A stretch main valve, stretch system and crane

Abstract

The application discloses a telescopic main valve, a telescopic system and a crane. The oil inlet of a first three-position four-way electromagnetic valve in the telescopic main valve is connected with the control port and the working oil port MX of a first cartridge valve. The oil return port of the three-position four-way electromagnetic valve is connected with the oil outlet of a first overflow valve and an electrically-controlled overflow valve. One working oil port of the first three-position four-way electromagnetic valve is connected with the oil inlet of the first overflow valve. The other working oil port of the first three-position four-way electromagnetic valve is connected with the oil inlet of the electrically-controlled overflow valve. The oil outlet of the first cartridge valve is connected with the working oil port MT, the oil return port T1 and the oil return port T2 respectively. The first three-position four-way electromagnetic valve determines whether the control port of the first cartridge valve is connected with the first overflow valve or the electrically-controlled overflow valve. The first overflow valve is provided with a fixed pressure value. The pressure setting value of the valve is steplessly controlled by controlling the input current of the electrically-controlled overflow valve. The application can realize stepless pressure adjustment, high integration, effectively prevent the telescopic cylinder from leaking and improve the amplitude response speed.

Description

Technical Field

[0001] The present invention relates to engineering machinery technology, and in particular to an extension-variable main valve, an extension-variable system and a crane. Background Art

[0002] Currently, in the field of construction cranes, telescopic main valves mostly use a reversing valve combination. While this provides convenient control, it is difficult to achieve high flow rates. As cranes' lifting tonnage increases, the size of components such as telescopic cylinders and luffing cylinders increases, requiring a larger main valve flow rate. Clearly, a reversing valve combination cannot meet this requirement. Existing large-tonnage telescopic main valves mostly use a cartridge valve combination, which can achieve high flow rates while also ensuring stable control.

[0003] like Figure 1 The existing telescopic main valve is composed of multiple cartridge valves and reversing valves, and is applied to the existing telescopic system (such as Figure 2 ), the hydraulic oil from the oil pump flows into the main valve through the oil inlet ports P1 and P2, and returns to the oil tank through the oil return ports T1 and T2. The P3 and P4 ports of the main valve are connected to the balancing valve of the large cavity of the telescopic cylinder, the P5 port of the main valve is connected to the small cavity of the telescopic cylinder, the P6 and P7 ports of the main valve are connected to the balancing valve of the large cavity of the amplitude cylinder, and the P8 and P9 ports of the main valve are connected to the power drop of the small cavity of the amplitude cylinder. Figure 1 As shown, the electromagnetic reversing valve 11 and the cartridge valves 12 and 13 act together at ports P3 and P4 to control the oil inlet to the large chamber of the telescopic cylinder. The electromagnetic reversing valves 14 and 15 and the cartridge valves 16 and 17 act together at port P5 to control the oil inlet to the small chamber of the telescopic cylinder. The electromagnetic reversing valve 18 and the cartridge valves 19 and 110 act together at ports P6, P7, P8, and P9 to control the oil inlet and return to the large and small chambers of the variable amplitude cylinder. However, the existing telescopic main valve has the following defects:

[0004] (1) The current main valve has only three levels of pressure control, such as Figure 3As shown, cartridge valve 113 is a pilot control valve. When the pressure in the oil circuit reaches the set value, the main oil circuit of cartridge valve 113 opens, and the oil at ports P1 and P2 directly passes through this valve and returns to the oil tank through port T, thus protecting the telescopic and luffing cylinders. The pressure control section includes cartridge valve 113, solenoid reversing valve 114, and three relief valves with different pressure settings. Generally, relief valve 115 has the lowest setting. When solenoid reversing valve 114 is in the neutral position, the pressure in the control oil chamber of cartridge valve 113 is determined by the minimum value of the three relief valves, namely relief valve 115. When the pressure at port P exceeds the pressure in the control oil chamber of cartridge valve 113 (the set pressure of relief valve 115), the main oil circuit of this valve is connected, and the oil at port P is directly returned to the tank. When the pressure at port P falls below the pressure in the control oil chamber of cartridge valve 113, the valve completely closes, disconnecting the main oil circuit, and telescopic and luffing operations proceed normally. This ensures that the pressure does not exceed the set value, thus providing protection. When solenoid valve 114 is in the left position, the pressure in the control oil chamber of cartridge valve 113 is determined by the setting of relief valve 117. When solenoid valve 114 is in the right position, the pressure in the control oil chamber of cartridge valve 113 is determined by the setting of relief valve 116. The protection principle is the same as that in the neutral position. It can be seen from this that this main valve has only three levels of pressure control, which are determined by the settings of relief valve 115, relief valve 116, and relief valve 117, respectively, which has limitations.

[0005] (2) The upper vehicle’s variable amplitude power lowering function is external, and the main valve of the extension and change is not highly centralized, that is, Figure 2 The power drop switching valve 112 in the luffing chamber is connected to the power drop device by the pipeline. It is an independent external component, which occupies the space resources of the crane equipment and will bring about problems such as space compactness during design.

[0006] (3) When the tower arm is working, the telescopic cylinder is not inserted with the arm pin. Under the maximum load, due to the internal leakage of the balance valve, the telescopic cylinder will slowly sink, causing the boom to automatically retract, posing a safety hazard. When the tower arm is working, the telescopic cylinder is not inserted with the arm pin. Due to the heavy tower arm and the internal leakage of the telescopic cylinder balance valve, the telescopic cylinder will slowly sink, causing the boom to automatically retract, posing a safety hazard. Figure 4 As shown, the P3 and P4 ports are connected to the telescopic oil cylinder's large cavity. Under the tower boom working condition, since the telescopic oil cylinder is not inserted with the arm pin, under the action of the tower boom's gravity, the balance valve of the telescopic oil cylinder's large cavity will leak internally, causing the oil in the large cavity to return to the P3 and P4 ports. Since the boom is fixed, the telescopic oil cylinder's large cavity does not need to be refilled with oil. Therefore, the electromagnetic reversing valve 11 is in the right position, the control oil cavity of the cartridge valve 12 is high pressure, the main oil circuit is completely closed, and the control oil cavity of the cartridge valve 13 is low pressure. The main oil circuit is connected, causing the oil in the telescopic oil cylinder's large cavity to return to the P3 and P4 ports through the cartridge valve 13 and return to the T1 and T2 ports, and then return to the oil tank. This also causes the oil in the telescopic oil cylinder's large cavity to decrease, the cylinder sinks, and the boom automatically retracts.

[0007] (4) The rise and fall of the variable amplitude oil cylinder is controlled by a two-way cartridge valve combination. Due to the poor consistency of domestic main valves, the start and stop of the variable amplitude is delayed by about 4-5 seconds. There is a main valve with this fault, such as Figure 5 As shown, when the amplitude adjustment is not working, the electromagnetic reversing valve 18 is in the right position, and the high-pressure oil from the P port connected to the oil pump reaches the control oil chamber of the cartridge valve 19 through the electromagnetic reversing valve 18. Due to the high oil pressure, the cartridge valve 19 is completely closed, and the control oil chamber of the cartridge valve 110 is connected to the T port through the electromagnetic reversing valve. The T port is connected to the oil tank and has a low pressure, which causes the cartridge valve 110 to be unable to be completely closed. When the boom cylinder needs to work, the solenoid reversing valve 18 is energized and works in the left position. The control oil chamber of the cartridge valve 19 is connected to the T port at low pressure through the solenoid reversing valve 18, the main oil circuit interface of the cartridge valve 19 is connected, and the oil at the P port flows to the P7 port through the cartridge valve 19; on the other hand, the control oil chamber of the cartridge valve 110 is connected to the P port at high pressure through the solenoid reversing valve 18, the cartridge valve 110 is completely closed, and the main oil circuit interface is not connected. However, since the control oil chamber of the cartridge valve 110 is at low pressure when the boom cylinder is not working, the valve is not completely closed. Therefore, during the process of the cartridge valve 110 being completely closed, part of the oil at the P port of the cartridge valve 19 will return through the cartridge valve 110, resulting in a start and stop delay in the boom action.

[0008] In summary, the existing telescopic main valve has the following defects: (a) It only has three levels of pressure control; (b) The upper vehicle boom power lowering function is external, and the telescopic main valve is not highly centralized; (c) When the tower boom is in operation, the telescopic cylinder does not insert the arm pin. Under maximum load, due to internal leakage of the balance valve, the telescopic cylinder will slowly sink, causing the boom to automatically retract, posing a safety hazard; (d) There is a start and stop delay in the boom action. Summary of the Invention

[0009] Purpose of the invention: The purpose of the present invention is to improve a pressure-adjustable telescopic main valve, telescopic system and crane that can meet the requirements of fine division of system pressure under multiple working conditions.

[0010] Technical solution: The telescopic main valve of the present invention includes a first three-position four-way solenoid valve, a first relief valve, an electrically controlled relief valve, a first cartridge valve, a working oil port MX, a working oil port MT, a first oil return port T1 and a second oil return port T2. The oil inlet of the first three-position four-way solenoid valve is connected to the control port and the working oil port MX of the first cartridge valve, the oil return port of the three-position four-way solenoid valve is connected to the oil outlet of the first relief valve and the electrically controlled relief valve, one working oil port of the first three-position four-way solenoid valve is connected to the oil inlet of the first relief valve, and the other working oil port of the first three-position four-way solenoid valve is connected to the oil inlet of the electrically controlled relief valve; the oil outlet of the first cartridge valve is respectively connected to the working oil port MT, the first oil return port T1 and the second oil return port T2; the first three-position four-way solenoid valve determines whether the control port of the first cartridge valve is connected to the first relief valve or It is connected to the electronically controlled relief valve, and the first relief valve sets a fixed pressure value, and the pressure setting value of the valve is steplessly controlled by controlling the input current of the electronically controlled relief valve; when the first three-position four-way solenoid valve is in the middle position, whether the main oil circuit of the first cartridge valve is opened is determined by the minimum value of the respective pressure setting values ​​of the first relief valve and the electronically controlled relief valve; when the first three-position four-way solenoid valve is in the left position, the control port of the first cartridge valve is connected to the electronically controlled relief valve, and at this time, the opening pressure of the main oil circuit of the first cartridge valve is steplessly adjusted by the electronically controlled relief valve; when the electronically controlled relief valve fails, the coil Y30 of the first three-position four-way solenoid valve is energized and is in the right position, the control port of the first cartridge valve is connected to the first relief valve, and the opening pressure of the main oil circuit of the first cartridge valve is determined by the pressure setting value of the first relief valve.

[0011] It also includes a second three-position four-way solenoid valve, a second cartridge valve, a third cartridge valve and a shuttle valve; the control ports of the second cartridge valve and the third cartridge valve are connected to the shuttle valve through the second three-position four-way solenoid valve, and the shuttle valve controls whether the main oil circuits of the second cartridge valve and the third cartridge valve are connected; the oil inlets of the second cartridge valve and the third cartridge valve are connected to the P3 port and the P4 port of the extension main valve; the three ports of the shuttle valve are respectively connected to the oil inlet P1, the oil inlet P3 and the oil return port T, and the port with the highest pressure value among the three ports serves as the output port of the shuttle valve, and the pressures of the P1 port, the P3 port and the T port indirectly control the control oil chambers of the second cartridge valve and the third cartridge valve.

[0012] It also includes a fifth solenoid valve, a sixth solenoid valve, a sixth cartridge valve and a seventh cartridge valve; the fifth solenoid valve and the sixth solenoid valve are two-position four-way solenoid reversing valves; the control port of the sixth cartridge valve is connected to the fifth solenoid valve, the control port of the seventh cartridge valve is connected to the sixth solenoid valve, and the oil inlets of the sixth cartridge valve and the seventh cartridge valve are connected to the oil inlet P10; the control oil chambers of the sixth cartridge valve and the seventh cartridge valve are controlled by the fifth solenoid valve and the sixth solenoid valve, thereby controlling the oil inlet P10, and the oil inlet P10 of the extension and variable main valve is used to connect to the extension and variable system's amplitude cylinder to control the power drop of the amplitude cylinder.

[0013] It also includes an eighth solenoid valve, a ninth cartridge valve, and a tenth cartridge valve, wherein the eighth solenoid valve is a three-position four-way solenoid reversing valve with a middle position of P type; one oil outlet of the eighth solenoid valve is connected to the control port of the ninth cartridge valve, and the other oil outlet is connected to the control port of the tenth cartridge valve; the oil return port of the eighth solenoid valve is connected to the working oil port Y of the extension and variable main valve, and the oil inlet of the eighth solenoid valve is connected to the high-pressure oil at port P; one working oil port of the ninth cartridge valve and the tenth cartridge valve are commonly connected to the P6 port and the P7 port of the extension and variable main valve, the other working oil port of the ninth cartridge valve is connected to the oil inlet P, and the other working oil port of the tenth cartridge valve is respectively connected to the return oil port T, the P8 port, and the P9 port.

[0014] The P6 and P7 ports of the telescopic main valve are used to connect the large chamber of the telescopic oil cylinder in the telescopic system, and the P8 and P9 ports of the telescopic main valve are used to connect the small chamber of the telescopic oil cylinder in the telescopic system. The oil inlet and return of the telescopic oil cylinder in the telescopic system are controlled by the eighth solenoid valve, the ninth cartridge valve and the tenth cartridge valve.

[0015] It also includes a third solenoid valve, a seventh solenoid valve, a fourth cartridge valve, and an eighth cartridge valve, wherein the third solenoid valve and the seventh solenoid valve are both two-position four-way solenoid reversing valves, the control port of the fourth cartridge valve is connected to the third solenoid valve, the control port of the eighth cartridge valve is connected to the seventh solenoid valve, and the oil inlets of the fourth cartridge valve and the eighth cartridge valve are both connected to the P5 port of the telescopic main valve, and the P5 port is used to connect to the small chamber of the telescopic oil cylinder in the telescopic system to control the oil inlet and return of the small chamber of the telescopic oil cylinder.

[0016] The present invention also includes a telescopic system which adopts a telescopic main valve.

[0017] The present invention also includes a crane, which adopts an extension and variation system.

[0018] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The pressure of the telescopic main valve is no longer limited to three levels, and the pressure is adjustable to form multiple pressure levels, which meets the requirements of multiple working conditions for fine division of system pressure; (2) The variable amplitude power drop function is integrated to achieve high centralization; (3) The control mode of the telescopic cylinder cartridge valve is optimized to effectively prevent the telescopic cylinder from leaking out; (4) The control mode of the variable amplitude cylinder cartridge valve is optimized to improve the response characteristics of the variable amplitude cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the principle diagram of the telescopic main valve in the prior art;

[0020] Figure 2 It is the principle diagram of the extension and transformation system in the prior art;

[0021] Figure 3 It is the pressure control principle diagram of the prior art;

[0022] Figure 4This is a working principle diagram of the telescopic oil cylinder in the prior art;

[0023] Figure 5 This is a schematic diagram of the luffing control principle of the prior art;

[0024] Figure 6 This is a schematic diagram of the expansion and contraction main valve of the present invention;

[0025] Figure 7 This is a schematic diagram of the pressure control principle of the telescopic main valve of the present invention;

[0026] Figure 8 This is a schematic diagram of the anti-external leakage principle of the telescopic oil cylinder of the present invention;

[0027] Figure 9 This is a control principle diagram of the variable amplitude oil cylinder cartridge valve of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is described in detail below in conjunction with specific implementation methods and the accompanying drawings.

[0029] The present invention includes a telescopic main valve, which is applied to a telescopic system, and the telescopic system is applied to a crane. Figure 6 As shown, the telescopic main valve of the present invention includes 10 cartridge valves, 8 solenoid reversing valves, and 5 relief valves, wherein the 10 cartridge valves are respectively a first cartridge valve 218, a second cartridge valve 29, a third cartridge valve 210, a fourth cartridge valve 211, a fifth cartridge valve 212, a sixth cartridge valve 213, a seventh cartridge valve 214, an eighth cartridge valve 215, a ninth cartridge valve 216, and a tenth cartridge valve 217; the 8 solenoid reversing valves are respectively a first three-position four-way solenoid valve 28, a second three-position four-way solenoid valve 21, a third solenoid valve 22, a fourth solenoid valve 23, a fifth solenoid valve 24, a sixth solenoid valve 25, a seventh solenoid valve 26, and an eighth solenoid valve 27; and the 5 relief valves are respectively a first relief valve 219, an electronically controlled relief valve 220, a third relief valve 221, a fourth relief valve 222, and a fifth relief valve 223.

[0030] The extension and variable main valve includes ports T1~T2 and ports P1~P11. Ports P1~P11 are used to connect the various parts 7 of the extension and variable system; among them, the oil return ports T1 and T2 are connected to the oil tank, the oil inlets P1 and P2 are connected to the pump group of the extension and variable system, the oil inlets P3 and P4 are connected to the large cavity of the telescopic cylinder of the extension and variable system, the oil inlet P5 is connected to the small cavity of the telescopic cylinder of the extension and variable system, the oil inlets P6 and P7 are connected to the large cavity of the amplitude adjustment cylinder of the extension and variable system, the oil inlets P8 and P9 are connected to the small cavity of the amplitude adjustment cylinder of the extension and variable system, and the oil inlet P10 is connected to the amplitude adjustment cylinder of the extension and variable system, and the power drop of the amplitude adjustment cylinder is controlled by port P10.

[0031] The second three-position four-way solenoid valve 21 acts on the control oil chambers of the second cartridge valve 29 and the third cartridge valve 210, thereby controlling the P3 and P4 ports to control the oil inlet and return of the large chamber of the telescopic cylinder; the third solenoid valve 22 and the seventh solenoid valve 26 act on the control oil chambers of the fourth cartridge valve 211 and the eighth cartridge valve 215, respectively, thereby simultaneously controlling the P5 port to control the oil inlet and return of the small chamber of the telescopic cylinder; the fifth solenoid valve 24 and the sixth solenoid valve 25 act on the control oil chambers of the sixth cartridge valve 213 and the seventh cartridge valve 214, respectively, thereby controlling the P10 port to control the power drop of the variable amplitude cylinder; the eighth solenoid valve 27 acts on the control oil chambers of the ninth cartridge valve 216 and the tenth cartridge valve 217, thereby controlling the P6P7 and P8P9 ports to control the oil inlet and return of the variable amplitude cylinder. The specific connection method is as follows:

[0032] like Figure 7 As shown, the three-stage pressure control of the original main valve is replaced by the first three-position four-way solenoid valve 28, the first relief valve 219 and the electronically controlled relief valve 220. The first cartridge valve 218 is consistent with the cartridge valve in the original main valve and also plays the role of preventing the system pressure from being too high. The oil inlet of the first three-position four-way solenoid valve 28 is connected to the control port and the working oil port MX of the first cartridge valve 218, and the oil return port of the three-position four-way solenoid valve 28 is connected to the oil outlets of the first relief valve 219 and the electric-controlled relief valve 220. One working oil port of the first three-position four-way solenoid valve 28 is connected to the oil inlet of the first relief valve 219, and the other working oil port of the first three-position four-way solenoid valve 28 is connected to the oil inlet of the electric-controlled relief valve 220; the oil outlet of the first cartridge valve 218 is respectively connected to the working oil port MT, the return oil port T1 and the return oil port T2; the first three-position four-way solenoid valve 28 determines whether the control port of the first cartridge valve 218 is connected to the first relief valve 219 or the electric-controlled relief valve 220. The first relief valve 219 is set to a fixed pressure value, which is controlled by controlling the input current of the electric-controlled relief valve 220 The pressure setting value of the valve is steplessly controlled; when the first three-position four-way solenoid valve 28 is in the middle position, whether the main oil circuit of the first cartridge valve 218 is opened is determined by the minimum value of the respective pressure setting values ​​of the first relief valve 219 and the electronically controlled relief valve 220; when the first three-position four-way solenoid valve 28 is in the left position, the control port of the first cartridge valve 218 is connected to the electronically controlled relief valve 220. At this time, the opening pressure of the main oil circuit of the first cartridge valve 218 is steplessly adjusted by the electronically controlled relief valve 220; when the electronically controlled relief valve 220 fails, the coil Y30 of the first three-position four-way solenoid valve 28 is energized and is in the right position. The control port of the first cartridge valve 218 is connected to the first relief valve 219. The opening pressure of the main oil circuit of the first cartridge valve 218 is determined by the pressure setting value of the first relief valve 219.

[0033] like Figure 8As shown, the control ports of the second cartridge valve 29 and the third cartridge valve 210 are both connected to the shuttle valve 224 through the second three-position four-way solenoid valve 21. The shuttle valve 224 controls whether the main oil circuits of the second cartridge valve 29 and the third cartridge valve 210 are connected; the oil inlets of the second cartridge valve 29 and the third cartridge valve 210 are connected to the P3 port and the P4 port of the extension main valve; the three ports of the shuttle valve 224 are respectively connected to the oil inlet P1, the oil inlet P3, and the oil return port T. The port with the highest pressure value among the three ports serves as the output port of the shuttle valve 224, and the pressures of the P1 port, the P3 port, and the T port indirectly control the control oil chambers of the second cartridge valve 29 and the third cartridge valve 210.

[0034] In this solution, a shuttle valve 224 is added to the original main valve, and the solenoid valve is replaced with a second, three-position, four-way solenoid valve 21. When operating in the tower boom mode, the balance valve in the telescopic cylinder's main chamber of the telescopic system experiences internal leakage, and oil again flows back to the telescopic main valve through ports P3 and P4. However, at this time, the second, three-position, four-way solenoid valve 21 is in the neutral position, and the control oil chambers of the second and third cartridge valves 29 and 210 are connected to the shuttle valve 224. This shuttle valve controls whether the main oil circuits of the second and third cartridge valves 29 and 210 are connected. The three ports of shuttle valve 224 are connected to ports P1, P3, and T, respectively. The shuttle valve 224 outputs the highest pressure among these three ports, and the pressures at these three ports indirectly control the control oil chambers of the cartridge valves. Due to the higher pressure at port P1, the main oil circuit of the third cartridge valve 210 is completely closed. Oil leaking back from the telescopic cylinder's main chamber cannot pass through the third cartridge valve 210 back to port T, effectively preventing external leakage of the telescopic cylinder.

[0035] like Figure 6 As shown, the third solenoid valve 22 and the seventh solenoid valve 26 are both two-position, four-way solenoid reversing valves. The control port of the fourth cartridge valve 211 is connected to the working oil port MX of the telescopic main valve. One oil outlet of the third solenoid valve 22 is connected to the working oil port MX of the telescopic main valve via the third relief valve 221, while the other oil outlet of the third solenoid valve 22 is connected to the working oil port MX of the telescopic main valve via the fourth relief valve 222. The control port of the eighth cartridge valve 215 is connected to the seventh solenoid valve 26. The oil inlets of the fourth and eighth cartridge valves 211 and 215 are both connected to port P5 of the telescopic main valve. Port P5 is used to connect to the small chamber of the telescopic oil cylinder in the telescopic system, controlling the oil supply and return of the small chamber. The fourth solenoid valve 23 is connected to the control port of the fifth cartridge valve 212, and the oil inlet of the fifth cartridge valve 212 is connected to port P11 of the telescopic main valve.

[0036] like Figure 6As shown, the fifth and sixth solenoid valves 24 and 25 are two-position, four-way solenoid reversing valves. The control port of the sixth cartridge valve 213 is connected to the oil outlet of the fifth solenoid valve 24, and the oil return port of the fifth solenoid valve 24 is connected to the working oil port Y of the telescopic main valve. The control port of the seventh cartridge valve 214 is connected to the sixth solenoid valve 25, and the oil outlet of the sixth solenoid valve 25 is connected to the working oil port Y of the telescopic main valve via the fifth relief valve 223. The oil inlets of the sixth and seventh cartridge valves 213 and 214 are connected to the oil inlet P10. The control oil chambers of the sixth and seventh cartridge valves 213 and 214 are controlled by the fifth and sixth solenoid valves 24 and 25, thereby controlling the oil inlet P10. The oil inlet P10 of the telescopic main valve is connected to the luffing cylinder of the telescopic system to control the power lowering of the luffing cylinder.

[0037] This solution improves the amplitude change responsiveness by optimizing the control method of the amplitude change cylinder cartridge valve, such as Figure 9 As shown, an eighth solenoid valve 27 is combined with a ninth cartridge valve 216 and a tenth cartridge valve 217, wherein the eighth solenoid valve 27 is a three-position four-way solenoid directional valve with a middle position of P type; one oil outlet of the eighth solenoid valve 27 is connected to the control port of the ninth cartridge valve 216, and the other oil outlet is connected to the control port of the tenth cartridge valve 217; the oil return port of the eighth solenoid valve 27 is connected to the working oil port Y of the extension and variable main valve, and the oil inlet of the eighth solenoid valve 27 is connected to the high-pressure oil at port P; one working oil port of the ninth cartridge valve 216 and the tenth cartridge valve 217 are commonly connected to ports P6 and P7 of the extension and variable main valve, another working oil port of the ninth cartridge valve 216 is connected to the oil inlet P, and another working oil port of the tenth cartridge valve 217 is connected to the return oil port T, port P8, and port P9, respectively. Ports P6 and P7 of the main telescopic valve are connected to the large chamber of the luffing cylinder in the telescopic system, while ports P8 and P9 of the main telescopic valve are connected to the small chamber of the luffing cylinder in the telescopic system. The oil supply and return to the luffing cylinder in the telescopic system are controlled by the eighth solenoid valve 27, the ninth cartridge valve 216, and the tenth cartridge valve 217. When the luffing cylinder in the telescopic system is not operating, since the eighth solenoid valve 27 is in the P position, the control oil chambers of the ninth and tenth cartridge valves 216 and 217 are connected to the high-pressure oil at port P through the eighth solenoid valve 27. At this time, the main oil circuits of the ninth and tenth cartridge valves 216 and 217 are both completely closed, preventing oil from reaching the luffing cylinder through port P. When the luffing cylinder is required to operate, the eighth solenoid valve 27 is in the left or right position, eliminating the need for the ninth or tenth cartridge valve 216 and 217 to transition from a partially closed state to a fully closed state. This effectively prevents the delayed response of the luffing cylinder, which is common with conventional main valves.

Claims

1. A telescopic main valve, characterized by: The invention comprises a first three-position four-way solenoid valve (28), a first relief valve (219), an electrically controlled relief valve (220), a first cartridge valve (218), a working oil port MX, a working oil port MT, a return oil port T1 and a return oil port T2. The oil inlet of the first three-position four-way solenoid valve (28) is connected to the control port and the working oil port MX of the first cartridge valve (218). The return oil port of the first three-position four-way solenoid valve (28) is connected to the first relief valve (219) and the oil outlet of the electrically controlled relief valve (220). One working oil port of the first three-position four-way solenoid valve (28) is connected to the oil inlet of the first relief valve (219). The other working oil port of the first three-position four-way solenoid valve (28) is connected to the oil inlet of the electrically controlled relief valve (220). The oil outlet of the first cartridge valve (218) is connected to the working oil port MT, the return oil port T1 and the return oil port T2 respectively. The first three-position four-way solenoid valve (28) determines whether the control port of the first cartridge valve (218) is connected to the first relief valve (219) or the electric-controlled relief valve (220). The first relief valve (219) is set to a fixed pressure value, and the pressure setting value of the valve is steplessly controlled by controlling the input current of the electric-controlled relief valve (220). When the first three-position four-way solenoid valve (28) is in the middle position, the minimum value of the respective pressure setting values ​​of the first relief valve (219) and the electric-controlled relief valve (220) determines whether the main oil circuit of the first cartridge valve (218) is open. When the first When the three-position four-way solenoid valve (28) is in the left position, the control port of the first cartridge valve (218) is connected to the electric-controlled relief valve (220). At this time, the opening pressure of the main oil circuit of the first cartridge valve (218) is steplessly adjusted by the electric-controlled relief valve (220). When the electric-controlled relief valve (220) fails, the coil Y30 of the first three-position four-way solenoid valve (28) is energized and is in the right position. The control port of the first cartridge valve (218) is connected to the first relief valve (219). The opening pressure of the main oil circuit of the first cartridge valve (218) is determined by the pressure setting value of the first relief valve (219).

2. The telescopic main valve according to claim 1, characterized in that: The system further comprises a second three-position four-way solenoid valve (21), a second cartridge valve (29), a third cartridge valve (210) and a shuttle valve (224); the control ports of the second cartridge valve (29) and the third cartridge valve (210) are connected to the shuttle valve (224) via the second three-position four-way solenoid valve (21); the shuttle valve (224) controls whether the main oil circuits of the second cartridge valve (29) and the third cartridge valve (210) are connected; the oil inlets of the second cartridge valve (29) and the third cartridge valve (210) are connected to the P3 port and the P4 port of the extension main valve; the three ports of the shuttle valve (224) are respectively connected to the oil inlet P1, the oil inlet P3 and the oil return port T; the port with the highest pressure value among the three ports serves as the output port of the shuttle valve (224), and the control oil chambers of the second cartridge valve (29) and the third cartridge valve (210) are indirectly controlled by the pressures of the P1 port, the P3 port and the T port.

3. The telescopic main valve according to claim 1, characterized in that: The invention also includes a fifth solenoid valve (24), a sixth solenoid valve (25), a sixth cartridge valve (213) and a seventh cartridge valve (214); the fifth solenoid valve (24) and the sixth solenoid valve (25) are two-position four-way solenoid reversing valves; the control port of the sixth cartridge valve (213) is connected to the fifth solenoid valve (24), the control port of the seventh cartridge valve (214) is connected to the sixth solenoid valve (25), and the oil inlets of the sixth cartridge valve (213) and the seventh cartridge valve (214) are connected to the oil inlet P10; the control oil chambers of the sixth cartridge valve (213) and the seventh cartridge valve (214) are controlled by the fifth solenoid valve (24) and the sixth solenoid valve (25), thereby controlling the oil inlet P10, and the oil inlet P10 of the telescopic main valve is used to connect to the variable amplitude oil cylinder of the telescopic system.

4. The telescopic main valve according to claim 1, characterized in that: It also includes an eighth solenoid valve (27), a ninth cartridge valve (216), and a tenth cartridge valve (217), wherein the eighth solenoid valve (27) is a three-position four-way solenoid directional valve, and the middle position is P-type; one oil outlet of the eighth solenoid valve (27) is connected to the control port of the ninth cartridge valve (216), and the other oil outlet is connected to the control port of the tenth cartridge valve (217); the return oil port of the eighth solenoid valve (27) is connected to the working oil port Y of the extension and variable main valve, and the oil inlet of the eighth solenoid valve (27) is connected to the high-pressure oil at the P port; one working oil port of the ninth cartridge valve (216) and the tenth cartridge valve (217) is commonly connected to the P6 port and the P7 port of the extension and variable main valve, the other working oil port of the ninth cartridge valve (216) is connected to the oil inlet P, and the other working oil port of the tenth cartridge valve (217) is respectively connected to the return oil port T, the P8 port, and the P9 port.

5. The telescopic main valve according to claim 4, characterized in that: The P6 port and the P7 port of the telescopic main valve are used to connect to the large chamber of the telescopic oil cylinder in the telescopic system, and the P8 port and the P9 port of the telescopic main valve are used to connect to the small chamber of the telescopic oil cylinder in the telescopic system. The oil inlet and return of the telescopic oil cylinder in the telescopic system are controlled by the eighth solenoid valve (27), the ninth cartridge valve (216) and the tenth cartridge valve (217).

6. The telescopic main valve according to claim 1, characterized in that: The system further comprises a third solenoid valve (22), a seventh solenoid valve (26), a fourth cartridge valve (211), and an eighth cartridge valve (215), wherein the third solenoid valve (22) and the seventh solenoid valve (26) are both two-position four-way solenoid reversing valves, the control port of the fourth cartridge valve (211) is connected to the third solenoid valve (22), the control port of the eighth cartridge valve (215) is connected to the seventh solenoid valve (26), and the oil inlets of the fourth cartridge valve (211) and the eighth cartridge valve (215) are both connected to the P5 port of the telescopic main valve, and the P5 port is used to connect to the small chamber of the telescopic oil cylinder in the telescopic system.

7. A stretching system, characterized by: The system adopts the telescopic main valve described in claim 1.

8. A crane, characterized in that: The crane adopts the extension and variation system described in claim 7.

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