An electrically controlled multi-gear speed matching operation wind power tower jacking hydraulic system and control method

Abstract

The present application relates to the technical field of wind power tower jacking hydraulic system, and particularly relates to an electric control multi-gear speed matching operation wind power tower jacking hydraulic system and a control method. In the heavy load jacking process, the feedback adjustment of the electromagnetic valve control current of the first working link and the second working link according to the piston rod displacement values of the left jacking oil cylinder and the right jacking oil cylinder can realize the synchronous extension of the left jacking oil cylinder and the right jacking oil cylinder, and the control current of the electromagnetic valve of the first working link and the second working link can control the heavy load jacking speed gear; in the heavy load descending process, the feedback control of the control current of the left electric control proportional balance valve and the right electric control proportional balance valve according to the rodless cavity pressure values of the left jacking oil cylinder and the right jacking oil cylinder can realize the synchronous retraction of the left jacking oil cylinder and the right jacking oil cylinder; the control current of the left electric control proportional balance valve and the right electric control proportional balance valve can control the heavy load descending speed gear, so that the jacking operation is safely and stably carried out.

Description

Technical Field

[0001] This invention relates to the field of hydraulic systems for lifting wind turbine towers, specifically to an electrically controlled multi-speed wind turbine tower lifting hydraulic system and control method. Background Technology

[0002] In the field of wind power installation, tower cranes are favored by users due to their high lifting height, convenient transportation, and efficient relocation. Wind power installation tower cranes are frequently used and relocated, requiring the jacking hydraulic system to operate at varying speeds and offering multiple speed levels to meet practical needs. Currently, there is a lack of a jacking hydraulic system that can safely perform lifting operations and stably control the speed levels. Summary of the Invention

[0003] The purpose of this invention is to provide an electrically controlled multi-speed wind turbine tower crane lifting hydraulic system and control method. During heavy-load lifting, the control current of the solenoid valves in the first and second working links is adjusted based on the piston rod displacement values ​​of the left and right lifting cylinders to achieve synchronous extension of the left and right lifting cylinders, ensuring safe lifting operations. During synchronous extension, the control current of the solenoid valves in the first and second working links can be controlled to maintain stable lifting speed. During heavy-load descent, the control current of the left and right electrically controlled proportional balance valves is adjusted based on the rodless chamber pressure values ​​of the left and right lifting cylinders to achieve synchronous retraction of the left and right lifting cylinders, ensuring safe descent operations. During synchronous retraction, the control current of the left and right electrically controlled proportional balance valves can be controlled to maintain stable descent speed.

[0004] In a first aspect, the present invention provides an electrically controlled multi-speed wind turbine tower lifting hydraulic system, comprising: Main motor pump set, including the main pump; The lifting cylinders include a left lifting cylinder and a right lifting cylinder; The load-sensitive proportional valve includes a first working link located between the main pump and the left lifting cylinder and a second working link located between the main pump and the right lifting cylinder; the first working link and the second working link are connected in parallel, and the extension and retraction states of the left lifting cylinder and the right lifting cylinder can be controlled respectively by controlling the energized state of the solenoid valves of the first working link and the second working link. The electronically controlled proportional balance valve includes a left electronically controlled proportional balance valve located between the first working link and the rodless chamber of the left lifting cylinder, and a right electronically controlled proportional balance valve located between the second working link and the rodless chamber of the right lifting cylinder. Sensor assembly for detecting piston rod displacement and rodless chamber pressure values ​​of the left and right lifting cylinders; During heavy-load lifting, the control current of the solenoid valves of the first and second working links is adjusted by feedback based on the piston rod displacement values ​​of the left and right lifting cylinders. This enables the synchronous extension of the left and right lifting cylinders, and the heavy-load lifting speed level can be controlled by controlling the magnitude of the control current of the solenoid valves of the first and second working links during the synchronous extension process. During the heavy-load descent process, the control current of the left and right electro-hydraulic proportional balance valves is fed back based on the pressure values ​​of the rodless chambers of the left and right lifting cylinders. This enables the synchronous retraction of the left and right lifting cylinders, and the heavy-load descent speed level can be controlled by controlling the magnitude of the control current of the left and right electro-hydraulic proportional balance valves during the synchronous retraction process.

[0005] Optionally, the P port of the load-sensitive proportional valve is connected to the oil outlet of the main pump; the A1 port of the first working connection is connected to the rodless chamber of the left lifting cylinder via the left electronically controlled proportional balance valve; the B1 port of the first working connection is connected to the rod chamber of the left lifting cylinder; the A2 port of the second working connection is connected to the rodless chamber of the right lifting cylinder via the right electronically controlled proportional balance valve; and the B2 port of the second working connection is connected to the rod chamber of the right lifting cylinder. When the first left solenoid valve of the first working link is energized, the main pump supplies oil to the rodless chamber of the left lifting cylinder, and the left lifting cylinder extends to perform lifting operations; when the second left solenoid valve of the first working link is energized, the main pump supplies oil to the rod chamber of the left lifting cylinder, and the left lifting cylinder retracts to perform lowering operations; by controlling the control current of the first and second left solenoid valves, the opening degree of the load-sensitive proportional valve can be controlled to control the amount of oil supplied by the main pump to the left lifting cylinder. When the first right solenoid valve of the second working link is energized, the main pump supplies oil to the rodless chamber of the right lifting cylinder, and the right lifting cylinder extends to perform lifting operations; when the second right solenoid valve of the second working link is energized, the main pump supplies oil to the rod chamber of the right lifting cylinder, and the right lifting cylinder retracts to perform lowering operations; by controlling the control current of the first and second right solenoid valves, the opening degree of the load-sensitive proportional valve can be controlled to control the amount of oil supplied by the main pump to the right lifting cylinder.

[0006] Optionally, the sensor assembly is also used to detect the rod chamber pressure values ​​of the left and right lifting cylinders; During the heavy-load descent process, the second left solenoid valve of the first working link is energized, and the second right solenoid valve of the second working link is energized. The control current of the second left solenoid valve and the second right solenoid valve is adjusted according to the rod chamber pressure values ​​of the left and right lifting cylinders, so that the main pump can replenish oil to the rod chamber of the left or right lifting cylinder to maintain the pressure of the left and right lifting cylinders at the preset value.

[0007] Optionally, the main motor pump set further includes a pilot pump, and also includes: The pilot control valve assembly has its P port connected to the oil outlet of the pilot pump, and its X1 and X2 ports connected to the control terminals of the left and right electrically controlled proportional balance valves, respectively. When the pilot pump outputs pilot oil through the X1 port of the pilot control valve group and acts on the control end of the left electronically controlled proportional balance valve, the left electronically controlled proportional balance valve is turned on. When the pilot pump outputs pilot oil through the X2 port of the pilot control valve group and acts on the control end of the right electronically controlled proportional balance valve, the right electronically controlled proportional balance valve is turned on.

[0008] Optionally, the pilot control valve group includes a first pilot directional valve, a second pilot directional valve, and a third pilot directional valve; The first pilot directional valve has its inlet port connected to the P port of the pilot control valve group and its return port connected to the oil tank. Its first working port is connected to the inlet port of the second pilot directional valve, and its second working port is connected in parallel to ports A1 and A2 of the pilot control valve group. When the first pilot directional valve is in the left position, its inlet port is connected to the first working port, and its return port is connected to the second working port. When the first pilot directional valve is in the right position, its inlet port is connected to the second working port, and its return port is connected to the first working port. The first working port of the first pilot directional valve is also connected in parallel to a pilot relief valve and an accumulator. The second pilot directional valve has an inlet port connected to the first working port of the first pilot directional valve, a return port connected to the oil tank, and an outlet port connected to the inlet port of the third pilot directional valve. When the second pilot directional valve is in the left position, the inlet port is connected to the return port, and when the second pilot directional valve is in the right position, the inlet port is connected to the outlet port. The third pilot directional valve has an inlet port connected to the outlet port of the second pilot directional valve, an outlet port connected to the oil tank, and an outlet port connected in parallel to ports X1 and X2 of the pilot control valve group. When the third pilot directional valve is in the left position, the outlet port and the outlet port are connected. When the third pilot directional valve is in the right position, the inlet port and the outlet port are connected. When the pilot pump can output pilot oil through ports X1 and X2 of the pilot control valve group to act on the control terminals of the left and right solenoid proportional balance valves, the left and right solenoid proportional balance valves are connected.

[0009] Optionally, it also includes: The auxiliary cylinder includes a left auxiliary cylinder and a right auxiliary cylinder, and the A1 port and A2 port of the pilot control valve group are respectively connected to the P port of the left auxiliary cylinder and the right auxiliary cylinder; An auxiliary cylinder control valve assembly is provided, wherein both the left and right auxiliary cylinders are connected to the auxiliary cylinder control valve assembly. The auxiliary cylinder control valve assembly includes a manually operated directional valve and a throttle shut-off valve. By switching the valve position of the manually operated directional valve, the extension or retraction state of the left or right auxiliary cylinder can be controlled. The throttle shut-off valve is located between the rodless chamber and the rod chamber of the left or right auxiliary cylinder, as well as between the rod chamber and the oil tank. When the throttle shut-off valve is open, the rodless chamber, the rod chamber, and the oil tank are all connected.

[0010] Optionally, it also includes: Emergency motor pump set, The emergency control valve has its P port connected to the oil outlet of the emergency motor pump unit and its X port connected to the X port of the pilot control valve unit; the X port of the pilot control valve unit can be connected to the X1 port and X2 port of the pilot control valve unit. An emergency branch switching valve is located between the load-sensitive proportional valve and the lifting cylinder; The A1 and B1 output ports of the emergency branch switching valve are respectively connected to the rodless chamber and the rod chamber of the left lifting cylinder, and the A2 and B2 output ports are respectively connected to the rodless chamber and the rod chamber of the right lifting cylinder. The A1 and B1 input ports of the emergency branch switching valve are respectively connected to the A1 and B1 ports of the first working link; the emergency A1 and emergency B1 ports of the emergency branch switching valve are respectively connected to the A1 and B1 ports of the emergency control valve; the A2 and B2 input ports of the emergency branch switching valve are respectively connected to the A2 and B2 ports of the second working link; the emergency A2 and emergency B2 ports of the emergency branch switching valve are respectively connected to the A2 and B2 ports of the emergency control valve. When the first working link malfunctions, the emergency A1 port of the emergency branch switching valve is connected to the A1 output port, and the emergency B1 port is connected to the B1 output port. The emergency motor pump group supplies oil to the left lifting cylinder through the emergency control valve and the emergency branch switching valve. When the second working link malfunctions, the emergency A2 port of the emergency branch switching valve is connected to the A2 output port, and the emergency B2 port is connected to the B2 output port. The emergency motor pump unit supplies oil to the right lifting cylinder through the emergency control valve and the emergency branch switching valve.

[0011] Optionally, the emergency control valve includes a first emergency reversing valve, a second emergency reversing valve, and a third emergency reversing valve; The first emergency directional valve has its inlet port connected to the P port of the emergency control valve, and its return port connected to the oil tank. Its first working port is connected to the X port of the emergency control valve via a solenoid directional valve, which is energized and conducts. Its second working port is connected in parallel to the inlets of the second and third emergency directional valves. When the first emergency directional valve is in the neutral position, its inlet port is connected to the return port. When the first emergency directional valve is in the left position, its inlet port is connected to the second working port, and its first working port is connected to the return port. When the first emergency directional valve is in the right position, its inlet port is connected to the first working port, and its second working port is connected to the return port. The second emergency directional valve has its inlet port connected to the second working port of the first emergency directional valve, and its return port connected to the oil tank. The first and second working ports are respectively connected to ports A1 and B1 of the emergency control valve. When the second emergency directional valve is in the left position, its inlet port is connected to port A1 of the emergency control valve, and its return port is connected to port B1 of the emergency control valve. When the second emergency directional valve is in the right position, its inlet port is closed, and its return port is connected to both ports A1 and B1 of the emergency control valve. The third emergency directional valve has its inlet port connected to the second working port of the first emergency directional valve, and its return port connected to the oil tank. The first and second working ports are respectively connected to ports A2 and B2 of the emergency control valve. When the second emergency directional valve is in the left position, its inlet port is connected to port A2 of the emergency control valve, and its return port is connected to port B2 of the emergency control valve. When the second emergency directional valve is in the right position, its inlet port is closed, and its return port is connected to both ports A2 and B2 of the emergency control valve.

[0012] Optionally, the rodless chambers of both the left and right lifting cylinders are connected to rodless chamber safety valves; the rod chambers of both the left and right lifting cylinders are sequentially connected to rod chamber safety valves and rod chamber back pressure valves (check valves).

[0013] Secondly, the present invention provides a control method for an electrically controlled multi-speed wind turbine tower crane jacking hydraulic system, which is based on the aforementioned electrically controlled multi-speed wind turbine tower crane jacking hydraulic system, and the control method includes: When heavy-load lifting is required, the main pump supplies oil to the rodless chambers of the left and right lifting cylinders through the first and second working connections, respectively. The left and right lifting cylinders extend to perform lifting. During the lifting process, the control current of the solenoid valves of the first and second working connections is adjusted based on the piston rod displacement values ​​of the left and right lifting cylinders to achieve synchronous extension of the left and right lifting cylinders. Furthermore, during the synchronous extension process, the heavy-load lifting speed can be controlled by adjusting the control current of the solenoid valves of the first and second working connections. When heavy-load descent is required, under the action of gravity, the hydraulic oil in the rodless chambers of the left and right lifting cylinders returns to the oil tank. During the descent, the control current of the left and right electro-hydraulic proportional balance valves is fed back based on the pressure values ​​in the rodless chambers of the left and right lifting cylinders to achieve synchronous retraction of the left and right lifting cylinders. During the synchronous retraction, the control current of the left and right electro-hydraulic proportional balance valves can be controlled to adjust the heavy-load descent speed.

[0014] Compared with the prior art, the present invention has the following beneficial effects: During heavy-load lifting, this invention uses the piston rod displacement values ​​of the left and right lifting cylinders to feedback adjust the control current of the solenoid valves in the first and second working links, enabling synchronous extension of the left and right lifting cylinders to ensure safe lifting operations. During synchronous extension, controlling the control current of the solenoid valves in the first and second working links controls the heavy-load lifting speed level for stable control. During heavy-load lowering, the pressure values ​​in the rodless chambers of the left and right lifting cylinders feedback control the control current of the left and right electrically controlled proportional balance valves, enabling synchronous retraction of the left and right lifting cylinders to ensure safe lowering operations. During synchronous retraction, controlling the control current of the left and right electrically controlled proportional balance valves controls the heavy-load lowering speed level for stable control. Attached Figure Description

[0015] Figure 1 This is a hydraulic schematic diagram of the hydraulic system for lifting wind turbine towers using electronic control and multi-speed operation, as described in an embodiment of the present invention.

[0016] The following are the labeling elements in the diagram: 1. Main motor pump unit; 2. Load-sensitive proportional valve; 3. Emergency branch switching valve; 4. Left lifting cylinder; 5. Right lifting cylinder; 6. Pilot control valve assembly; 7. Left auxiliary cylinder; 8. Right auxiliary cylinder; 9. Emergency motor pump unit; 10. Emergency control valve; 11. Independent circulating filter and heat dissipation unit; 12. Hydraulic accessory unit; 101. Rodless chamber safety valve; 102. Rod chamber safety valve; 103. Rod chamber back pressure valve check valve; 201. First pilot relief valve; 202. Pilot safety valve; 301. Manual directional valve; 302. Hydraulic lock; 303. First throttle shut-off valve; 304. Second throttle shut-off valve; 401. Second pilot relief valve. Detailed Implementation

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] The following explains the relevant terminology: Tower cranes, or simply tower cranes, are primarily used for hoisting wind power projects and building construction. Multi-speed control refers to the hydraulic system's design with multiple speed settings to control the actuators, improving operational efficiency and meeting the needs of users under different working conditions. Tower crane lifting and lowering (lowering) refer to the tower crane's use of a hydraulic lifting system to control the extension or retraction of lifting cylinders, thereby raising or lowering the crane itself and ultimately adding or removing standard tower sections. The tower crane lifting hydraulic system is the power source for raising and lowering the tower crane.

[0020] To make the purpose, technical solution, and advantages of this invention patent clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] Depend on Figure 1As shown in the hydraulic system schematic, a high-efficiency, electrically controlled, multi-speed, multi-stage wind turbine tower crane jacking hydraulic system comprises a main motor pump unit 1 (main pump and pilot pump), two jacking cylinders (left and right jacking cylinders), two auxiliary cylinders (left and right auxiliary cylinders), and an electrical control system, forming a dual-cylinder jacking system. The hydraulic system integrates a main jacking unit, auxiliary cylinder unit, emergency jacking unit, independent circulation filtration and heat dissipation unit 11, hydraulic accessory unit 12 (air filter, level gauge, oil temperature sensor), and the electrical control system.

[0022] The basic circuit of the main lifting unit of this hydraulic system consists of a main motor pump unit 1, a load-sensitive proportional valve 2, an emergency branch switching valve 3, and a left lifting cylinder 4 / right lifting cylinder 5. The load-sensitive proportional valve 2 adopts a two-way valve and an electro-proportional control method, serving as the main lifting unit directional valve for both the left lifting cylinder 4 and the right lifting cylinder 5, thereby realizing the control of the lifting cylinder's extension and retraction directional action and extension and retraction speed.

[0023] The emergency switching valve 3 integrates solenoid directional valves -Y11 to -Y14 (-Y11a / -Y12a / -Y13a / -Y14a are normally open, -Y11b / -Y12b / -Y13b / -Y14b are normally closed) to achieve switching control between the main lifting circuit and the emergency lifting circuit. The lifting cylinder integrates a lifting cylinder control valve group consisting of an electronically controlled proportional balance valve -Y15, a rodless chamber safety valve 101, a rod chamber safety valve 102, a rod chamber back pressure check valve 103, a rodless chamber pressure sensor -P03, and a rod chamber pressure sensor -P04, as well as a displacement sensor -S01. The electrical components in the left and right lifting cylinder hydraulic circuits are distinguished by the numbers a and b, respectively. The rodless chambers of the left lifting cylinder 4 and the right lifting cylinder 5 are both connected to rodless chamber safety valves 101; the rod chambers of the left lifting cylinder 4 and the right lifting cylinder 5 are each connected in sequence to rod chamber safety valves 102 and rod chamber back pressure valves 103.

[0024] The basic circuit oil circuit connection relationship of the main lifting unit is as follows: The main pump outlet of the two-stage pump of the main motor pump group 1 (main pump + pilot pump) is connected to the oil inlet P port of the load-sensitive proportional valve 2. The A1 port of the first working link of the load-sensitive proportional valve 2 is connected to the oil inlet A1 port of the -Y11a solenoid directional valve on the emergency branch switching valve 3. The oil outlet A1 port of the -Y11a solenoid directional valve is connected to the A port of the -Y15a electronically controlled proportional balance valve on the left lifting cylinder 4. The B port of the left lifting cylinder 4 is connected to the oil outlet B1 port of the -Y13a solenoid directional valve on the emergency branch switching valve 3. The oil inlet B1 port of the -Y13a solenoid directional valve is connected to the B1 port of the first working link of the load-sensitive proportional valve 2. The A2 port of the second working link of the load-sensitive proportional valve 2 is connected to the A2 port of the -Y12a solenoid directional valve on the emergency branch switching valve 3. The A2 port of the -Y12a solenoid directional valve is connected to the A port of the -Y15b electronically controlled proportional balance valve on the right lifting cylinder. The B port of the right lifting cylinder 5 is connected to the B2 port of the -Y14a solenoid directional valve on the emergency branch switching valve 3. The B2 port of the -Y14a solenoid directional valve is connected to the B2 port of the second working link of the load-sensitive proportional valve 2.

[0025] The P port of the load-sensitive proportional valve 2 is connected to the oil outlet of the main pump. The A1 port of the first working link is connected to the rodless chamber of the left lifting cylinder 4 through the left electronically controlled proportional balance valve, and the B1 port of the first working link is connected to the rod chamber of the left lifting cylinder 4. The A2 port of the second working link is connected to the rodless chamber of the right lifting cylinder 5 through the right electronically controlled proportional balance valve, and the B2 port of the second working link is connected to the rod chamber of the right lifting cylinder 5. When the first left solenoid valve (-Y9a) of the first working link is energized, the main pump supplies oil to the rodless chamber of the left lifting cylinder 4, and the left lifting cylinder 4 extends; when the second left solenoid valve (-Y9b) of the first working link is energized, the main pump supplies oil to the rod chamber of the left lifting cylinder 4, and the left lifting cylinder 4 retracts to perform lifting operations; by controlling the control current of the first left solenoid valve (-Y9a) and the second left solenoid valve (-Y9b), the opening degree of the load-sensitive proportional valve 2 can be controlled to control the amount of oil supplied by the main pump to the left lifting cylinder 4; When the first right solenoid valve (-Y10a) of the second working link is energized, the main pump supplies oil to the rodless chamber of the right lifting cylinder 5, and the right lifting cylinder 5 extends; when the second right solenoid valve (-Y10b) of the second working link is energized, the main pump supplies oil to the rod chamber of the right lifting cylinder 5, and the right lifting cylinder 5 retracts to perform a lowering operation; by controlling the control current of the first right solenoid valve (-Y10a) and the second right solenoid valve (-Y10b), the opening degree of the load-sensitive proportional valve 2 can be controlled to control the amount of oil supplied by the main pump to the right lifting cylinder 5.

[0026] The pilot pump outlet of the two-unit pump assembly 1 (main pump + pilot pump) is connected to the P port of the pilot control valve assembly 6. The X1 and X2 ports of the pilot control valve assembly 6 are respectively connected to the X ports of the left solenoid proportional balance valve (Y15a) on the left lifting cylinder 4 and the right solenoid proportional balance valve (Y15b) on the right lifting cylinder 5. The T1, T2, and T3 ports of the pilot control valve assembly 6 are connected back to the oil tank. The pilot control valve assembly 6 includes a first pilot directional valve, a second pilot directional valve, and a third pilot directional valve.

[0027] The first pilot directional valve has its inlet port connected to the P port of the pilot control valve group 6, and its return port connected to the oil tank. Its first working port is connected to the inlet port of the second pilot directional valve, and its second working port is connected in parallel to ports A1 and A2 of the pilot control valve group 6. When the first pilot directional valve is in the left position, its inlet port is connected to the first working port, and its return port is connected to the second working port. When the first pilot directional valve is in the right position, its inlet port is connected to the second working port, and its return port is connected to the first working port. The first working port of the first pilot directional valve is also connected in parallel to a first pilot relief valve 201 and an accumulator. The second pilot directional valve has an inlet port connected to the first working port of the first pilot directional valve, a return port connected to the oil tank, and an outlet port connected to the inlet port of the third pilot directional valve. When the second pilot directional valve is in the left position, the inlet port is connected to the return port, and when the second pilot directional valve is in the right position, the inlet port is connected to the outlet port. The third pilot directional valve has its inlet port connected to the outlet port of the second pilot directional valve, its return port connected to the oil tank, and its outlet port connected in parallel to the X1 and X2 ports of the pilot control valve group 6. When the third pilot directional valve is in the left position, the outlet port and the return port are connected. When the third pilot directional valve is in the right position, the inlet port and the outlet port are connected. When the pilot pump can output pilot oil through the X1 and X2 ports of the pilot control valve group 6 to act on the control terminals of the left and right solenoid proportional balance valves, the left and right solenoid proportional balance valves are connected.

[0028] The load feedback LS port of the load-sensitive proportional valve 2 is connected to the main pump LS port, the main return oil R port and the drain oil T port are connected back to the oil tank, and the M port is connected to the pressure sensor-P01.

[0029] The drain port L of the left lifting cylinder 4 / right lifting cylinder 5, the return port LT of the rodless chamber safety valve 101 and the rod chamber safety valve 102 are respectively connected back to the oil tank.

[0030] The basic circuit of the auxiliary cylinder unit in this hydraulic system consists of a pilot pump, a pilot control valve group 6, and an auxiliary cylinder. The oil circuit connections of the basic circuit of the auxiliary cylinder unit are as follows: ports A1 and A2 of the pilot control valve group are connected to the P port of the left auxiliary cylinder 7 or the right auxiliary cylinder 8, respectively. The T port of the left auxiliary cylinder 7 or the right auxiliary cylinder 8 is connected back to the oil tank. The auxiliary cylinder integrates an auxiliary cylinder control valve group consisting of a manual directional valve 301, a hydraulic lock 302, and a first throttle shut-off valve 303 / second throttle shut-off valve 304. The extension and retraction state of the left auxiliary cylinder 7 or the right auxiliary cylinder 8 can be controlled by switching the valve position of the manual operation directional valve 301; the throttling shut-off valve is provided between the rodless chamber and the rod chamber of the left auxiliary cylinder 7 or the right auxiliary cylinder 8, and between the rod chamber and the oil tank, the first throttling shut-off valve 303 and the second throttling shut-off valve 304. When both the first throttling shut-off valve 303 and the second throttling shut-off valve 304 are open, the rodless chamber, the rod chamber and the oil tank can be connected.

[0031] The basic circuit of the emergency lifting unit of this hydraulic system consists of an emergency motor pump group 9, an emergency control valve 10, an emergency branch switching valve 3, and a left lifting cylinder 4 / right lifting cylinder 5. The emergency control valve 10 integrates a three-position four-way solenoid directional valve-Y4 / Y5, a solenoid directional valve-Y6, a two-position four-way solenoid directional valve-Y7, a two-position four-way solenoid directional valve-Y8, and a second pilot relief valve 401.

[0032] The basic circuit oil circuit connection relationship of the emergency lifting unit is as follows: the outlet of the emergency motor pump group pump 9 is connected to the emergency control valve 10P port, the emergency control valve 10X port is connected to the pilot control valve group 6X port, the emergency A1 / B1 / A2 / B2 ports on the emergency control valve 10 are respectively connected to the emergency A1 / B1 / A2 / B2 ports on the emergency branch switching valve 3, and the T port on the emergency control valve 10 is connected back to the oil tank.

[0033] The A1 and B1 output ports of the emergency branch switching valve 3 are respectively connected to the rodless chamber and the rod chamber of the left lifting cylinder 4, and the A2 and B2 output ports are respectively connected to the rodless chamber and the rod chamber of the right lifting cylinder 5. The A1 and B1 input ports of the emergency branch switching valve 3 are respectively connected to the A1 and B1 ports of the first working link; the emergency A1 and emergency B1 ports of the emergency branch switching valve 3 are respectively connected to the A1 and B1 ports of the emergency control valve; the A2 and B2 input ports of the emergency branch switching valve 3 are respectively connected to the A2 and B2 ports of the second working link; and the emergency A2 and emergency B2 ports of the emergency branch switching valve 3 are respectively connected to the A2 and B2 ports of the emergency control valve 6. When the first working link malfunctions, the emergency A1 port of the emergency branch switching valve 3 is connected to the A1 output port, and the emergency B1 port is connected to the B1 output port. The emergency motor pump group 9 supplies oil to the left lifting cylinder 4 through the emergency control valve 6 and the emergency branch switching valve 3. When the second working link malfunctions, the emergency A2 port of the emergency branch switching valve 3 is connected to the A2 output port, and the emergency B2 port is connected to the B2 output port. The emergency motor pump group 9 supplies oil to the right lifting cylinder 5 through the emergency control valve 6 and the emergency branch switching valve 3.

[0034] The pilot control valve group integrates a two-position four-way first emergency directional valve-Y1, a two-position three-way second emergency directional valve-Y2, a two-position three-way third emergency directional valve-Y3, a pilot relief valve 201, and a pilot safety valve 202. It also integrates a high-pressure filter at port P, a pressure sensor-P02 at port M, and an accumulator at port K.

[0035] The first emergency directional valve has its inlet port connected to the P port of the emergency control valve 10, and its return port connected to the oil tank. Its first working port is connected to the X port of the emergency control valve 10 via a solenoid directional valve. Its second working port is connected in parallel to the inlets of the second and third emergency directional valves. When the first emergency directional valve is in the neutral position, its inlet port is connected to the return port. When the first emergency directional valve is in the left position, its inlet port is connected to the second working port, and its first working port is connected to the return port. When the first emergency directional valve is in the right position, its inlet port is connected to the first working port, and its second working port is connected to the return port. The second emergency directional valve has its inlet port connected to the second working port of the first emergency directional valve, and its return port connected to the oil tank. The first and second working ports are respectively connected to ports A1 and B1 of the emergency control valve 10. When the second emergency directional valve is in the left position, its inlet port is connected to port A1 of the emergency control valve 10, and its return port is connected to port B1 of the emergency control valve 10. When the second emergency directional valve is in the right position, its inlet port is closed, and its return port is connected to both ports A1 and B1 of the emergency control valve 10. The third emergency directional valve has its inlet port connected to the second working port of the first emergency directional valve, and its return port connected to the oil tank. The first and second working ports are respectively connected to ports A2 and B2 of the emergency control valve 10. When the second emergency directional valve is in the left position, its inlet port is connected to port A2 of the emergency control valve 10, and its return port is connected to port B2 of the emergency control valve 10. When the second emergency directional valve is in the right position, its inlet port is closed, and its return port is connected to both ports A2 and B2 of the emergency control valve 10.

[0036] In this embodiment, the main lifting system has a single-cylinder action function. For example, the load-sensitive proportional valve 2's -Y9a solenoid valve is energized by the hydraulic system's electronic control system. At this time, oil enters the rodless chamber of the left lifting cylinder 4, and oil returns from the rod chamber, causing the left lifting cylinder 4 to extend outward.

[0037] When the load-sensitive proportional valve 2's -Y9b solenoid valve is energized, the pilot control valve group 6's -Y2 and -Y3 solenoid valves, and the left electrically controlled proportional balance valve -Y15a are simultaneously energized, oil enters the rod chamber of the left lifting cylinder 4, and oil returns from the rodless chamber, causing the left lifting cylinder 4 to retract. Similarly, through the control logic of the hydraulic system's electrical control system, the independent action of the right lifting cylinder is achieved, thereby meeting the single-cylinder operation conditions of the tower crane.

[0038] The main lifting system has a dual-cylinder synchronous action function. Through the hydraulic system and the electronic control system, the -Y9a solenoid valve of the load-sensitive proportional valve 2 and the -Y10a solenoid valve of the load-sensitive proportional valve 2 are energized at the same time. At this time, the left lifting cylinder 4 and the right lifting cylinder 5 extend outward at the same time.

[0039] When the load-sensitive proportional valve 2's -Y9b solenoid valve is energized, the load-sensitive proportional valve 2's -Y10b solenoid valve, the pilot control valve group 6's -Y2 solenoid valve, and the -Y3 solenoid valve are simultaneously energized, the left solenoid proportional balance valve -Y15a and the right solenoid proportional balance valve -Y15b are simultaneously energized, at this time, the left lifting cylinder 4 and the right lifting cylinder 5 are simultaneously retracted.

[0040] The electronic control system monitors the displacement values ​​fed back by the displacement sensors S01a / S01b of the two lifting cylinders in real time, and automatically determines and compares the allowable deviation value through the control logic. The closed-loop feedback adjusts the output current value of the load-sensitive proportional valve 2 (-Y9a / -Y9b / -Y10a / Y10b) to perform correction adjustment and realize synchronous control of the two cylinders.

[0041] The main lifting system in this embodiment has a multi-speed operation function. When the main lifting system operates with a single cylinder or with two cylinders operating synchronously (usually with two cylinders operating synchronously), the electronic control system matches the valve core output flow characteristics of the load-sensitive proportional valve 2 to control the current value (closed-loop control logic), outputting multiple flow rates (for example: speed 1 corresponds to lifting cylinder running at 0.3 m / min, speed 2 corresponds to lifting cylinder running at 0.5 m / min, speed 3 corresponds to lifting cylinder running at 0.7 m / min, speed 4 corresponds to lifting cylinder running at 1 m / min, speed 5 corresponds to lifting cylinder running at 1.5 m / min, etc. It should be noted that the multiple speeds in this embodiment are designed and output as target values ​​according to user needs. This embodiment can also achieve stepless output of any target speed from the lowest to the highest speed), controlling the fast and slow extension and retraction of the two lifting cylinders respectively, thereby realizing the multi-speed operation of the lifting cylinders.

[0042] The main lifting system in this embodiment has a heavy-load recovery pressure control and oil replenishment function. When the tower crane is in heavy-load descent mode, the electronic control system monitors the load pressure fed back by the rodless chamber pressure sensors -P03a / P03b of the lifting cylinder in real time and matches the control current values ​​of the -Y15a and -Y15b solenoid valves (closed-loop control logic) according to the load flow characteristics of the electronically controlled proportional balance valve, so as to realize synchronous heavy-load recovery of the two cylinders. The control current values ​​of the -Y15a and -Y15b solenoid valves have multiple output levels, realizing multi-speed operation of heavy-load descent. During the heavy-load descent process, this embodiment also incorporates a closed-loop feedback control of the rod chamber pressure of the lifting cylinder. The electronic control system monitors the load pressure fed back by the rod chamber pressure sensors -P04a / P04b in real time and matches the control current values ​​(closed-loop control logic) of the -Y9b and -Y10b solenoid valves to replenish oil to the rod chamber of the lifting cylinder, maintaining the pressure in the rod chamber at 2MPa~5MPa. This prevents the risk of cavitation in the rod chamber during heavy-load descent and reduces vibration during high-speed heavy-load descent.

[0043] Furthermore, the hydraulic system in this embodiment has an auxiliary cylinder floating function. The electronic control system energizes the Y1 solenoid valve of the pilot control valve group 6, so that the pilot pump oil source is switched through the -Y1 solenoid valve and output from the A1 / A2 ports to the auxiliary cylinder control valve group. By manually operating the reversing valve 301, the extension and retraction of the auxiliary cylinder are controlled, thereby realizing the lifting of the crossbeam of the push-pull tower crane. During the operation of the lifting cylinder, the first throttle shut-off valve 303 and the second throttle shut-off valve 304 on the auxiliary cylinder control valve group are opened to connect the rodless chamber and the rod chamber of the auxiliary cylinder and connect it to the high-level oil tank, so that the auxiliary cylinder is in a floating state, which solves the problem of pressure buildup in the auxiliary cylinder caused by angle changes during the operation of the lifting cylinder.

[0044] The hydraulic system in this embodiment also has emergency lifting and lowering functions. When the main unit experiences an abnormal power failure, this embodiment uses a low-power emergency generator to provide a weak current power supply to the electrical control system and start the low-power emergency motor pump group. The electrical control system controls the solenoid valves -Y4 and -Y7 / Y8 on the emergency control valve 10 to be energized simultaneously, as well as the solenoid directional valves -Y11a / -Y11b / -Y12a / -Y12b / -Y13a / -Y13b / -Y14a / -Y14b on the emergency branch switching valve 3 to be energized simultaneously. At this time, the rodless chamber of the lifting cylinder receives oil, and the rod chamber returns oil, enabling the two lifting cylinders to perform emergency lifting.

[0045] The solenoid valves -Y5 and -Y6 on the emergency control valve 10 are simultaneously energized by the electronic control system, and the proportional balance valves -Y15a / -Y15b of the two lifting cylinders are given a control current value. At this time, the lifting cylinders slowly descend under the action of the load gravity to realize emergency lowering.

[0046] In addition, the hydraulic system in this embodiment has an independent circulation filtration and heat dissipation function. The electronic control system detects the hydraulic oil temperature value fed back by the oil temperature sensor in real time. According to the designed maximum oil temperature requirement, the independent circulation filtration and heat dissipation unit 11 is started to ensure the hydraulic system's operating oil temperature and oil cleanliness.

[0047] In summary, the high-efficiency, multi-speed, electrically controlled wind turbine tower crane jacking hydraulic system of this embodiment consists of one hydraulic station, two jacking cylinders, two auxiliary cylinders, and one electrical control system. The hydraulic station integrates a main jacking system, pilot and auxiliary control systems, an emergency jacking system, and an independent circulating filtration and cooling system. The main jacking system uses an LRDS-controlled load-sensitive pump and two electrically controlled load-sensitive proportional multi-way valves. By designing the proportional valve core and matching the gear control current (outputting control current corresponding to each gear), it achieves flow output from low speed to high speed, controlling the fast and slow extension and retraction of the two jacking cylinders, thus enabling multi-speed operation of the jacking cylinders. The jacking cylinders integrate an electro-proportional control balance valve, also matching the gear control current, enabling multi-speed descent of the jacking cylinders under heavy load conditions. During heavy-load descent, the electrical control system is designed with closed-loop feedback control logic for the rod chamber pressure of the jacking cylinders, achieving rod chamber oil replenishment and pressure control during heavy-load descent to prevent cavitation and vibration. The pilot and auxiliary control system consists of a pilot control valve assembly. Through solenoid valve switching, it provides pilot oil supply to the two lifting cylinder balance valves (left and right electro-hydraulic proportional balance valves) and oil supply to the two auxiliary cylinders from the pilot control valve assembly 6. The pilot control valve assembly has two inlets. Under normal operating conditions, the oil supply for the pilot control valve assembly 6 is provided by a pilot pump; in emergency operating conditions, the oil supply for the pilot control valve assembly is provided by an emergency pump.

[0048] This hydraulic system also employs a parallel emergency lifting system, with independent emergency motor pump sets and emergency control valve sets. The corresponding solenoid valves are controlled by an electronic control system to achieve emergency lifting and lowering of the tower crane. The system features an independent circulating filtration and cooling system that automatically starts and stops according to the operating conditions, ensuring system cleanliness and thermal balance, and resolving contamination and overheating issues associated with rapid relocation and frequent operation of wind power tower cranes. The system uses electronic control, employing electronic logic to operate the tower crane's lifting cylinders, auxiliary cylinders, and emergency lifting operations. Displacement feedback closed-loop control enables synchronous operation of both cylinders. This invention provides detailed hydraulic principles, clearly explaining the principles behind the various functions.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydraulic system for lifting wind turbine towers using electronic control and multi-speed operation, characterized in that, include: Main motor pump set, including the main pump; The lifting cylinders include a left lifting cylinder and a right lifting cylinder; The load-sensitive proportional valve includes a first working link located between the main pump and the left lifting cylinder and a second working link located between the main pump and the right lifting cylinder; the first working link and the second working link are connected in parallel, and the extension and retraction states of the left lifting cylinder and the right lifting cylinder can be controlled respectively by controlling the energized state of the solenoid valves of the first working link and the second working link. The electronically controlled proportional balance valve includes a left electronically controlled proportional balance valve located between the first working link and the rodless chamber of the left lifting cylinder, and a right electronically controlled proportional balance valve located between the second working link and the rodless chamber of the right lifting cylinder. Sensor assembly for detecting piston rod displacement and rodless chamber pressure values ​​of the left and right lifting cylinders; During heavy-load lifting, the control current of the solenoid valves of the first and second working links is adjusted by feedback based on the piston rod displacement values ​​of the left and right lifting cylinders. This enables the synchronous extension of the left and right lifting cylinders, and the heavy-load lifting speed level can be controlled by controlling the magnitude of the control current of the solenoid valves of the first and second working links during the synchronous extension process. During the heavy-load descent process, the control current of the left and right electric proportional balance valves is fed back to control the pressure values ​​of the rodless chambers of the left and right lifting cylinders. This enables the synchronous retraction of the left and right lifting cylinders. Furthermore, during the synchronous retraction process, the control current of the left and right electric proportional balance valves can be controlled to adjust the heavy-load descent speed. The sensor assembly is also used to detect the rod chamber pressure values ​​of the left and right lifting cylinders; During the heavy-load descent process, the second left solenoid valve of the first working link is energized, and the second right solenoid valve of the second working link is energized. The control current of the second left solenoid valve and the second right solenoid valve is adjusted according to the rod chamber pressure values ​​of the left and right lifting cylinders, so that the main pump can replenish oil to the rod chamber of the left or right lifting cylinder to maintain the pressure of the left and right lifting cylinders at the preset value.

2. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 1, characterized in that, The P port of the load-sensitive proportional valve is connected to the oil outlet of the main pump. The A1 port of the first working link is connected to the rodless chamber of the left lifting cylinder through the left electronically controlled proportional balance valve, and the B1 port of the first working link is connected to the rod chamber of the left lifting cylinder. The A2 port of the second working link is connected to the rodless chamber of the right lifting cylinder through the right electronically controlled proportional balance valve, and the B2 port of the second working link is connected to the rod chamber of the right lifting cylinder. When the first left solenoid valve of the first working link is energized, the main pump supplies oil to the rodless chamber of the left lifting cylinder, and the left lifting cylinder extends to perform lifting operations; when the second left solenoid valve of the first working link is energized, the main pump supplies oil to the rod chamber of the left lifting cylinder, and the left lifting cylinder retracts to perform lowering operations; by controlling the control current of the first and second left solenoid valves, the opening degree of the load-sensitive proportional valve can be controlled to control the amount of oil supplied by the main pump to the left lifting cylinder. When the first right solenoid valve of the second working link is energized, the main pump supplies oil to the rodless chamber of the right lifting cylinder, and the right lifting cylinder extends to perform lifting operations; when the second right solenoid valve of the second working link is energized, the main pump supplies oil to the rod chamber of the right lifting cylinder, and the right lifting cylinder retracts to perform lowering operations; by controlling the control current of the first and second right solenoid valves, the opening degree of the load-sensitive proportional valve can be controlled to control the amount of oil supplied by the main pump to the right lifting cylinder.

3. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 1, characterized in that, The main motor pump set also includes a pilot pump, and further includes: The pilot control valve assembly has its P port connected to the oil outlet of the pilot pump, and its X1 and X2 ports connected to the control terminals of the left and right electrically controlled proportional balance valves, respectively. When the pilot pump outputs pilot oil through the X1 port of the pilot control valve group and acts on the control end of the left electronically controlled proportional balance valve, the left electronically controlled proportional balance valve is turned on. When the pilot pump outputs pilot oil through the X2 port of the pilot control valve group and acts on the control end of the right electronically controlled proportional balance valve, the right electronically controlled proportional balance valve is turned on.

4. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 3, characterized in that, The pilot control valve group includes a first pilot directional valve, a second pilot directional valve, and a third pilot directional valve; The first pilot directional valve has its inlet port connected to the P port of the pilot control valve group and its return port connected to the oil tank. Its first working port is connected to the inlet port of the second pilot directional valve, and its second working port is connected in parallel to ports A1 and A2 of the pilot control valve group. When the first pilot directional valve is in the left position, its inlet port is connected to the first working port, and its return port is connected to the second working port. When the first pilot directional valve is in the right position, its inlet port is connected to the second working port, and its return port is connected to the first working port. The first working port of the first pilot directional valve is also connected in parallel to a pilot relief valve and an accumulator. The second pilot directional valve has its inlet port connected to the first working port of the first pilot directional valve, its return port connected to the oil tank, and its outlet port connected to the inlet port of the third pilot directional valve. When the second pilot directional valve is in the left position, its inlet port is connected to the return port, and when the second pilot directional valve is in the right position, its inlet port is connected to the outlet port. The third pilot directional valve has an inlet port connected to the outlet port of the second pilot directional valve, an outlet port connected to the oil tank, and an outlet port connected in parallel to ports X1 and X2 of the pilot control valve group. When the third pilot directional valve is in the left position, the outlet port and the outlet port are connected. When the third pilot directional valve is in the right position, the inlet port and the outlet port are connected. When the pilot pump can output pilot oil through ports X1 and X2 of the pilot control valve group to act on the control terminals of the left and right solenoid proportional balance valves, the left and right solenoid proportional balance valves are connected.

5. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 4, characterized in that, Also includes: The auxiliary cylinder includes a left auxiliary cylinder and a right auxiliary cylinder, and the A1 port and A2 port of the pilot control valve group are respectively connected to the P port of the left auxiliary cylinder and the right auxiliary cylinder; An auxiliary cylinder control valve assembly is provided, wherein both the left and right auxiliary cylinders are connected to the auxiliary cylinder control valve assembly. The auxiliary cylinder control valve assembly includes a manually operated directional valve and a throttle shut-off valve. By switching the valve position of the manually operated directional valve, the extension or retraction state of the left or right auxiliary cylinder can be controlled. The throttle shut-off valve is located between the rodless chamber and the rod chamber of the left or right auxiliary cylinder, as well as between the rod chamber and the oil tank. When the throttle shut-off valve is open, the rodless chamber, the rod chamber, and the oil tank are all connected.

6. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 3, characterized in that, Also includes: Emergency motor pump set, The emergency control valve has its P port connected to the oil outlet of the emergency motor pump unit and its X port connected to the X port of the pilot control valve group; the X port of the pilot control valve group can be connected to the X1 port and X2 port of the pilot control valve group. An emergency branch switching valve is located between the load-sensitive proportional valve and the lifting cylinder; The A1 and B1 output ports of the emergency branch switching valve are respectively connected to the rodless chamber and the rod chamber of the left lifting cylinder, and the A2 and B2 output ports are respectively connected to the rodless chamber and the rod chamber of the right lifting cylinder. The A1 and B1 input ports of the emergency branch switching valve are respectively connected to the A1 and B1 ports of the first working link; the emergency A1 and emergency B1 ports of the emergency branch switching valve are respectively connected to the A1 and B1 ports of the emergency control valve; the A2 and B2 input ports of the emergency branch switching valve are respectively connected to the A2 and B2 ports of the second working link; the emergency A2 and emergency B2 ports of the emergency branch switching valve are respectively connected to the A2 and B2 ports of the emergency control valve. When the first working link malfunctions, the emergency A1 port of the emergency branch switching valve is connected to the A1 output port, and the emergency B1 port is connected to the B1 output port. The emergency motor pump unit supplies oil to the left lifting cylinder through the emergency control valve and the emergency branch switching valve. When the second working link malfunctions, the emergency A2 port of the emergency branch switching valve is connected to the A2 output port, and the emergency B2 port is connected to the B2 output port. The emergency motor pump unit supplies oil to the right lifting cylinder through the emergency control valve and the emergency branch switching valve.

7. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 6, characterized in that, The emergency control valve includes a first emergency reversing valve, a second emergency reversing valve, and a third emergency reversing valve; The first emergency directional valve has its inlet port connected to the P port of the emergency control valve, and its return port connected to the oil tank. Its first working port is connected to the X port of the emergency control valve via a solenoid directional valve, which is energized and conducts. Its second working port is connected in parallel to the inlets of the second and third emergency directional valves. When the first emergency directional valve is in the neutral position, its inlet port is connected to the return port. When the first emergency directional valve is in the left position, its inlet port is connected to the second working port, and its first working port is connected to the return port. When the first emergency directional valve is in the right position, its inlet port is connected to the first working port, and its second working port is connected to the return port. The second emergency directional valve has its inlet port connected to the second working port of the first emergency directional valve, and its return port connected to the oil tank. The first and second working ports are respectively connected to ports A1 and B1 of the emergency control valve. When the second emergency directional valve is in the left position, its inlet port is connected to port A1 of the emergency control valve, and its return port is connected to port B1 of the emergency control valve. When the second emergency directional valve is in the right position, its inlet port is closed, and its return port is connected to both ports A1 and B1 of the emergency control valve. The third emergency directional valve has its inlet port connected to the second working port of the first emergency directional valve, and its return port connected to the oil tank. The first and second working ports are respectively connected to ports A2 and B2 of the emergency control valve. When the second emergency directional valve is in the left position, its inlet port is connected to port A2 of the emergency control valve, and its return port is connected to port B2 of the emergency control valve. When the second emergency directional valve is in the right position, its inlet port is closed, and its return port is connected to both ports A2 and B2 of the emergency control valve.

8. The electrically controlled multi-speed wind turbine tower lifting hydraulic system according to claim 1, characterized in that, The rodless chambers of both the left and right lifting cylinders are connected to rodless chamber safety valves; the rod chambers of both the left and right lifting cylinders are sequentially connected to rod chamber safety valves and rod chamber back pressure valves (check valves).

9. A control method for a hydraulic system for lifting a wind turbine tower crane using electronic control and multi-speed operation, characterized in that, The lifting hydraulic system for wind turbine towers, based on any one of claims 1-8, is used for lifting. The control method includes: When heavy-load lifting is required, the main pump supplies oil to the rodless chambers of the left and right lifting cylinders through the first and second working connections, respectively. The left and right lifting cylinders extend to perform lifting. During the lifting process, the control current of the solenoid valves of the first and second working connections is adjusted based on the piston rod displacement values ​​of the left and right lifting cylinders to achieve synchronous extension of the left and right lifting cylinders. Furthermore, during the synchronous extension process, the heavy-load lifting speed can be controlled by adjusting the control current of the solenoid valves of the first and second working connections. When heavy-load descent is required, under the action of gravity, the hydraulic oil in the rodless chambers of the left and right lifting cylinders returns to the oil tank. During the descent, the control current of the left and right electro-hydraulic proportional balance valves is fed back based on the pressure values ​​in the rodless chambers of the left and right lifting cylinders to achieve synchronous retraction of the left and right lifting cylinders. During the synchronous retraction, the control current of the left and right electro-hydraulic proportional balance valves can be controlled to adjust the heavy-load descent speed.

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