A switching type multi-way directional control valve for a straight boom crane

Abstract

This invention discloses a switching multi-way directional valve for a straight boom crane, comprising: an oil inlet link, an oil circuit switching control link, and several proportional working links. The oil inlet link is connected to the several proportional working links via the oil circuit switching control link. The oil circuits of the oil inlet link, the oil circuit switching control link, and the several proportional working links are interconnected. The oil inlet link is externally connected to a pump source, which supplies oil to the oil inlet link. The oil circuit switching control link is also externally connected to a lowering multi-way valve. By switching the oil circuit switching control link, the oil inlet link is controlled to supply oil to the several proportional working links or the lowering multi-way valve. The proportional working links have four functions, which respectively control the four actions of hoisting, telescopic, slewing, and luffing. When the switching valve is in the spring position, the oil inlet link supplies oil to the hoisting, telescopic, slewing, and luffing actions. When the switching solenoid valve is energized, the oil circuit switches to supply oil to the lowering multi-way valve. The oil circuit connection is simple, the switching is reliable, and there will be no malfunctions. When the switching valve is stuck, it will not cause pump damage.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control, and more specifically to a switching multi-way directional valve for a straight boom crane. Background Technology

[0002] The control system of a straight boom truck-mounted crane typically includes a lower outrigger control system and an upper operating control system. The operating control system usually includes telescopic, luffing, winching, and slewing functions. Currently, the upper operating control system typically uses a single-pump proportional valve control method, while the lower outrigger operation uses a throttling speed control system. The flow and pressure requirements of the upper and lower outrigger multi-way valves differ significantly. Current solutions often use three-way switching valves, but in actual use, the oil circuit connection is complex, the fault feedback rate is high, and valve jamming or misoperation can easily lead to pressure buildup and damage to the hydraulic pump. To solve these problems, a switching multi-way directional valve for straight boom cranes is proposed. Summary of the Invention

[0003] To address the problems of the existing technology, this invention provides a switching multi-way directional valve for straight boom cranes. It solves the problem that existing truck-mounted cranes rely on a three-way switching valve for flow and pressure differentiation control during single-pump control of the loading and unloading process. This results in complex system piping connections, a high failure rate, and the risk of pump outlet pressure buildup and damage to the hydraulic pump due to valve jamming or misoperation. The switching multi-way directional valve for straight boom cranes consists of one inlet line, four proportional working lines, and one oil circuit switching control line. The inlet line draws oil from the pump source, and the four proportional working lines control the four actions of hoisting, telescopic, slewing, and luffing respectively. When the switching valve is in the spring position, the inlet line supplies oil to the hoisting, telescopic, slewing, and luffing actions. When the switching solenoid valve is energized, the oil circuit switches to supply oil to the unloading multi-way valve. The oil circuit connection is simple, the switching is reliable, and misoperation is prevented. Furthermore, pump damage is not caused by valve jamming.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a switching type multi-way directional valve for a straight boom crane, comprising: an oil inlet link, an oil circuit switching control link, and several proportional working links. The oil inlet link is connected to the several proportional working links through the oil circuit switching control link. The oil passages of the oil inlet link, the oil circuit switching control link, and the several proportional working links are interconnected. The oil inlet link is externally connected to a pump source, which supplies oil to the oil inlet link. The oil circuit switching control link is also externally connected to a downhill multi-way valve. By switching the oil circuit switching control link, the oil inlet link is controlled to supply oil to the several proportional working links or the downhill multi-way valve.

[0005] Furthermore, the P oil inlet channel, LS control channel, T return channel, MX channel, and L channel in the oil inlet connection, oil circuit switching control connection, and several proportional working connections are interconnected.

[0006] Furthermore, the oil inlet assembly includes: a relief valve, an unloading valve, a three-way compensator, a pilot pressure reducing valve, a throttling damper, and a pressure stabilizing valve. The inlet of the relief valve is connected to the control port of the three-way compensator and the LS control oil passage, respectively. The outlet of the relief valve is connected to the T return oil passage. The inlet of the three-way compensator is connected to the P inlet oil passage, and the outlet of the three-way compensator is connected to the T return oil passage. The inlet of the unloading valve is connected to the LS control oil passage, and the outlet of the unloading valve is connected to the T return oil passage. The LS control oil passage and the MX oil passage are connected through the pilot pressure reducing valve and the throttling damper. The P inlet oil passage and the T return oil passage are connected through the pressure stabilizing valve.

[0007] Furthermore, the oil circuit switching control unit includes: an electro-proportional pressure reducing valve, a throttling damper, an oil circuit switching valve, a shuttle valve, and a U-channel. The U-channel is externally connected to a multi-way valve for the vehicle. The shuttle valve is installed on the LS control channel, and its common port is connected to the LS control channel in the inlet connection through the throttling damper. One of its ports is connected to the multi-way valve for the vehicle through the U-channel, and the other port is connected to the LS control channels in several proportional working connections. The inlet of the oil circuit switching valve is connected to the P inlet channel of the inlet connection through the P inlet channel. One of the working outlets of the oil circuit switching valve is connected to the P inlet channels of several proportional working connections through the P inlet channel. The other working outlet of the oil circuit switching valve is connected to the U-channel. The spring port of the oil circuit switching valve is connected to the L-channel. The valve core control port of the oil circuit switching valve is connected to the outlet of the electro-proportional pressure reducing valve through the throttling damper. The inlet of the electro-proportional pressure reducing valve is connected to the MX-channel, and the pressure relief port of the electro-proportional pressure reducing valve is connected to the L-channel.

[0008] Furthermore, the oil circuit switching valve is a two-position three-way directional valve.

[0009] Furthermore, the proportional control assembly includes: a three-way pressure compensator, a three-position seven-way directional valve, a check valve, an electro-proportional pressure reducing valve, working oil passage A, and working oil passage B. The inlet and upper chamber port of the three-way pressure compensator are connected to one of the ports of the three-position seven-way directional valve. The load-sensitive port and lower chamber port of the three-way pressure compensator are connected to the LS control oil passage. The neutral throttle port of the three-way pressure compensator is connected to one of the ports of the three-position seven-way directional valve via a check valve. One of the ports of the three-position seven-way directional valve is connected to... The P inlet oil passage is connected. Two of the oil ports of the three-position seven-way directional valve are connected to the working oil passage A and the working oil passage B, respectively. Two of the oil ports of the three-position seven-way directional valve are connected to the T return oil passage. The valve core control port of the three-position seven-way directional valve is connected to the MX oil passage through the electro-proportional pressure reducing valve. The spring oil port of the three-position seven-way directional valve is connected to the L oil passage through the electro-proportional pressure reducing valve. The pressure relief ports of the two electro-proportional pressure reducing valves connected to the three-position seven-way directional valve are connected to the L oil passage. The working oil passages A and B are connected to the external actuator.

[0010] Furthermore, a balance valve is also provided, and the working oil passages A and B are connected to the T return oil passage through the balance valve.

[0011] Its working method includes: When operating the proportional control unit alone, the oil enters the upper or lower position of the three-position seven-way directional valve, and then the high-pressure oil enters the upper chamber of the three-way pressure compensator, causing the three-way pressure compensator to move down and first to the middle position. The oil returns to the upper or lower position of the three-position seven-way directional valve through the middle position throttle port and the three-position seven-way directional valve. The function of the middle position throttle port of the three-way pressure compensator makes the extension and retraction action start smoothly. At this time, there is no oil pressure in the LS control oil passage, and the three-way flow valve is still in the open state. Some oil returns through the three-way flow valve, and the pressure is not high. After the actuator starts, the pressure continues to rise, and the three-way pressure compensator continues to move down. The three-way pressure compensator reaches the upper position, and the high-pressure oil enters the LS control oil passage, thereby causing the three-way flow valve to close, and all the pump oil enters the actuator to operate.

[0012] Furthermore, if the operator needs to operate the downcarriage multi-way valve, the proportional pressure reducing valve of the oil circuit switching control needs to be energized. After the proportional pressure reducing valve of the oil circuit switching control is energized, the pilot oil flows through the inlet of the proportional pressure reducing valve to the pressure relief port, and then through the throttling damper to the valve core control port of the oil circuit switching valve. The oil circuit switching valve switches to the upper position and supplies oil to the external downcarriage multi-way valve from the U oil passage. The pressure of the U oil passage enters the shuttle valve through one of the ports of the shuttle valve, and then through the common port of the shuttle valve through the throttling damper to the control port of the three-way compensator. According to the outrigger load of the downcarriage multi-way valve, sufficient pressure is provided to drive the outrigger to move.

[0013] Furthermore, the proportional control unit is provided with four components: hoisting proportional control unit, telescopic control proportional control unit, slewing proportional control unit, and luffing proportional control unit. These components control the four actions of hoisting, telescopicing, slewing, and luffing, respectively.

[0014] Furthermore, the oil inlet link, oil circuit switching control link, hoisting proportional working link, telescopic proportional working link, slewing proportional working link, and luffing proportional working link are arranged in parallel to form a switching type multi-way directional valve.

[0015] Furthermore, the hoisting proportional working link, telescopic proportional working link, and luffing proportional working link adopt proportional working links without balance valves, while the slewing proportional working link adopts a proportional working link with a balance valve.

[0016] Furthermore, the oil inlet coupling is equipped with a P port connected to the P oil inlet channel, an LS port connected to the LS control channel, a T port connected to the T return oil channel, an MX port connected to the MX pilot oil channel, and an L port connected to the L drain oil channel. The luffing proportional working coupling is equipped with a T port connected to the T return oil channel.

[0017] The beneficial effects of this invention are:

[0018] (1) Compared with the three-way switching valve, it has a higher degree of integration and relatively simple pipeline connection. The oil inlet three-way compensator and overflow valve can effectively protect the system pump source;

[0019] (2) The switching oil circuit is controlled by the proportional pressure reducing valve, which can set different output flow rates to adapt to different outrigger action requirements and can achieve reliable interlocking when getting on and off the vehicle;

[0020] (3) The oil circuit connection is simple and the switching is reliable. There will be no malfunctions. When the switching valve is stuck, it will not cause damage to the pump. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention;

[0022] In the diagram: 1. Oil inlet valve; 2. Oil circuit switching control valve; 3. Proportional working valve; 4. Relief valve; 5. Unloading valve; 6. Three-way compensator; 7. Pilot pressure reducing valve; 8. Throttling damper; 9. Pressure stabilizing valve; 10. Electro-proportional pressure reducing valve; 11. Oil circuit switching valve; 12. Shuttle valve; 13. U-shaped oil passage; 14. Three-way pressure compensator; 15. Three-position seven-way directional valve; 16. Check valve; 17. Working oil passage A; 18. Working oil passage B. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0025] like Figure 1 As shown, a switching type multi-way directional valve for a straight boom crane includes: an oil inlet link 1, an oil circuit switching control link 2, and several proportional working links 3. The oil inlet link 1 is connected to the several proportional working links 3 through the oil circuit switching control link 2. The oil passages of the oil inlet link 1, the oil circuit switching control link 2, and the several proportional working links 3 are connected. The oil inlet link 1 is externally connected to a pump source, which supplies oil to the oil inlet link 1. The oil circuit switching control link 2 is also externally connected to a downhill multi-way valve. By switching the oil circuit switching control link 2, the oil inlet link 1 is controlled to supply oil to the several proportional working links 3 or the downhill multi-way valve.

[0026] The P oil inlet passage, LS control passage, T return passage, MX passage, and L passage in the oil inlet link 1, oil circuit switching control link 2, and several proportional working links 3 are connected.

[0027] The oil inlet assembly 1 includes: a relief valve 4, an unloading valve 5, a three-way compensator 6, a pilot pressure reducing valve 7, a throttling damper 8, and a pressure regulating valve 9. The inlet of the relief valve 4 is connected to the control port of the three-way compensator 6 and the LS control oil passage, respectively. The outlet of the relief valve 4 is connected to the T return oil passage. The inlet of the three-way compensator 6 is connected to the P inlet oil passage, and the outlet of the three-way compensator 6 is connected to the T return oil passage. The inlet of the unloading valve 5 is connected to the LS control oil passage, and the outlet of the unloading valve 5 is connected to the T return oil passage. The LS control oil passage and the MX oil passage are connected through the pilot pressure reducing valve 7 and the throttling damper 8. The P inlet oil passage and the T return oil passage are connected through the pressure regulating valve 9.

[0028] The oil circuit switching control unit 2 includes: an electro-proportional pressure reducing valve 10, a throttle damper 8, an oil circuit switching valve 11, a shuttle valve 12, and a U-shaped oil passage 13. The U-shaped oil passage 13 is externally connected to a multi-way valve for the vehicle. The shuttle valve 12 is installed on the LS control oil passage, and its common port is connected to the LS control oil passage in the inlet unit 1 via the throttle damper 8. One of its ports is connected to the multi-way valve for the vehicle via the U-shaped oil passage 13, and the other port is connected to the LS control oil passages in several proportional working units 3. The inlet of the oil circuit switching valve 11 is connected to the inlet oil passage via the P-shaped oil passage. The P-inlet oil passage of oil circuit 1 is connected. One of the working outlets of oil circuit switching valve 11 is connected to the P-inlet oil passages of several proportional working circuits 3 through the P-inlet oil passage. The other working outlet of oil circuit switching valve 11 is connected to the U-line oil passage 13. The spring oil port of oil circuit switching valve 11 is connected to the L-line oil passage. The valve core control port of oil circuit switching valve 11 is connected to the outlet of electro-proportional pressure reducing valve 10 through the throttling damper 8. The inlet of electro-proportional pressure reducing valve 10 is connected to the MX-line oil passage. The pressure relief port of electro-proportional pressure reducing valve 10 is connected to the L-line oil passage.

[0029] The oil circuit switching valve 11 is a two-position three-way directional valve. By introducing a two-position three-way directional valve in the oil circuit switching control link 2, the oil circuit oil supply switching between the upper and lower vehicles is realized. The two-position three-way directional valve supplies oil for the upper vehicle operation in the spring position. When the electro-proportional pressure reducing valve 10 is energized, the switching valve switches, and the system supplies oil to the lower vehicle multi-way valve, realizing the switching. A damper is set in front of the valve core control port of the two-position three-way directional valve to prevent pressure shock caused by excessive switching speed and increase system stability. A shuttle valve 12 is set at the outlet of the oil supply to the lower vehicle multi-way valve controlled by the two-position three-way directional valve. This is to enable the load pressure to be fed back to the three-way compensator 6 during the upper and lower vehicle operations, to establish sufficient system pressure to drive the load. A throttling damper 8 is set between the shuttle valve 12 and the three-way compensator 6. On the one hand, it works with the shuttle valve 12 to provide load feedback to the three-way compensator 6. On the other hand, it plays a buffering role to achieve smooth pressure build-up.

[0030] The proportional working link 3 includes: a three-way pressure compensator 14, a three-position seven-way directional valve 15, a check valve 16, an electro-proportional pressure reducing valve 10, working oil passage A, and working oil passage B18. The inlet and upper chamber oil port of the three-way pressure compensator 14 are connected to one of the oil ports of the three-position seven-way directional valve 15. The load-sensitive port and lower chamber oil port of the three-way pressure compensator 14 are connected to the LS control oil passage. The middle position throttle port of the three-way pressure compensator 14 is connected to one of the oil ports of the three-position seven-way directional valve 15 through the check valve 16. One of the oil ports of the three-position seven-way directional valve 15 is connected to... The P inlet oil passage is connected. Two of the oil ports of the three-position seven-way directional valve 15 are connected to the working oil passage A and the working oil passage B18, respectively. Two of the oil ports of the three-position seven-way directional valve 15 are connected to the T return oil passage. The valve core control port of the three-position seven-way directional valve 15 is connected to the MX oil passage through the electro-proportional pressure reducing valve 10. The spring oil port of the three-position seven-way directional valve 15 is connected to the L oil passage through the electro-proportional pressure reducing valve 10. The pressure relief ports of the two electro-proportional pressure reducing valves 10 connected to the three-position seven-way directional valve 15 are connected to the L oil passage. The working oil passage A and the working oil passage B18 are connected to the external actuator.

[0031] The proportional working link 3 is also equipped with a balance valve, and the working oil passage A and working oil passage B18 are connected to the T return oil passage through the balance valve.

[0032] Its working methods include:

[0033] Oil inlet 1 introduces the pump power into port P, and a pressure stabilizing valve 9 is installed in oil inlet 1 to maintain the stability of the LS control oil passage; the set pressure of the overflow valve 4 is the rated pressure of the system to prevent overload of the proportional working link 3 in this multi-way valve control system; when the three-position seven-way directional valve 15 in the proportional working link 3 is in the neutral position, there is no oil pressure in the upper and lower chambers of the three-way pressure compensator 14 in the proportional working link 3, so the three-way pressure compensator 14 in the proportional working link 3 is in the lower position. Therefore, as long as the system pressure overcomes the spring force of the three-way flow valve, the three-way flow valve can be opened to achieve neutral position unloading, resulting in low system energy consumption and low heat generation.

[0034] When operating the proportional control unit 3 alone, the oil enters the upper or lower position of the three-position seven-way directional valve 15. Then, the high-pressure oil enters the upper chamber of the three-way pressure compensator 14, causing the three-way pressure compensator 14 to move downwards and first to the middle position. The oil returns to the upper or lower position of the three-position seven-way directional valve 15 through the middle position throttle port and the three-position seven-way directional valve 15. The function of the middle position throttle port of the three-way pressure compensator 14 ensures a smooth start to the telescopic action. At this time, there is no oil pressure in the LS control oil passage, and the three-way flow valve is still in the open state. Some oil returns through the three-way flow valve, and the pressure is not high. After the actuator starts, the pressure continues to rise, and the three-way pressure compensator 14 continues to move downwards. The three-way pressure compensator 14 reaches the upper position, and the high-pressure oil enters the LS control oil passage, thereby causing the three-way flow valve to close, and all the pump oil enters the actuator to operate.

[0035] If the operator needs to operate the downcarriage multi-way valve, the electro-proportional pressure reducing valve 10 of the oil circuit switching control link 2 needs to be energized. After the electro-proportional pressure reducing valve 10 of the oil circuit switching control link 2 is energized, the pilot oil flows through the inlet of the electro-proportional pressure reducing valve 10 to the pressure relief port, and enters the valve core control port of the oil circuit switching valve 11 after passing through the throttling damper 8. The oil circuit switching valve 11 switches to the upper position and supplies oil to the external downcarriage multi-way valve from the U oil passage 13. The pressure of the U oil passage 13 enters the shuttle valve 12 through one of the oil ports of the shuttle valve 12, and then reaches the control port of the three-way compensator 6 from the common port of the shuttle valve 12 through the throttling damper 8. According to the outrigger load of the downcarriage multi-way valve, sufficient pressure is provided to drive the outrigger to move.

[0036] In this example, there are four proportional working links 3. The proportional working links 3 are connected to external actuators such as hoists, telescopic actuators, slewing actuators, and luffing actuators through working oil passages A and B18, respectively controlling the four actions of hoisting, telescopicing, slewing, and luffing. The four proportional working links 3 are respectively hoisting proportional working link 3, telescopic proportional working link 3, slewing proportional working link 3, and luffing proportional working link 3, and control the four actions of hoisting, telescopicing, slewing, and luffing through the hoisting proportional working link 3, telescopic proportional working link 3, slewing proportional working link 3, and luffing proportional working link 3.

[0037] The oil inlet control 1, oil circuit switching control 2, hoisting proportional control 3, telescopic proportional control 3, slewing proportional control 3, and luffing proportional control 3 are arranged in parallel to form a switching type multi-way directional valve.

[0038] The hoisting proportional working link 3, telescopic proportional working link 3, and luffing proportional working link 3 use proportional working link 3 without a balance valve, while the slewing proportional working link 3 uses proportional working link 3 with a balance valve.

[0039] The oil inlet coupling 1 is equipped with a P oil port connected to the P oil inlet channel, an LS oil port connected to the LS control channel, a T oil port connected to the T return oil channel, an MX oil port connected to the MX pilot oil channel, and an L oil port connected to the L drain oil channel. The luffing proportional working coupling 3 is equipped with a T oil port connected to the T return oil channel.

[0040] In this example, the switching multi-way directional valve used for the boom crane is controlled by a single pump system.

[0041] In this example, the oil inlet line 1 introduces the pump power into the P oil port, and a pressure stabilizing valve 9 is installed in the oil inlet line 1 to maintain the stability of the LS control oil passage. The set pressure of the overflow valve 4 is the rated pressure of the system to prevent overload of the telescopic, luffing, and winch functions in this multi-way valve control system. When the three-position seven-way directional valve 15 in the winch proportional working line 3, telescopic proportional working line 3, slewing proportional working line 3, and luffing proportional working line 3 is in the neutral position, there is no oil pressure in the upper and lower chambers of the three-way pressure compensator 14 in the winch proportional working line 3, telescopic proportional working line 3, slewing proportional working line 3, and luffing proportional working line 3. This makes the three-way pressure compensator 14 in the lower position. Therefore, as long as the system pressure overcomes the spring force of the three-way flow valve, the three-way flow valve can be opened to achieve neutral unloading, resulting in low system energy consumption and low heat generation.

[0042] In this example, when the operator operates the telescopic proportional control link 3 alone, the oil enters the upper or lower position of the three-position seven-way directional valve 15 in the telescopic proportional control link 3. Then, the high-pressure oil enters the upper chamber of the three-way pressure compensator 14 in the telescopic proportional control link 3, causing the three-way pressure compensator 14 to move down and initially to the middle position. The oil returns to the upper or lower position of the three-position seven-way directional valve 15 in the telescopic proportional control link 3 through the middle position throttle port and the one-way valve 16 in the telescopic proportional control link 3. The function of the middle position throttle port of the three-way pressure compensator 14 ensures a smooth start to the telescopic action. At this time, there is no oil pressure in the LS control oil passage, and the three-way flow valve is still in the open state. Some oil returns through the three-way flow valve, and the pressure is not high. After the telescopic action starts, the pressure continues to rise, and the three-way pressure compensator 14 in the telescopic proportional control link 3 continues to move down. The three-way pressure compensator 14 in the telescopic proportional control link 3 reaches the upper position, and the high-pressure oil enters the control oil circuit, thereby causing the three-way flow valve to close and all the pumped oil to enter the telescopic action.

[0043] In this example, when the operator operates the luffing proportional control unit 3 alone, the pumped oil enters the upper or lower position of the three-position seven-way directional valve 15 in the luffing proportional control unit 3. Then, the high-pressure oil enters the upper chamber of the three-way pressure compensator 14 in the luffing proportional control unit 3, causing the three-way pressure compensator 14 to move downwards, initially to the neutral position. The oil then returns to the upper or lower position of the three-position seven-way directional valve 15 in the luffing proportional control unit 3 through the neutral position throttle orifice and the one-way valve 16. The function of the throttle port in the middle position of the pressure compensator 14 ensures a smooth start to the luffing action. At this time, there is no oil pressure in the LS control oil passage, and the three-way flow valve is still in the open state. Some oil returns through the three-way flow valve, and the pressure is not high. After the luffing action starts, the pressure continues to rise, and the three-way pressure compensator 14 in the luffing proportional working link 3 continues to move down. The three-way pressure compensator 14 in the luffing proportional working link 3 reaches the upper position, and the high-pressure oil enters the control oil circuit, thereby closing the three-way flow valve and allowing all the pumped oil to enter the luffing action.

[0044] In this example, when the operator operates the hoisting proportional control link 3 alone, the hydraulic fluid enters the upper or lower position of the three-position seven-way directional valve 15 in the hoisting proportional control link 3. Then, the high-pressure oil enters the upper chamber of the three-way pressure compensator 14 in the hoisting proportional control link 3, causing the three-way pressure compensator 14 to move downwards, initially to the middle position. The hydraulic fluid then returns to the upper or lower position of the three-position seven-way directional valve 15 in the hoisting proportional control link 3 through the middle position throttle orifice and the one-way valve 16. The function of the throttling port of the pressure compensator 14 ensures a smooth start to the hoisting action. At this time, there is no oil pressure in the LS control oil passage, and the three-way flow valve is still open. Some oil returns through the three-way flow valve, and the pressure is not high. After the hoisting action starts, the pressure continues to rise, and the three-way pressure compensator 14 in the hoisting proportional working link 3 continues to move down. The three-way pressure compensator 14 in the hoisting proportional working link 3 reaches the upper position, and the high-pressure oil enters the control oil circuit, thereby closing the three-way flow valve and allowing all the oil to enter the hoisting action.

[0045] In this example, when the operator operates the rotary proportional control link 3 alone, the oil enters the upper or lower position of the three-position seven-way directional valve 15 in the rotary proportional control link 3. Then, the high-pressure oil enters the upper chamber of the three-way pressure compensator 14 in the rotary proportional control link 3, causing the three-way pressure compensator 14 to move downwards, initially to the neutral position. The oil then returns to the upper or lower position of the three-position seven-way directional valve 15 in the rotary proportional control link 3 through the neutral position throttle orifice and the one-way valve 16. The function of the throttle port in the middle position of the pressure compensator 14 ensures a smooth start to the slewing action. At this time, there is no oil pressure in the LS control oil passage, and the three-way flow valve is still in the open state. Some oil returns through the three-way flow valve, and the pressure is not high. After the hoisting action starts, the pressure continues to rise, and the three-way pressure compensator 14 in the slewing proportional working link 3 continues to move down. The three-way pressure compensator 14 in the slewing proportional working link 3 reaches the upper position, and the high-pressure oil enters the control oil circuit, thereby closing the three-way flow valve and allowing all the oil to enter the slewing action.

[0046] If the operator needs to operate the downcarriage multi-way valve, the electro-proportional pressure reducing valve 10 of the oil circuit switching control link 2 needs to be energized. After the electro-proportional pressure reducing valve 10 of the oil circuit switching control link 2 is energized, the pilot oil flows through the inlet of the electro-proportional pressure reducing valve 10 to the pressure relief port, and enters the valve core control port of the oil circuit switching valve 11 after passing through the throttling damper 8. The oil circuit switching valve 11 switches to the upper position and supplies oil to the external downcarriage multi-way valve from the U oil passage 13. The pressure of the U oil passage 13 enters the shuttle valve 12 through one of the oil ports of the shuttle valve 12, and then reaches the control port of the three-way compensator 6 from the common port of the shuttle valve 12 through the throttling damper 8. According to the outrigger load of the downcarriage multi-way valve, sufficient pressure is provided to drive the outrigger to move.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A switching multi-way directional valve for a straight boom crane, characterized in that, include: The system includes an oil inlet connection, an oil circuit switching control connection, and several proportional working connections. The oil inlet connection is connected to several proportional working connections through the oil circuit switching control connection. The oil passages between the oil inlet connection, the oil circuit switching control connection, and the several proportional working connections are interconnected. The oil inlet connection is connected to an external pump source, which supplies oil to the oil inlet connection. The oil circuit switching control connection is also connected to an external off-road multi-way valve. By switching the oil circuit switching control connection, the oil inlet connection is controlled to supply oil to several proportional working connections or the off-road multi-way valve. The P oil inlet channel, LS control channel, T return channel, MX channel, and L channel in the oil inlet connection, oil circuit switching control connection, and several proportional working connections are interconnected. The oil inlet assembly includes: a relief valve, an unloading valve, a three-way compensator, a pilot pressure reducing valve, a throttle damper, and a pressure stabilizing valve. The inlet of the relief valve is connected to the control port of the three-way compensator and the LS control oil passage, respectively. The outlet of the relief valve is connected to the T return oil passage. The inlet of the three-way compensator is connected to the P inlet oil passage, and the outlet of the three-way compensator is connected to the T return oil passage. The inlet of the unloading valve is connected to the LS control oil passage, and the outlet of the unloading valve is connected to the T return oil passage. The LS control oil passage and the MX oil passage are connected through the pilot pressure reducing valve and the throttle damper. The P inlet oil passage and the T return oil passage are connected through the pressure stabilizing valve. The oil circuit switching control unit includes: an electro-proportional pressure reducing valve, a throttling damper, an oil circuit switching valve, a shuttle valve, and a U-channel. The U-channel is externally connected to a multi-way valve for the vehicle. The shuttle valve is located on the LS control channel, and its common port is connected to the LS control channel in the inlet connection through the throttling damper. One of its ports is connected to the multi-way valve for the vehicle through the U-channel, and the other port is connected to the LS control channels in several proportional working connections. The inlet of the oil circuit switching valve is connected to the P inlet channel of the inlet connection through the P inlet channel. One of the working outlets of the oil circuit switching valve is connected to the P inlet channels of several proportional working connections through the P inlet channel. The other working outlet of the oil circuit switching valve is connected to the U-channel. The spring port of the oil circuit switching valve is connected to the L-channel. The valve core control port of the oil circuit switching valve is connected to the outlet of the electro-proportional pressure reducing valve through the throttling damper. The inlet of the electro-proportional pressure reducing valve is connected to the MX-channel. The pressure relief port of the electro-proportional pressure reducing valve is connected to the L-channel. The proportional control unit has four components: hoisting proportional control unit, telescopic proportional control unit, slewing proportional control unit, and luffing proportional control unit. These components control the four actions of hoisting, telescopicing, slewing, and luffing, respectively. The oil inlet control, oil circuit switching control, hoisting proportional control, telescopic proportional control, slewing proportional control, and luffing proportional control are arranged in parallel to form a switching type multi-way directional valve.

2. A switching multi-way directional valve for a straight boom crane according to claim 1, characterized in that, The proportional control assembly includes: a three-way pressure compensator, a three-position seven-way directional valve, a check valve, an electro-proportional pressure reducing valve, working oil passage A, and working oil passage B. The inlet and upper chamber port of the three-way pressure compensator are connected to one port of the three-position seven-way directional valve. The load-sensitive port and lower chamber port of the three-way pressure compensator are connected to the LS control oil passage. The neutral throttle port of the three-way pressure compensator is connected to one port of the three-position seven-way directional valve via a check valve. One port of the three-position seven-way directional valve is connected to the P inlet... The oil passages are connected. Two of the oil ports of the three-position seven-way directional valve are connected to working oil passage A and working oil passage B respectively. Two of the oil ports of the three-position seven-way directional valve are connected to the T return oil passage. The valve core control port of the three-position seven-way directional valve is connected to the MX oil passage through an electro-proportional pressure reducing valve. The spring oil port of the three-position seven-way directional valve is connected to the L oil passage through an electro-proportional pressure reducing valve. The pressure relief ports of the two electro-proportional pressure reducing valves connected to the three-position seven-way directional valve are connected to the L oil passage. Working oil passages A and B are connected to external actuators.

3. A switching multi-way directional valve for a straight boom crane according to claim 2, characterized in that, A balance valve is also provided, and the working oil passages A and B are connected to the T return oil passage through the balance valve.

4. A switching multi-way directional valve for a straight boom crane according to claim 1, characterized in that, The hoisting proportional working link, telescopic proportional working link, and luffing proportional working link use proportional working links without balance valves, while the slewing proportional working link uses proportional working links with balance valves.

5. A switching multi-way directional valve for a straight boom crane according to claim 1, characterized in that, The oil inlet coupling is equipped with a P port connected to the P oil inlet channel, an LS port connected to the LS control channel, a T port connected to the T return oil channel, an MX port connected to the MX pilot oil channel, and an L port connected to the L drain oil channel. The luffing proportional working coupling is equipped with a T port connected to the T return oil channel.

Images