A crane hydraulic system and a method of operating the same

Abstract

A kind of crane hydraulic system, including two main pumps, two electromagnetic reversing valves and four electromagnetic ball valves, two main pumps each include main pump body, load sensing control valve, constant pressure control valve, in amplitude single-acting mode, two electromagnetic reversing valves are all de-energized, first, third electromagnetic ball valve is energized, second, fourth electromagnetic ball valve is de-energized, the load sensing control valve left position of main pump works, two main pumps are in load sensing mode, for amplitude hydraulic cylinder oil supply, in hoisting single-acting mode, two electromagnetic reversing valves are all energized, first, third electromagnetic ball valve is de-energized, second, fourth electromagnetic ball valve is energized, two main pumps are in constant pressure mode, for hoisting hydraulic motor oil supply, in amplitude-hoisting linkage mode, first electromagnetic reversing valve is de-energized, so that first main pump works in load sensing mode, second electromagnetic reversing valve is energized, so that second main pump works in constant pressure mode.The present application is adapted to different work requirements by the switching of main pump working mode.

Description

Technical Field

[0001] This invention belongs to the field of crane hydraulic technology, specifically relating to a crane hydraulic system and its operation method. Background Technology

[0002] In marine environments, the crane base moves with the waves, causing the cargo suspended by the hook to move as well. When loading and unloading delicate cargo, to reduce cargo movement, the crane needs an active compensation function. This involves the winch automatically retracting and extending the wire rope to counteract wave-induced movement, reducing relative motion between the seabed and the cargo, and improving the safety of cargo and personnel. During loading and unloading operations, before and after activating and deactivating the active compensation function, the crane requires other actions such as luffing and slewing to adjust to the optimal operating posture. Because the active compensation system has a complex control system, a simple and reliable emergency lifting system is needed to replace it in case of power or control system failure, ensuring operational safety. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned problems in the prior art by providing a crane hydraulic system and its operation method that adapts to lifting and luffing operations by switching the pump's operating mode.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] A crane hydraulic system includes a first main pump, a second main pump, a first solenoid directional valve, a second solenoid directional valve, a luffing hydraulic cylinder, and a hoisting hydraulic motor. The inlets of the first main pump and the second main pump are connected to an oil tank.

[0006] Both the first and second main pumps include a main pump body, a load-sensitive control valve, and a constant pressure control valve. The A port of the load-sensitive control valve and the A port of the constant pressure control valve are connected to the outlet of the main pump body. The B port of the constant pressure control valve is connected to the oil tank through the P port of the load-sensitive control valve and the B port of the load-sensitive control valve in sequence. The P port of the constant pressure control valve is connected to the variable cylinder of the main pump body. The sensitive control port X of the load-sensitive control valve in the first main pump is connected to the P port of the first solenoid directional valve. The sensitive control port X of the load-sensitive control valve in the second main pump is connected to the P port of the second solenoid directional valve. The A ports of the first and second solenoid directional valves are connected to the two oil chambers of the variable amplitude hydraulic cylinder. The B ports of the first and second solenoid directional valves are connected to the outlet of the main pump body in the first main pump and the outlet of the main pump body in the second main pump, respectively. The T ports of the first and second solenoid directional valves are connected to the oil tank.

[0007] The system also includes a first electromagnetic ball valve, a second electromagnetic ball valve, a third electromagnetic ball valve, and a fourth electromagnetic ball valve. One end of the first and second electromagnetic ball valves is connected to the outlet of the main pump body of the first main pump, and the other end of the first and second electromagnetic ball valves is connected to an oil chamber of the luffing hydraulic cylinder and port A of the hoisting hydraulic motor, respectively. One end of the third and fourth electromagnetic ball valves is connected to the outlet of the second main pump, and the other end of the third and fourth electromagnetic ball valves is connected to an oil chamber of the luffing hydraulic cylinder and port A of the hoisting hydraulic motor, respectively. The other oil chamber of the luffing hydraulic cylinder and port B of the hoisting hydraulic motor are both connected to the oil tank.

[0008] The system also includes a high-voltage accumulator and a low-voltage accumulator, which are respectively connected to ports A and B of the lifting hydraulic motor.

[0009] The system also includes an emergency pump, a manual proportional directional valve, a first reversing valve, and a second reversing valve. The inlet and outlet of the emergency pump are connected to the oil tank and the P port of the manual proportional directional valve, respectively. The T port of the manual proportional directional valve is connected to the oil tank. The A and B ports of the manual proportional directional valve are connected to the B ports of the first and second reversing valves, respectively. The A ports of the first and second reversing valves are both connected to the oil tank. The P ports of the first and second reversing valves are connected to the A and B ports of the lifting hydraulic motor, respectively.

[0010] The system also includes a luffing proportional directional valve and a hoisting lock valve. The P port of the luffing proportional directional valve is connected to the first and third solenoid ball valves, the T port of the luffing proportional directional valve is connected to the oil tank, and the A and B ports of the luffing proportional directional valve are respectively connected to the two oil chambers of the luffing hydraulic cylinder. One end of the hoisting lock valve is connected to the second and fourth solenoid ball valves, and the other end of the hoisting lock valve is connected to the A port of the hoisting hydraulic motor.

[0011] The system also includes a first lifting balance valve, a second lifting balance valve, and a three-way differential pressure compensator. The A port of the first lifting balance valve is connected to the P port of the first directional valve and the control port of the second lifting balance valve. The A port of the second lifting balance valve is connected to the P port of the second directional valve and the control port of the first lifting balance valve. The B ports of the first and second lifting balance valves are respectively connected to the lifting lock valve and the B port of the lifting hydraulic motor. The A and B ports of the three-way differential pressure compensator are respectively connected to the outlet of the oil tank and the emergency pump. The control port of the three-way differential pressure compensator is connected to the A and B ports of the manual proportional directional valve.

[0012] The system also includes a luffing balance valve, a high-pressure relief valve, a low-pressure relief valve, and a replenishing oil pump. Ports A and B of the luffing balance valve are connected to port A of the luffing proportional directional valve and one oil chamber of the luffing hydraulic cylinder, respectively. The control port of the luffing balance valve is connected to the other oil chamber of the luffing hydraulic cylinder. One end of the low-pressure relief valve is connected to the oil tank, and the other end of the low-pressure relief valve is connected to port B of the hoisting hydraulic motor and one end of the high-pressure relief valve. The other end of the high-pressure relief valve is connected to the hoisting lock valve. The inlet and outlet of the replenishing oil pump are connected to the oil tank and port B of the hoisting hydraulic motor, respectively.

[0013] The system also includes a luffing shuttle valve, a first hoisting shuttle valve, a second hoisting shuttle valve, a third hoisting shuttle valve, and a fourth hoisting shuttle valve. Ports A and B of the luffing shuttle valve are connected to the two oil chambers of the luffing hydraulic cylinder, respectively. Port C of the luffing shuttle valve is connected to port A of the first solenoid directional valve and port A of the second solenoid directional valve. Ports A and B of the first hoisting shuttle valve are connected to both ends of the hoisting lock valve, respectively. Port C of the first hoisting shuttle valve is connected to the control port of the hoisting hydraulic motor and port C of the second hoisting shuttle valve. Ports A and B of the second hoisting shuttle valve are connected to ports P of the first and second directional valves, respectively. Ports A and B of the third hoisting shuttle valve are connected to ports A of the first and second directional valves, respectively. Port C of the third hoisting shuttle valve is connected to the oil tank. Ports A and B of the fourth hoisting shuttle valve are connected to ports A and B of the manual proportional directional valve, respectively. Port C of the fourth hoisting shuttle valve is connected to the control port of the three-way differential pressure compensator.

[0014] A method for operating a crane hydraulic system includes a normal operating method, wherein the normal operating method includes a luffing single-action mode, a hoisting single-action mode, and a luffing-hoisting linkage mode, wherein...

[0015] In the luffing single-action mode, both the first and second solenoid directional valves are de-energized and operate in their right position, i.e., port P is connected to port A. The load-sensitive control valves in the first and second main pumps operate in their left position, so that both the first and second main pumps operate in load-sensitive mode. At the same time, the first and third solenoid ball valves are energized, while the second and fourth solenoid ball valves are de-energized. Both the first and second main pumps supply oil to the luffing hydraulic cylinder to achieve luffing operation.

[0016] In the single-action lifting mode, both the first and second solenoid directional valves are energized and operate in the left position, i.e., port P and port B are connected. At this time, the load-sensitive control valve always operates in the right position, and only the constant pressure control valve is active. Both the first and second main pumps operate in constant pressure mode. Meanwhile, the first and third solenoid ball valves are de-energized, while the second and fourth solenoid ball valves are energized. Both the first and second main pumps supply oil to the lifting hydraulic motor to achieve the lifting operation.

[0017] In the luffing-hoisting linkage mode, the first solenoid directional valve is de-energized, causing the load-sensitive control valve in the first main pump to operate in the left position, i.e., the first main pump operates in load-sensitive mode. The first solenoid ball valve is energized, and the second solenoid ball valve is de-energized. The first main pump supplies oil to the luffing hydraulic cylinder to achieve luffing operation. At the same time, the second solenoid directional valve is energized, causing the second main pump to operate in constant pressure mode. The third solenoid ball valve is de-energized, and the fourth solenoid ball valve is energized. The second main pump supplies oil to the hoisting hydraulic motor to achieve hoisting operation.

[0018] The system also includes a high-voltage accumulator and a low-voltage accumulator, which are respectively connected to ports A and B of the lifting hydraulic motor.

[0019] In the luffing-lifting linkage mode, during the load lowering process, a portion of the oil from port A of the lifting hydraulic motor flows into the high-pressure accumulator for storage and is released during the load lifting process; during the load lifting process, a portion of the oil from port B of the lifting hydraulic motor flows into the low-pressure accumulator for storage and is released during the load lowering process.

[0020] The system also includes an emergency pump, a manual proportional directional valve, a first reversing valve, and a second reversing valve. The two ends of the emergency pump are connected to the oil tank and the P port of the manual proportional directional valve, respectively. The T port of the manual proportional directional valve is connected to the oil tank. The A and B ports of the manual proportional directional valve are connected to the B ports of the first reversing valve and the second reversing valve, respectively. The A ports of the first reversing valve and the second reversing valve are both connected to the oil tank. The P ports of the first reversing valve and the second reversing valve are connected to the A and B ports of the lifting hydraulic motor, respectively.

[0021] The operating method also includes the following emergency lifting method:

[0022] In emergency situations, the first and second directional control valves switch to the left position, meaning port P is connected to port B. When lifting a load, the manual proportional directional valve operates in the left position, meaning port P is connected to port A and port B is connected to port T. The oil flowing from the emergency pump outlet passes sequentially through port P of the manual proportional directional valve, port A of the manual proportional directional valve, port B of the first directional control valve, and port P of the first directional control valve before entering port A of the lifting hydraulic motor. The oil flowing from port B of the lifting hydraulic motor then passes sequentially through port P of the second directional control valve, port B of the second directional control valve, and port B of the manual proportional directional valve. The oil flows out of the emergency pump outlet and then through the P port of the manual proportional directional valve, the B port of the manual proportional directional valve, the B port of the second directional valve, and the P port of the second directional valve before entering the B port of the lifting hydraulic motor. The oil flowing out of the A port of the lifting hydraulic motor then flows through the P port of the first directional valve, the B port of the first directional valve, the A port of the manual proportional directional valve, and the T port of the manual proportional directional valve before returning to the oil tank.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The present invention discloses a crane hydraulic system comprising a first electromagnetic ball valve, a second electromagnetic ball valve, a third electromagnetic ball valve, and a fourth electromagnetic ball valve. Both a first main pump and a second main pump include a main pump body, a load-sensitive control valve, and a constant pressure control valve. Port A of the load-sensitive control valve and port A of the constant pressure control valve are connected to the outlet of the main pump body. Port B of the constant pressure control valve is connected to an oil tank via ports P and B of the load-sensitive control valve. Port P of the constant pressure control valve is connected to the variable displacement cylinder of the main pump body. The sensitive control port X of the load-sensitive control valve in the first main pump is connected to port P of the first electromagnetic directional valve. The sensitive control port X of the load-sensitive control valve in the second main pump is connected to port P of the second electromagnetic directional valve. Ports A of both the first and second electromagnetic directional valves are connected to both sides of the luffing hydraulic cylinder. Ports B of the first and second electromagnetic directional valves are respectively connected to the first main pump. The main pump body outlet of the first main pump and the main pump body outlet of the second main pump are connected. The T ports of the first and second electromagnetic directional valves are both connected to the oil tank. One end of the first and second electromagnetic ball valves is connected to the main pump body outlet of the first main pump, and the other end of the first and second electromagnetic ball valves is connected to one oil chamber of the luffing hydraulic cylinder and the A port of the hoisting hydraulic motor, respectively. One end of the third and fourth electromagnetic ball valves is connected to the main pump body outlet of the second main pump, and the other end of the third and fourth electromagnetic ball valves is connected to one oil chamber of the luffing hydraulic cylinder and the A port of the hoisting hydraulic motor, respectively. The other oil chamber of the luffing hydraulic cylinder and the B port of the hoisting hydraulic motor are both connected to the oil tank. The system adds a load-sensitive control valve and a constant pressure control valve to the main pump to adapt to three different operating requirements: luffing single-action, hoisting single-action, and luffing-hoisting linkage, by switching the working mode of the main pump.

[0025] 2. The crane hydraulic system of the present invention further includes a high-pressure accumulator and a low-pressure accumulator, which are respectively connected to ports A and B of the lifting hydraulic motor. During the lowering of the load, a portion of the oil from port A of the lifting hydraulic motor flows into the high-pressure accumulator for storage and is released during the lifting of the load; during the lifting of the load, a portion of the oil from port B of the lifting hydraulic motor flows into the low-pressure accumulator for storage and is released during the lowering of the load. The system achieves active compensation for lifting through the high and low pressure accumulators, which plays a role in energy saving and absorbing pressure shock.

[0026] 3. The crane hydraulic system of the present invention further includes an emergency pump, a manual proportional directional valve, a first directional valve, and a second directional valve. The two ends of the emergency pump are respectively connected to the oil tank and the P port of the manual proportional directional valve. The T port of the manual proportional directional valve is connected to the oil tank. The A and B ports of the manual proportional directional valve are respectively connected to the B port of the first directional valve and the B port of the second directional valve. The A ports of the first directional valve and the A ports of the second directional valve are both connected to the oil tank. The P ports of the first directional valve and the P ports of the second directional valve are respectively connected to the A and B ports of the lifting hydraulic motor. By configuring a simple and reliable emergency lifting subsystem, the system realizes emergency lifting when the power system or control system fails, effectively improving the safety of the system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Figure 2 for Figure 1 Enlarged view of part A.

[0029] Figure 3 for Figure 1 Enlarged view of part B.

[0030] In the diagram, the following valves are included: First Main Pump 1, Second Main Pump 2, First Solenoid Directional Valve 3, Second Solenoid Directional Valve 4, Luffing Hydraulic Cylinder 5, Lifting Hydraulic Motor 6, Main Pump Body 7, Variable Cylinder 71, Load Sensitive Control Valve 8, Constant Pressure Control Valve 9, Oil Tank 10, First Solenoid Ball Valve 11, Second Solenoid Ball Valve 12, Third Solenoid Ball Valve 13, Fourth Solenoid Ball Valve 14, Luffing Proportional Directional Valve 15, Lifting Lock Valve 16, Luffing Balance Valve 17, High Pressure Relief Valve 18, Low Pressure Relief Valve 19, Makeup Pump 20, High Pressure Accumulator 21, Low Pressure Accumulator 22, Emergency Pump 31, Manual Proportional Directional Valve 32, First Directional Valve 33, Second Directional Valve 34, First Lifting Balance Valve 35, Second Lifting Balance Valve 36, Three-Way Differential Pressure Compensator 37, Luffing Shuttle Valve 41, First Lifting Shuttle Valve 42, Second Lifting Shuttle Valve 43, Third Lifting Shuttle Valve 44, Fourth Lifting Shuttle Valve 45. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] The functions and principles of each component in this invention are explained below:

[0033] First main pump 1, second main pump 2:

[0034] In this invention, a load-sensitive control valve 8 and a constant-pressure control valve 9 are provided in both the first main pump 1 and the second main pump 2. The spring setting pressures of the load-sensitive control valve 8 and the constant-pressure control valve 9 can be 2.5 MPa and 28 MPa, respectively. When the outlet pressure of the first main pump 1 and the second main pump 2 is less than 28 MPa, the constant-pressure control valve 9 operates in the right position, and the oil in the spring chamber of the variable cylinder 71 returns to the oil tank, so that the first main pump 1 and the second main pump 2 always operate at the maximum displacement. When the outlet pressure of the first main pump 1 and the second main pump 2 rises to 28 MPa, the constant-pressure control valve 9 operates in the left position, and the oil enters the spring chamber of the variable cylinder 71, so that the displacement of the first main pump 1 and the second main pump 2 decreases, and the output flow rate adapts to the load demand.

[0035] When the first solenoid directional valve 3 is de-energized, it operates in the right position, with port P connected to port A. At this time, ports A and B of the amplitude proportional directional valve 15 are connected to the sensitive control port X of the load-sensitive control valve 8. Port A of the load-sensitive control valve 8 is always connected to the outlet of the first main pump 1 and port P of the amplitude proportional directional valve 15. The first main pump 1 changes its discharge rate so that its outlet pressure is always 2.5 MPa higher than the pressure of the sensitive control port X. The first main pump 1 operates in load-sensitive mode.

[0036] When the first solenoid directional valve 3 is energized, it operates in the left position, with port B connected to port P. That is, the sensitive control port X of the load-sensitive control valve 8 is connected to the outlet of the first main pump 1. Under the action of the 2.5MPa spring force, the load-sensitive control valve 8 always operates in the right position, and only the constant pressure control valve 9 is active. The first main pump 1 operates in constant pressure mode.

[0037] Luffing proportional directional valve 15: Luffing proportional directional valve 15 is used to control the extension and retraction direction and speed of the piston rod of the luffing hydraulic cylinder 5. When the luffing proportional directional valve 15 is in the neutral position, its A and B ports are connected to the T port, and the pressure is basically zero. Therefore, the outlet pressure of the luffing shuttle valve 41 is also basically zero. At this time, the outlet pressure of the main pump body 7 of the first main pump 1, i.e., the outlet pressure of the first main pump 1, is 2.5 MPa, and its output flow only maintains its own leakage, remaining in standby mode. When the luffing proportional directional valve 15 is in the left position, the P port is connected to the A port, and the B port is connected to the T port. The pressure at the A port is greater than the pressure at the B port. Therefore, the C port of the luffing shuttle valve 41 is the pressure at the A port of the luffing proportional directional valve 15, and is connected to the sensitive control port X of the load-sensitive control valve 8 in the first main pump 1. At this time, the outlet pressure of the main pump body 7 of the first main pump 1, i.e., the outlet pressure of the first main pump 1, is always 2.5 MPa higher than the A port pressure of the luffing proportional directional valve 15. Since the pressure difference remains unchanged, the luffing proportional directional valve 15... The inlet flow rate of valve 5 (i.e., the output flow rate of the first main pump 1) is only related to its opening. When the opening of the luffing proportional directional valve 15 increases, if the outlet flow rate of the first main pump 1 remains unchanged, the pressure difference of the luffing proportional directional valve 15 will be less than 2.5 MPa. The balance state of the load-sensitive control valve 8 will be broken, causing the displacement and outlet flow rate of the first main pump 1 to increase, so as to maintain the pressure difference at 2.5 MPa. When the opening of the luffing proportional directional valve 15 decreases, the displacement and outlet flow rate of the first main pump 1 decrease. When the luffing proportional directional valve 15 is in the left position, its working principle is the same as that in the left position.

[0038] Lifting lock valve 16: When the lifting lock valve 16 is de-energized, the hydraulic fluid at port A of the lifting hydraulic motor 6 can neither enter nor exit, thus acting as a lock; when the lifting lock valve 16 is energized, the lifting hydraulic motor 6 operates normally.

[0039] Luffing balance valve 17: Used to balance the load of luffing hydraulic cylinder 5. When lifting the load, the luffing balance valve 17 operates in the left position, and the oil flows from port A to port B, which is equivalent to a check valve. When lowering the load, the luffing balance valve 17 operates in the right position under the pressure of port B of the luffing proportional directional valve 15, and the oil flows from port B to port A. The opening size is adjusted according to the load size and the pressure of port B of the luffing proportional directional valve 15.

[0040] High-pressure relief valve 18: Used to limit the maximum working pressure of port A of the lifting hydraulic motor 6.

[0041] Oil replenishment pump 20: Oil replenishment pump 20 provides a stable output pressure through low-pressure relief valve 19 to provide a pressure oil source for port B of lifting hydraulic motor 6.

[0042] Manual proportional directional valve 32: The manual proportional directional valve 32 is used to control the rotation direction and speed of the lifting hydraulic motor. When the manual proportional directional valve 32 is in the neutral position, its A and B ports are connected to the T port, and the outlet oil of the emergency pump 31 returns to the oil tank through the three-way differential pressure compensator 37, with a pressure of 2.5 MPa. When the manual proportional directional valve 32 is in the left position, its P port is connected to the A port, and its B port is connected to the T port. The pressure at the A port is greater than the pressure at the B port. Therefore, the outlet of the fourth lifting shuttle valve 45 is at the pressure at the A port, and it is connected to the control port of the three-way differential pressure compensator 37. At this time, the outlet pressure of the emergency pump 31 (i.e., the P port of the manual proportional directional valve) is always 2.5 MPa higher than the pressure at the A port. When the manual proportional directional valve 32 is in the right position, port P is connected to port B, and port A is connected to port T. The pressure at port B is greater than the pressure at port A. Therefore, the outlet of the fourth lifting shuttle valve 45 is the pressure at port B, which is connected to the control port of the three-way differential pressure compensator 37. At this time, the outlet pressure of the emergency pump 31 (i.e., port P of the manual proportional directional valve) is always 2.5 MPa higher than the pressure at port B.

[0043] First directional valve 33 and second directional valve 34: These valves control whether ports A and B of the manual proportional directional valve 32 are connected to ports A and B of the lifting hydraulic motor 6. During normal operation, both valves operate in the right-hand position, providing isolation and preventing misoperation. In emergency situations, both valves switch to the left-hand position, controlling the lifting hydraulic motor via the manual proportional directional valve 32.

[0044] The first lifting balance valve 35 and the second lifting balance valve 36: During normal operation, the first lifting balance valve 35 and the second lifting balance valve 36 are used to isolate ports A and B of the lifting hydraulic motor 6. Due to the inevitable leakage of the first lifting balance valve 35 and the second lifting balance valve 36 during long-term operation, the leaked oil can be discharged back to the oil tank through the first reversing valve 33, the second reversing valve 34, and the third lifting shuttle valve 44. At the same time, the first lifting balance valve 35 is also used to balance the load of the lifting hydraulic motor 6. When lifting the load, the first lifting balance valve 35 operates in the left position, and the oil flows from port A to port B, which is equivalent to a check valve; when lowering the load, the first lifting balance valve 35 operates in the right position under the pressure of port B of the manual proportional directional valve 32, and the oil flows from port B to port A. The opening size of the balance valve is adjusted according to the load size and the pressure of port B of the manual proportional directional valve 32.

[0045] First lifting shuttle valve 42: During normal operation, the first lifting shuttle valve 42 is used to lead the high-pressure oil at the inlet and outlet of the lifting lock valve 16 to the control port of the lifting hydraulic motor 6. When the power system or control system fails and is in an emergency state, the lifting hydraulic motor 6 is forced to a large displacement to play a safety protection role.

[0046] Second lifting shuttle valve 43: The second lifting shuttle valve 43 is used to lead the high-pressure oil at the P port of the first reversing valve 33 and the second reversing valve 34 to the control port of the lifting hydraulic motor 6. When the motor variable solenoid valve is de-energized, the lifting hydraulic motor 6 is forced to change to a large displacement, which plays a safety protection role.

[0047] Example 1:

[0048] See Figures 1-3A crane hydraulic system includes a first main pump 1, a second main pump 2, a first solenoid directional valve 3, a second solenoid directional valve 4, a luffing hydraulic cylinder 5, a hoisting hydraulic motor 6, a first solenoid ball valve 11, a second solenoid ball valve 12, a third solenoid ball valve 13, a fourth solenoid ball valve 14, a luffing proportional directional valve 15, a hoisting lock valve 16, a high-pressure relief valve 18, a low-pressure relief valve 19, and a replenishing pump 20. Both the first main pump 1 and the second main pump 2 include a main pump body 7, a load-sensitive control valve 8, and a constant-pressure control valve 9. The inlet of the main pump body 7 is connected to an oil tank 10. Port A of the load-sensitive control valve 8 and the constant-pressure control valve 9 are both connected to the main pump... The outlet of the main body 7 is connected to the oil tank 10 via the B port of the constant pressure control valve 9, which is connected to the P port of the load-sensitive control valve 8. The P port of the constant pressure control valve 9 is connected to the variable cylinder 71 of the main pump body 7. The sensitive control port X of the load-sensitive control valve 8 in the first main pump 1 is connected to the P port of the first solenoid directional valve 3. The sensitive control port X of the load-sensitive control valve 8 in the second main pump 2 is connected to the P port of the second solenoid directional valve 4. The A ports of the first solenoid directional valve 3 and the second solenoid directional valve 4 are both connected to the two oil chambers of the variable amplitude hydraulic cylinder 5. The T ports of the first solenoid directional valve 3 and the second solenoid directional valve 4 are both connected to the oil tank 10 via the P port of the load-sensitive control valve 8, which is connected to the oil tank 10. The P port of the constant pressure control valve 9 is connected to the variable cylinder 71 of the main pump body 7. The sensitive control port X of the load-sensitive control valve 8 in the first main pump 1 is connected to the P port of the second solenoid directional valve 4. The A ports of the first solenoid directional valve 3 and the second solenoid directional valve 4 are both connected to the oil tank 10. Connected to the oil tank 10, the B port of the first electromagnetic directional valve 3 and the B port of the second electromagnetic directional valve 4 are respectively connected to the liquid outlet of the main pump body 7 in the first main pump 1 and the liquid outlet of the main pump body 7 in the second main pump 2. One end of the first electromagnetic ball valve 11 and the second electromagnetic ball valve 12 are connected to the liquid outlet of the main pump body 7 of the first main pump 1, and the other end of the first electromagnetic ball valve 11 and the second electromagnetic ball valve 12 are respectively connected to the P port of the luffing proportional directional valve 15 and one end of the lifting lock valve 16. One end of the third electromagnetic ball valve 13 and the fourth electromagnetic ball valve 14 are connected to the liquid outlet of the main pump body 7 of the second main pump 2, and the other end of the third electromagnetic ball valve 13 and the fourth electromagnetic ball valve 14 are connected to the liquid outlet of the main pump body 7 of the second main pump 2. The ends of the pump 20 are respectively connected to the P port of the luffing proportional directional valve 15 and one end of the lifting lock valve 16. The A and B ports of the luffing proportional directional valve 15 are respectively connected to the two oil chambers of the luffing hydraulic cylinder 5. The T port of the luffing proportional directional valve 15 is connected to the oil tank 10. The other end of the lifting lock valve 16 is connected to the A port of the lifting hydraulic motor 6. One end of the low-pressure relief valve 19 is connected to the oil tank 10. The other end of the low-pressure relief valve 19 is connected to the B port of the lifting hydraulic motor 6 and one end of the high-pressure relief valve 18. The other end of the high-pressure relief valve 18 is connected to the lifting lock valve 16. The inlet and outlet ports of the replenishing pump 20 are respectively connected to the oil tank 10 and the B port of the lifting hydraulic motor 6.

[0049] The above-mentioned crane hydraulic system operation method includes a normal operation method, which includes luffing single-action mode, hoisting single-action mode, and luffing-hoisting linkage mode, wherein...

[0050] In the luffing single-action mode, the first solenoid directional valve 3 and the second solenoid directional valve 4 are both de-energized and operate in their right position, that is, the P port is connected to the A port. The load-sensitive control valve 8 in the first main pump 1 and the second main pump 2 operates in the left position, so that the first main pump 1 and the second main pump 2 both operate in the load-sensitive mode. At the same time, the first solenoid ball valve 11 and the third solenoid ball valve 13 are energized, and the second solenoid ball valve 12 and the fourth solenoid ball valve 14 are de-energized. The first main pump 1 and the second main pump 2 supply oil to the luffing hydraulic cylinder 5 to realize the luffing operation, so as to improve the speed and efficiency of the luffing action. By controlling the direction and opening size of the luffing proportional directional valve 15, the extension and retraction direction and speed of the piston rod of the luffing hydraulic cylinder 5 are controlled.

[0051] In the single-action lifting mode, both the first solenoid directional valve 3 and the second solenoid directional valve 4 are energized and operate in the left position, i.e., port P and port B are connected. At this time, the load-sensitive control valve 8 always operates in the right position, and only the constant pressure control valve 9 is active. Both the first main pump 1 and the second main pump 2 operate in constant pressure mode. At the same time, the first solenoid ball valve 11 and the third solenoid ball valve 13 are de-energized, while the second solenoid ball valve 12 and the fourth solenoid ball valve 14 are energized. Both the first main pump 1 and the second main pump 2 supply oil to the lifting hydraulic motor 6 to achieve the lifting operation.

[0052] In the luffing-hoisting linkage mode, the first solenoid directional valve 3 is de-energized, causing the load-sensitive control valve 8 in the first main pump 1 to operate in the left position, i.e., the first main pump 1 operates in load-sensitive mode. The first solenoid ball valve 11 is energized, and the second solenoid ball valve 12 is de-energized. The first main pump 1 supplies oil to the luffing hydraulic cylinder 5 to achieve luffing operation. At the same time, the second solenoid directional valve 4 is energized, causing the second main pump 2 to operate in constant pressure mode. The third solenoid ball valve 13 is de-energized, and the fourth solenoid ball valve 14 is energized. The second main pump 2 then powers the hoisting hydraulic motor. 6. Oil supply is used to achieve the lifting operation, which includes: when the rope is retracted, the lifting lock valve 16 is energized, and the oil flowing out of the second main pump 2 enters the A port of the lifting hydraulic motor 6 through the lifting lock valve 16, flows out from the B port of the lifting hydraulic motor 6, and returns to the oil tank 10 through the low-pressure relief valve 19; when the rope is released, the replenishing oil pump 20 pumps the oil in the oil tank 10 into the B port of the lifting hydraulic motor 6, and flows out from the A port of the lifting hydraulic motor 6, and returns to the oil tank 10 through the lifting lock valve 16, the high-pressure relief valve 18, and the low-pressure relief valve 19.

[0053] Example 2:

[0054] The difference from Example 1 is as follows:

[0055] The system also includes a variable amplitude balance valve 17, whose A and B ports are respectively connected to the A port of the variable amplitude proportional directional valve 15 and one oil chamber of the variable amplitude hydraulic cylinder 5, and whose control port is connected to the other oil chamber of the variable amplitude hydraulic cylinder 5.

[0056] Example 3:

[0057] The difference from Example 1 is as follows:

[0058] The system also includes a high-voltage accumulator 21 and a low-voltage accumulator 22, which are respectively connected to ports A and B of the lifting hydraulic motor 6.

[0059] In the luffing-lifting linkage mode, during the load lowering process, a portion of the oil from port A of the lifting hydraulic motor 6 flows into the high-pressure accumulator 21 for storage and is released during the load lifting process; during the load lifting process, a portion of the oil from port B of the lifting hydraulic motor 6 flows into the low-pressure accumulator 22 for storage and is released during the load lowering process.

[0060] Example 4:

[0061] The difference from Example 1 is as follows:

[0062] The system also includes an emergency pump 31, a manual proportional directional valve 32, a first reversing valve 33, and a second reversing valve 34. The two ends of the emergency pump 31 are connected to the oil tank 10 and the P port of the manual proportional directional valve 32, respectively. The T port of the manual proportional directional valve 32 is connected to the oil tank 10. The A and B ports of the manual proportional directional valve 32 are connected to the B port of the first reversing valve 33 and the B port of the second reversing valve 34, respectively. The A ports of the first reversing valve 33 and the second reversing valve 34 are both connected to the oil tank 10. The P ports of the first reversing valve 33 and the second reversing valve 34 are connected to the A and B ports of the lifting hydraulic motor 6, respectively.

[0063] The operating method also includes the following emergency lifting method:

[0064] In emergency situations, the first directional valve 33 and the second directional valve 34 switch to the left position, meaning port P is connected to port B. When lifting a load, the manual proportional directional valve 32 operates in the left position, meaning port P is connected to port A and port B is connected to port T. The oil flowing from the outlet of the emergency pump 31 passes sequentially through port P of the manual proportional directional valve 32, port A of the manual proportional directional valve 32, port B of the first directional valve 33, and port P of the first directional valve 33 before entering port A of the lifting hydraulic motor 6. The oil flowing from port B of the lifting hydraulic motor 6 then passes sequentially through port P of the second directional valve 34, port B of the second directional valve 34, and port B of the manual proportional directional valve 32. The oil flows back to the oil tank 10 after passing through the T port of the manual proportional directional valve 32. When lowering the load, the manual proportional directional valve 32 operates in the right position, that is, the P port is connected to the B port and the A port is connected to the T port. The oil flowing out of the outlet of the emergency pump 31 passes through the P port of the manual proportional directional valve 32, the B port of the manual proportional directional valve 32, the B port of the second reversing valve 34, and the P port of the second reversing valve 34 in sequence before entering the B port of the lifting hydraulic motor 6. The oil flowing out of the A port of the lifting hydraulic motor 6 passes through the P port of the first reversing valve 33, the B port of the first reversing valve 33, the A port of the manual proportional directional valve 32, and the T port of the manual proportional directional valve 32 in sequence before returning to the oil tank 10.

[0065] Example 5:

[0066] The difference from Example 4 is that:

[0067] The system also includes a first lifting balance valve 35, a second lifting balance valve 36, and a three-way differential pressure compensator 37. The A port of the first lifting balance valve 35 is connected to the P port of the first reversing valve 33 and the control port of the second lifting balance valve 36. The A port of the second lifting balance valve 36 is connected to the P port of the second reversing valve 34 and the control port of the first lifting balance valve 35. The B ports of the first lifting balance valve 35 and the B ports of the second lifting balance valve 36 are respectively connected to the lifting lock valve 16 and the B port of the lifting hydraulic motor 6. The A and B ports of the three-way differential pressure compensator 37 are respectively connected to the outlet of the oil tank 10 and the emergency pump 31. The control port of the three-way differential pressure compensator 37 is connected to the A and B ports of the manual proportional directional valve 32.

[0068] Example 6:

[0069] The difference from Example 5 is that:

[0070] The system also includes a luffing shuttle valve 41, a first hoisting shuttle valve 42, a second hoisting shuttle valve 43, a third hoisting shuttle valve 44, and a fourth hoisting shuttle valve 45. Ports A and B of the luffing shuttle valve 41 are connected to the two oil chambers of the luffing hydraulic cylinder 5, respectively. Port C of the luffing shuttle valve 41 is connected to port A of the first solenoid directional valve 3 and port A of the second solenoid directional valve 4. Ports A and B of the first hoisting shuttle valve 42 are connected to both ends of the hoisting lock valve 16, respectively. Port C of the first hoisting shuttle valve 42 is connected to the control port of the hoisting hydraulic motor 6 and the control port of the second hoisting shuttle valve 45. The C port of valve 43 is connected, the A and B ports of the second lifting shuttle valve 43 are connected to the P port of the first reversing valve 33 and the P port of the second reversing valve 34, respectively, the A and B ports of the third lifting shuttle valve 44 are connected to the A port of the first reversing valve 33 and the A port of the second reversing valve 34, respectively, the C port of the third lifting shuttle valve 44 is connected to the oil tank 10, the A and B ports of the fourth lifting shuttle valve 45 are connected to the A and B ports of the manual proportional directional valve 32, respectively, and the C port of the fourth lifting shuttle valve 45 is connected to the control port of the three-way differential pressure compensator 37.

Claims

1. A crane hydraulic system, comprising a first main pump (1), a second main pump (2), a first solenoid directional valve (3), a second solenoid directional valve (4), a luffing hydraulic cylinder (5), and a hoisting hydraulic motor (6), wherein the inlets of the first main pump (1) and the second main pump (2) are connected to an oil tank (10), characterized in that: Both the first main pump (1) and the second main pump (2) include a main pump body (7), a load-sensitive control valve (8), and a constant pressure control valve (9). The A port of the load-sensitive control valve (8) and the A port of the constant pressure control valve (9) are connected to the outlet of the main pump body (7). The B port of the constant pressure control valve (9) is connected to the oil tank (10) in sequence through the P port of the load-sensitive control valve (8) and the B port of the load-sensitive control valve (8). The P port of the constant pressure control valve (9) is connected to the variable cylinder (71) of the main pump body (7). The sensitive control port X of the load-sensitive control valve (8) in the first main pump (1) is connected to the first solenoid directional valve. (3) is connected to the P port, the sensitive control port X of the load sensitive control valve (8) in the second main pump (2) is connected to the P port of the second electromagnetic directional valve (4), the A port of the first electromagnetic directional valve (3) and the A port of the second electromagnetic directional valve (4) are both connected to the two oil chambers of the variable amplitude hydraulic cylinder (5), the B port of the first electromagnetic directional valve (3) and the B port of the second electromagnetic directional valve (4) are respectively connected to the liquid outlet of the main pump body (7) in the first main pump (1) and the liquid outlet of the main pump body (7) in the second main pump (2), and the T port of the first electromagnetic directional valve (3) and the T port of the second electromagnetic directional valve (4) are both connected to the oil tank (10); The system also includes a first electromagnetic ball valve (11), a second electromagnetic ball valve (12), a third electromagnetic ball valve (13), and a fourth electromagnetic ball valve (14). One end of the first electromagnetic ball valve (11) and the second electromagnetic ball valve (12) are connected to the outlet of the main pump body (7) of the first main pump (1). The other end of the first electromagnetic ball valve (11) and the second electromagnetic ball valve (12) are respectively connected to an oil chamber of the luffing hydraulic cylinder (5) and port A of the lifting hydraulic motor (6). One end of the third electromagnetic ball valve (13) and the fourth electromagnetic ball valve (14) are connected to the outlet of the main pump body (7) of the second main pump (2). The other end of the third electromagnetic ball valve (13) and the fourth electromagnetic ball valve (14) are respectively connected to an oil chamber of the luffing hydraulic cylinder (5) and port A of the lifting hydraulic motor (6). The other oil chamber of the luffing hydraulic cylinder (5) and port B of the lifting hydraulic motor (6) are both connected to the oil tank (10).

2. A crane hydraulic system according to claim 1, characterized in that: The system also includes a high-pressure accumulator (21) and a low-pressure accumulator (22), which are respectively connected to ports A and B of the lifting hydraulic motor (6).

3. A crane hydraulic system according to claim 1 or 2, characterized in that: The system also includes an emergency pump (31), a manual proportional directional valve (32), a first directional valve (33), and a second directional valve (34). The inlet and outlet of the emergency pump (31) are connected to the oil tank (10) and the P port of the manual proportional directional valve (32), respectively. The T port of the manual proportional directional valve (32) is connected to the oil tank (10). The A and B ports of the manual proportional directional valve (32) are connected to the B port of the first directional valve (33) and the B port of the second directional valve (34), respectively. The A port of the first directional valve (33) and the A port of the second directional valve (34) are both connected to the oil tank (10). The P port of the first directional valve (33) and the P port of the second directional valve (34) are connected to the A and B ports of the lifting hydraulic motor (6), respectively.

4. A crane hydraulic system according to claim 3, characterized in that: The system also includes a luffing proportional directional valve (15) and a lifting lock valve (16). The P port of the luffing proportional directional valve (15) is connected to the first electromagnetic ball valve (11) and the third electromagnetic ball valve (13). The T port of the luffing proportional directional valve (15) is connected to the oil tank (10). The A and B ports of the luffing proportional directional valve (15) are connected to the two oil chambers of the luffing hydraulic cylinder (5) respectively. One end of the lifting lock valve (16) is connected to the second electromagnetic ball valve (12) and the fourth electromagnetic ball valve (14). The other end of the lifting lock valve (16) is connected to the A port of the lifting hydraulic motor (6).

5. A crane hydraulic system according to claim 4, characterized in that: The system also includes a first lifting balance valve (35), a second lifting balance valve (36), and a three-way differential pressure compensator (37). The A port of the first lifting balance valve (35) is connected to the P port of the first reversing valve (33) and the control port of the second lifting balance valve (36). The A port of the second lifting balance valve (36) is connected to the P port of the second reversing valve (34) and the control port of the first lifting balance valve (35). The B port of the first lifting balance valve (35) and the B port of the second lifting balance valve (36) are connected to the lifting lock valve (16) and the B port of the lifting hydraulic motor (6), respectively. The A and B ports of the three-way differential pressure compensator (37) are connected to the outlet of the oil tank (10) and the emergency pump (31), respectively. The control port of the three-way differential pressure compensator (37) is connected to the A and B ports of the manual proportional directional valve (32).

6. A crane hydraulic system according to claim 4, characterized in that: The system also includes a luffing balance valve (17), a high-pressure relief valve (18), a low-pressure relief valve (19), and a replenishing pump (20). The A and B ports of the luffing balance valve (17) are connected to the A port of the luffing proportional directional valve (15) and one oil chamber of the luffing hydraulic cylinder (5), respectively. The control port of the luffing balance valve (17) is connected to the other oil chamber of the luffing hydraulic cylinder (5). One end of the low-pressure relief valve (19) is connected to the oil tank (10). The other end of the low-pressure relief valve (19) is connected to the B port of the hoisting hydraulic motor (6) and one end of the high-pressure relief valve (18). The other end of the high-pressure relief valve (18) is connected to the hoisting lock valve (16). The inlet and outlet ports of the replenishing pump (20) are connected to the oil tank (10) and the B port of the hoisting hydraulic motor (6), respectively.

7. A crane hydraulic system according to claim 5, characterized in that: The system also includes a luffing shuttle valve (41), a first hoisting shuttle valve (42), a second hoisting shuttle valve (43), a third hoisting shuttle valve (44), and a fourth hoisting shuttle valve (45). The A and B ports of the luffing shuttle valve (41) are respectively connected to the two oil chambers of the luffing hydraulic cylinder (5). The C port of the luffing shuttle valve (41) is connected to the A port of the first solenoid directional valve (3) and the A port of the second solenoid directional valve (4). The A and B ports of the first hoisting shuttle valve (42) are respectively connected to the two ends of the hoisting lock valve (16). The C port of the first hoisting shuttle valve (42) is connected to the control port of the hoisting hydraulic motor (6) and the second hoisting lock valve (45). The C port of the shuttle valve (43) is connected, the A and B ports of the second lifting shuttle valve (43) are connected to the P port of the first reversing valve (33) and the P port of the second reversing valve (34) respectively, the A and B ports of the third lifting shuttle valve (44) are connected to the A port of the first reversing valve (33) and the A port of the second reversing valve (34) respectively, the C port of the third lifting shuttle valve (44) is connected to the oil tank (10), the A and B ports of the fourth lifting shuttle valve (45) are connected to the A and B ports of the manual proportional directional valve (32) respectively, and the C port of the fourth lifting shuttle valve (45) is connected to the control port of the three-way differential pressure compensator (37).

8. A method for operating the hydraulic system of a crane according to claim 1, characterized in that: The operating method includes a normal operating method, which includes luffing single-action mode, hoisting single-action mode, and luffing-hoisting linkage mode, wherein... In the variable luffing single-action mode, the first electromagnetic reversing valve (3) and the second electromagnetic reversing valve (4) are de-energized and operate in the right position, that is, the P port is connected to the A port. The load-sensitive control valve (8) in the first main pump (1) and the second main pump (2) operates in the left position, so that the first main pump (1) and the second main pump (2) both operate in the load-sensitive mode. At the same time, the first electromagnetic ball valve (11) and the third electromagnetic ball valve (13) are energized, and the second electromagnetic ball valve (12) and the fourth electromagnetic ball valve (14) are de-energized. The first main pump (1) and the second main pump (2) both supply oil to the variable luffing hydraulic cylinder (5) to realize the variable luffing operation. In the single-action lifting mode, the first solenoid directional valve (3) and the second solenoid directional valve (4) are energized and operate in the left position, that is, the P port is connected to the B port. At this time, the load-sensitive control valve (8) always operates in the right position, and only the constant pressure control valve (9) is active. The first main pump (1) and the second main pump (2) are both operating in the constant pressure mode. At the same time, the first solenoid ball valve (11) and the third solenoid ball valve (13) are de-energized, and the second solenoid ball valve (12) and the fourth solenoid ball valve (14) are energized. The first main pump (1) and the second main pump (2) supply oil to the lifting hydraulic motor (6) to realize the lifting operation. In the luffing-lifting linkage mode, the first solenoid directional valve (3) is de-energized, causing the load-sensitive control valve (8) in the first main pump (1) to operate in the left position, that is, the first main pump (1) operates in the load-sensitive mode, the first solenoid ball valve (11) is energized, the second solenoid ball valve (12) is de-energized, and the first main pump (1) supplies oil to the luffing hydraulic cylinder (5) to realize the luffing operation; at the same time, the second solenoid directional valve (4) is energized, causing the second main pump (2) to operate in the constant pressure mode, the third solenoid ball valve (13) is de-energized, the fourth solenoid ball valve (14) is energized, and the second main pump (2) supplies oil to the lifting hydraulic motor (6) to realize the lifting operation.

9. The method for operating a crane hydraulic system according to claim 8, characterized in that: The system also includes a high-voltage accumulator (21) and a low-voltage accumulator (22), which are respectively connected to ports A and B of the lifting hydraulic motor (6); In the variable amplitude-lifting linkage mode, during the load lowering process, a portion of the oil coming out of port A of the lifting hydraulic motor (6) flows into the high-pressure accumulator (21) for storage and is released during the load lifting process; during the load lifting process, a portion of the oil coming out of port B of the lifting hydraulic motor (6) flows into the low-pressure accumulator (22) for storage and is released during the load lowering process.

10. A method for operating a crane hydraulic system according to claim 8, characterized in that: The system also includes an emergency pump (31), a manual proportional directional valve (32), a first reversing valve (33), and a second reversing valve (34). The two ends of the emergency pump (31) are connected to the oil tank (10) and the P port of the manual proportional directional valve (32), respectively. The T port of the manual proportional directional valve (32) is connected to the oil tank (10). The A and B ports of the manual proportional directional valve (32) are connected to the B port of the first reversing valve (33) and the B port of the second reversing valve (34), respectively. The A port of the first reversing valve (33) and the A port of the second reversing valve (34) are both connected to the oil tank (10). The P port of the first reversing valve (33) and the P port of the second reversing valve (34) are connected to the A and B ports of the lifting hydraulic motor (6), respectively. The operating method also includes the following emergency lifting method: In emergency situations, the first directional valve (33) and the second directional valve (34) switch to the left position, i.e., port P is connected to port B. When lifting the load, the manual proportional directional valve (32) operates in the left position, i.e., port P is connected to port A and port B is connected to port T. The oil flowing out of the emergency pump (31) outlet passes through port P of the manual proportional directional valve (32), port A of the manual proportional directional valve (32), port B of the first directional valve (33), and port P of the first directional valve (33) before entering port A of the lifting hydraulic motor (6). The oil flowing out of port B of the lifting hydraulic motor (6) passes through port P of the second directional valve (34), port B of the second directional valve (34), port B of the manual proportional directional valve (32), and port T of the manual proportional directional valve (31). The oil flows back to the oil tank (10) after the T port of the proportional directional valve (32). When the load is lowered, the manual proportional directional valve (32) is in the right position, that is, the P port is connected to the B port and the A port is connected to the T port. The oil flowing out of the outlet of the emergency pump (31) passes through the P port of the manual proportional directional valve (32), the B port of the manual proportional directional valve (32), the B port of the second reversing valve (34), and the P port of the second reversing valve (34) in sequence and then enters the B port of the lifting hydraulic motor (6). The oil flowing out of the A port of the lifting hydraulic motor (6) passes through the P port of the first reversing valve (33), the B port of the first reversing valve (33), the A port of the manual proportional directional valve (32), and the T port of the manual proportional directional valve (32) in sequence and then returns to the oil tank (10).

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