A hydraulic system and control method for crane overload protection

Abstract

The present invention provides a hydraulic system and a control method for crane overload protection. The specific steps include: S1 The overload three-position seven-way directional control valve is commutated, and the P port of the overload three-position seven-way directional control valve is connected to the B port, and the oil tank conveys hydraulic oil to the winch control module; S2 When the double-extension crane reaches the upper limit position of hoisting, the overload second two-position two-way directional control valve is commutated, so that the P port of the overload second two-position two-way directional control valve is connected to the B port; S3 The winch control module controls the overload first two-position two-way directional control valve to be commutated, and the P port of the overload first two-position two-way directional control valve is connected to the B port; S4 The oil tank continues to supply oil to the winch control module through the overload three-position seven-way directional control valve; S5 The redundant hydraulic oil can flow back to the oil tank from the overload first two-position two-way directional control valve.

Description

Technical Field

[0001] The present invention relates to the technical field of telescopic crane systems, and particularly relates to a hydraulic system and a control method for crane overload protection. Background Art

[0002] A ship crane is a machine used by a transport ship for hoisting and loading / unloading goods. It is an important part of the ship. Due to the limited space on the ship, various use equipment and the hull structure layout are very compact. The working stability of the ship crane directly affects the safety of cargo transportation. For safety reasons, when the ship crane is restricted by the installation location and nearby fixed or non-fixed obstacles, each ship must add a mandatory automatic limit function, which is divided into two types: full limit and area limit. The full limit means that the crane is not allowed to enter the rotation area under any working conditions; the area limit means that the crane can only rotate into the area when the boom elevation angle is higher than a certain angle, and after entering this area, the boom elevation angle cannot be lower than the conditional height. The existing limit implementation method is to pre-weld limit baffles in the limited area with obstacles according to the hull layout drawing, and select hydraulic or electrical limit switches to sense the area boundary to achieve the limit stop function.

[0003] In the patent document with the Chinese patent application number 201810944519.3 and the publication date of October 23, 2018, a double-telescopic self-balancing tower crane for a cargo ship is disclosed. Usually, the telescopic base assembly and the telescopic self-balancing boom assembly in the double-telescopic self-balancing tower crane are retracted and docked. During work, it is not subject to full limit and area limit. The telescopic self-balancing boom assembly that can be raised and rotated and the hoisting mechanism therein can directly load and unload goods with small and large spans between the ship and the dock, eliminating the dependence on the dock crane. The characteristics of the double-telescopic self-balancing tower crane for a cargo ship are: the double-telescopic self-balancing tower crane is installed on the cargo ship, and usually, the telescopic base assembly and the telescopic self-balancing boom assembly in the double-telescopic self-balancing tower crane are retracted and docked; for the double-telescopic self-balancing tower crane, the telescopic base assembly is installed on the cargo ship, and the telescopic self-balancing boom assembly is arranged on the rotating assembly in the telescopic base assembly.

[0004] However, the double-telescopic crane in this application does not control the recovery of the cable. In this way, during work, it is easy to cause the cable to collide with the boom when the cable is recovered, resulting in damage to the hook. Therefore, it is necessary to manually observe the progress of the cable recovery during the cable recovery. When approaching the limit position, manual operation is required to stop the cable recovery. Therefore, the manual workload is increased, and manual observation is prone to errors. Summary of the Invention

[0005] The present invention provides a hydraulic system and a control method for crane overload protection. The system and control method of the present invention can achieve the lifting control of a double-extension crane, making the lifting of the double-extension crane stable and preventing the double-extension crane from lifting beyond the upper limit.

[0006] To achieve the above object, the technical solution of the present invention is: A hydraulic system for crane overload protection includes a hydraulic control system and a double-extension crane. The hydraulic control system includes a multi-way valve group, an oil tank, an oil pump, an overload protection valve group, and a winch control module. One end of the oil tank is connected to the oil pump, and the other end of the oil pump is connected to the oil inlet end of the multi-way valve group. The oil outlet end of the multi-way valve group is connected to the oil tank. The overload protection valve group is connected to the multi-way valve group, and the overload protection valve group is used to drive the double-extension crane to lift.

[0007] The multi-way valve group includes a slewing valve group, a lifting valve group, and a telescopic valve group. The oil inlet ends of the slewing valve group, the lifting valve group, and the telescopic valve group are connected to the oil pump, and the oil outlet ends of the slewing valve group, the lifting valve group, and the telescopic valve group are connected to the oil tank.

[0008] The overload protection valve group includes an overload first two-position two-way directional valve, an overload relief valve, an overload three-position seven-way directional valve, an overload second two-position two-way directional valve, and an overload oil drain and pressure stabilizing valve group. The P port of the overload three-position seven-way directional valve is connected to the oil pump, the T port of the overload three-position seven-way directional valve is connected to the oil tank, the B port of the overload three-position seven-way directional valve is connected to the MW1 port of the winch control module, the A port of the overload three-position seven-way directional valve is connected to the MW2 port of the winch control module, the oil drain port of the overload three-position seven-way directional valve is connected to the overload oil drain and pressure stabilizing valve group, and the overload oil drain and pressure stabilizing valve group is also connected to the P port of the overload first two-position two-way directional valve. The B port of the overload first two-position two-way directional valve is connected to one end of the overload relief valve, the other end of the overload relief valve is connected to the oil tank, the T port of the overload first two-position two-way directional valve is connected to the oil tank, and the A port of the overload first two-position two-way directional valve is normally closed. The control port of the overload first two-position two-way directional valve is connected to the B port of the overload second two-position two-way directional valve. The MW2 port of the winch control module is also connected to the P port of the overload second two-position two-way directional valve. The T port of the overload second two-position two-way directional valve is connected to the oil tank, and the A port of the overload second two-position two-way directional valve is normally closed.

[0009] A control method for a hydraulic system for crane overload protection includes the following steps.

[0010] S1 The overload three-position seven-way directional valve is commutated, connecting the P port and the B port of the overload three-position seven-way directional valve, and the oil tank conveys hydraulic oil to the winch control module.

[0011] S2 When the double-extension crane reaches the upper limit of lifting, the overload second two-position two-way directional valve is commutated, making the P port and the B port of the overload second two-position two-way directional valve connected.

[0012] The S3 winch control module controls the overload first two-position two-way directional valve to change its direction, connecting the P port of the overload first two-position two-way directional valve to the B port.

[0013] The S4 oil tank continues to supply oil to the winch control module through the overload three-position seven-way directional valve.

[0014] The excess hydraulic oil can flow back to the oil tank from the overload first two-position two-way directional valve.

[0015] In the above-mentioned hydraulic system for crane overload protection, during operation, the hydraulic control system controls the double telescopic crane to perform telescopic actions. The overload three-position seven-way directional valve changes its direction, connecting the P port of the overload three-position seven-way directional valve to the B port, so that the oil tank supplies hydraulic oil to the winch control module through the overload three-position seven-way directional valve. When the double telescopic crane reaches the upper limit position of hoisting, the overload second two-position two-way directional valve changes its direction, making the P port of the overload second two-position two-way directional valve communicate with the B port. The MW2 end of the winch control module can then supply hydraulic oil to the control end of the overload first two-position two-way directional valve through the overload second two-position two-way directional valve, thereby controlling the overload first two-position two-way directional valve to change its direction and connecting the P port of the overload first two-position two-way directional valve to the B port. Thus, the oil tank continues to supply oil to the winch control module through the overload three-position seven-way directional valve, and the excess hydraulic oil can flow back to the oil tank from the overload first two-position two-way directional valve, thereby controlling the double telescopic crane to stop hoisting after reaching the upper limit position of hoisting. Through the above settings, it is ensured that the double telescopic crane will not exceed the upper limit position of hoisting during hoisting.

[0016] Further, the telescopic valve group includes a telescopic three-position seven-way directional valve, a telescopic one-way valve, a first-stage telescopic oil cylinder, and a second-stage telescopic oil cylinder. One end of the telescopic one-way valve is connected to the oil pump, and the other end of the telescopic one-way valve is connected to the P port of the telescopic three-position seven-way directional valve. The B port of the telescopic three-position seven-way directional valve is connected to one end of the first-stage telescopic oil cylinder and the second-stage telescopic oil cylinder. The A port of the telescopic three-position seven-way directional valve is connected to the other end of the first-stage telescopic oil cylinder and the second-stage telescopic oil cylinder. The T port of the telescopic three-position seven-way directional valve is connected to the oil tank; the drain port of the telescopic three-position seven-way directional valve is connected to the telescopic drain and pressure stabilizing valve group. With the above settings, the telescopic action of the double telescopic crane is realized through the telescopic valve group.

[0017] Further, the slewing valve group includes a slewing three-position seven-way directional valve, a slewing one-way valve, and a slewing output system. One end of the slewing one-way valve is connected to the oil pump, and the other end of the slewing one-way valve is connected to the P port of the slewing three-position seven-way directional valve. The B port of the slewing three-position seven-way directional valve is connected to the SW1 end of the slewing output system. The A port of the slewing three-position seven-way directional valve is connected to the SW2 end of the slewing output system. The T port of the slewing three-position seven-way directional valve is connected to the oil tank; the SWT end of the slewing output system is connected to the oil tank.

[0018] With the above settings, when the double telescopic crane needs to turn, the swing three-position seven-way directional control valve changes its position, causing the P port of the swing three-position seven-way directional control valve to communicate with the B port, and the A port of the swing three-position seven-way directional control valve to communicate with the T port. Thus, the hydraulic oil can flow through the swing three-position seven-way directional control valve to the swing output system to control the swing output system, enabling the double telescopic motor to turn.

[0019] Furthermore, the lifting valve group includes a lifting three-position seven-way directional control valve, a lifting check valve, and a lifting oil cylinder. One end of the lifting check valve is connected to the oil pump, and the other end of the lifting check valve is connected to the P port of the lifting three-position seven-way directional control valve. The B port of the lifting three-position seven-way directional control valve is connected to one end of the lifting oil cylinder, the A port of the lifting three-position seven-way directional control valve is connected to the other end of the lifting oil cylinder, and the T port of the lifting three-position seven-way directional control valve is connected to the fuel tank.

[0020] With the above settings, when the telescopic crane needs to lift, the lifting three-position seven-way directional control valve changes its position, causing the P port of the lifting three-position seven-way directional control valve to communicate with the B port, and the A port of the lifting three-position seven-way directional control valve to communicate with the T port. The hydraulic oil can then flow through the lifting three-position seven-way directional control valve to one end of the lifting oil cylinder, and the hydraulic oil flows back to the fuel tank from the other end of the lifting oil cylinder. Thus, it can drive the lifting oil cylinder to extend to control the double telescopic crane to rise. When the telescopic crane needs to lower, the lifting three-position seven-way directional control valve changes its position, causing the P port of the lifting three-position seven-way directional control valve to communicate with the A port, and the B port of the lifting three-position seven-way directional control valve to communicate with the T port. The hydraulic oil can then flow through the lifting three-position seven-way directional control valve to the other end of the lifting oil cylinder, and the hydraulic oil flows back to the fuel tank from one end of the lifting oil cylinder. Thus, it can drive the lifting oil cylinder to retract to control the double telescopic crane to lower.

[0021] Furthermore, the telescopic oil drain and pressure stabilizing valve group includes a telescopic oil drain first shuttle valve, a telescopic oil drain second shuttle valve, a telescopic oil drain first relief valve, and a telescopic oil drain second relief valve. The oil drain port of the telescopic three-position seven-way directional control valve is connected to the oil inlet ends at both ends of the telescopic oil drain first shuttle valve. The oil outlet end of the telescopic oil drain first shuttle valve is connected to the oil inlet end of one end of the telescopic oil drain second shuttle valve. The oil inlet end of the other end of the telescopic oil drain second shuttle valve is connected to the fuel tank, and the oil outlet end of the telescopic oil drain second shuttle valve is connected to the fuel tank. One oil inlet end of the telescopic oil drain first shuttle valve is also connected to one end of the telescopic oil drain first relief valve, and the other end of the telescopic oil drain first relief valve is connected to the fuel tank. The other oil inlet end of the telescopic oil drain first shuttle valve is also connected to one end of the telescopic oil drain second relief valve, and the other end of the telescopic oil drain second relief valve is connected to the fuel tank. Through the setting of the telescopic oil drain and pressure stabilizing valve group, the stability of oil drain can be ensured when the telescopic valve group drains oil. When the telescopic valve group drains oil, the excess hydraulic oil flows back to the fuel tank through the telescopic oil drain first relief valve and the telescopic oil drain second relief valve. The two relief valves enable the hydraulic oil to be shunted during oil drain, thus making the flow of the hydraulic oil stable and the flow rate not too large.

[0022] Furthermore, an emergency pump valve group is provided between the fuel tank and the winch control module. The emergency pump valve group includes an emergency manual pump, an emergency check valve, a first diaphragm valve, and a second diaphragm valve. One end of the emergency manual pump is connected to the fuel tank, and the other end of the emergency manual pump is connected to one end of the emergency check valve. The other end of the emergency check valve is connected to the winch control module; a first diaphragm valve is connected between the emergency manual pump and the fuel tank, and a second diaphragm valve is connected between one end of the emergency manual pump and the other end of the emergency check valve.

[0023] With this arrangement, through the setting of the emergency pump valve group, when the double telescopic crane encounters special circumstances and cannot be started normally, the emergency pump supplies oil to the double telescopic crane, enabling the double telescopic crane to perform emergency work and preventing accidents from occurring.

[0024] Furthermore, a filter valve group is provided between the oil outlet end of the multi-way valve group and the fuel tank. The filter valve group includes a filter, an oil pressure gauge, and a filter check valve. One end of the filter is connected to the oil outlet end of the multi-way valve group, the other end of the filter is connected to the fuel tank, the filter check valve is arranged in parallel with the filter, and an oil pressure gauge is also connected to one end of the filter. With this arrangement, the returned hydraulic oil is filtered by the filter valve group, ensuring that the hydraulic oil returned to the fuel tank does not contain too many impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a simple schematic diagram of the hydraulic control system of the present invention.

[0026] Figure 2 It is a schematic diagram of the hook limit valve group and the overload protection valve group of the present invention.

[0027] Figure 3 It is a schematic diagram of the winch control module and the telescopic valve group of the present invention.

[0028] Figure 4 It is Figure 3 The enlarged view at position Z in

[0029] Figure 5 It is Figure 2 The enlarged view at position Y in

[0030] Figure 6 It is a schematic diagram of the lifting valve group and the telescopic valve group in the multi-way valve group of the present invention.

[0031] Figure 7 It is a schematic diagram of the lifting valve group and the telescopic valve group of the present invention.

[0032] Figure 8 It is Figure 2 The enlarged view at position E in

[0033] Figure 9Schematic diagram of the emergency pump valve group of the present invention.

[0034] Figure 10 Schematic diagram of the filter valve group of the present invention.

[0035] Figure 11 Schematic structural diagram of the double telescopic crane controlled by the hydraulic control system of the present invention.

[0036] Figure 12 Schematic structural diagram of the hook mechanism of the present invention.

[0037] Figure 13 Schematic structural diagram of the lifting limit assembly of the present invention.

[0038] Figure 14 Control flow chart of the hydraulic system for crane overload protection of the present invention. Detailed implementation manners

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0040] As Figures 1 to 14 shown, a hydraulic system for crane overload protection includes a hydraulic control system 1 and a double telescopic crane 2. The hydraulic control system is used to control the double telescopic crane 2 (shown in Figure 11 ). The hydraulic control system 1 includes a multi-way valve group 3, an oil tank 10, an oil pump 11, an overload protection valve group 5, and a winch control module 12. One end of the oil tank 10 is connected to the oil pump 11, and the other end of the oil pump 11 is connected to the inlet end of the multi-way valve group 3. The outlet end of the multi-way valve group 3 is connected to the oil tank 10. The hydraulic control system 1 further includes a hook limit valve group 4. The hook limit valve group 4 is connected to the control end of the multi-way valve group 3, and an overload protection valve group 5 is provided on the hook limit valve group 4. The winch control module is used to control the double telescopic crane to perform lifting and extension.

[0041] The multi-way valve group 3 includes a slewing valve group 31, a lifting valve group 32, and a telescopic valve group 33. The inlet ends of the slewing valve group 31, the lifting valve group 32, and the telescopic valve group 33 are connected to the oil pump 11, and the outlet ends of the slewing valve group 31, the lifting valve group 32, and the telescopic valve group 33 are connected to the oil tank 10. The multi-way valve group 3 is used to drive the double telescopic crane 2.

[0042] As Figure 1 and Figure 2As shown, the hook limit valve group 4 includes a limit first two-position two-way changeover valve 41 and a limit second two-position two-way changeover valve 42. The P port of the limit first two-position two-way changeover valve 41 is connected to the telescopic valve group 33. The T port of the limit first two-position two-way changeover valve 41 is connected to the oil tank 10. The B port of the limit first two-position two-way changeover valve 41 is connected to the oil tank 10. The control port 41K of the limit first two-position two-way changeover valve 41 is connected to the MWL port of the winch control module 12. The A port of the limit first two-position two-way changeover valve 41 is normally closed.

[0043] The A port of the limit second two-position two-way changeover valve 42 is connected to the overload protection valve group 5. The T port of the limit second two-position two-way changeover valve 42 is connected to the oil tank 10. The B port of the limit second two-position two-way changeover valve 42 is connected to the oil tank 10. The control port 42K of the limit second two-position two-way changeover valve 42 is connected to the MWL port of the winch control module 12. The P port of the limit second two-position two-way changeover valve 42 is normally closed.

[0044] As Figures 1 to 4 shown, the overload protection valve group 5 includes an overload first two-position two-way changeover valve 51, an overload relief valve 52, an overload three-position seven-way changeover valve 53, an overload second two-position two-way changeover valve 54, and an overload oil drain and pressure stabilizing valve group 55. The P port of the overload three-position seven-way changeover valve 53 is connected to the connecting oil pump 11. The T port of the overload three-position seven-way changeover valve 53 is connected to the oil tank 10. The B port of the overload three-position seven-way changeover valve 53 is connected to the MW1 port of the winch control module 12. The A port of the overload three-position seven-way changeover valve 53 is connected to the MW2 port of the winch control module 12. The oil drain port 53K of the overload three-position seven-way changeover valve 53 is connected to the overload oil drain and pressure stabilizing valve group 55. The overload oil drain and pressure stabilizing valve group 55 is also connected to the P port of the overload first two-position two-way changeover valve 51. The B port of the overload first two-position two-way changeover valve 51 is connected to one end of the overload relief valve 52. The other end of the overload relief valve 52 is connected to the oil tank 10. The T port of the overload first two-position two-way changeover valve 51 is connected to the oil tank 10. The A port of the overload first two-position two-way changeover valve 51 is normally closed. The control port 51K of the overload first two-position two-way changeover valve 51 is connected to the B port of the overload second two-position two-way changeover valve 54 (shown in Figure 4 ). The MW2 port of the winch control module 12 is also connected to the P port of the overload second two-position two-way changeover valve 54. The T port of the overload second two-position two-way changeover valve 54 is connected to the oil tank 10. The A port of the overload second two-position two-way changeover valve 54 is normally closed.

[0045] As Figure 2 and Figure 5As shown, the overload oil-draining and pressure-stabilizing valve group 55 includes an overload oil-draining first shuttle valve 551, an overload oil-draining second shuttle valve 552, an overload oil-draining first overflow valve 553, and an overload oil-draining second overflow valve 554. The oil-draining port 53K of the overload three-position seven-way directional control valve 53 is connected to the oil-inlet ends 551P at both ends of the overload oil-draining first shuttle valve 551. The oil-outlet end 551T of the overload oil-draining first shuttle valve 551 is connected to the oil-inlet end 552P at one end of the overload oil-draining second shuttle valve 552. The oil-inlet end 552P at the other end of the overload oil-draining second shuttle valve 552 is connected to the fuel tank 10. The oil-outlet end of the overload oil-draining second shuttle valve is connected to the fuel tank. One oil-inlet end of the overload oil-draining first shuttle valve 551 is also connected to one end of the overload oil-draining first overflow valve 553, and the other end of the overload oil-draining first overflow valve 553 is connected to the fuel tank 10. The oil-inlet end at the other end of the overload oil-draining first shuttle valve 551 is also connected to one end of the overload oil-draining second overflow valve 554, and the other end of the overload oil-draining second overflow valve 554 is connected to the fuel tank 10. The oil-inlet port of the overload oil-draining first shuttle valve is also connected to the P port of the overload first two-position two-way directional control valve. Through the setting of the overload oil-draining and pressure-stabilizing valve group, the stability of oil-draining can be ensured when the overload valve group drains oil. When the overload valve group drains oil, the excess hydraulic oil flows back to the fuel tank through the overload oil-draining first overflow valve and the overload oil-draining second overflow valve. The two overflow valves play a role in splitting the hydraulic oil during oil-draining, so that the hydraulic oil flows stably and the flow rate is not too large.

[0046] As Figures 1 to 5As shown, the telescopic valve group 33 includes a telescopic three-position seven-way directional control valve 331, a telescopic check valve 332, a primary telescopic oil cylinder 333, and a secondary telescopic oil cylinder 334. One end of the telescopic check valve 332 is connected to the oil pump 11, and the other end of the telescopic check valve 332 is connected to the P port of the telescopic three-position seven-way directional control valve 331. The B port of the telescopic three-position seven-way directional control valve 331 is connected to one end of the primary telescopic oil cylinder 333 and the secondary telescopic oil cylinder 334. The A port of the telescopic three-position seven-way directional control valve 331 is connected to the other end of the primary telescopic oil cylinder 333 and the secondary telescopic oil cylinder 334. In this embodiment, one end of the primary telescopic oil cylinder 333 and the secondary telescopic oil cylinder 334 is represented by C, and the other end of the primary telescopic oil cylinder 333 and the secondary telescopic oil cylinder 334 is represented by D. The T port of the telescopic three-position seven-way directional control valve 331 is connected to the oil tank 10. The drain port 331K of the telescopic three-position seven-way directional control valve 331 is connected to the P port of the limit first two-position two-way directional control valve 41. A telescopic drain pressure stabilizing valve group 335 is connected between the drain port 331K of the telescopic three-position seven-way directional control valve 331 and the P port of the limit first two-position two-way directional control valve 41. In this embodiment, a balance oil circuit is connected between the telescopic three-position seven-way directional control valve 331 and the primary telescopic oil cylinder 333 and the secondary telescopic oil cylinder 334. The balance oil circuit is used to keep the hydraulic oil output to the primary telescopic oil cylinder and the secondary telescopic oil cylinder in a stable state. The specific oil circuit is prior art and will not be elaborated below.

[0047] In the above structure, during operation, the hydraulic control system 1 controls the telescopic movement of the double-telescopic crane 2. The overload three-position seven-way directional control valve 53 changes its direction, connecting the P port of the overload three-position seven-way directional control valve 53 to the B port, so that the oil tank 10 supplies hydraulic oil to the winch control module 12 through the overload three-position seven-way directional control valve 53. When the double-telescopic crane 2 extends to the upper limit position, the MWL port of the winch control module 12 supplies hydraulic oil to the control end 41K of the limit first two-position two-way directional control valve 41 to control the direction change of the limit first two-position two-way directional control valve 41, connecting the P port of the limit first two-position two-way directional control valve 41 to the B port of the limit first two-position two-way directional control valve 41, so that the oil circuit between the oil discharge port 331K of the telescopic three-position seven-way directional control valve 331 and the oil tank 10 is connected. Thus, the oil tank 10 continues to supply oil to the first-stage telescopic cylinder 333 and the second-stage telescopic cylinder 334 through the telescopic three-position seven-way directional control valve 331, and the excess hydraulic oil can flow back to the oil tank 10 through the limit first two-position two-way directional control valve 41, while the first-stage telescopic cylinder 333 and the second-stage telescopic cylinder 334 remain in the extended state. In this embodiment, the hydraulic control system pre-sets the preset value of the extended upper limit position of the double-telescopic crane. When the double-telescopic crane reaches the preset value of the extended upper limit position, the winch control module controls the limit first two-position two-way directional control valve to change its direction and drain oil to achieve the extension control of the double-telescopic crane, so as to ensure that the double-telescopic motor 2 maintains the extended action and does not exceed the upper limit of extension; when the double-telescopic crane 2 reaches the upper limit position of lifting, the overload second two-position two-way directional control valve 54 changes its direction, making the P port of the overload second two-position two-way directional control valve 54 communicate with the B port. The MW2 port of the winch control module 12 can then supply hydraulic oil to the control end 51K of the overload first two-position two-way directional control valve 51 through the overload second two-position two-way directional control valve 54, thereby controlling the overload first two-position two-way directional control valve 51 to change its direction and connecting the P port of the overload first two-position two-way directional control valve 51 to the B port. Thus, the oil tank 10 continues to supply oil to the winch control module 12 through the overload three-position seven-way directional control valve 53, and the excess hydraulic oil can flow back to the oil tank 10 from the overload first two-position two-way directional control valve 51, so as to control the lifting of the double-telescopic crane 2 not to exceed the upper limit position of lifting. In this embodiment, the hydraulic control system pre-sets the preset value of the upper limit position of lifting of the double-telescopic crane. When the double-telescopic crane reaches the preset value of the upper limit position of lifting, the overload second two-position two-way directional control valve changes its direction, so that the winch control module controls the overload first two-position two-way directional control valve to change its direction and drain oil to achieve the lifting control of the double-telescopic crane. Through the above settings, it is ensured that the double-telescopic crane will not cause damage to the structure of the telescopic arm due to excessive extension during operation, and it can also ensure that the double-telescopic crane will not exceed the upper limit position of lifting when lifting.

[0048] As Figure 6 and Figure 7As shown, the swing valve group 31 includes a swing three-position seven-way directional control valve 311, a swing check valve 312, and a swing output system 313. One end of the swing check valve 312 is connected to the oil pump 11, and the other end of the swing check valve 312 is connected to the P port of the swing three-position seven-way directional control valve 311. The B port of the swing three-position seven-way directional control valve 311 is connected to the SW1 port of the swing output system 313, the A port of the swing three-position seven-way directional control valve 311 is connected to the SW2 port of the swing output system 313, and the T port of the swing three-position seven-way directional control valve 311 is connected to the fuel tank 10. The SWT port of the swing output system 313 is connected to the fuel tank 10.

[0049] With the above settings, when the double-extension crane needs to turn, the swing three-position seven-way directional control valve 311 changes its position, causing the P port of the swing three-position seven-way directional control valve 311 to communicate with the B port, and the A port of the swing three-position seven-way directional control valve 311 to communicate with the T port. Thus, the hydraulic oil can flow through the swing three-position seven-way directional control valve to the swing output system 313 to control the swing output system 313, enabling the double-extension motor to turn.

[0050] As Figure 6 and Figure 7 shown, the lifting valve group 32 includes a lifting three-position seven-way directional control valve 321, a lifting check valve 322, and a lifting cylinder 323. One end of the lifting check valve 322 is connected to the oil pump 11, and the other end of the lifting check valve 322 is connected to the P port of the lifting three-position seven-way directional control valve 321. The B port of the lifting three-position seven-way directional control valve 321 is connected to one end 3231 of the lifting cylinder 323, the A port of the lifting three-position seven-way directional control valve 321 is connected to the other end 3232 of the lifting cylinder 323, and the T port of the lifting three-position seven-way directional control valve 321 is connected to the fuel tank 10.

[0051] With the above settings, when the telescopic crane needs to lift, the lifting three-position seven-way directional control valve 321 changes its position, causing the P port of the lifting three-position seven-way directional control valve 321 to communicate with the B port, and the A port of the lifting three-position seven-way directional control valve 321 to communicate with the T port. The hydraulic oil can then flow through the lifting three-position seven-way directional control valve to one end of the lifting cylinder 323, and the hydraulic oil flows back to the fuel tank 10 from the other end of the lifting cylinder 323. Thus, the lifting cylinder 323 can be driven to extend to control the double-extension crane to rise. When the telescopic crane needs to lower, the lifting three-position seven-way directional control valve 321 changes its position, causing the P port of the lifting three-position seven-way directional control valve 321 to communicate with the A port, and the B port of the lifting three-position seven-way directional control valve 321 to communicate with the T port. The hydraulic oil can then flow through the lifting three-position seven-way directional control valve to the other end of the lifting cylinder 323, and the hydraulic oil flows back to the fuel tank 10 from one end of the lifting cylinder 323. Thus, the lifting cylinder 323 can be driven to retract to control the double-extension crane to lower.

[0052] As Figure 2 and Figure 8As shown, the telescopic oil-discharging pressure-stabilizing valve group 335 includes a telescopic oil-discharging first shuttle valve 3351, a telescopic oil-discharging second shuttle valve 3352, a telescopic oil-discharging first overflow valve 3353, and a telescopic oil-discharging second overflow valve 3354. The oil-discharging port 331K of the telescopic three-position seven-way directional control valve 331 is connected to the oil-inlet port 3351P at both ends of the telescopic oil-discharging first shuttle valve 3351. The oil-outlet port 3351T of the telescopic oil-discharging first shuttle valve 3351 is connected to the oil-inlet port 3352P at one end of the telescopic oil-discharging second shuttle valve 3352. The oil-inlet port 3352P at the other end of the telescopic oil-discharging second shuttle valve 3352 is connected to the fuel tank 10. The oil-outlet port 3352T of the telescopic oil-discharging second shuttle valve 3352 is connected to the fuel tank 10. The oil-inlet port at one end of the telescopic oil-discharging first shuttle valve 3351 is also connected to one end of the telescopic oil-discharging first overflow valve 3353, and the other end of the telescopic oil-discharging first overflow valve 3353 is connected to the fuel tank 10. The oil-inlet port at the other end of the telescopic oil-discharging first shuttle valve 3351 is also connected to one end of the telescopic oil-discharging second overflow valve 3354, and the other end of the telescopic oil-discharging second overflow valve 3354 is connected to the fuel tank 10. The oil-inlet port of the telescopic oil-discharging first shuttle valve 3351 is also connected to the P port of the limit first two-position two-way directional control valve 41. Through the setting of the telescopic oil-discharging pressure-stabilizing valve group, the stability of oil discharge can be ensured when the telescopic valve group discharges oil. When the telescopic valve group discharges oil, the excess hydraulic oil flows back to the fuel tank through the telescopic oil-discharging first overflow valve and the telescopic oil-discharging second overflow valve. The two overflow valves play a role in splitting the hydraulic oil during oil discharge, so that the hydraulic oil flows stably and the flow rate is not too large.

[0053] As Figure 9 shown, an emergency pump valve group 6 is provided between the fuel tank 10 and the winch control module 12. The emergency pump valve group 6 includes an emergency manual pump 61, an emergency check valve 62, a first diaphragm valve 63, and a second diaphragm valve 64. One end of the emergency manual pump 61 is connected to the fuel tank 10, and the other end of the emergency manual pump 61 is connected to one end of the emergency check valve 62. The other end of the emergency check valve 62 is connected to the winch control module 12. A first diaphragm valve 63 is connected between the emergency manual pump 61 and the fuel tank 10, and a second diaphragm valve 64 is connected between one end of the emergency manual pump 61 and the other end of the emergency check valve 62.

[0054] With this setting, through the setting of the emergency pump valve group, when the double-telescopic crane encounters special circumstances and cannot be started normally, the emergency pump supplies oil to the double-telescopic crane, enabling the double-telescopic crane to perform emergency work and preventing accidents from occurring.

[0055] As Figure 10As shown in the figure, a filter valve group 7 is provided between the oil outlet end of the multi-way valve group 3 and the fuel tank 10. The filter valve group 7 includes a filter 71, an oil pressure gauge 72, and a filter check valve 73. One end of the filter 71 is connected to the oil outlet end of the multi-way valve group 3, and the other end of the filter 71 is connected to the fuel tank 10. The filter check valve 73 is arranged in parallel with the filter 71, and an oil pressure gauge 72 is also connected to one end of the filter 71. With this arrangement, the returned hydraulic oil is filtered by the filter valve group, ensuring that the hydraulic oil returned to the fuel tank does not contain too many impurities.

[0056] As Figure 11 shown in the figure, the double telescopic crane 2 includes a base 21, a main boom 22, a first-stage telescopic boom 23, a second-stage telescopic boom 24, and a hook mechanism 25. One end of the main boom 22 is hinged to the top of the base 21. A first-stage telescopic oil cylinder 333 is arranged inside the main boom 22. A first-stage accommodation groove 221 for accommodating the first-stage telescopic boom 23 is provided at the other end of the main boom 22. The first-stage telescopic boom 23 is arranged in the first-stage accommodation groove 221 and connected to the first-stage telescopic oil cylinder 333. A second-stage telescopic oil cylinder 334 is arranged inside the first-stage telescopic boom 23. A second-stage accommodation groove 231 for accommodating the second-stage telescopic boom 24 is provided at one end of the first-stage telescopic boom 23. One end of the second-stage telescopic boom 24 is arranged in the second-stage accommodation groove 231 and connected to the second-stage telescopic oil cylinder 334. The other end of the second-stage telescopic boom 24 is provided with a hook mechanism 25; A lifting oil cylinder 323 is provided at the bottom end of the base 21. The cylinder body of the lifting oil cylinder 323 is hinged to the base 21, and the piston rod of the lifting oil cylinder 323 is hinged to the main boom 22. A control room (not shown in the figure) is provided on the base 21. In this embodiment, the control room is used to drive the double telescopic hook to work.

[0057] The lifting oil cylinder 323 is controlled by a lifting valve group 32 to realize the lifting or lowering of the double telescopic motor 2.

[0058] A slewing mechanism (not shown in the figure) is also provided on the base 21. The slewing mechanism is connected to a slewing output system, and the slewing mechanism is controlled by a slewing valve group to realize the steering of the double telescopic motor. In this embodiment, the slewing mechanism is a common rotating device, which will not be described in detail below.

[0059] With the above settings, when the double telescopic crane 2 is working, the staff is located in the control room 20. According to the position of the goods to be lifted, the staff controls the first-stage telescopic oil cylinder 333 to drive the first-stage telescopic boom 23 to extend, and the second-stage telescopic oil cylinder 334 to drive the second-stage telescopic boom 24 to extend. When the extension length reaches the appropriate position, the extension is stopped; The staff controls the hook mechanism 25 to hook the goods and lift the goods for transfer through the control room 20, thus completing the hook work, and the process is simple and effective.

[0060] As Figure 11 and Figure 12As shown, the hook mechanism 25 includes a hoisting winch 251, a cable 252, a hook pulley 253, a hook 254 and a hoisting limit component 26. The hoisting winch 251 is arranged on the main boom 22, and a hook pulley 253 is provided at the other end of the secondary telescopic boom 24. One end of the cable 252 is wound and connected to the hoisting winch 251, and the other end of the cable 252 is arranged on the hook pulley 253. A hook 254 is provided at the end of the cable 252, and a hoisting limit component 26 is provided on the cable 252 between the hook 254 and the hook pulley 253.

[0061] With the above arrangement, a hoisting limit component 26 is provided on the cable 252. When the cable 252 is retracted to a certain length, the cable 252 will be blocked by the hoisting limit component 26, so that the hook 254 will not touch the hook pulley 253 and cause damage to the structure of the hook mechanism 25.

[0062] As Figures 11 to 13 shown, the hoisting limit component 26 includes a hoisting limit base 261, a hoisting limit stop 262, a hoisting limit sliding seat 263 and a hoisting limit trigger switch 264. The hoisting limit trigger switch 264 is arranged in the hoisting limit base 261 through a trigger switch fixing seat 2641. A hoisting limit sliding seat 263 is provided below the hoisting limit base 261. A hoisting limit groove 2631 is provided on the end face of the hoisting limit sliding seat 263 away from the hoisting limit base 261, and a hoisting limit connecting screw 265 is provided in the hoisting limit groove 2631. The hoisting limit sliding seat 263 is slidably connected to the hoisting limit base 261 through the hoisting limit connecting screw 265, and the hoisting limit trigger switch 264 is in contact connection with the hoisting limit sliding seat 263. The end of the cable 252 passes through the hoisting limit base 261 and is connected to the hook 254. A hoisting limit stop 262 is provided on the cable 252 between the hook 254 and the hoisting limit sliding seat 263. The hoisting limit trigger switch 264 is electrically connected to the hoisting winch 251. In this embodiment, the winch control module drives the hoisting winch to realize the retraction and extension of the cable, and the winch control module is electrically connected to the overload second two-way two-position directional valve.

[0063] With the above settings, when the cable 252 is retracted, the cable 252 drives the lifting limit stop 262 provided on the cable 252 to rise. When the lifting limit stop 262 touches the lifting limit slide base 263 and continues to rise, when the lifting limit slide base 263 is driven by the lifting limit stop 262 to rise and touches the lifting limit trigger switch 264, the lifting limit trigger switch 264 sends a signal to the winch control module, causing the winch control module to drive the overload second two-position two-way directional valve to change direction, and then causing the winch control module to control the overload first two-position two-way directional valve to change direction. As a result, the excess hydraulic oil flows back to the fuel tank, so that the lifting winch 251 stops working and the cable 252 stops rising, preventing the hook 254 from touching the hook pulley 253.

[0064] As Figure 13 shown, the lifting limit connection screw 265 includes a lifting limit portion 2651 and a lifting connection portion 2652. One end of the lifting connection portion 2652 is fixedly connected to the lifting limit base 261, and the other end of the lifting connection portion 2652 passes through the lifting limit slide base 263 and extends into the lifting limit groove 2631. The lifting limit portion 2651 is slidably disposed in the lifting limit groove 2631 and is connected to the lifting connection portion 2652.

[0065] With the above settings, through the lifting limit connection screw 265, a certain space is reserved between the lifting limit slide base 263 and the lifting limit base 261, so that when the lifting limit stop 262 is driven by the cable 252 to rise and touches the lifting limit slide base 263, it will not directly collide with the lifting limit base 261, thus protecting the structure of the lifting limit assembly 26 from being easily damaged.

[0066] A control method for a hydraulic system of a crane overload protection is as follows:

[0067] S1 The overload three-position seven-way directional valve changes direction, connecting the P port of the overload three-position seven-way directional valve to the B port, and the fuel tank supplies hydraulic oil to the winch control module.

[0068] S2 When the double telescopic crane reaches the upper limit of lifting, the overload second two-position two-way directional valve changes direction, so that the P port and the B port of the overload second two-position two-way directional valve are connected.

[0069] S3 The winch control module controls the overload first two-position two-way directional valve to change direction, connecting the P port of the overload first two-position two-way directional valve to the B port.

[0070] S4 The fuel tank continues to supply oil to the winch control module through the overload three-position seven-way directional valve.

[0071] S5 The excess hydraulic oil can flow back to the fuel tank from the overload first two-position two-way directional valve.

Claims

1. A hydraulic system for crane overload protection, comprising a hydraulic control system and a double telescopic crane, characterized in that: The hydraulic control system includes a multi-way valve group, an oil tank, an oil pump, an overload protection valve group, and a winch control module. One end of the oil tank is connected to the oil pump, and the other end of the oil pump is connected to the inlet end of the multi-way valve group. The outlet end of the multi-way valve group is connected to the oil tank. The overload protection valve group is connected to the multi-way valve group, and the winch control module is used to drive the double-extension crane to lift. The multi-way valve group includes a slewing valve group, a lifting valve group, and a telescopic valve group. The inlet ends of the slewing valve group, the lifting valve group, and the telescopic valve group are connected to the oil pump, and the outlet ends of the slewing valve group, the lifting valve group, and the telescopic valve group are connected to the oil tank. The overload protection valve group includes an overload first two-position two-way directional control valve, an overload relief valve, an overload three-position seven-way directional control valve, an overload second two-position two-way directional control valve, and an overload oil-draining and pressure-stabilizing valve group. The P port of the overload three-position seven-way directional control valve is connected to the oil pump, the T port of the overload three-position seven-way directional control valve is connected to the oil tank, the B port of the overload three-position seven-way directional control valve is connected to the MW1 port of the winch control module, the A port of the overload three-position seven-way directional control valve is connected to the MW2 port of the winch control module, the oil-draining port of the overload three-position seven-way directional control valve is connected to the overload oil-draining and pressure-stabilizing valve group, the overload oil-draining and pressure-stabilizing valve group is also connected to the P port of the overload first two-position two-way directional control valve, the B port of the overload first two-position two-way directional control valve is connected to one end of the overload relief valve, the other end of the overload relief valve is connected to the oil tank, the T port of the overload first two-position two-way directional control valve is connected to the oil tank, and the A port of the overload first two-position two-way directional control valve is normally closed. The control port of the overload first two-position two-way directional control valve is connected to the B port of the overload second two-position two-way directional control valve, and the MW2 port of the winch control module is also connected to the P port of the overload second two-position two-way directional control valve. The T port of the overload second two-position two-way directional control valve is connected to the oil tank, and the A port of the overload second two-position two-way directional control valve is normally closed. The telescopic valve group includes a telescopic three-position seven-way directional control valve, a telescopic check valve, a first-stage telescopic oil cylinder, and a second-stage telescopic oil cylinder. One end of the telescopic check valve is connected to the oil pump, and the other end of the telescopic check valve is connected to the P port of the telescopic three-position seven-way directional control valve. The B port of the telescopic three-position seven-way directional control valve is connected to one end of the first-stage telescopic oil cylinder and the second-stage telescopic oil cylinder, the A port of the telescopic three-position seven-way directional control valve is connected to the other end of the first-stage telescopic oil cylinder and the second-stage telescopic oil cylinder, and the T port of the telescopic three-position seven-way directional control valve is connected to the oil tank. The oil-draining port of the telescopic three-position seven-way directional control valve is connected to the telescopic oil-draining and pressure-stabilizing valve group. The slewing valve group includes a slewing three-position seven-way directional control valve, a slewing check valve, and a slewing output system. One end of the slewing check valve is connected to the oil pump, and the other end of the slewing check valve is connected to the P port of the slewing three-position seven-way directional control valve. The B port of the slewing three-position seven-way directional control valve is connected to the SW1 port of the slewing output system, the A port of the slewing three-position seven-way directional control valve is connected to the SW2 port of the slewing output system, and the T port of the slewing three-position seven-way directional control valve is connected to the oil tank. The SWT port of the slewing output system is connected to the oil tank.

2. The hydraulic system for crane overload protection according to claim 1, characterized in that: The lifting valve group includes a lifting three-position seven-way directional control valve, a lifting check valve and a lifting oil cylinder. One end of the lifting check valve is connected to an oil pump, and the other end of the lifting check valve is connected to the P port of the lifting three-position seven-way directional control valve. The B port of the lifting three-position seven-way directional control valve is connected to one end of the lifting oil cylinder, the A port of the lifting three-position seven-way directional control valve is connected to the other end of the lifting oil cylinder, and the T port of the lifting three-position seven-way directional control valve is connected to a fuel tank.

3. The hydraulic system for crane overload protection according to claim 1, characterized in that: The telescopic oil-draining and pressure-stabilizing valve group includes a telescopic oil-draining first shuttle valve, a telescopic oil-draining second shuttle valve, a telescopic oil-draining first relief valve and a telescopic oil-draining second relief valve. The oil-draining port of the telescopic three-position seven-way directional control valve is connected to the oil-inlet ends at both ends of the telescopic oil-draining first shuttle valve. The oil-outlet end of the telescopic oil-draining first shuttle valve is connected to the oil-inlet end of one end of the telescopic oil-draining second shuttle valve. The oil-inlet end of the other end of the telescopic oil-draining second shuttle valve is connected to the fuel tank, and the oil-outlet end of the telescopic oil-draining second shuttle valve is connected to the fuel tank. The oil-inlet end of one end of the telescopic oil-draining first shuttle valve is further connected to one end of the telescopic oil-draining first relief valve, and the other end of the telescopic oil-draining first relief valve is connected to the fuel tank. The oil-inlet end of the other end of the telescopic oil-draining first shuttle valve is further connected to one end of the telescopic oil-draining second relief valve, and the other end of the telescopic oil-draining second relief valve is connected to the fuel tank.

4. The hydraulic system for crane overload protection according to claim 1, characterized in that: An emergency pump valve group is provided between the fuel tank and the winch control module. The emergency pump valve group includes an emergency manual pump, an emergency check valve, a first diaphragm valve and a second diaphragm valve. One end of the emergency manual pump is connected to the fuel tank, and the other end of the emergency manual pump is connected to one end of the emergency check valve. The other end of the emergency check valve is connected to the winch control module. A first diaphragm valve is connected between the emergency manual pump and the fuel tank, and a second diaphragm valve is connected between one end of the emergency manual pump and the other end of the emergency check valve.

5. A hydraulic system for crane overload protection according to claim 1, characterized in that: A filter valve group is provided between the oil-outlet end of the multi-way valve group and the fuel tank. The filter valve group includes a filter, an oil pressure gauge and a filter check valve. One end of the filter is connected to the oil-outlet end of the multi-way valve group, the other end of the filter is connected to the fuel tank, the filter check valve is arranged in parallel with the filter, and an oil pressure gauge is further connected to one end of the filter.

6. A control method for a hydraulic system of a crane overload protection according to claim 1, characterized in that It includes the following steps: S1: The overload three-position seven-way directional control valve is commutated, and the P port of the overload three-position seven-way directional control valve is connected to the B port, and the fuel tank delivers hydraulic oil to the winch control module. S2: When the double-telescopic crane reaches the upper limit position of lifting, the overload second two-position two-way directional control valve is commutated, so that the P port and the B port of the overload second two-position two-way directional control valve are connected. S3: The winch control module controls the overload first two-position two-way directional control valve to be commutated, and connects the P port of the overload first two-position two-way directional control valve to the B port. S4: The fuel tank continues to supply oil to the winch control module through the overload three-position seven-way directional control valve. S5: The excess hydraulic oil can flow back to the fuel tank from the overload first two-position two-way directional control valve.

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