the oil tank, and the A end of the brake reversing valve is connected to the control end of the brake valve. The control end of the brake reversing valve is connected to the oil inlet pipeline and the oil outlet pipeline.

6. An overload protection system according to claim 1, characterized in that: A spring is also provided on the second control end of the first switch valve, and the hydraulic oil pressure at the second control end plus the pressure of the spring is greater than the hydraulic oil pressure at the first control end of the first switch valve.

7. An overload protection system according to claim 1, characterized in that: The first port of the first shuttle valve is connected to the A end of the first control reversing valve and the A end of the second control reversing valve, the second port of the first shuttle valve is connected to the oil tank, and the third port of the first shuttle valve is connected to the second control end of the first switch valve.

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