A crane hydraulic system and control method

Abstract

The present invention provides a crane hydraulic system and control method, wherein the hydraulic system comprises a telescopic oil cylinder, an oil supply end and a driving end, wherein the oil supply end comprises an oil tank, a variable hydraulic pump, a hydraulically controlled proportional reversing valve and a relief valve; the driving end comprises an accumulator, a cylinder arm pin switching valve, a first reversing valve, a second reversing valve, a ball valve, a quick-change joint, a cylinder pin oil cylinder and an arm pin oil cylinder; the present invention eliminates a separate cylinder arm pin driving system, and the accumulator stores the oil of the system at high pressure as a driving oil source for the cylinder arm pin action; the piston rod of the cylinder arm pin oil cylinder is fixed, and the cylinder arm pin is pulled out when the cylinder arm pin oil cylinder has a rod chamber filled with oil, and when the oil is returned, the cylinder arm pin oil cylinder has a rod chamber and a rodless chamber connected to realize rapid release of the cylinder arm pin, and the cylinder arm pin action is switched by changing the direction of the cylinder arm pin switching valve; when the arm pin is pulled out in an emergency, the system pressure is increased to switch the first reversing valve and the second reversing valve, and the high-pressure oil enters the arm pin hydraulic cylinder to realize the arm pin pulling action.

Description

Technical Field

[0001] The invention belongs to the technical field of cranes, and in particular relates to a crane hydraulic system and a control method. Background Art

[0002] The principle of the single-cylinder bolt telescopic system adopts the industry's general technical route. The drive of the cylinder arm pin movement requires a separate oil supply system. When the telescopic cylinder is extended and retracted, the flow of the active core tube must be guaranteed while the system pressure must be guaranteed, resulting in large power loss. The telescopic cylinder has a movable core tube, which has a complex structure and high processing precision requirements, resulting in a high price for the telescopic cylinder and difficulty in further improving its lightweight. Due to the poor compactness of the telescopic cylinder, the single-cylinder bolt telescopic system is difficult to promote and apply in small-tonnage products; small tonnage is limited by the width of the arm tail, the cylinder head body cannot be expanded, resulting in the piston rod cannot be expanded, so it is difficult to arrange the movable core tube. Summary of the invention

[0003] The purpose of the present invention is to provide a crane hydraulic system and control method, so that the existing single-cylinder latch telescopic system of the crane needs to be controlled by another pump when the cylinder arm pin moves, resulting in poor energy saving of the system; the telescopic cylinder is provided with a movable core tube, which has a complex structure and high processing accuracy requirements, resulting in a high telescopic cylinder and poor lightweight; due to the poor compactness of the telescopic cylinder, the single-cylinder latch telescopic system is difficult to promote and apply in small-tonnage products.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a crane hydraulic system, comprising a telescopic oil cylinder, an oil supply end and a driving end, wherein the oil supply end comprises an oil tank, a hydraulically controlled proportional reversing valve and a relief valve, wherein a rod chamber of the telescopic oil cylinder is connected to the oil tank via a relief valve, and a rodless chamber of the telescopic oil cylinder is connected to the oil tank via a passage of the hydraulically controlled proportional reversing valve; another passage of the hydraulically controlled proportional reversing valve is connected in parallel with the relief valve, and control ends on both sides of the hydraulically controlled proportional reversing valve are respectively connected to electric proportional pressure reducing valves, and the electric proportional pressure reducing valves are respectively connected to pilot oil and an oil tank;

[0006] The driving end includes an accumulator, a cylinder arm pin switching valve, a ball valve, a quick-change joint, a cylinder pin cylinder and an arm pin cylinder; the cylinder arm pin switching valve is provided with an A port, a B port, a P port and a T port, the P port and the A port are respectively connected to the rod chamber of the arm pin cylinder, and the accumulator is respectively connected to the P port and the rod chamber of the telescopic cylinder; the B port is connected to the rod chamber of the cylinder pin cylinder through a ball valve and a quick-change joint; the T port is respectively connected to the rodless chambers of the arm pin cylinder, the cylinder pin cylinder and the telescopic cylinder, and the T port is also connected to the rod chamber of the telescopic cylinder.

[0007] Optionally, a first reversing valve and a second reversing valve are respectively provided between the P port and the A port and the rod chamber of the arm pin cylinder, and the control ends of the first reversing valve and the second reversing valve are respectively connected to the P port.

[0008] Optionally, the arm pin oil cylinder and the cylinder pin oil cylinder are respectively connected to the arm pin mechanism and the cylinder pin mechanism, and the arm and cylinder pulling are achieved through the oil inlet and return of the rod chamber and the rodless chamber of the arm pin oil cylinder and the cylinder pin oil cylinder.

[0009] Optionally, a first one-way valve is further provided between the rod chamber of the telescopic oil cylinder and the accumulator, and the first one-way valve is connected from the telescopic oil cylinder to the accumulator.

[0010] Optionally, a second one-way valve and a third one-way valve are respectively provided between the T-port and the rod chamber and the rodless chamber of the telescopic cylinder, and the second one-way valve and the third one-way valve are both connected from the T-port to the direction of the telescopic cylinder.

[0011] Optionally, the oil supply end further includes a balancing valve, the rodless chamber of the telescopic cylinder is connected to the hydraulically controlled proportional reversing valve through the balancing valve, and the control end of the balancing valve is connected to the rod chamber of the telescopic cylinder.

[0012] In a second aspect, the present invention provides a control method for a crane hydraulic system based on the above, comprising:

[0013] Normal puller pin operation:

[0014] Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator;

[0015] The P port and the A port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve and the second reversing valve to reach the rod chamber of the arm pin cylinder, driving the arm pin cylinder to realize the arm pin pulling operation;

[0016] Normal cylinder pin operation:

[0017] Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator;

[0018] The P port and the B port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve to reach the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the cylinder pin pulling operation;

[0019] Emergency arm pin operation:

[0020] Adjusting the overflow pressure of the overflow valve to make it greater than the switching pressure of the first reversing valve and the second reversing valve;

[0021] Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator, so that the oil pressure of the accumulator is greater than the preset pressure of the first reversing valve and the second reversing valve;

[0022] The high-pressure oil in the accumulator reaches the rod chamber of the arm pin cylinder through the first reversing valve, driving the arm pin cylinder to realize the emergency arm pin extraction operation;

[0023] Emergency cylinder pin operation:

[0024] The control ball valve is closed, and an external high-pressure oil source is connected through a quick-change joint. The high-pressure oil from the high-pressure oil source reaches the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the emergency cylinder pin pulling operation.

[0025] Optionally, controlling the telescopic cylinder to perform a retracting action includes:

[0026] The hydraulic proportional reversing valve is controlled by adjusting the input current of the electric proportional pressure reducing valve, and the telescopic cylinder is controlled to perform the retraction action through the action of the hydraulic proportional reversing valve.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The invention provides a crane hydraulic system and control method, which improve the energy saving and compactness of the crane hydraulic system, reduce weight and cost; compared with the prior art, a separate cylinder arm pin system is eliminated, thereby improving energy saving; the movable core in the telescopic cylinder is eliminated, the structure of the telescopic cylinder is simplified, the processing difficulty is reduced, and the cost of the telescopic cylinder is greatly reduced; the contradiction of "the movable core tube restricts the inner diameter of the telescopic cylinder piston rod" is solved, so that the single-cylinder latch system can be extended to small and medium-tonnage products; the other chamber of the cylinder arm pin cylinder is used as an "oil return tank" to quickly absorb the oil released from the high-pressure chamber of the cylinder arm pin cylinder, thereby solving the contradiction of "the high pressure in the low-pressure chamber of the telescopic cylinder when releasing the cylinder arm pin, resulting in a high back pressure of the cylinder arm pin cylinder oil discharge", and improving the release responsiveness and reliability of the cylinder arm pin. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 is a schematic diagram of a crane hydraulic system provided by an embodiment of the present invention;

[0031] Marked in the figure: 20. Oil tank, 21. Variable hydraulic pump, 22. Electric proportional pressure reducing valve, 23. Hydraulic controlled proportional reversing valve, 24. Balance valve, 25. Telescopic cylinder, 26. One-way valve group, 27. Cylinder arm pin switching valve, 28. Ball valve, 29. Arm pin cylinder, 210. Cylinder pin cylinder, 211. First reversing valve, 212. Second reversing valve, 213. Accumulator, 214. Overflow valve, 215. Quick-change connector, 216. Cylinder pin mechanism, 217. Arm pin mechanism, 218. Pilot oil. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] like Figure 1 As shown, a crane hydraulic system provided by an embodiment of the present invention includes a telescopic cylinder 25, an oil supply end and a drive end.

[0035] The oil supply end includes an oil tank 20, a variable hydraulic pump 21, a hydraulically controlled proportional reversing valve 23 and an overflow valve 214. The rod chamber of the telescopic cylinder 25 is connected to the oil tank 20 through the overflow valve 214, and the rodless chamber of the telescopic cylinder 25 is connected to the oil tank 20 through a passage of the hydraulically controlled proportional reversing valve 23; another passage of the hydraulically controlled proportional reversing valve 23 is connected in parallel with the overflow valve 214, and the control ends on both sides of the hydraulically controlled proportional reversing valve 23 are respectively connected to the electric proportional pressure reducing valve 22, and the electric proportional pressure reducing valve 22 is respectively connected to the pilot oil 218 and the oil tank 20; the oil supply end also includes a balancing valve 24, and the rodless chamber of the telescopic cylinder 25 is connected to the hydraulically controlled proportional reversing valve 23 through the balancing valve 24, and the control end of the balancing valve 24 is connected to the rod chamber of the telescopic cylinder 25.

[0036] The driving end includes an accumulator 213, a cylinder arm pin switching valve 27, a first reversing valve 211, a second reversing valve 212, a ball valve 28, a quick-change joint 215, a cylinder pin cylinder 210 and an arm pin cylinder 29; the cylinder arm pin switching valve 27 is provided with an A port, a B port, a P port and a T port, the P port and the A port are respectively connected to the rod chamber of the arm pin cylinder 29 through the first reversing valve 211 and the second reversing valve 212, the control ends of the first reversing valve 211, the second reversing valve 212 and the accumulator 213 are all connected to the P port, and the accumulator 213 is also connected to the rod chamber of the telescopic cylinder 25; the B port is connected to the rod chamber of the cylinder pin cylinder 210 through the ball valve 28 and the quick-change joint 215; the T port is respectively connected to the rodless chambers of the arm pin cylinder 29, the cylinder pin cylinder 210 and the telescopic cylinder 25, and the T port is also connected to the rod chamber of the telescopic cylinder 25.

[0037] A first one-way valve is also arranged between the rod chamber of the telescopic cylinder 25 and the accumulator 213, and the first one-way valve is connected from the telescopic cylinder 25 to the accumulator 2123; a second one-way valve and a third one-way valve are respectively arranged between the T port and the rod chamber and the rodless chamber of the telescopic cylinder 25, and the second one-way valve and the third one-way valve are both connected from the T port to the direction of the telescopic cylinder 25; the first one-way valve, the second one-way valve and the third one-way valve constitute a one-way valve group 26.

[0038] The arm pin oil cylinder 29 and the cylinder pin oil cylinder 210 are connected to the arm pin mechanism 217 and the cylinder pin mechanism 216 respectively, and the arm and cylinder pulling are realized by the oil inlet and return of the rod chamber and the rodless chamber of the arm pin oil cylinder 29 and the cylinder pin oil cylinder 210.

[0039] In this embodiment, the separate cylinder arm pin driving system is eliminated, and the accumulator 213 stores the oil at the high pressure of the system as the driving oil source for the cylinder arm pin movement. The piston rods of the cylinder pin cylinder 210 and the arm pin cylinder 29 are fixed on the telescopic cylinder 25, and the cylinder bodies of the cylinder pin cylinder 210 and the arm pin cylinder 29 are fixed on the cylinder pin mechanism 216 and the arm pin mechanism 217. The oil inlet and return of the cylinder pin cylinder 210 and the arm pin cylinder 29 are all through the piston rods of the cylinder pin cylinder 210 and the arm pin cylinder 29. When the rod chamber of the cylinder pin cylinder 210 and the arm pin cylinder 29 is filled with oil, the cylinder arm pin is pulled out. When the oil is returned, the large and small chambers of the cylinder arm pin cylinder are connected to achieve rapid release of the cylinder arm pin, and the cylinder arm pin action is switched by changing the direction of the cylinder arm pin switching valve 27; when pulling out the arm pin in an emergency, the system pressure is increased to switch the first reversing valve 211 and the second reversing valve 212, and the high-pressure oil enters the arm pin cylinder 29 to achieve the arm pin pulling action; the high-pressure oil source is externally connected through the quick-change joint 215, and the high-pressure oil reaches the rod chamber of the cylinder pin cylinder 210 to achieve the emergency cylinder pin pulling action.

[0040] Embodiment 2:

[0041] An embodiment of the present invention provides a control method for a crane hydraulic system based on the above, comprising:

[0042] (1) Normal arm pin extraction operation:

[0043] Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator;

[0044] The P port and the A port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve and the second reversing valve to reach the rod chamber of the arm pin cylinder, driving the arm pin cylinder to realize the arm pin pulling operation;

[0045] When the arm pin needs to be reset, the cylinder arm pin switching valve loses power, the rod chamber and the rodless chamber of the arm pin cylinder are connected, and the rodless chamber of the arm pin cylinder is used as a "return oil tank". Since the volume of the rodless chamber is much larger than the volume of the rod chamber, under the action of the spring force, the oil in the rod chamber quickly enters the rodless chamber to realize the rapid reset of the cylinder arm pin, thereby improving the responsiveness.

[0046] (2) Normal cylinder pin extraction operation:

[0047] Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator;

[0048] The P port and the B port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve to reach the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the cylinder pin pulling operation;

[0049] When the cylinder pin needs to be reset, the same procedure is followed as described above for resetting the cylinder pin.

[0050] (3) Emergency arm pin extraction operation:

[0051] Adjusting the overflow pressure of the overflow valve to make it greater than the switching pressure of the first reversing valve and the second reversing valve;

[0052] Control the telescopic cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic cylinder into the accumulator, so that the oil pressure of the accumulator is greater than the preset pressure of the first reversing valve and the second reversing valve; (Since the opening pressure of the first reversing valve is greater than the set opening pressure of the second reversing valve, the first reversing valve will be reversed after the second reversing valve is reversed)

[0053] The high-pressure oil in the accumulator reaches the rod chamber of the arm pin cylinder through the first reversing valve, driving the arm pin cylinder to realize the emergency arm pin extraction operation;

[0054] (4) Emergency cylinder pin puller operation:

[0055] The control ball valve is closed, and an external high-pressure oil source is connected through a quick-change joint. The high-pressure oil from the high-pressure oil source reaches the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the emergency cylinder pin pulling operation.

[0056] (5) Controlling the telescopic cylinder to perform the retraction action includes:

[0057] The hydraulic proportional reversing valve is controlled by adjusting the input current of the electric proportional pressure reducing valve, and the telescopic cylinder is controlled to perform the retraction action through the action of the hydraulic proportional reversing valve.

[0058] The extension and retraction of the telescopic cylinder is controlled by a hydraulically controlled proportional reversing valve. Two electric proportional pressure reducing valves respectively control the control oil pressure at both ends of the valve stem of the hydraulically controlled proportional reversing valve. Therefore, the movement of the valve stem of the hydraulically controlled proportional reversing valve can be controlled by adjusting the input current of the electric proportional pressure reducing valve, that is, the displacement of the valve stem of the hydraulically controlled proportional reversing valve is related to the input current of the electric proportional pressure reducing valve. Therefore, the requirements of the telescopic hydraulic system characteristics under different working conditions of the telescopic system can be met by adjusting the current output by the controller to the electric proportional pressure reducing valve.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A crane hydraulic system, It is characterized in that It includes a telescopic oil cylinder, an oil supply end and a driving end, the oil supply end includes an oil tank, a hydraulically controlled proportional reversing valve and a relief valve, the rod chamber of the telescopic oil cylinder is connected to the oil tank through the relief valve, the hydraulically controlled proportional reversing valve is a three-position four-way hydraulically controlled proportional reversing valve, the hydraulically controlled proportional reversing valve includes an oil inlet, an oil return port and two working oil ports, the oil inlet is connected to the outlet of the variable hydraulic pump, the oil return port is connected to the oil tank, one working oil port is connected to the rod chamber of the telescopic oil cylinder, the other working oil port is connected to the rodless chamber of the telescopic oil cylinder, the working oil port connected to the rod chamber of the telescopic oil cylinder is also connected to the inlet of the relief valve, the oil return port of the hydraulically controlled proportional reversing valve is connected to the outlet of the relief valve, and the outlet of the relief valve is also connected to the oil tank, The control ends on both sides of the hydraulically controlled proportional reversing valve are respectively connected to electric proportional pressure reducing valves, and the electric proportional pressure reducing valves are respectively connected to the pilot oil and the oil tank; The driving end includes an accumulator, a cylinder arm pin switching valve, a ball valve, a quick-change joint, a cylinder pin cylinder and an arm pin cylinder; the cylinder arm pin switching valve is provided with an A port, a B port, a P port and a T port, the P port and the A port are respectively connected to the rod chamber of the arm pin cylinder, and the accumulator is respectively connected to the P port and the rod chamber of the telescopic cylinder; the B port is connected to the rod chamber of the cylinder pin cylinder through a ball valve and a quick-change joint; the T port is respectively connected to the rodless chambers of the arm pin cylinder, the cylinder pin cylinder and the telescopic cylinder, and the T port is also connected to the rod chamber of the telescopic cylinder; a first one-way valve is also provided between the rod chamber of the telescopic cylinder and the accumulator, and the first one-way valve is conducted from the telescopic cylinder to the accumulator; a second one-way valve and a third one-way valve are respectively provided between the T port and the rod chamber and the rodless chamber of the telescopic cylinder, and the second one-way valve and the third one-way valve are both conducted from the T port to the telescopic cylinder; A first reversing valve is further provided between the P port and the rod chamber of the arm pin oil cylinder, and a second reversing valve is further provided between the A port and the rod chamber of the arm pin oil cylinder, and control ends of the first reversing valve and the second reversing valve are respectively connected to the P port; Normal puller pin operation: Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator; The P port and the A port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve and the second reversing valve to reach the rod chamber of the arm pin cylinder, driving the arm pin cylinder to realize the arm pin pulling operation; Normal cylinder pin operation: Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator; The P port and the B port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve to reach the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the cylinder pin pulling operation; The emergency boom pin extraction operation of the crane hydraulic system includes: Adjusting the overflow pressure of the overflow valve to make it greater than the switching pressure of the first reversing valve and the second reversing valve; Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator, so that the oil pressure of the accumulator is greater than the preset pressure of the first reversing valve and the second reversing valve. The second reversing valve is a two-way two-way normally open valve, and the first reversing valve is a two-position two-way normally closed valve. Since the pressure of the first reversing valve is greater than the set opening pressure of the second reversing valve, the first reversing valve is switched to open after the second reversing valve is switched to close; The high-pressure oil in the accumulator reaches the rod chamber of the arm pin cylinder through the first reversing valve, driving the arm pin cylinder to realize the emergency arm pin extraction operation; The emergency cylinder pin extraction operation of the crane hydraulic system includes: The control ball valve is closed, and an external high-pressure oil source is connected through a quick-change joint. The high-pressure oil from the high-pressure oil source reaches the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the emergency cylinder pin pulling operation.

2. A crane hydraulic system according to claim 1, It is characterized in that The arm pin oil cylinder and the cylinder pin oil cylinder are connected to the arm pin mechanism and the cylinder pin mechanism respectively, and the arm and cylinder are pulled out by the oil inlet and return of the rod chamber and the rodless chamber of the arm pin oil cylinder and the cylinder pin oil cylinder.

3. A crane hydraulic system according to claim 1, It is characterized in that The oil supply end also includes a balancing valve, the rodless chamber of the telescopic oil cylinder is connected to the hydraulic proportional reversing valve through the balancing valve, and the control end of the balancing valve is connected to the rod chamber of the telescopic oil cylinder.

4. A control method for a crane hydraulic system according to any one of claims 1 to 3, It is characterized in that include: Normal puller pin operation: Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator; The P port and the A port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve and the second reversing valve to reach the rod chamber of the arm pin cylinder, driving the arm pin cylinder to realize the arm pin pulling operation; Normal cylinder pin operation: Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator; The P port and the B port of the control cylinder arm pin switching valve are connected, and the high-pressure oil of the accumulator passes through the cylinder arm pin switching valve to reach the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the cylinder pin pulling operation; Emergency pin extraction operations include: Adjusting the overflow pressure of the overflow valve to make it greater than the switching pressure of the first reversing valve and the second reversing valve; Control the telescopic oil cylinder to perform the retraction action, and charge the high-pressure oil in the rod chamber of the telescopic oil cylinder into the accumulator, so that the oil pressure of the accumulator is greater than the preset pressure of the first reversing valve and the second reversing valve. The second reversing valve is a two-way two-way normally open valve, and the first reversing valve is a two-position two-way normally closed valve. Since the pressure of the first reversing valve is greater than the set opening pressure of the second reversing valve, the first reversing valve is switched to open after the second reversing valve is switched to close; The high-pressure oil in the accumulator reaches the rod chamber of the arm pin cylinder through the first reversing valve, driving the arm pin cylinder to realize the emergency arm pin extraction operation; The emergency cylinder pin extraction operation of the crane hydraulic system includes: The control ball valve is closed, and an external high-pressure oil source is connected through a quick-change joint. The high-pressure oil from the high-pressure oil source reaches the rod chamber of the cylinder pin cylinder, driving the cylinder pin cylinder to realize the emergency cylinder pin pulling operation.

5. A method for controlling a crane hydraulic system according to claim 4, It is characterized in that The control of the telescopic cylinder to perform the retracting action includes: The hydraulic proportional reversing valve is controlled by adjusting the input current of the electric proportional pressure reducing valve, and the telescopic cylinder is controlled to perform the retraction action through the action of the hydraulic proportional reversing valve.

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