Multi-stage ram hydraulic control system and crane

Abstract

The present application relates to hydraulic system of engineering machinery, provide a kind of multistage cylinder hydraulic control system, including control valve and multistage cylinder, multistage cylinder includes several sequentially connected upper stage cylinder and lower stage cylinder, control valve controls the extension and retraction action of upper stage cylinder and lower stage cylinder by first working oil path and second working oil path, the rodless cavity of adjacent upper stage cylinder is sequentially connected between the rodless cavity of lower stage cylinder by first sequence valve, switch valve and second sequence valve, oil path is connected control valve by first working oil path between switch valve and second sequence valve, the rod cavity of upper stage cylinder and the rod cavity of lower stage cylinder are connected control valve by second working oil path.The multistage cylinder hydraulic control system of the present application can realize the sequential extension and retraction of binding type double-stage cylinder and the independent extension and retraction of second stage cylinder, select the most suitable extension and retraction mode according to working condition, improve work efficiency.The present application also provides a kind of crane.

Description

Technical Field

[0001] This invention relates to hydraulic systems for engineering machinery, specifically to a multi-stage hydraulic cylinder control system. It also relates to a crane. Background Technology

[0002] Many telescopic boom cranes, especially truck-mounted cranes with straight booms, employ a bundled two-stage hydraulic cylinder and wire rope telescopic mechanism. This mechanism combines a primary telescopic cylinder, a secondary telescopic cylinder, and an extension and retraction wire rope to achieve the telescopic boom's extension and retraction function. The extension and retraction sequence of the two-stage cylinders is as follows: During extension, the primary cylinder extends the first section of the telescopic boom, followed by the secondary cylinder extending the second section and the extension wire rope mechanism, which in turn extends the remaining section of the boom simultaneously. During retraction, the secondary cylinder retracts the second section of the telescopic boom and the retraction wire rope mechanism simultaneously. After the secondary cylinder has fully retracted, the primary cylinder retracts the first section of the telescopic boom. By controlling the sequential extension and retraction of the two-stage cylinders, the telescopic boom can achieve maximum lifting capacity under medium-to-long boom conditions, effectively extending the service life of the first section of the telescopic boom in such conditions.

[0003] In existing technologies, the sequential extension and retraction control of a bundled two-stage hydraulic cylinder mainly achieves the required sequential extension and retraction through a sequence valve installed in the hydraulic circuits of the first-stage and second-stage cylinders. The first-stage cylinder extends first, and when the pressure oil exceeds the set pressure of the sequence valve after the first-stage cylinder is fully extended, the second-stage cylinder extends. During retraction, the second-stage cylinder retracts first due to the difference in cylinder diameter between the first and second-stage cylinders and the friction of the boom. However, due to factors such as boom manufacturing errors and variations in the opening pressure of the sequence valve with flow rate, the boom retraction often lacks sequence. Furthermore, because the second-stage cylinder simultaneously drives multiple boom sections to extend and retract synchronously via a wire rope sling mechanism, when lifting lighter loads at medium to long working amplitudes, it is necessary to extend the first-stage cylinder before extending the second-stage cylinder, making it impossible to achieve the goal of the second-stage cylinder extending and retracting first, thus failing to drive the synchronous extension and retraction of multiple boom sections and increase work efficiency.

[0004] In view of the above problems, the present invention provides a multi-stage hydraulic cylinder control system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a multi-stage hydraulic cylinder control system, which can realize the sequential extension and retraction of the bundled two-stage hydraulic cylinders and the individual extension and retraction of the second-stage hydraulic cylinder, and select the most suitable extension and retraction method according to the working conditions to improve work efficiency.

[0006] The technical problem that this invention also aims to solve is to provide a crane that can realize sequential extension and retraction of a bundled double-stage hydraulic cylinder and individual extension and retraction of a second-stage hydraulic cylinder, and select the most suitable extension and retraction method according to the working conditions to improve work efficiency.

[0007] To address the aforementioned technical problems, this invention provides a multi-stage hydraulic cylinder control system, comprising a control valve and a multi-stage hydraulic cylinder. The multi-stage hydraulic cylinder includes several sequentially connected upper-stage and lower-stage hydraulic cylinders. The control valve controls the extension and retraction of the upper-stage and lower-stage hydraulic cylinders via a first working oil circuit and a second working oil circuit. A sequence control valve group is provided between the rodless chamber of an adjacent upper-stage hydraulic cylinder and the rodless chamber of an adjacent lower-stage hydraulic cylinder. The sequence control valve group includes a first sequence valve, a switching valve, and a second sequence valve connected in sequence. The first sequence valve is connected to the rodless chamber of the upper-stage hydraulic cylinder, and the second sequence valve is connected to the rodless chamber of the lower-stage hydraulic cylinder. The oil circuit between the switching valve and the second sequence valve is connected to the control valve via the first working oil circuit. The rod chamber of the upper-stage hydraulic cylinder and the rod chamber of the lower-stage hydraulic cylinder are connected to the control valve via the second working oil circuit.

[0008] Specifically, the multi-stage hydraulic cylinder includes a first-stage hydraulic cylinder and a second-stage hydraulic cylinder. The first-stage hydraulic cylinder includes a first-stage rod chamber and a first-stage rodless chamber. The second-stage hydraulic cylinder includes a second-stage rod chamber and a second-stage rodless chamber. The first-stage rodless chamber is connected to the second-stage rodless chamber in sequence through the first sequence valve, the switching valve, and the second sequence valve. The first-stage rod chamber is connected to the second-stage rod chamber.

[0009] Preferably, the first-stage piston rod of the first-stage cylinder is provided with a first-stage piston rod oil passage and a first-stage central tube oil passage, and the second-stage piston rod of the second-stage cylinder is provided with a second-stage piston rod oil passage and a second-stage central tube oil passage. The first working oil circuit is connected to the oil circuit between the switching valve and the second sequence valve through the first-stage central tube oil passage. The second sequence valve is connected to the second-stage rodless chamber through the second-stage central tube oil passage. The second working oil circuit is connected to the first-stage rod chamber through the first-stage piston rod oil passage. The second-stage piston rod oil passage is connected to the second-stage rod chamber of the piston rod, and the first-stage rod chamber is connected to the second-stage piston rod oil passage.

[0010] Preferably, the control valve further includes a balance valve, and the control valve is connected to the first working oil circuit and the second working oil circuit through the balance valve.

[0011] Specifically, the control valve is a three-position four-way directional valve with a Y-type center position function.

[0012] Specifically, the switching valve is a solenoid directional valve.

[0013] Preferably, the set value of the first sequence valve is greater than the set value of the second sequence valve.

[0014] Specifically, both the first sequence valve and the second sequence valve are one-way sequence valves.

[0015] Preferably, the second sequence valve is a sequence valve with return oil pressure compensation.

[0016] Furthermore, the present invention provides a crane including a multi-stage hydraulic cylinder control system as described in any of the above technical solutions.

[0017] The beneficial effects of the present invention through the above solution are as follows:

[0018] This invention relates to a multi-stage hydraulic cylinder control system. By configuring a first sequence valve, a switching valve, and a second sequence valve, when sequential extension and retraction of the upper and lower stage cylinders are required, the switching valve remains open. Under the action of the first and second sequence valves, the upper and lower stage cylinders extend and retract sequentially. When the lower stage cylinder needs to extend or retract independently, the switching valve remains closed, preventing the oil in the rodless chamber of the upper stage cylinder from communicating with the system's oil circuit. The upper stage cylinder remains inactive, allowing independent control of the lower stage cylinder's extension and retraction. This multi-stage hydraulic cylinder control system can select the appropriate extension and retraction method according to the working conditions, improving work efficiency and exhibiting good extension and retraction reliability.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a hydraulic schematic diagram of a specific embodiment of the multi-stage hydraulic cylinder control system of the present invention;

[0022] Figure 2 This is a schematic diagram of the first-stage hydraulic cylinder;

[0023] Figure 3 This is a schematic diagram of the second-stage hydraulic cylinder. Figure 1 ;

[0024] Figure 4 This is a schematic diagram of the second-stage hydraulic cylinder. Figure 2 ;

[0025] Figure 5 This is a schematic diagram of the working process of the multi-stage hydraulic cylinder control system of the present invention.

[0026] Explanation of reference numerals in the attached figures

[0027] 1. Control valve 101 First working oil circuit

[0028] 102 Second working oil circuit 2 balance valve

[0029] 3. First-stage hydraulic cylinder 31. First-stage rod chamber

[0030] 32 First-stage rodless chamber; 33 First-stage piston rod oil passage

[0031] 34 First-stage central tube oil passage; 35 First-stage piston rod

[0032] 36-interface one, 37-interface two

[0033] 38-pin interface 3, 39-pin interface 4

[0034] 4. First sequence valve; 5. Switch valve

[0035] 6 Second sequence valve 7 Second stage hydraulic cylinder

[0036] 71 Second-stage rod-mounted cavity 72 Second-stage rodless cavity

[0037] 73 Second-stage center tube oil passage; 74 Second-stage piston rod oil passage

[0038] 75 Second-stage piston rod 76 Interface five

[0039] 77 Interface Six Y1 Electromagnet Detailed Implementation

[0040] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention, and the scope of protection of the present invention is not limited to the specific embodiments described below.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "forming," "having," "setting," and "connecting," etc., should be interpreted broadly. For example, a connection can be a direct connection or an indirect connection through an intermediate medium; it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate connector; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] In this invention, unless otherwise specified, the directional terms "upper," "lower," and "middle," etc., used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. The directional terms of this invention should be understood in conjunction with the actual installation state.

[0043] This invention provides a multi-stage hydraulic control system for hydraulic cylinders, including a control valve 1 and a multi-stage hydraulic cylinder. The multi-stage hydraulic cylinder includes several upper-stage and lower-stage hydraulic cylinders connected in sequence. The control valve 1 controls the extension and retraction of the upper-stage and lower-stage hydraulic cylinders through a first working oil circuit 101 and a second working oil circuit 102. A sequence control valve group is provided between the rodless chamber of an adjacent upper-stage hydraulic cylinder and the rodless chamber of a lower-stage hydraulic cylinder. The sequence control valve group includes a first sequence valve 4, a switching valve 5, and a second sequence valve 6 connected in sequence. The first sequence valve 4 is connected to the rodless chamber of the upper-stage hydraulic cylinder, and the second sequence valve 6 is connected to the rodless chamber of the lower-stage hydraulic cylinder. The oil circuit between the switching valve 5 and the second sequence valve 6 is connected to the control valve 1 through the first working oil circuit 101. The rod chamber of the upper-stage hydraulic cylinder and the rod chamber of the lower-stage hydraulic cylinder are connected to the control valve 1 through the second working oil circuit 102. When the upper and lower level cylinders need to extend and retract sequentially, the switching valve remains open. Under the action of the first and second sequence valves, the upper and lower level cylinders extend and retract in sequence. When the lower level cylinder needs to extend and retract independently, the switching valve remains closed, so that the oil in the rodless chamber of the upper level cylinder is not connected to the system oil circuit, and the upper level cylinder does not move. This allows the lower level cylinder to be controlled to extend and retract independently. This enables the multi-stage cylinder hydraulic control system of the present invention to select the appropriate extension and retraction method according to the working conditions, improve work efficiency, and have good extension and retraction reliability.

[0044] See Figure 1 As a specific embodiment of the multi-stage hydraulic cylinder control system of the present invention, the multi-stage hydraulic cylinder is a two-stage hydraulic cylinder, including a first-stage hydraulic cylinder 3 and a second-stage hydraulic cylinder 7. The first-stage hydraulic cylinder 3 includes a first-stage rod chamber 31 and a first-stage rodless chamber 32. The second-stage hydraulic cylinder 7 includes a second-stage rod chamber 71 and a second-stage rodless chamber 72. The first-stage rodless chamber 32 is connected to the second-stage rodless chamber 72 in sequence through a first sequence valve 4, a switching valve 5 and a second sequence valve 6. The first-stage rod chamber 31 is connected to the second-stage rod chamber 71.

[0045] To reduce the piping layout of the multi-stage hydraulic cylinder control system of this invention and prevent excessive piping from hindering the extension and retraction of the cylinders, see [reference needed]. Figure 2-4 The first-stage piston rod 35 of the first-stage cylinder 3 is provided with a first-stage piston rod oil passage 33 and a first-stage central tube oil passage 34. The second-stage piston rod 75 of the second-stage cylinder 7 is provided with a second-stage piston rod oil passage 74 and a second-stage central tube oil passage 73. The first working oil circuit 101 is connected to the oil circuit between the switching valve 5 and the second sequence valve 6 through the first-stage central tube oil passage 34. The second sequence valve 6 is connected to the second-stage rodless chamber 72 through the second-stage central tube oil passage 73. The second working oil circuit 102 is connected to the first-stage rod chamber 31 through the first-stage piston rod oil passage 33. The second-stage piston rod oil passage 74 is connected to the second-stage piston rod chamber 71. The first-stage rod chamber 31 is connected to the second-stage piston rod oil passage 74.

[0046] Further, see Figure 2-4 The first-stage cylinder 3 has interfaces 36, 37, 38, and 39 on its cylinder body, and the second-stage cylinder 7 has interfaces 76 and 77 on its cylinder body. The first-stage central pipe oil passage 34 connects to interfaces 37 and 38 via internal oil passages on the cylinder body of the first-stage cylinder 3. The first-stage rod chamber 31 connects to interface 36, and the first-stage rodless chamber 32 connects to interface 39. The second-stage central pipe oil passage 73 connects to interface 76, and the second-stage piston rod oil passage 74 connects to interface 77. The switching valve 5 is connected to interface 38, and the first sequence valve 4... Connecting interface 4 (39), the switching valve 5 is then connected to the first sequence valve 4 via an external oil circuit, so that the first-stage central pipe oil passage 34 is connected to the first-stage rodless chamber 32 sequentially through the switching valve 5 and the first sequence valve 4; the second sequence valve 6 is connected to interface 2 (37) and interface 5 (76) respectively, so that the first-stage central pipe oil passage 34 is connected to the second-stage rodless chamber 72 sequentially through the second sequence valve 6 and the second-stage central pipe oil passage 73; interface 1 (36) is connected to interface 6 (77) via an external oil circuit, so that the first-stage piston rod oil passage 33, the first-stage rod chamber 31, the second-stage piston rod oil passage 74, and the second-stage rod chamber 71 are connected sequentially. This technical solution makes the overall pipeline layout of the multi-stage hydraulic cylinder control system of the present invention simpler and more convenient.

[0047] See Figure 1 In a preferred embodiment, the multi-stage hydraulic cylinder control system of the present invention further includes a balance valve 2, which enables the multi-stage hydraulic cylinder control system of the present invention to have a load holding function and avoid uncontrollable retraction of the hydraulic cylinder. Specifically, the control valve 1 is connected to the first working oil circuit 101 and the second working oil circuit 102 through the balance valve 2. The second working oil circuit 102 is connected to the control end of the sequence valve in the balance valve 2. When the first stage cylinder 3 and / or the second stage cylinder 7 needs to extend, the output oil of the control valve 1 flows directly to the first working oil circuit 101 through the check valve in the balance valve 2, and the second working oil circuit 102 returns oil directly through the control valve 1. When the first stage cylinder 3 and / or the second stage cylinder 7 needs to retract, the output oil of the control valve 1 flows to the second working oil circuit 102. The oil pressure of the second working oil circuit 102 acts on the control end of the sequence valve in the balance valve 2, thereby opening the sequence valve. The oil in the first working oil circuit 101 can flow to the control valve 1 through the sequence valve for return oil.

[0048] It should be noted that, see Figure 1The control valve 1 is a three-position four-way directional valve with a Y-type neutral position function. The three-position four-way directional valve includes an upper position, a neutral position, and a lower position. When its valve core moves to the upper position, oil enters through the first working oil circuit 101 and returns through the second working oil circuit 102. When the valve core moves to the lower position, oil returns through the first working oil circuit 101 and enters through the second working oil circuit 102. When the valve core moves to the neutral position, the balance valve 2 can unload oil through the control valve 1, thereby protecting the first-stage cylinder 3 and the second-stage cylinder 7 from sliding down under load.

[0049] Preferably, the switching valve 5 is a two-position two-way electromagnetic directional valve, which is controlled by an electromagnet Y1. When the electromagnet Y1 is de-energized, the electromagnetic directional valve is in the open state, so that the first-stage central pipe oil passage 34 is connected to the first sequence valve 4, thereby enabling the first-stage cylinder 3 and the second-stage cylinder 7 to extend and retract sequentially under the action of the first sequence valve 4 and the second sequence valve 6. When the electromagnet Y1 is energized, the electromagnetic directional valve is in the closed state, so that the first-stage central pipe oil passage 34 and the first sequence valve 4 are cut off, and the first-stage rodless chamber 32 cannot supply or return oil, thereby enabling the second-stage cylinder 7 to extend and retract independently.

[0050] Preferably, the set value of the first sequence valve 4 is greater than the set value of the second sequence valve 6. When the first stage cylinder 3 is fully extended, the oil pressure of the first stage central pipe oil passage 73 can preferentially open the second sequence valve 6 to supply oil to the second stage rodless chamber 72. The first sequence valve 4 will not open, so that the pressure drop is small during the extension of the second stage cylinder 7, thereby improving the load-bearing capacity of the second stage cylinder 7 to drive the other stages of telescopic arms to extend synchronously.

[0051] It should be noted that both the first sequence valve 4 and the second sequence valve 6 are one-way sequence valves. The first-stage central pipe oil passage 34 can directly supply oil to the first-stage rodless chamber 32 through the one-way valve of the first sequence valve 4. When the first-stage rodless chamber 32 returns oil, it returns oil to the first-stage central pipe oil passage 34 when the return oil pressure is greater than the set pressure of the first sequence valve 4. When the inlet oil pressure of the first-stage central pipe oil passage 34 is greater than the set pressure of the second sequence valve 6, it supplies oil to the second-stage rodless chamber 72. The second-stage rodless chamber 72 can directly return oil to the first-stage central pipe oil passage 34 through the one-way valve of the second sequence valve 6.

[0052] In addition, the second sequence valve 6 is a sequence valve with return oil pressure compensation. When the second rodless chamber 72 returns oil through the check valve of the second sequence valve 6, the pressure of the output oil of the check valve can act on the second sequence valve 6, thereby opening the second sequence valve 6. The check valve and the sequence valve return oil together, reducing the pressure loss during oil return.

[0053] To better understand the technical solution of the multi-stage hydraulic cylinder control system of the present invention, the workflow is described below in conjunction with preferred technical features.

[0054] See Figure 1-5 The multi-stage hydraulic cylinder consists of two stages, including a first-stage cylinder 3 and a second-stage cylinder 7. The first-stage cylinder 3 drives the first section of the telescopic arm to extend and retract, while the second-stage cylinder 7 drives the second-stage telescopic arm and the extended wire rope mechanism to synchronously extend and retract the remaining telescopic arms. The multi-stage hydraulic control system of this invention can select the sequential extension and retraction of the first-stage cylinder 3 and the second-stage cylinder 7, or it can select the extension and retraction of the second-stage cylinder 7 alone, as detailed below:

[0055] When the first-stage cylinder 3 and the second-stage cylinder 7 need to extend sequentially, the control valve 1 first switches from the neutral position to the upper position. Pressure oil flows into the first-stage central pipe oil passage 34 through the balance valve 2. The electromagnet Y1 is de-energized, and the switching valve 5 is open, allowing the pressure oil in the first-stage central pipe oil passage 34 to flow into the switching valve 5 and then into the first-stage rodless chamber 32 through the first sequence valve 4. Furthermore, the pressure oil in the first-stage central pipe oil passage 34 can also flow through the second sequence valve 6 and the second-stage central pipe oil passage 73 into the second-stage rodless chamber 72. Because... Since the oil pressure has not reached the set pressure of the second sequence valve 6, the pressurized oil preferentially enters the first rodless chamber 32 through the check valve of the first sequence valve 4. At this time, the first rod chamber 31 can return oil to the second working oil circuit 102 through the first piston rod oil passage 33. Thus, under the action of the pressurized oil, the first stage cylinder 3 extends to drive the first telescopic arm to extend outward. When the first stage piston rod 35 is fully extended, the control valve 1 switches back to the neutral position. At this time, the first telescopic arm is also fully extended, reaching the maximum arm length of the first telescopic arm. When the first-stage cylinder 3 extends to its maximum stroke, if the control valve 1 continues to be switched to the upper position, the oil pressure flowing from the first-stage central pipe oil passage to the second sequence valve 6 increases until the pressure exceeds the set pressure of the second sequence valve 6. Then, the pressurized oil opens the second sequence valve 6 and enters the second-stage rodless chamber 72. At this time, the second-stage rod chamber 71 can flow back to the second working oil circuit 102 through the second-stage piston rod oil passage 74, the first-stage rod chamber 31, and the first-stage piston rod oil passage 33 in sequence. Thus, under the action of the pressurized oil, the second-stage cylinder 7 extends the second-stage telescopic arm and drives the remaining telescopic arm to extend synchronously through the wire rope mechanism until the telescopic arm is fully extended. The control valve 1 then switches back to the neutral position, realizing the full extension of the boom.

[0056] When the boom is fully extended, retraction requires the second-stage cylinder 7 to retract first, followed by the first-stage cylinder 1. First, control valve 1 switches from the neutral position to the lower position, allowing pressurized oil to flow sequentially through the first-stage piston rod oil passage 3, the first-stage rod chamber 31, and the first-stage piston rod oil passage 74 into the second-stage rod chamber 71. At this time, the switching valve 5 is not energized. Because the return oil pressure in the first-stage rodless chamber 32 does not reach the set pressure of the first sequence valve 4, the oil in the second-stage rodless chamber 72 preferentially flows through the check valve in the second sequence valve 6 to the first-stage central pipe oil passage 34, and then returns through the first working oil circuit 101. Therefore, under the action of pressurized oil, the second-stage cylinder 7 retracts the second-stage telescopic boom, and the remaining telescopic boom retracts synchronously via the wire rope mechanism. When the second-stage cylinder 7 is fully retracted, the pressurized oil enters the first-stage rod chamber 31 through the first-stage piston rod oil passage 33, thereby pushing the first-stage piston rod 35. At this time, the return oil pressure of the first-stage rodless chamber 32 is greater than the set pressure of the first sequence valve 4, which can open the first sequence valve 4 and return oil to the first working oil circuit 101 through the switching valve 5 and the first-stage central pipe oil passage 34 in sequence. Under the action of the pressurized oil, the first-stage cylinder 3 retracts to drive the first telescopic boom until it is fully retracted. The control valve 1 switches back to the neutral position, thus realizing the full retraction of the boom.

[0057] When the second-stage cylinder 7 needs to extend independently, the electromagnet Y1 is energized first, and the control valve 1 switches from the neutral position to the upper position. The pressure oil enters the first-stage central pipe oil passage 34 through the balance valve 2. At this time, the switch valve 5 is in the closed state, closing the oil passage from the pressure oil to the first-stage rodless chamber 32. The first-stage cylinder 3 cannot perform extension and retraction. As the pressure increases, when the pressure oil exceeds the set value of the second sequence valve 6, the pressure oil in the first-stage central pipe oil passage 34 opens the second sequence valve 6 and enters the second-stage rodless chamber 72 through the second-stage central pipe oil passage 73. The second-stage rod chamber 71 can return to the second working oil passage 102 in sequence through the second-stage piston rod oil passage 74, the first-stage rodless chamber 31, and the first-stage piston rod oil passage 33. Under the action of the pressure oil, the second-stage cylinder 7 extends independently, enabling the second-stage telescopic arm to extend. It also drives the remaining telescopic arms to extend synchronously through the wire rope mechanism, realizing the priority extension of the second telescopic arm to the top arm.

[0058] When the second-stage cylinder 7 needs to retract independently, the electromagnet Y1 is energized first, and the control valve 1 switches from the neutral position to the lower position. The pressurized oil flows sequentially through the first-stage piston rod oil passage 3, the first-stage rod chamber 31, and the first-stage piston rod oil passage 74 into the second-stage rod chamber 71. At this time, the switch valve 5 is in the closed state, and the first-stage rodless chamber 32 cannot return oil through the switch valve 5. At this time, the oil in the second-stage rodless chamber 72 flows first through the check valve in the second sequence valve 6 to the first-stage central pipe oil passage 34, and returns oil through the first working oil circuit 101. Therefore, under the action of the pressurized oil, the second-stage cylinder 7 retracts, and drives the wire rope lasso mechanism to retract the remaining multi-section arm synchronously.

[0059] Meanwhile, when the first-stage cylinder 3 extends first, it can be energized by the user through the switch at any position. The switch valve 5 is in the closed state, which closes the oil passage from the pressure oil in the first-stage central pipe oil passage 34 to the first-stage rodless chamber 32, causing the first-stage cylinder 1 to stop extending. At this time, the pressure increases. When the oil pressure is greater than the set pressure of the second sequence valve 6, the pressure oil in the first-stage central pipe oil passage 34 opens the second sequence valve 6 and enters the second-stage rodless chamber 72 through the second-stage central pipe oil passage 73, causing the second-stage cylinder 7 to extend.

[0060] Through the above scheme, the multi-stage hydraulic control system of the present invention can control the sequential extension and retraction of the first-stage hydraulic cylinder 3 and the second-stage hydraulic cylinder 7, and can also control the extension and retraction of the second-stage hydraulic cylinder 7 individually, thereby enabling the selection of a suitable extension and retraction method according to the working conditions and improving work efficiency.

[0061] In addition, the present invention also provides a crane including the multi-stage hydraulic cylinder control system of the present invention, and therefore has all its beneficial effects, which will not be elaborated here.

[0062] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0063] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0064] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A multi-stage hydraulic cylinder control system, characterized in that, The system includes a control valve (1) and a multi-stage hydraulic cylinder. The multi-stage hydraulic cylinder includes several upper-stage hydraulic cylinders and lower-stage hydraulic cylinders connected in sequence. The control valve (1) controls the extension and retraction of the upper-stage hydraulic cylinders and the lower-stage hydraulic cylinders through a first working oil circuit (101) and a second working oil circuit (102). A sequence control valve group is provided between the rodless chamber of the adjacent upper-stage hydraulic cylinder and the rodless chamber of the lower-stage hydraulic cylinder. The sequence control valve group includes a first sequence valve (4), a switch valve (5), and a second sequence valve (6) connected in sequence. The first sequence valve (4) is connected to the rodless chamber of the upper-stage hydraulic cylinder, and the second sequence valve (6) is connected to the rodless chamber of the lower-stage hydraulic cylinder. The oil circuit between the switch valve (5) and the second sequence valve (6) is connected to the control valve (1) through the first working oil circuit (101). The rod chamber of the upper-stage hydraulic cylinder and the rod chamber of the lower-stage hydraulic cylinder are connected to the control valve (1) through the second working oil circuit (102). The switching valve (5) is configured such that when the upper-level cylinder and the lower-level cylinder extend and retract in sequence, the switching valve (5) remains in a connected state; when the lower-level cylinder needs to extend and retract independently, the switching valve (5) remains in a closed state.

2. The multi-stage hydraulic cylinder control system according to claim 1, characterized in that, The multi-stage cylinder includes a first-stage cylinder (3) and a second-stage cylinder (7). The first-stage cylinder (3) includes a first-stage rod chamber (31) and a first-stage rodless chamber (32). The second-stage cylinder (7) includes a second-stage rod chamber (71) and a second-stage rodless chamber (72). The first-stage rodless chamber (32) is connected to the second-stage rodless chamber (72) in sequence through the first sequence valve (4), the switching valve (5), and the second sequence valve (6). The first-stage rod chamber (31) is connected to the second-stage rod chamber (71).

3. The multi-stage hydraulic cylinder control system according to claim 2, characterized in that, The first stage piston rod (35) of the first stage cylinder (3) is provided with a first stage piston rod oil passage (33) and a first stage central tube oil passage (34). The second stage piston rod (75) of the second stage cylinder (7) is provided with a second stage piston rod oil passage (74) and a second stage central tube oil passage (73). The first working oil circuit (101) is connected to the oil circuit between the switching valve (5) and the second sequence valve (6) through the first stage central tube oil passage (34). The second sequence valve (6) is connected to the second stage rodless chamber (72) through the second stage central tube oil passage (73). The second working oil circuit (102) is connected to the first stage rod chamber (31) through the first stage piston rod oil passage (33). The second stage piston rod oil passage (74) is connected to the second stage piston rod rod chamber (71). The first stage rod chamber (31) is connected to the second stage piston rod oil passage (74).

4. The multi-stage hydraulic cylinder control system according to claim 1, characterized in that, It also includes a balance valve (2), through which the control valve (1) is connected to the first working oil circuit (101) and the second working oil circuit (102).

5. The multi-stage hydraulic cylinder control system according to claim 1, characterized in that, The control valve (1) is a three-position four-way directional valve with Y-type center position function.

6. The multi-stage hydraulic cylinder control system according to any one of claims 1-5, characterized in that, The switching valve (5) is an electromagnetic directional valve.

7. The multi-stage hydraulic cylinder control system according to any one of claims 1-5, characterized in that, The set value of the first sequence valve (4) is greater than the set value of the second sequence valve (6).

8. The multi-stage hydraulic cylinder control system according to any one of claims 1-5, characterized in that, Both the first sequence valve (4) and the second sequence valve (6) are one-way sequence valves.

9. The multi-stage hydraulic cylinder control system according to any one of claims 1-5, characterized in that, The second sequence valve (6) is a sequence valve with return oil pressure compensation.

10. A crane, characterized in that, The multi-stage hydraulic cylinder control system includes any one of claims 1-9.

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