A winch oil circuit control method with multiple drain oil circuits

Abstract

The present invention provides a control method for a winch oil circuit with multiple drain oil circuits, and the specific steps include: (1) the oil tank supplies oil to the oil inlet pipe through the hydraulic pump; (2) the hydraulic oil flows to the first port of the motor through the oil inlet pipe; (3) the hydraulic oil flows into the return oil pipe through the second port of the motor and flows back to the oil tank through the return oil pipe to realize circulation and drive the motor to rotate; (5) if it is necessary to quickly release the rope; (6) the first port and the second port of the first switch valve are disconnected; (7) the hydraulic oil cannot flow back to the oil tank from the return oil pipe but flows to the second port of the motor; (8) the oil circuit between the oil inlet pipe and the pilot relief valve and the return oil pipe is opened; (9) the oil tank continues to output hydraulic oil to the oil inlet pipe; (10) the hydraulic oil flows to the return oil pipe through the pilot relief valve and the second pilot relief valve and then flows back to the oil inlet pipe through the motor to realize circulation.

Description

Technical Field

[0001] The present invention relates to the technical field of winch control systems, and in particular to a control method for a winch oil circuit having multiple drain oil circuits. Background Art

[0002] Hydraulic winches are widely used in shipbuilding and other engineering industries. As the rated load and working speed requirements of winches continue to increase, the winch power is getting bigger and bigger, and the required flow rate is also getting bigger and bigger.

[0003] Chinese patent application number 201310420155.6, published on December 25, 2013, discloses an energy-saving lifting system for a hydraulic crane. The system includes a hydraulic oil tank, a hydraulic pump, a lifting motor, and a control valve. The hydraulic pump is driven by a prime mover, with its inlet connected to the hydraulic oil tank and its outlet connected to the lifting motor via a control valve. The hydraulic oil tank is connected to an accumulator hydraulic pump and a hydraulic pump, respectively. The accumulator hydraulic pump is connected to an unloading relief valve, which is connected to an accumulator and a hydraulically controlled one-way valve. The hydraulically controlled one-way valve is connected to a three-position, four-way valve. The hydraulic pump is connected to a relief valve and a three-position, four-way valve, respectively. The three-position, four-way valve is connected to the lifting motor via a shuttle valve and a two-way balancing valve. The lifting motor is equipped with a normally closed brake. This energy-saving lifting system for a hydraulic crane has a rational structure and reliable performance. It can recycle gravitational potential energy, reduce lifting power loss, and minimize wear on the accumulator hydraulic pump and the sheave.

[0004] As in the prior art of the document, the rope-collecting and rope-releasing is performed by setting a reversing valve in the oil circuit. When it is necessary to switch between rope-collecting and rope-releasing, the reversing valve is used to reverse the flow direction of the hydraulic oil. Since the hydraulic oil flows to the motor at a uniform speed, if the winch on the hull accidentally hooks the other hull when lifting the cargo on the other hull, the hull is likely to drift with the wind and waves due to the factors of wind and waves at sea. At this time, if the cable is not released quickly, the other hull may easily drag the winch to move, which may damage the entire crane and may also affect the structure of the hull. In addition, the oil circuit has only one oil drain circuit, which may easily lead to the inability to speed up the flow of hydraulic oil, which may easily lead to the winch not having enough time to release the rope and cause an accident. Summary of the Invention

[0005] The present invention provides a control method for a winch oil circuit with multiple drain oil circuits, which can increase the circulation speed of the hydraulic oil in the oil circuit, thereby accelerating the winch rope releasing speed. At the same time, by setting multiple drain oil circuits, the fluidity of the hydraulic oil is improved.

[0006] To achieve the above object, the technical solution of the present invention is: a control method for a winch oil circuit having multiple drain oil circuits, which is implemented by a hydraulic system, and the specific steps include:

[0007] (1) The oil tank supplies oil to the oil inlet pipe through the hydraulic pump.

[0008] (2) The hydraulic oil flows through the oil inlet pipe to the first port of the motor.

[0009] (3) The hydraulic oil in the oil return pipeline flows to the first control end of the first switch valve to drive the first port and the second port of the first switch valve to communicate.

[0010] (4) The hydraulic oil flows into the oil return pipe through the second port of the motor and then flows back to the oil tank through the oil return pipe to realize circulation and drive the motor to rotate.

[0011] (5) If you need to release the rope quickly.

[0012] (6) The oil tank supplies oil to the second control end of the first switch valve, and the first switch valve switches and controls the first port and the second port to be disconnected.

[0013] (7) The hydraulic oil cannot flow back to the oil tank from the return oil pipe but flows to the second port of the motor.

[0014] (8) Control the pilot relief valve to open so that the oil circuit between the oil inlet pipe, the pilot relief valve and the oil return pipe is connected.

[0015] (81) If it is necessary to increase the circulation speed of the hydraulic oil.

[0016] (82) The second pilot-operated relief valve is controlled to open, so that the oil path between the oil inlet pipeline and the second pilot-operated relief valve and the oil return pipeline is connected.

[0017] (9) The oil tank continues to output hydraulic oil to the oil inlet pipe.

[0018] (10) The hydraulic oil flows through the pilot relief valve and the second pilot relief valve to the return oil pipe and then flows back to the oil inlet pipe through the motor to achieve circulation, driving the winch to quickly release the rope.

[0019] The hydraulic system includes an oil tank, a pilot-operated relief valve, a first switch valve and a motor. The oil tank is provided with a hydraulic pump, the hydraulic pump is connected to a first port of the motor through an oil inlet pipe, and a second port of the motor is connected to the oil tank through an oil return pipe. A pilot-operated relief valve is provided between the oil inlet pipe and the oil return pipe, the oil inlet end of the pilot relief valve is connected to the oil inlet pipe, and the oil outlet end of the pilot relief valve is connected to the oil return pipe; a first switch valve is provided on the oil return pipe, the first port of the first switch valve is connected to the second port of the motor through the oil return pipe, the second port of the first switch valve is connected to the oil tank through the oil return pipe, the first control end of the first switch valve is connected to the first port and the second port of the first switch valve, the second control end of the first switch valve is connected to the oil tank, the first control end of the first switch valve controls the connection between the first port and the second port of the first switch valve, and the second control end of the first switch valve controls the disconnection between the first port and the second port of the first switch valve; and a second pilot-operated relief valve is also provided, the oil inlet end of the second pilot relief valve is connected to the oil inlet pipe, and the oil outlet end of the pilot relief valve is connected to the oil return pipe.

[0020] When the cam is in operation, the hydraulic oil in the oil tank is supplied to the oil inlet pipe, which then passes through the motor and the oil return pipe, and then enters the oil tank for circulation to realize the rope retraction 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 the 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 reverse and connect the first port and the second port, thereby connecting the oil return pipe with the oil tank, and the hydraulic oil can flow back to the oil tank to realize circulation. When the load is lifted by an erroneous operation, which is in the rope retraction state, the oil tank supplies oil to the second control end of the first switch valve, driving the first switch valve to reverse and control the first port and the second port to be disconnected, thereby preventing the hydraulic oil from flowing back to the oil tank from the return pipe but flowing to the second port of the motor; since the oil pressure in the oil inlet pipe is greater than the regulating pressure of the pilot relief valve, the pilot oil circuit of the pilot relief valve is opened to relieve the pressure to the oil return pipe. When the oil pressure at the oil pump is too low, the oil in the oil pumping station will start to increase, and the oil pressure at the end of the oil pumping station connected to the motor will increase. When the oil pressure at the oil pumping station is too high, the oil pressure at the oil pumping station will start to increase, and the oil pressure at the end of the oil pumping station connected to the motor will increase. When the oil pressure at the oil pumping station is too high, the oil pressure at the oil pumping station will start to increase, and the oil pressure at the oil pumping station will start to increase. When the oil pressure at the oil pumping station is too high, the oil pressure at the oil pumping station will start to increase, and the oil pressure at the oil pumping station will start to increase.

[0021] Furthermore, a second switch valve is provided between the oil inlet end of the pilot relief valve and the oil inlet pipeline, the first port of the second switch valve is connected to the oil inlet pipeline, and the second port of the second switch valve is connected to the oil inlet end of the pilot relief valve.

[0022] The above arrangement, by providing the second switch valve, enables the oil circuit between the oil inlet pipe 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.

[0023] Furthermore, a third switch valve is provided between the oil inlet end of the second pilot-operated relief valve and the oil inlet pipeline, wherein a first port of the third switch valve is connected to the oil inlet pipeline, and a second port of the third switch valve is connected to the oil inlet end of the pilot-operated relief valve.

[0024] The above arrangement, by providing the third switch valve, enables the oil circuit between the oil inlet pipeline and the second pilot-operated relief valve to be opened only when the second pilot-operated relief valve is needed, thereby facilitating control of the hydraulic system.

[0025] 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.

[0026] The above setting, by setting a balancing valve group, makes the hydraulic oil output of the oil inlet pipeline stable.

[0027] Furthermore, a brake valve is provided on the motor, and the control end of the brake valve is connected to the oil inlet pipe and the oil outlet pipe 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 pipe and the oil outlet pipe.

[0028] The above setting connects the oil inlet pipe and the oil outlet pipe through the control end of the brake valve reversing valve. When the winch is to be started, the hydraulic oil in the oil inlet pipe and the oil outlet pipe 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 from 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.

[0029] 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.

[0030] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the hydraulic system of the present invention.

[0032] Figure 2 for Figure 1 Enlarged view of point A in the middle.

[0033] Figure 3 This is the working principle of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1-Figure 2 As shown, a hydraulic system includes an oil tank 1, a pilot relief valve 2, a first switch valve 3, a motor 4 and a second pilot relief valve 6. A hydraulic pump (not shown in the figure) is provided on the oil tank 1. The hydraulic pump is connected to a first port 41 of the motor 4 through an oil inlet pipe 11. The second port 42 of the motor 4 is connected to the oil tank 1 through an oil return pipe 12. A pilot relief valve 2 is provided between the oil inlet pipe 11 and the oil return pipe 12. The oil inlet end of the pilot relief valve 2 is connected to the oil inlet pipe 11, and the oil outlet end of the pilot relief valve 2 is connected to the oil return pipe 12. A first switch valve 3 is provided on the oil return pipe 12. The first port 41 of the first switch valve 3 is connected to the oil inlet pipe 11. The second port 42 of the motor 4 is connected to the oil return pipe 12, the second port of the first switch valve 3 is connected to the oil tank 1 through the oil return pipe 12, the 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, the 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 connection between the first port and the second port of the first switch valve 3, and the second control end 32 of the first switch valve 3 controls the disconnection between the first port and the second port of the first switch valve 3, the oil inlet end of the second pilot overflow valve 6 is connected to the oil inlet pipe 11, and the oil outlet end of the pilot overflow valve 6 is connected to the oil return pipe 12.

[0036] A second on-off valve 21 is provided between the oil inlet end of the pilot-operated relief valve 2 and the oil inlet pipeline. A first port of the second on-off valve 21 is connected to the oil inlet pipeline 11, and a second port of the second on-off valve 21 is connected to the oil inlet end of the pilot-operated relief valve 2. The provision of the second on-off valve 21 allows the oil circuit between the oil inlet pipeline 11 and the pilot-operated relief valve 2 to be opened only when the pilot-operated relief valve 2 is needed, thereby facilitating control of the hydraulic system.

[0037] A third on-off valve 61 is provided between the oil inlet end of the second pilot-operated relief valve 6 and the oil inlet pipeline 11. A first port of the third on-off valve 61 is connected to the oil inlet pipeline 11, and a second port of the third on-off valve 61 is connected to the oil inlet end of the pilot-operated relief valve 6. The provision of the third on-off valve 61 allows the oil passage between the oil inlet pipeline 11 and the second pilot-operated relief valve 6 to be opened only when the second pilot-operated relief valve 6 is needed, thereby facilitating control of the hydraulic system.

[0038] A balancing valve assembly 5 is provided on the oil inlet pipeline 11. The balancing valve assembly 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 via the oil inlet pipeline 11, and the oil outlet end of the balancing relief valve 51 is connected to the hydraulic pump via 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. The provision of the balancing valve assembly 5 ensures a stable output of hydraulic oil from the oil inlet pipeline 11.

[0039] like Figure 1 As shown, a brake valve 43 is also provided on the motor 4. The control end of the brake valve 43 is connected to the oil inlet and oil outlet pipes via 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 pipe 11 and the oil outlet pipe 12. The control end K of the brake valve reversing valve 44 is connected to the oil inlet pipe 11 and the oil outlet pipe 12. When the winch is to be started, the hydraulic oil in the oil inlet pipe 11 and the oil outlet pipe 12 flows to the control end of the brake reversing valve 44, and the brake reversing valve 44 is controlled to reverse so that the A end is connected to the P end, thereby causing the hydraulic oil output from the oil tank 1 to flow to the control end of the brake valve 43, thereby driving the brake valve 43 to open, facilitating the rotation of the motor 4.

[0040] like Figure 2 As shown, a spring 33 is further provided at the second control end 32 of the first switching valve 3. 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 switching valve 3. The provision of the spring 33 ensures that when the first switching valve 3 is closed, the hydraulic oil pressure flowing from the oil tank 1 into the second control end 32 of the first switching valve 3 plus the elastic force of the spring 33 overcomes the hydraulic oil pressure at the first control end 31 of the first switching valve 3, thereby driving the first switching valve 3 to close and preventing the hydraulic oil from flowing back to the oil tank through the oil return pipe 12.

[0041] In this embodiment, an electromagnetic reversing valve (not shown in the figure) is provided between the second control end of the first switch valve and the oil tank. When the electromagnetic reversing valve is switched, the oil circuit between the first switch valve and the second control end is connected, and the oil tank outputs hydraulic oil to the second control end of the first switch valve.

[0042] A method for controlling a winch oil circuit having multiple drain oil circuits, comprising the following steps:

[0043] (1) The oil tank supplies oil to the oil inlet pipe through the hydraulic pump.

[0044] (2) The hydraulic oil flows through the oil inlet pipe to the first port of the motor.

[0045] (3) The hydraulic oil in the oil return pipeline flows to the first control end of the first switch valve to drive the first port and the second port of the first switch valve to communicate.

[0046] (4) The hydraulic oil in the oil return pipeline flows to the first control end of the first switch valve to drive the first port and the second port of the first switch valve to communicate.

[0047] (5) If you need to release the rope quickly.

[0048] (6) The oil tank supplies oil to the second control end of the first switch valve, and the first switch valve switches and controls the first port and the second port to be disconnected.

[0049] (7) The hydraulic oil cannot flow back to the oil tank from the return oil pipe but flows to the second port of the motor.

[0050] (8) Control the pilot relief valve to open so that the oil circuit between the oil inlet pipe, the pilot relief valve and the oil return pipe is connected.

[0051] (81) If it is necessary to increase the circulation speed of the hydraulic oil.

[0052] (82) The second pilot-operated relief valve is controlled to open, so that the oil path between the oil inlet pipeline and the second pilot-operated relief valve and the oil return pipeline is connected.

[0053] (9) The oil tank continues to output hydraulic oil to the oil inlet pipe.

[0054] (10) The hydraulic oil flows through the pilot relief valve and the second pilot relief valve to the return oil pipe and then flows back to the oil inlet pipe through the motor to achieve circulation, driving the winch to quickly release the rope.

[0055] 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 return oil pipe 12 to circulate and realize the rope reeling operation. At the same time, a first switch valve 3 is provided on the return oil pipe 12. When the motor 4 rotates normally, the oil tank 1 delivers hydraulic oil to the motor 4 through the oil inlet pipe 11 and flows into the return oil pipe 12 through the motor 4. The hydraulic oil in the return oil pipe 12 flows to the first control end 31 of the first switch valve 3, thereby driving the first switch valve 3. The first and second ports are switched and connected, thereby connecting the return oil pipe 12 with the oil tank, and the hydraulic oil can flow back to the oil tank 1 to realize circulation. When the weight is hoisted by mistake, it is in the rope-retracting state, and the oil tank 1 flows oil to the second control end 32 of the first switch valve 3, driving the first switch valve 3 to switch and control the first and second ports to be disconnected, thereby preventing the hydraulic oil from flowing back to the oil tank 1 from the return oil pipe 12 but flowing to the second port 42 of the motor 4; since the oil pressure in the oil inlet pipe 11 is greater than the regulating pressure of the pilot-operated relief valve, the pilot-operated relief valve The pilot oil circuit of the pilot relief valve 2 is opened to release the pressure to the return oil pipe 12, thereby increasing the oil pressure on the return oil pipe 12 and making the oil pressure at the end of the motor 4 connected to the return oil pipe 12 greater than the oil pressure at the end of the motor connected to the oil inlet pipe 11. Due to the overflow effect of the pilot relief valve 2, 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 4, and increasing the pressure. The increase in the rotation speed of motor 4 enables rapid rope release; at the same time, by setting a second pilot overflow valve, when it is necessary to increase the circulation speed of the hydraulic oil, the second pilot overflow valve is controlled to open, so that the oil circuit between the oil inlet pipe and the second pilot overflow valve and the return oil pipe is connected; the hydraulic oil flows to the return oil pipe through the pilot overflow valve and the second pilot overflow valve, and then flows back to the oil inlet pipe through the motor to achieve circulation. By adding multiple connected oil circuits in the oil inlet pipe and the oil outlet pipe, the circulation flow of the hydraulic oil is accelerated, thereby accelerating the rope release of the winch.

Claims

1. A method for controlling a winch oil circuit having multiple drain oil circuits, implemented by a hydraulic system, characterized in that: The specific steps include: (1) The oil tank supplies oil to the oil inlet pipe through the hydraulic pump; (2) The hydraulic oil flows through the oil inlet pipe to the first port of the motor; (3) The hydraulic oil in the oil return pipeline flows to the first control end of the first switch valve to drive the first port and the second port of the first switch valve to communicate; (4) The hydraulic oil flows into the oil return pipe through the second port of the motor and then flows back to the oil tank through the oil return pipe to realize circulation and drive the motor to rotate; (5) If you need to release the rope quickly; (6) The oil tank flows into the second control end of the first switch valve, and the first switch valve switches and controls the first port and the second port to be disconnected; (7) The hydraulic oil cannot flow back to the tank from the return oil pipe but flows to the second port of the motor; (8) Control the pilot relief valve to open, so that the oil inlet pipeline is connected to the pilot relief valve and the oil return pipeline; (81) If it is necessary to increase the circulation speed of the hydraulic oil; (82) Control the second pilot-operated relief valve to open, so that the oil inlet pipeline is connected to the second pilot-operated relief valve and the oil return pipeline; (9) The oil tank continues to output hydraulic oil to the oil inlet pipe; (10) The hydraulic oil flows through the pilot relief valve and the second pilot relief valve to the return oil pipe and then flows back to the oil inlet pipe through the motor to achieve circulation, driving the winch to quickly release the rope; The hydraulic system includes an oil tank, a pilot-operated relief valve, a first switch valve 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 pipe, and a second port of the motor is connected to the oil tank through a return oil pipe. A pilot-operated relief valve is provided between the oil inlet pipe and the return oil pipe, the oil inlet end of the pilot relief valve is connected to the oil inlet pipe, and the oil outlet end of the pilot relief valve is connected to the return oil pipe; a first switch valve is provided on the return oil pipe, the first port of the first switch valve is connected to the second port of the motor through the return oil pipe, the second port of the first switch valve is connected to the oil tank through the return oil pipe, the first control end of the first switch valve is connected to the first port and the second port of the first switch valve, the second control end of the first switch valve is connected to the oil tank, 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; It also includes a second pilot-operated relief valve, wherein the oil inlet end of the second pilot-operated relief valve is connected to the oil inlet pipeline, and the oil outlet end of the second pilot-operated relief valve is connected to the oil return pipeline.

2. The method for controlling a winch oil circuit having multiple drain oil circuits 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, wherein 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.

3. The method for controlling a winch oil circuit having multiple drain oil circuits according to claim 1, characterized in that: A third switch valve is provided between the oil inlet end of the second pilot-operated relief valve and the oil inlet pipeline, wherein a first port of the third switch valve is connected to the oil inlet pipeline, and a second port of the third switch valve is connected to the oil inlet end of the second pilot-operated relief valve.

4. The method for controlling a winch oil circuit having multiple drain oil circuits 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. The method for controlling a winch oil circuit having multiple drain oil circuits according to claim 1, characterized in that: A brake valve is also provided on the motor. The control end of the brake valve is connected to the oil inlet pipe and the oil return pipe 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. The control end of the brake reversing valve is connected to the oil inlet pipe and the oil return pipe.

6. The method for controlling a winch oil circuit having multiple drain oil circuits according to claim 1, characterized in that: A spring is further 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.

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