A high-low speed control method through multiple oil taking points

Abstract

The application provides a high-low speed control method through multiple oil taking points, and the specific steps include: (1) low speed lifting of a winch; (11) oil tank discharges oil from a second oil outlet, hydraulic oil flowing into a motor flows out from a second port of the motor and flows back to the oil tank from a second return oil outlet through a B end of a second cartridge valve, so as to drive the motor to rotate; (2) high speed lifting of the winch; (21) the oil tank discharges oil from a first oil outlet, hydraulic oil flowing into the motor flows out from the second port of the motor and flows back to the oil tank from a first return oil outlet through a B end of a first cartridge valve, so as to drive the motor to rotate; (3) low speed descending of the winch; (31) the oil tank discharges oil from the second return oil outlet, hydraulic oil flowing into the motor flows out from a 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) high speed descending of the winch; (41) the oil tank discharges oil from the first return oil outlet, 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 present application relates to the technical field of winch control systems, and particularly relates to a high-low speed control method through multiple oil taking points. BACKGROUND

[0002] The offshore deck crane is one of the important equipment of the ship, which usually needs to be lifted, amplitude changed and rotated, and the core executive element of the lifting and rotating mechanism is generally completed by the hydraulic motor. In the use process, the deck crane often encounters different working conditions, such as the need to adjust the low-speed heavy load, high-speed light load and fine lifting, etc. In order to adapt to different working conditions, the speed of the hydraulic motor needs to be controlled.

[0003] For example, Chinese patent application No. 202310003646.4, published on April 14, 2023, discloses a hydraulic motor, which comprises 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 communicated with the plunger motor through the stop valve, the first working port and the second working port of the variable control valve are communicated with the working port of the plunger motor, the third working port and the fourth working port of the variable control valve are communicated with the working port of the servo valve, the fifth working port of the variable control valve is communicated with the oil outlet of the stop valve, the sixth working port of the variable control valve is communicated with the low-pressure oil port of the hydraulic oil source, the oil outlet of the stop valve is communicated with the fifth working port of the variable control valve, and the unloading control oil port of the stop valve is communicated with the low-pressure oil port of the hydraulic oil source. The design not only can realize the bidirectional variable control of the hydraulic motor through the proportional position of the variable control valve and the servo valve, but also can accurately adjust the plunger motor through changing the loading amplitude of the servo valve.

[0004] However, the hydraulic system of the document adjusts the speed of the motor by setting multiple control valves, which can accurately control the speed of the motor. For example, in order to control the winch to rise at low speed, rise at high speed, descend at low speed and descend at high speed, four separate hydraulic circuits need to be set up, which makes the control process of the whole oil circuit complex, so that the motor cannot be driven by a simple way. SUMMARY

[0005] The present application provides a high-low speed control method through multiple oil taking points, which can control the winch to adjust the lifting and descending speed according to the actual needs by selecting multiple oil taking points.

[0006] To achieve the above object, the technical scheme of the present application is: a high-low speed control method realized through multiple oil taking points, realized through a hydraulic control system, the hydraulic system comprising a first oil outlet, a second oil outlet, and a first oil return port and a second oil return port, the first oil return port and the second oil return port being connected with a first cartridge valve and a second cartridge valve respectively, the first oil outlet and the second oil outlet being connected with a motor, the first cartridge valve being used for high speed control, and the second cartridge valve being used for low speed control; the specific steps comprising:

[0007] (1) low speed lifting of the winch.

[0008] (11) controlling the oil tank to discharge oil from the second oil outlet, the oil path of the hydraulic oil being divided into two paths.

[0009] (12) one path of the hydraulic oil entering the motor through a first port of the motor.

[0010] (13) the other path of the hydraulic oil flowing to a control end of the first cartridge valve to drive the first cartridge valve to close.

[0011] (14) the hydraulic oil flowing into the motor flowing out from a second port of the motor and flowing back to the oil tank from the second oil return port through a B end of the second cartridge valve to drive the motor to rotate for low speed lifting.

[0012] (2) high speed lifting of the winch.

[0013] (21) controlling the oil tank to discharge oil from the first oil outlet, the oil path of the hydraulic oil being divided into two paths.

[0014] (22) one path of the hydraulic oil entering the motor through the first port of the motor.

[0015] (23) the other path of the hydraulic oil flowing to a control end of the second cartridge valve to drive the second cartridge valve to close.

[0016] (24) the hydraulic oil flowing into the motor flowing out from the second port of the motor and flowing back to the oil tank from the first oil return port through a B end of the first cartridge valve to drive the motor to rotate for high speed lifting.

[0017] (3) low speed lowering of the winch.

[0018] (31) controlling the oil tank to discharge oil from the second oil return port, the oil path of the hydraulic oil being divided into two paths.

[0019] (32) one path of the hydraulic oil entering the second cartridge valve through an A end of the second cartridge valve and flowing to the second port of the motor through a B end of the second cartridge valve.

[0020] (33) the other path of the hydraulic oil flowing to a control end of the first cartridge valve to drive the first cartridge valve to close.

[0021] (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 to drive the motor to rotate for low-speed lowering.

[0022] (4) High-speed lowering of the winch.

[0023] (41) The oil tank is controlled to discharge oil from the first oil return port, and the oil path of the hydraulic oil is divided into two paths.

[0024] (42) One path of the hydraulic oil 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.

[0025] (43) The other path of the hydraulic oil flows to the control end of the second cartridge valve to drive the second cartridge valve to close.

[0026] (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 to drive the motor to rotate for high-speed lowering.

[0027] The above method, by setting two cartridge valves with different flow capacities, different oil outlets or oil return ports can be selected when the winch is running at different speeds, and when ascending at low speed, the first cartridge valve is closed, and only the oil path from the second oil outlet through the motor and then into the second cartridge valve to flow back to the oil tank is needed, when high lifting is needed, the second cartridge valve is closed, and only the oil path from the first oil outlet through the motor and then into the first cartridge valve to flow back to the oil tank is needed, and when lowering at high and low speeds, one of the cartridge valves is also controlled to close, and then the corresponding oil return port of the other cartridge valve is started to input and then pass through the motor to return to the oil outlet, thereby controlling the two oil outlets and two oil return ports to achieve the control of four speed states, the control method is simple and reliable.

[0028] Further, a first shuttle valve is arranged 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.

[0029] The above arrangement controls the flow direction of the hydraulic oil through the first shuttle valve, thereby facilitating the control of the first cartridge valve.

[0030] Further, a second shuttle valve is arranged 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.

[0031] The above arrangement controls the flow direction of the hydraulic oil through the second shuttle valve, thereby facilitating the control of the second cartridge valve.

[0032] Further, a first balance valve is arranged between the first oil outlet and the motor, the first balance valve comprising a first overflow valve and a first check valve, an oil inlet end of the first overflow valve being connected to a first port of the motor, an oil outlet end of the first overflow valve being connected to the first oil outlet, an oil inlet end of the first check valve being connected to the first oil outlet, an oil outlet end of the first check valve being connected to the first port of the motor, and a control end of the first overflow valve being connected to the first oil return port.

[0033] Step (4) further comprises:

[0034] (41) The oil tank discharges oil from the first oil return port, and the oil circuit of the hydraulic oil is divided into three paths.

[0035] (45) The third path of the hydraulic oil flows to the control end of the first overflow valve.

[0036] (46) The first overflow valve is opened, the first oil inlet port is communicated with the first port of the motor, and the hydraulic oil flows back to the oil tank from the first oil outlet.

[0037] The above arrangement, by arranging the first balance valve, stabilizes the hydraulic oil pressure flowing from the first oil outlet to the motor.

[0038] Further, a second balance valve is arranged between the second oil outlet and the motor, the second balance valve comprising a second overflow valve and a second check valve, an oil inlet end of the second overflow valve being connected to the first port of the motor, an oil outlet end of the second overflow valve being connected to the second oil outlet, an oil inlet end of the second check valve being connected to the second oil outlet, an oil outlet end of the second check valve being connected to the first port of the motor, and a control end of the second overflow valve being connected to the second oil return port.

[0039] Step (3) further comprises:

[0040] (31) The oil tank discharges oil from the second oil return port, and the oil circuit of the hydraulic oil is divided into three paths.

[0041] (35) The third path of the hydraulic oil flows to the control end of the second overflow valve.

[0042] (36) The second overflow valve is opened, the second oil inlet port is communicated with the first port of the motor, and the hydraulic oil flows back to the oil tank from the second oil outlet.

[0043] The above arrangement, by arranging the second balance valve, stabilizes the hydraulic oil pressure flowing from the second oil outlet to the motor.

[0044] Further, a third shuttle valve is arranged between the first oil outlet and the second shuttle valve, a first port of the third shuttle valve being connected to the first oil outlet, a second port of the third shuttle valve being connected to the first oil return port, and a third port of the third shuttle valve being connected to a first port of the second shuttle valve.

[0045] The above setting drives the first port and the third port of the third shuttle valve to communicate by the flow of hydraulic oil to the third shuttle valve, so that the hydraulic oil flows to the second shuttle valve through the third shuttle valve and flows into the control end of the second cartridge valve through the second shuttle valve to drive the second cartridge valve to close.

[0046] Further, the fourth shuttle valve is further provided between the second oil outlet and the first shuttle valve, the first port of the fourth shuttle valve is connected with the second oil outlet, the second port of the fourth shuttle valve is connected with the first oil outlet, and the third port of the fourth shuttle valve is connected with the first port of the first shuttle valve.

[0047] The above setting drives the first port and the third port of the third shuttle valve to communicate by the flow of hydraulic oil to the third shuttle valve, so that the hydraulic oil flows to the second shuttle valve through the third shuttle valve and flows into the control end of the second cartridge valve through the second shuttle valve to drive the second cartridge valve to close.

[0048] Further, the manual oil pump is further provided between the second port of the first shuttle valve and the second port of the second shuttle valve and the oil tank.

[0049] The above setting drives the first port and the third port of the third shuttle valve to communicate by the flow of hydraulic oil to the third shuttle valve, so that the hydraulic oil flows to the second shuttle valve through the third shuttle valve and flows into the control end of the second cartridge valve through the second shuttle valve to drive the second cartridge valve to close. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a schematic diagram of the hydraulic system of the present application.

[0051] Figure 2 It is a working flow chart of the present application.

[0052] Figure 3 It is a hydraulic oil flow direction chart when the winch is in low-speed lifting in the present application.

[0053] Figure 4 It is a hydraulic oil flow direction chart when the winch is in high-speed lifting in the present application. DETAILED DESCRIPTION

[0054] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0055] As Figures 1-4As shown, a hydraulic control system includes a first cartridge valve 1 and a second cartridge valve 2, the A port of the first cartridge valve 1 is connected to the first return port 31 of an oil tank 3, the B port of the first cartridge valve 1 is connected to the second port 41 of a motor 4, the A port of the second cartridge valve 2 is connected to the second return port 32 of the oil tank 3, 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 port 33 and the second oil outlet port 34 of the oil tank 3, the first oil outlet port 33 is also connected to the control end 21 of the second cartridge valve 2, and the second oil outlet port 34 is also connected to the control end 11 of the first cartridge valve 1; the first oil outlet port 31 of the oil tank 3 is connected to the control end 21 of the second cartridge valve 2, and the second oil outlet port 34 is connected to the control end 11 of the first cartridge valve 1; the first return port 31 is also connected to the control end 21 of the second cartridge valve 2, and the second return port 32 is also connected to the control end 11 of the first cartridge valve 1; the hydraulic oil flow of the first cartridge valve 1 is higher than that of the second cartridge valve 2.

[0056] A first shuttle valve 12 is arranged between the control end 11 of the first cartridge valve 1 and the second return port 32, the first port 121 of the first shuttle valve 12 is connected to the second return port 32, the second port 122 of the first shuttle valve 12 is connected to the oil tank 3, and the 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 through the first shuttle valve 12, thereby facilitating the control of the first cartridge valve 1.

[0057] A second shuttle valve 22 is arranged between the control end 21 of the second cartridge valve 2 and the first return port 31, the first port 221 of the second shuttle valve 22 is connected to the first return port 31, the second port 222 of the second shuttle valve 22 is connected to the oil tank 3, and the 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 through the second shuttle valve 22, thereby facilitating the control of the second cartridge valve 2.

[0058] A first balance valve 35 is arranged between the first oil outlet port 33 and the motor 4, the first balance valve 35 includes a first overflow valve 351 and a first one-way 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 port 33, the oil inlet end of the first one-way valve 352 is connected to the first oil outlet port 33, and the oil outlet end of the first one-way 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 return port 31. By arranging the first balance valve 35, the hydraulic oil pressure flowing from the first oil outlet port 33 to the motor 4 is stabilized.

[0059] A second balance valve 36 is provided between the second oil outlet 34 and the motor 4. The second balance valve 36 includes a second relief valve 361 and a second check valve 362. The oil inlet end of the second relief valve 361 is connected to the first port 42 of the motor 4, and the oil outlet end of the second relief valve 361 is connected to the second oil outlet 34. The oil inlet end of the second check valve 362 is connected to the second oil outlet 34, and the oil outlet end of the second check valve 362 is connected to the first port 42 of the motor 4. The control end 3611 of the second relief valve 361 is connected to the second return port 32. By setting the second balance valve 36, the hydraulic oil pressure flowing from the second oil outlet 34 to the motor 4 is stabilized.

[0060] A third shuttle valve 23 is provided between the first oil outlet 33 and the second shuttle valve 22. The first port 231 of the third shuttle valve 23 is connected to the first oil outlet 33, the second port 232 of the third shuttle valve 23 is connected to the first oil return port 31, and the third port 233 of the third shuttle valve 23 is connected to the first port 221 of the second shuttle valve 22. 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 connect, so that the hydraulic oil flows through the third shuttle valve 23 to the second shuttle valve 22 and then through the second shuttle valve 22 into the control terminal 21 of the second cartridge valve 2, driving the second cartridge valve 2 to close.

[0061] A fourth shuttle valve 24 is also provided between the second oil outlet 34 and the first shuttle valve 12. 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, which drives the first port 241 and the third port 243 of the fourth shuttle valve 24 to connect, so that the hydraulic oil flows through the fourth shuttle valve 24 to the first shuttle valve 12 and then through the first shuttle valve 12 into the control terminal 11 of the first cartridge valve 1, driving the first cartridge valve 1 to close.

[0062] A manual oil pump 39 is provided between the second port 122 of the first shuttle valve 12 and the second port 222 of the second shuttle valve 22 and the oil tank 3. The manual oil pump 39 allows hydraulic oil to be drawn into the control terminals of the first cartridge valve 1 and the second cartridge valve 2 when maintenance or repair of the oil circuit is required, thereby driving the first cartridge valve 1 and the second cartridge valve 2 to close.

[0063] like Figure 2 As shown, a method for achieving high and low speed control through multiple oil sampling points includes the following steps:

[0064] (1) The winch lifts at low speed. For example... Figure 3 As shown, the method of deleting hydraulic lines that do not have oil flow and keeping those that do has oil flow is used to explain the situation when the winch is hoisting at low speed.

[0065] (11) The oil tank 3 discharges oil from the second oil outlet 34, and the oil circuit of the hydraulic oil is divided into two paths.

[0066] (12) One path of the hydraulic oil enters the motor 4 through the first port 42 of the motor 4.

[0067] (13) The other path of the hydraulic oil flows to the control end 11 of the first cartridge valve 1 to drive the first cartridge valve 1 to close.

[0068] (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 for low-speed hoisting.

[0069] (2) High-speed hoisting of the winch. Figure 4 As shown in the figure, the case of high-speed hoisting of the winch is described in the way that the hydraulic circuit through which no oil flows is deleted and the hydraulic circuit through which oil flows is retained.

[0070] (21) The oil tank 3 discharges oil from the first oil outlet 33, and the oil circuit of the hydraulic oil is divided into two paths.

[0071] (22) One path of the hydraulic oil enters the motor 4 through the first port 42 of the motor 4.

[0072] (23) The other path of the hydraulic oil flows to the control end 21 of the second cartridge valve 2 to drive the second cartridge valve 2 to close.

[0073] (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 for high-speed hoisting.

[0074] (3) Low-speed descending of the winch.

[0075] (31) The oil tank 3 discharges oil from the second oil return port 32, and the oil circuit of the hydraulic oil is divided into three paths.

[0076] (32) One path of the 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.

[0077] (33) The other path of the hydraulic oil flows to the control end 11 of the first cartridge valve 1 to drive the first cartridge valve 1 to close.

[0078] (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 for low-speed descending.

[0079] (35) The third path of the hydraulic oil flows to the control end 3611 of the second overflow valve 361.

[0080] (36) The second overflow valve 361 is opened, and the second oil inlet 34 is communicated with the first port 42 of the motor 4, and the hydraulic oil flows back to the oil tank from the second oil outlet 34.

[0081] (4) The winch is lowered at high speed.

[0082] (41) The oil tank 3 discharges oil from the first oil return port 31, and the hydraulic oil is divided into three paths.

[0083] (42) One path of the 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.

[0084] (43) Another path of the hydraulic oil flows to the control end 21 of the second cartridge valve 2, and drives the second cartridge valve 2 to close.

[0085] (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 lower at high speed.

[0086] (45) The third path of the hydraulic oil flows to the control end 3511 of the first overflow valve 351.

[0087] (46) The first overflow valve 351 is opened, and the first oil inlet 33 is communicated with the first port 42 of the motor 4, and the hydraulic oil flows back to the oil tank from the first oil outlet 33.

[0088] The working principle of the present application is that by setting two cartridge valves with different flow capacities, different oil outlets or oil return ports can be selected when the winch is running at different speeds, and when ascending at low speed, the first cartridge valve is closed, and only the oil path from the second oil outlet passes through the motor and then enters the second cartridge valve to flow back to the oil tank. When high-rise lifting is required, the second cartridge valve is closed, and only the oil path from the first oil outlet passes through the motor and then enters the first cartridge valve to flow back to the oil tank. Similarly, when descending at high and low speeds, one of the cartridge valves is closed, and then the oil return port of the other corresponding cartridge valve is started to input and then pass through the motor to return to the oil outlet, thereby controlling the two oil outlets and two oil return ports to realize the control of four speed states. The control method is simple and reliable.

Claims

1. A method for high-low speed control by multiple oil taking points, realized by a hydraulic control system, characterized in that: The hydraulic system comprises a first oil outlet, a second oil outlet, and a first oil return and a second oil return, the first oil return and the second oil return are connected with the first cartridge valve and the second cartridge valve respectively, the first oil outlet and the second oil outlet are connected with the 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 comprise: (1) low-speed lifting of the winch; (11) the oil tank is controlled to discharge oil from the second oil outlet, and the oil circuit of the hydraulic oil is divided into two paths; (12) one path of the hydraulic oil enters the motor through the first port of the motor; (13) the other path of the hydraulic oil flows to the control end of the first cartridge valve to drive 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 through the B end of the second cartridge valve, so that the motor is driven to rotate to perform low-speed lifting; (2) high-speed lifting of the winch; (21) the oil tank is controlled to discharge oil from the first oil outlet, and the oil circuit of the hydraulic oil is divided into two paths; (22) one path of the hydraulic oil enters the motor through the first port of the motor; (23) the other path of the hydraulic oil flows to the control end of the second cartridge valve to drive 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 through the B end of the first cartridge valve, so that the motor is driven to rotate to perform high-speed lifting; (3) low-speed lowering of the winch; (31) the oil tank is controlled to discharge oil from the second oil return, and the oil circuit of the hydraulic oil is divided into two paths; (32) one path of the hydraulic oil 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) the other path of the hydraulic oil flows to the control end of the first cartridge valve to drive 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, so that the motor is driven to rotate to perform low-speed lowering; (4) high-speed lowering of the winch; (41) the oil tank is controlled to discharge oil from the first oil return, and the oil circuit of the hydraulic oil is divided into two paths; (42) one path of the hydraulic oil 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) the other path of the hydraulic oil flows to the control end of the second cartridge valve to drive 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, so that the motor is driven to rotate to perform high-speed lowering; The hydraulic control system comprises a first cartridge valve and a second cartridge valve, an A port of the first cartridge valve is connected with a first return oil port of an oil tank, a B port of the first cartridge valve is connected with a second port of a motor, an A port of the second cartridge valve is connected with a second return oil port of the oil tank, and a B port of the second cartridge valve is connected with the second port of the motor; a first oil outlet port of the oil tank is connected with a first port of the motor, the first oil outlet port is further connected with a control port of the second cartridge valve, and a second oil outlet port of the oil tank is further connected with the control port of the first cartridge valve; the first oil outlet port of the oil tank is connected with the control port of the second cartridge valve, and the second oil outlet port of the oil tank is connected with the control port of the first cartridge valve; the first return oil port is further connected with the control port of the second cartridge valve, and the second return oil port is further connected with the control port of the first cartridge valve; a hydraulic oil flow of the first cartridge valve is higher than a hydraulic oil flow of the second cartridge valve.

2. The method for high and low speed control through multiple oil taking points according to claim 1, characterized in that: A first shuttle valve is arranged between the control port of the first cartridge valve and the second return oil port, a first port of the first shuttle valve is connected with the second return oil port, a second port of the first shuttle valve is connected with the oil tank, and a third port of the first shuttle valve is connected with the control port of the first cartridge valve.

3. The method of claim 2, wherein the method is characterized by: A second shuttle valve is arranged between the control port of the second cartridge valve and the first return oil port, a first port of the second shuttle valve is connected with the first return oil port, a second port of the second shuttle valve is connected with the oil tank, and a third port of the second shuttle valve is connected with the control port of the second cartridge valve.

4. The method of claim 1, wherein the method is characterized by: A first balance valve is arranged between the first oil outlet port and the motor, the first balance valve comprises a first overflow valve and a first one-way valve, an oil inlet end of the first overflow valve is connected with the first port of the motor, an oil outlet end of the first overflow valve is connected with the first oil outlet port, an oil inlet end of the first one-way valve is connected with the first oil outlet port, and an oil outlet end of the first one-way valve is connected with the first port of the motor; a control end of the first overflow valve is connected with the first return oil port; Step (4) further comprises: (41) the oil tank discharges oil from the first return oil port, and the oil path of the hydraulic oil is divided into three paths; (45) the third path of the hydraulic oil flows to the control end of the first overflow valve; (46) the first overflow valve is opened, the first oil inlet port is communicated with the first port of the motor, and the hydraulic oil flows back to the oil tank from the first oil outlet port.

5. The method of claim 1, wherein the method is characterized by: A second balance valve is arranged between the second oil outlet port and the motor, the second balance valve comprises a second overflow valve and a second one-way valve, an oil inlet end of the second overflow valve is connected with the first port of the motor, an oil outlet end of the second overflow valve is connected with the second oil outlet port, an oil inlet end of the second one-way valve is connected with the second oil outlet port, and an oil outlet end of the second one-way valve is connected with the first port of the motor; a control end of the second overflow valve is connected with the second return oil port; Step (3) further comprises: (31) the oil tank discharges oil from the second return oil port, and the oil path of the hydraulic oil is divided into three paths; (35) the third path of the hydraulic oil flows to the control end of the second overflow valve; (36) the second overflow valve is opened, the second oil inlet port is communicated with the first port of the motor, and the hydraulic oil flows back to the oil tank from the second oil outlet port.

6. The method of claim 3, wherein the method is characterized by: A third shuttle valve is further arranged between the first oil outlet port and the second shuttle valve, a first port of the third shuttle valve is connected with the first oil outlet port, a second port of the third shuttle valve is connected with the first return oil port, and a third port of the third shuttle valve is connected with a first port of the second shuttle valve; The step (23) specifically comprises another hydraulic oil flow to the third spool valve, the first port and the third port of the third spool valve are communicated, so that the hydraulic oil flows to the second spool valve through the third spool valve and flows into the control end of the second cartridge valve through the second spool valve to drive the second cartridge valve to close.

7. The method of claim 2, wherein the method is characterized by: A fourth spool valve is further arranged between the second oil outlet and the first spool valve, the first port of the fourth spool valve is connected with the second oil outlet, the second port of the fourth spool valve is connected with the first oil outlet, and the third port of the fourth spool valve is connected with the first port of the first spool valve; The step (13) specifically comprises another hydraulic oil flow to the fourth spool valve, the first port and the third port of the fourth spool valve are communicated, so that the hydraulic oil flows to the first spool valve through the fourth spool valve and flows into the control end of the first cartridge valve through the first spool valve to drive the first cartridge valve to close.

8. The method of claim 3, wherein the method is characterized by: A manual oil pump is arranged between the second port of the first spool valve and the second port of the second spool valve and the oil tank.

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