Method for realizing high and low speed control through multiple oil extraction points

Abstract

The invention provides a method for realizing high and low speed control through a plurality of oil extraction points. The method comprises the following specific steps: (1) lifting a winch at a low speed; (11) the oil tank discharges oil from a second oil outlet, and the hydraulic oil flowing into the motor flows out from a second port of the motor and flows back to the oil tank from a second oil return port through the end B of the second cartridge valve so as to drive the motor to rotate; (2) hoisting the winch at a high speed; (21) the oil tank discharges oil from a first oil outlet, and the hydraulic oil flowing into the motor flows out from a second port of the motor and flows back to the oil tank from a first oil return port through the end B of the first cartridge valve so as to drive the motor to rotate; (3) descending the winch at a low speed; (31) the oil tank discharges oil from the second oil return port, and the hydraulic oil flowing into the motor flows out from the first port of the motor and flows back to the oil tank from the second oil outlet so as to drive the motor to rotate; (4) descending the winch at a high speed; and (41) the oil tank discharges oil from the first oil return port, and the hydraulic oil flowing into the motor flows back to the oil tank from the first port of the motor so as to drive the motor to rotate.

Description

Technical Field

[0001] The invention relates to the technical field of winch control systems, and in particular to a method for realizing high and low speed control through multiple oil extraction points. Background Art

[0002] The offshore deck crane is one of the important equipment of the ship. It usually needs to perform lifting, luffing and slewing. The core actuators of the lifting and slewing mechanisms are generally completed by hydraulic motors. During use, the deck crane often encounters different working conditions, such as the need to adjust low speed and heavy load, high speed and light load, and fine lifting. In order to adapt to different working conditions, the speed of the hydraulic motor needs to be controlled.

[0003] For example, the patent document with Chinese patent application number 202310003646.4 and publication date 2023.04.14 discloses a hydraulic motor, which includes: a plunger motor, a variable control valve, a servo valve, a stop valve and a safety valve; the high-pressure oil port of the hydraulic oil source is connected to the plunger motor after passing through the stop valve, the first working port and the second working port of the variable control valve are connected to the working port of the plunger motor, the third working port and the fourth working port of the variable control valve are connected to the working port of the servo valve, the fifth working port of the variable control valve is connected to the oil outlet of the stop valve, the sixth working port of the variable control valve is connected to the low-pressure oil port of the hydraulic oil source, the oil outlet of the stop valve is connected to the fifth working port of the variable control valve, and the unloading control oil port of the stop valve is connected to the low-pressure oil port of the hydraulic oil source. This design can not only realize the bidirectional variable control of the hydraulic motor through the proportional position of the variable control valve and the servo valve, but also accurately perform stepless speed regulation on the plunger motor by changing the loading amplitude of the servo valve.

[0004] However, the hydraulic system of the document adjusts the speed of the motor by setting up multiple control valves. Although this can accurately control the speed of the motor, if the winch is to be raised at a low speed, raised at a high speed, lowered at a low speed, and lowered at a high speed, four separate hydraulic circuits need to be set up respectively. This makes the control process of the entire oil circuit complicated, and thus the motor cannot be driven in a simple way. Summary of the invention

[0005] The present invention provides a method for realizing high and low speed control through multiple oil taking points, and can control the winch to adjust the lifting and lowering speed according to actual needs through the selection of multiple oil taking points.

[0006] To achieve the above object, the technical solution of the present invention is: a method for realizing high and low speed control through multiple oil extraction points, which is realized by a hydraulic control system, wherein the hydraulic system comprises a first oil outlet, a second oil outlet, and a first oil return port and a second oil return port, wherein the first oil return port and the second oil return port are respectively connected to a first cartridge valve and a second cartridge valve, wherein the first oil outlet and the second oil outlet are connected to a motor, wherein the first cartridge valve is used for high speed control, and the second cartridge valve is used for low speed control; the specific steps include: (1) Winch hoisting at low speed.

[0007] (11) The control oil tank discharges oil from the second oil outlet, and the hydraulic oil circuit is divided into two paths.

[0008] (12) A hydraulic oil path enters the motor through the first port of the motor.

[0009] (13) Another line of hydraulic oil flows to the control end of the first cartridge valve, driving the first cartridge valve to close.

[0010] (14) The hydraulic oil flowing into the motor flows out from the second port of the motor and flows back to the oil tank from the second oil return port through the B end of the second cartridge valve, thereby driving the motor to rotate and perform low-speed lifting.

[0011] (2) High-speed lifting by winch.

[0012] (21) The control oil tank discharges oil from the first oil outlet, and the hydraulic oil circuit is divided into two paths.

[0013] (22) A hydraulic oil path enters the motor through the first port of the motor.

[0014] (23) Another line of hydraulic oil flows to the control end of the second cartridge valve, driving the second cartridge valve to close.

[0015] (24) The hydraulic oil flowing into the motor flows out from the second port of the motor and flows back to the oil tank from the first oil return port through the B end of the first cartridge valve, thereby driving the motor to rotate and perform high-speed lifting.

[0016] (3) The winch descends at a low speed.

[0017] (31) The control oil tank discharges oil from the second oil return port, and the hydraulic oil circuit is divided into two paths.

[0018] (32) A hydraulic oil path enters the second cartridge valve through the A end of the second cartridge valve and flows to the second port of the motor through the B end of the second cartridge valve.

[0019] (33) Another line of hydraulic oil flows to the control end of the first cartridge valve, driving the first cartridge valve to close.

[0020] (34) The hydraulic oil flowing into the motor flows out from the first port of the motor and flows back to the oil tank from the second oil outlet, thereby driving the motor to rotate and perform low-speed descent.

[0021] (4) The winch descends at high speed.

[0022] (41) The control oil tank discharges oil from the first oil return port, and the hydraulic oil circuit is divided into two paths.

[0023] (42) A hydraulic oil path enters the first cartridge valve through the A end of the first cartridge valve and flows to the second port of the motor through the B end of the first cartridge valve.

[0024] (43) Another line of hydraulic oil flows to the control end of the second cartridge valve, driving the second cartridge valve to close.

[0025] (44) The hydraulic oil flowing into the motor flows out from the first port of the motor and flows back to the oil tank from the first oil outlet, thereby driving the motor to rotate and descend at a high speed.

[0026] The above method sets two cartridge valves with different flow rates, so that different oil outlets or oil return ports can be selected when the winch is running at different speeds. When rising at a low speed, the first cartridge valve is closed, and the oil path only needs to pass from the second oil outlet through the motor to enter the second cartridge valve and flow back to the oil tank. When high lifting is required, the second cartridge valve is closed, and the oil path only needs to pass from the first oil outlet through the motor to enter the first cartridge valve and flow back to the oil tank. Similarly, when descending at high or low speeds, one of the cartridge valves is controlled to be closed, and then the oil return port of the other corresponding cartridge valve is started and then returned to the oil outlet through the motor. Therefore, four speed states can be controlled by controlling two oil outlets and two oil return ports, and the control method is simple and reliable.

[0027] Furthermore, a first shuttle valve is provided between the control end of the first cartridge valve and the second oil return port, the first port of the first shuttle valve is connected to the second oil return port, 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 control end of the first cartridge valve.

[0028] The above arrangement controls the flow direction of the hydraulic oil through the arrangement of the first shuttle valve, thereby facilitating the control of the first cartridge valve.

[0029] Furthermore, a second shuttle valve is provided between the control end of the second cartridge valve and the first oil return port, the first port of the second shuttle valve is connected to the first oil return port, the second port of the second shuttle valve is connected to the oil tank, and the third port of the second shuttle valve is connected to the control end of the second cartridge valve.

[0030] The above arrangement controls the flow direction of the hydraulic oil through the arrangement of the second shuttle valve, thereby facilitating the control of the second cartridge valve.

[0031] Furthermore, a first balancing valve is provided between the first oil outlet and the motor, the first balancing valve comprising a first overflow valve and a first check valve, the oil inlet end of the first overflow valve is connected to the first port of the motor, the oil outlet end of the first overflow valve is connected to the first oil outlet, the oil inlet end of the first check valve is connected to the first oil outlet, and the oil outlet end of the first check valve is connected to the first port of the motor; the control end of the first overflow valve is connected to the first oil return port.

[0032] Step (4) specifically also includes: (41) The oil tank discharges oil from the first oil return port, and the hydraulic oil circuit is divided into three routes.

[0033] (45) The third hydraulic oil flows to the control end of the first overflow valve.

[0034] (46) The first overflow valve is opened, the first oil inlet is connected to the first port of the motor, and the hydraulic oil flows back to the oil tank from the first oil outlet.

[0035] The above arrangement, by providing the first balancing valve, stabilizes the pressure of the hydraulic oil flowing from the first oil outlet to the motor.

[0036] Further, a second balancing valve is provided between the second oil outlet and the motor, the second balancing valve comprises a second overflow valve and a second one-way valve, the oil inlet end of the second overflow valve is connected to the first port of the motor, the oil outlet end of the second overflow valve is connected to the second oil outlet, the oil inlet end of the second one-way valve is connected to the second oil outlet, and the oil outlet end of the second one-way valve is connected to the first port of the motor; the control end of the second overflow valve is connected to the second oil return port; Step (3) specifically also includes: (31) The oil tank discharges oil from the second oil return port, and the hydraulic oil circuit is divided into three routes.

[0037] (35) The third hydraulic oil flows to the control end of the second overflow valve.

[0038] (36) The second overflow valve is opened, the second oil inlet is connected to the first port of the motor, and the hydraulic oil flows back to the oil tank from the second oil outlet.

[0039] The above arrangement, by providing the second balancing valve, stabilizes the pressure of the hydraulic oil flowing from the second oil outlet to the motor.

[0040] Furthermore, a third shuttle valve is provided between the first oil outlet and the second shuttle valve, wherein the first port of the third shuttle valve is connected to the first oil outlet, the second port of the third shuttle valve is connected to the first oil return port, and the third port of the third shuttle valve is connected to the first port of the second shuttle valve.

[0041] The above arrangement allows the hydraulic oil to flow to the third shuttle valve, driving the first port and the third port of the third shuttle valve to be connected, so that the hydraulic oil flows through the third shuttle valve to the second shuttle valve and flows through the second shuttle valve into the control end of the second cartridge valve, driving the second cartridge valve to close.

[0042] Furthermore, a fourth shuttle valve is provided between the second oil outlet and the first shuttle valve, wherein the first port of the fourth shuttle valve is connected to the second oil outlet, the second port of the fourth shuttle valve is connected to the first oil outlet, and the third port of the fourth shuttle valve is connected to the first port of the first shuttle valve; The above arrangement allows the hydraulic oil to flow to the fourth shuttle valve, driving the first port and the third port of the fourth shuttle valve to be connected, so that the hydraulic oil flows through the fourth shuttle valve to the first shuttle valve and flows through the first shuttle valve into the control end of the first cartridge valve, driving the first cartridge valve to close.

[0043] Furthermore, a manual oil pump is provided between the second port of the first shuttle valve, the second port of the second shuttle valve and the oil tank.

[0044] The above arrangement, through the setting of the manual oil pump, enables the hydraulic oil to be pumped into the control ends of the first cartridge valve and the second cartridge valve through the manual oil pump when the oil circuit needs to be maintained and repaired, thereby driving the first cartridge valve and the second cartridge valve to close. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the hydraulic system of the present invention.

[0046] Figure 2 It is the work flow chart of the present invention.

[0047] Figure 3 This is a flow diagram of the hydraulic oil when the winch is hoisted at a low speed in the present invention.

[0048] Figure 4 This is a flow diagram of the hydraulic oil when the winch in the present invention is lifted at high speed. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] like Figure 1-4As shown, a hydraulic control system includes a first cartridge valve 1 and a second cartridge valve 2, wherein the A port of the first cartridge valve 1 is connected to the first oil return port 31 of the oil tank 3, the B port of the first cartridge valve 1 is connected to the second port 41 of the motor 4, the A port of the second cartridge valve 2 is connected to the second oil return port 32 of the oil tank 3, and the B port of the second cartridge valve 2 is connected to the second port 41 of the motor 4; the first port 42 of the motor 4 is connected to the first oil outlet 33 and the second oil outlet 34 of the oil tank 3, and the first oil outlet 3 3 is also connected to the control end 21 of the second cartridge valve 2, and the second oil outlet 34 is also connected to the control end 11 of the first cartridge valve 1; the first oil outlet 31 of the oil tank 3 is connected to the control end 21 of the second cartridge valve 2, and the second oil outlet 34 is connected to the control end 11 of the first cartridge valve 1; the first oil return port 31 is also connected to the control end 21 of the second cartridge valve 2, and the second oil return port 32 is also connected to the control end 11 of the first cartridge valve 1; the hydraulic oil flow rate of the first cartridge valve 1 is higher than the hydraulic oil flow rate of the second cartridge valve 2.

[0051] A first shuttle valve 12 is provided between the control end 11 of the first cartridge valve 1 and the second oil return port 32, wherein a first port 121 of the first shuttle valve 12 is connected to the second oil return port 32, a second port 122 of the first shuttle valve 12 is connected to the oil tank 3, and a third port 123 of the first shuttle valve 12 is connected to the control end 11 of the first cartridge valve 1. The flow direction of the hydraulic oil is controlled by the setting of the first shuttle valve 12, thereby facilitating the control of the first cartridge valve 1.

[0052] A second shuttle valve 22 is provided between the control end 21 of the second cartridge valve 2 and the first oil return port 31, wherein a first port 221 of the second shuttle valve 22 is connected to the first oil return port 31, a second port 222 of the second shuttle valve 22 is connected to the oil tank 3, and a third port 223 of the second shuttle valve 22 is connected to the control end 21 of the second cartridge valve 2. The flow direction of the hydraulic oil is controlled by the setting of the second shuttle valve 22, thereby facilitating the control of the second cartridge valve 2.

[0053] A first balancing valve 35 is provided between the first oil outlet 33 and the motor 4. The first balancing valve 35 includes a first overflow valve 351 and a first check valve 352. The oil inlet end of the first overflow valve 351 is connected to the first port 42 of the motor 4, the oil outlet end of the first overflow valve 351 is connected to the first oil outlet 33, the oil inlet end of the first check valve 352 is connected to the first oil outlet 33, and the oil outlet end of the first check valve 352 is connected to the first port 42 of the motor 4; the control end 3511 of the first overflow valve 351 is connected to the first oil return port 31. By providing the first balancing valve 35, the pressure of the hydraulic oil flowing from the first oil outlet 33 to the motor 4 is stabilized.

[0054] A second balancing valve 36 is provided between the second oil outlet 34 and the motor 4, and the second balancing valve 36 includes a second overflow valve 361 and a second one-way valve 362, the oil inlet end of the second overflow valve 361 is connected to the first port 42 of the motor 4, the oil outlet end of the second overflow valve 361 is connected to the second oil outlet 34, the oil inlet end of the second one-way valve 362 is connected to the second oil outlet 34, and the oil outlet end of the second one-way valve 362 is connected to the first port 42 of the motor 4; the control end 3611 of the second overflow valve 361 is connected to the second oil return port 32; by setting the second balancing valve 36, the pressure of the hydraulic oil flowing from the second oil outlet 34 to the motor 4 is stabilized.

[0055] A third shuttle valve 23 is further provided between the first oil outlet 33 and the second shuttle valve 22, wherein a first port 231 of the third shuttle valve 23 is connected to the first oil outlet 33, a second port 232 of the third shuttle valve 23 is connected to the first oil return port 31, and a third port 233 of the third shuttle valve 23 is connected to the first port 221 of the second shuttle valve 22. The hydraulic oil flows to the third shuttle valve 23, driving the first port 231 and the third port 233 of the third shuttle valve 23 to communicate, so that the hydraulic oil flows to the second shuttle valve 22 through the third shuttle valve 23 and flows into the control end 21 of the second cartridge valve 2 through the second shuttle valve 22, driving the second cartridge valve 2 to close.

[0056] A fourth shuttle valve 24 is further provided between the second oil outlet 34 and the first shuttle valve 12, wherein the first port 241 of the fourth shuttle valve 24 is connected to the second oil outlet 34, the second port 242 of the fourth shuttle valve 24 is connected to the first oil outlet 33, and the third port 243 of the fourth shuttle valve 24 is connected to the first port 121 of the first shuttle valve 12; the hydraulic oil flows to the fourth shuttle valve 24, driving the first port 241 and the third port 243 of the fourth shuttle valve 24 to be connected, so that the hydraulic oil flows to the first shuttle valve 12 through the fourth shuttle valve 24 and flows into the control end 11 of the first cartridge valve 1 through the first shuttle valve 12, driving the first cartridge valve 1 to close.

[0057] A manual oil pump 39 is provided between the second port 122 of the first shuttle valve 12, the second port 222 of the second shuttle valve 22 and the oil tank 3. By providing the manual oil pump 39, when the oil circuit needs to be maintained and repaired, the manual oil pump 39 can pump hydraulic oil into the control ends of the first cartridge valve 1 and the second cartridge valve 2, thereby driving the first cartridge valve 1 and the second cartridge valve 2 to close.

[0058] like Figure 2 As shown, a method for realizing high and low speed control through multiple oil extraction points includes the following specific steps: (1) Winch hoisting at low speed. Figure 3 As shown, the situation when the winch is lifted at a low speed is explained by deleting the hydraulic circuit where no oil flows and retaining the hydraulic circuit where oil flows.

[0059] (11) The oil tank 3 discharges oil from the second oil outlet 34, and the hydraulic oil circuit is divided into two circuits.

[0060] (12) A hydraulic oil path enters the motor 4 through the first port 42 of the motor 4 .

[0061] (13) Another line of hydraulic oil flows to the control end 11 of the first cartridge valve 1, driving the first cartridge valve 1 to close.

[0062] (14) The hydraulic oil flowing into the motor 4 flows out from the second port 41 of the motor 4 and flows back to the oil tank 3 from the second oil return port 32 through the B end of the second cartridge valve 2, thereby driving the motor 4 to rotate and perform low-speed lifting.

[0063] (2) High-speed lifting by winch. Figure 4 As shown, the situation when the winch is lifted at high speed is explained by deleting the hydraulic circuit where no oil flows and retaining the hydraulic circuit where oil flows.

[0064] (21) The oil tank 3 discharges oil from the first oil outlet 33, and the hydraulic oil circuit is divided into two circuits.

[0065] (22) A hydraulic oil path enters the motor 4 through the first port 42 of the motor 4.

[0066] (23) Another path of hydraulic oil flows to the control end 21 of the second cartridge valve 2, driving the second cartridge valve 2 to close.

[0067] (24) The hydraulic oil flowing into the motor 4 flows out from the second port 41 of the motor 4 and flows back to the oil tank 3 from the first oil return port 31 through the B end of the first cartridge valve 1, thereby driving the motor 4 to rotate and perform high-speed lifting.

[0068] (3) The winch descends at a low speed.

[0069] (31) The oil tank 3 discharges oil from the second oil return port 32, and the hydraulic oil circuit is divided into three paths.

[0070] (32) A path of hydraulic oil enters the second cartridge valve 2 through the A end of the second cartridge valve 2, and flows to the second port 41 of the motor 4 through the B end of the second cartridge valve 2.

[0071] (33) Another line of hydraulic oil flows to the control end 11 of the first cartridge valve 1, driving the first cartridge valve 1 to close.

[0072] (34) The hydraulic oil flowing into the motor 1 flows out from the first port 10 of the motor 1 and flows back to the oil tank 3 from the second oil outlet 34, thereby driving the motor 4 to rotate and perform low-speed descent.

[0073] (35) The third hydraulic oil flows to the control end 3611 of the second overflow valve 361.

[0074] (36) The second overflow valve 361 is opened, the second oil inlet 34 is connected to the first port 42 of the motor 4 , and the hydraulic oil flows back to the oil tank from the second oil outlet 34 .

[0075] (4) The winch descends at high speed.

[0076] (41) The oil tank 3 discharges oil from the first oil return port 31, and the hydraulic oil circuit is divided into three circuits.

[0077] (42) A path of hydraulic oil enters the first cartridge valve 1 through the A end of the first cartridge valve 1, and flows to the second port 41 of the motor 4 through the B end of the first cartridge valve 1.

[0078] (43) Another path of hydraulic oil flows to the control end 21 of the second cartridge valve 2, driving the second cartridge valve 2 to close.

[0079] (44) The hydraulic oil flowing into the motor 4 flows out from the first port 42 of the motor 4 and flows back to the oil tank 3 from the first oil outlet 33, thereby driving the motor 4 to rotate and descend at a high speed.

[0080] (45) The third hydraulic oil flows to the control end 3511 of the first overflow valve 351.

[0081] (46) The first overflow valve 351 is opened, the first oil inlet 33 is connected to the first port 42 of the motor 4 , and the hydraulic oil flows back to the oil tank from the first oil outlet 33 .

[0082] The working principle of the present invention is as follows: by setting two cartridge valves with different flow rates, different oil outlets or oil return ports can be selected when the winch is running at different speeds, and when rising at a low speed, the first cartridge valve is closed, and the oil path only needs to pass through the motor from the second oil outlet to enter the second cartridge valve and flow back to the oil tank. When a high lifting is required, the second cartridge valve is closed, and the oil path only needs to pass through the motor from the first oil outlet to enter the first cartridge valve and flow back to the oil tank. Similarly, when descending at high or low speeds, one of the cartridge valves is controlled to be closed, and then the oil return port of the other corresponding cartridge valve is started and then returned to the oil outlet through the motor. Thus, four speed states can be controlled by controlling two oil outlets and two oil return ports, and the control method is simple and reliable.

Claims

1. A method for realizing high and low speed control through multiple oil extraction points, realized by a hydraulic control system, characterized in that: The hydraulic system comprises a first oil outlet, a second oil outlet, a first oil return port and a second oil return port, the first oil return port and the second oil return port are connected to a first cartridge valve and a second cartridge valve respectively, the first oil outlet and the second oil outlet are connected to a motor, the first cartridge valve is used for high-speed control, and the second cartridge valve is used for low-speed control; the specific steps include: (1) Winch hoisting at low speed; (11) The control oil tank discharges oil from the second oil outlet, and the hydraulic oil circuit is divided into two circuits; (12) One hydraulic oil enters the motor through the first port of the motor; (13) Another line of hydraulic oil flows to the control end of the first cartridge valve, driving the first cartridge valve to close; (14) The hydraulic oil flowing into the motor flows out from the second port of the motor and flows back to the oil tank from the second oil return port through the B end of the second cartridge valve, thereby driving the motor to rotate and perform low-speed lifting; (2) High-speed lifting of winch; (21) The control oil tank discharges oil from the first oil outlet, and the hydraulic oil circuit is divided into two circuits; (22) A hydraulic oil path enters the motor through the first port of the motor; (23) Another line of hydraulic oil flows to the control end of the second cartridge valve, driving the second cartridge valve to close; (24) The hydraulic oil flowing into the motor flows out from the second port of the motor and flows back to the oil tank from the first oil return port through the B end of the first cartridge valve, thereby driving the motor to rotate and perform high-speed lifting; (3) The winch descends at a low speed; (31) The control oil tank discharges oil from the second oil return port, and the hydraulic oil circuit is divided into two paths; (32) One hydraulic oil path enters the second cartridge valve through the A end of the second cartridge valve, and flows to the second port of the motor through the B end of the second cartridge valve; (33) Another hydraulic oil flows to the control end of the first cartridge valve, driving the first cartridge valve to close; (34) The hydraulic oil flowing into the motor flows out from the first port of the motor and flows back to the oil tank from the second oil outlet, thereby driving the motor to rotate and perform low-speed descent; (4) The winch descends at high speed; (41) The control oil tank discharges oil from the first oil return port, and the hydraulic oil circuit is divided into two circuits; (42) A hydraulic oil path enters the first cartridge valve through the A end of the first cartridge valve, and flows to the second port of the motor through the B end of the first cartridge valve; (43) Another line of hydraulic oil flows to the control end of the second cartridge valve, driving the second cartridge valve to close; (44) The hydraulic oil flowing into the motor flows out from the first port of the motor and flows back to the oil tank from the first oil outlet, thereby driving the motor to rotate and descend at high speed; The hydraulic control system includes a first cartridge valve and a second cartridge valve, wherein the A port of the first cartridge valve is connected to the first oil return port of the oil tank, the B port of the first cartridge valve is connected to the second port of the motor, the A port of the second cartridge valve is connected to the second oil return port of the oil tank, and the B end of the second cartridge valve is connected to the second port of the motor; the first port of the motor is connected to the first oil outlet and the second oil outlet of the oil tank, the first oil outlet is also connected to the control end of the second cartridge valve, and the second oil outlet is also connected to the control end of the first cartridge valve; the first oil outlet of the oil tank is connected to the control end of the second cartridge valve, and the second oil outlet is connected to the control end of the first cartridge valve; the first oil return port is also connected to the control end of the second cartridge valve, and the second oil return port is also connected to the control end of the first cartridge valve; the hydraulic oil flow rate of the first cartridge valve is higher than the hydraulic oil flow rate of the second cartridge valve.

2. A method for realizing high and low speed control through multiple oil extraction points according to claim 1, characterized in that: A first shuttle valve is provided between the control end of the first cartridge valve and the second oil return port, wherein the first port of the first shuttle valve is connected to the second oil return port, 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 control end of the first cartridge valve.

3. A method for realizing high and low speed control through multiple oil extraction points according to claim 2, characterized in that: A second shuttle valve is provided between the control end of the second cartridge valve and the first oil return port, the first port of the second shuttle valve is connected to the first oil return port, the second port of the second shuttle valve is connected to the oil tank, and the third port of the second shuttle valve is connected to the control end of the second cartridge valve.

4. The method for realizing high and low speed control through multiple oil extraction points according to claim 1, characterized in that: A first balancing valve is provided between the first oil outlet and the motor, the first balancing valve comprising a first overflow valve and a first check valve, the oil inlet end of the first overflow valve is connected to the first port of the motor, the oil outlet end of the first overflow valve is connected to the first oil outlet, the oil inlet end of the first check valve is connected to the first oil outlet, and the oil outlet end of the first check valve is connected to the first port of the motor; the control end of the first overflow valve is connected to the first oil return port; Step (4) specifically also includes: (41) The oil tank discharges oil from the first oil return port, and the hydraulic oil circuit is divided into three routes; (45) The third hydraulic oil flows to the control end of the first relief valve; (46) The first overflow valve is opened, the first oil inlet is connected to the first port of the motor, and the hydraulic oil flows back to the oil tank from the first oil outlet.

5. The method for realizing high and low speed control through multiple oil extraction points according to claim 1, characterized in that: A second balancing valve is provided between the second oil outlet and the motor, the second balancing valve comprises a second overflow valve and a second one-way valve, the oil inlet end of the second overflow valve is connected to the first port of the motor, the oil outlet end of the second overflow valve is connected to the second oil outlet, the oil inlet end of the second one-way valve is connected to the second oil outlet, and the oil outlet end of the second one-way valve is connected to the first port of the motor; the control end of the second overflow valve is connected to the second oil return port; Step (3) specifically also includes: (31) The oil tank discharges oil from the second oil return port, and the hydraulic oil circuit is divided into three routes; (35) The third hydraulic oil flows to the control end of the second relief valve; (36) The second overflow valve is opened, the second oil inlet is connected to the first port of the motor, and the hydraulic oil flows back to the oil tank from the second oil outlet.

6. A method for realizing high and low speed control through multiple oil extraction points according to claim 3, characterized in that: A third shuttle valve is further provided between the first oil outlet and the second shuttle valve, wherein the first port of the third shuttle valve is connected to the first oil outlet, the second port of the third shuttle valve is connected to the first oil return port, and the third port of the third shuttle valve is connected to the first port of the second shuttle valve; Step (23) specifically includes another path of hydraulic oil flowing to the third shuttle valve, the first port and the third port of the third shuttle valve being connected, so that the hydraulic oil flows through the third shuttle valve to the second shuttle valve and flows through the second shuttle valve into the control end of the second cartridge valve, driving the second cartridge valve to close.

7. The method for realizing high and low speed control through multiple oil extraction points according to claim 2, characterized in that: A fourth shuttle valve is further provided between the second oil outlet and the first shuttle valve, wherein the first port of the fourth shuttle valve is connected to the second oil outlet, the second port of the fourth shuttle valve is connected to the first oil outlet, and the third port of the fourth shuttle valve is connected to the first port of the first shuttle valve; Step (13) specifically includes another path of hydraulic oil flowing to the fourth shuttle valve, the first port and the third port of the fourth shuttle valve being connected, so that the hydraulic oil flows through the fourth shuttle valve to the first shuttle valve and flows through the first shuttle valve into the control end of the first cartridge valve, driving the first cartridge valve to close.

8. The method for realizing high and low speed control through multiple oil extraction points according to claim 3, characterized in that: A manual oil pump is provided between the second port of the first shuttle valve, the second port of the second shuttle valve and the oil tank.

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