Hydraulic system and crane

Abstract

The present application discloses a hydraulic system and a crane; wherein the hydraulic system includes: a telescopic oil cylinder having a rod chamber and a rodless chamber; a hydraulic valve group including a first working oil port and a second working oil port; the first working oil port is connected to the rod chamber through a first working oil circuit; the second working oil port is connected to the rodless chamber through a second working oil circuit; the hydraulic valve group is capable of connecting the first working oil circuit with the second working oil circuit; wherein the hydraulic valve group is capable of controlling the flow direction of the hydraulic oil to achieve: when the telescopic oil cylinder extends with an empty arm, the hydraulic valve group controls the connection between the first working oil circuit and the second working oil circuit to realize a differential connection circuit; when the telescopic oil cylinder extends / retracts with an arm, the hydraulic valve group controls the hydraulic oil circuit to not differentially connect, and the hydraulic oil circulates through the oil tank. The present application can flexibly select the optimal hydraulic oil circuit flow direction under three working conditions, thereby improving the efficiency of the crane's telescopic arm, and has high comprehensive cost-effectiveness and strong flexibility and applicability.

Description

Technical Field

[0001] The present application relates to the technical field of lifting equipment, and more specifically to a hydraulic system, and also to a crane having the hydraulic system. Background Art

[0002] Currently, boom extension and retraction hydraulic systems primarily use an electro-hydraulic reversing valve to control the telescopic cylinder's extension and retraction. When the cylinder extends, oil enters the rodless chamber and exits the rod chamber, returning to the tank through the reversing valve. When the cylinder retracts, oil enters the rod chamber and exits the rodless chamber, returning to the tank through the reversing valve. This boom hydraulic system provides high thrust and a strong boom load capacity. However, when the boom is extended, the telescopic cylinder's efficiency is low. Summary of the Invention

[0003] In view of this, the present application provides a hydraulic system, and the present application also provides a crane having the above hydraulic system.

[0004] In order to achieve the above objectives, this application provides the following technical solutions:

[0005] A hydraulic system comprising:

[0006] Telescopic cylinder, having a rod chamber and a rodless chamber;

[0007] A hydraulic valve group, comprising a first working oil port and a second working oil port;

[0008] The first working oil port is connected to the rod chamber through a first working oil passage;

[0009] The second working oil port is connected to the rodless chamber through a second working oil passage;

[0010] The hydraulic valve group is capable of connecting the first working oil circuit with the second working oil circuit;

[0011] The hydraulic valve group can control the flow direction of the hydraulic oil to achieve:

[0012] The hydraulic oil flows into the rodless chamber through the second working oil passage, and the hydraulic oil in the rod chamber flows out through the first working oil passage;

[0013] or,

[0014] The hydraulic oil flows into the rod chamber through the first working oil passage, and the hydraulic oil in the rodless chamber flows out through the second working oil passage;

[0015] or,

[0016] The hydraulic oil flows into the rodless chamber through the second working oil passage, and at the same time, the hydraulic oil in the rod chamber merges with the second working oil passage through the first working oil passage and flows into the rodless chamber.

[0017] Optionally, in the above hydraulic system, the hydraulic valve group includes:

[0018] an electro-hydraulic reversing valve, the electro-hydraulic reversing valve being provided with the first working oil port and the second working oil port;

[0019] a first on-off valve connected to the first working oil circuit;

[0020] connecting the working oil circuits to connect the first working oil circuit with the second working oil circuit;

[0021] a second on-off valve connected to the connecting working oil path;

[0022] The on-off valve control unit is used to control the on-off of the first on-off valve and the on-off of the second on-off valve.

[0023] Optionally, in the above hydraulic system,

[0024] The first on-off valve is a first cartridge valve; the second on-off valve is a second cartridge valve;

[0025] The on-off valve control unit is a control oil reversing unit, which can control whether the control oil flows to the control oil port of the first cartridge valve and simultaneously control whether the control oil flows to the control oil port of the second cartridge valve.

[0026] Optionally, in the above hydraulic system, the control oil reversing unit includes:

[0027] A control oil reversing valve comprises an oil inlet, a first oil outlet and a second oil outlet;

[0028] a first control oil circuit, connecting the first working oil port to the oil inlet;

[0029] a second control oil circuit, connecting the second working oil port to the oil inlet;

[0030] a third control oil circuit, connecting the first oil outlet to the control oil port of the first cartridge valve;

[0031] a fourth control oil circuit, connecting the second oil outlet to the control oil port of the second cartridge valve;

[0032] Wherein, a first one-way valve is provided on the first control oil circuit to control the control oil in the first control oil circuit to flow only to the control oil reversing valve;

[0033] A second one-way valve is provided on the second control oil circuit to control the control oil in the second control oil circuit to flow only toward the control oil reversing valve;

[0034] The control oil reversing valve can control whether the control oil flows out from the first oil outlet and simultaneously control whether the control oil flows out from the second oil outlet.

[0035] Optionally, in the above hydraulic system, the control oil reversing valve is a three-position four-way electromagnetic reversing valve.

[0036] Optionally, in the above hydraulic system, the control oil reversing valve includes: a first reversing valve and a second reversing valve; the first reversing valve and the second reversing valve are both two-position four-way electromagnetic reversing valves;

[0037] The oil inlet of the first reversing valve and the oil inlet of the second reversing valve are both connected to the oil inlet;

[0038] The first reversing valve includes the first oil outlet;

[0039] The second reversing valve includes the second oil outlet;

[0040] The control oil flows out from the first oil outlet and the second oil outlet by controlling the potential transformation of the first reversing valve and the potential transformation of the second reversing valve.

[0041] Optionally, in the above hydraulic system, the hydraulic valve group includes: a power-off protection control oil circuit;

[0042] The power-off protection control oil circuit connects the rod chamber to the third control oil circuit;

[0043] When the control oil reversing valve is at the off position, the third control oil circuit is connected to the fourth control oil circuit.

[0044] Optionally, in the above hydraulic system,

[0045] The third control oil circuit is connected to a first throttling damper;

[0046] The fourth control oil circuit is connected to a second throttling damper.

[0047] Optionally, in the above hydraulic system,

[0048] The first working oil circuit is provided with a relief valve; and / or,

[0049] The second working oil circuit is provided with a balancing valve, and a control oil circuit of the balancing valve is connected to the first working oil circuit.

[0050] A crane is provided with the above hydraulic system for controlling the extension and retraction of the crane's boom.

[0051] The hydraulic system provided by the present application can select the oil flow direction of the hydraulic oil of the telescopic cylinder according to the working conditions: ① When the telescopic cylinder is extended with its empty arm, the hydraulic oil flows from the oil tank to the rodless chamber, and at the same time, the hydraulic oil in the rod chamber flows to the rodless chamber, realizing differential connection; the differential principle is adopted for empty extension, which improves the extension speed of the telescopic cylinder; ② When the telescopic cylinder is extended with its arm, the hydraulic oil flows from the oil tank to the rodless chamber, and at the same time, the hydraulic oil in the rod chamber flows back to the oil tank; with this oil flow downward, the thrust of the telescopic cylinder is large and the load capacity of the extension arm is strong; ③ When the telescopic cylinder is retracted with its arm, the hydraulic oil flows from the oil tank to the rod chamber, and at the same time, the hydraulic oil in the rodless chamber flows back to the oil tank. The hydraulic system of the present application can flexibly select the best hydraulic oil flow direction under three working conditions, and has high comprehensive cost performance and strong flexibility and applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0053] Figure 1 This is a schematic diagram of the hydraulic system of this application;

[0054] Figure 2 This is a structural diagram of another embodiment of the hydraulic system of the present application;

[0055] Figure 3 This is a structural diagram of the control oil reversing unit in the hydraulic system of this application.

[0056] Figure 1-Figure 3 middle:

[0057] 1- telescopic cylinder, 2- hydraulic valve group, 3- first working oil circuit, 4- second working oil circuit, 5- overflow valve, 6- balancing valve;

[0058] 21 - first working oil port, 22 - second working oil port, 23 - first on-off valve, 24 - connecting working oil circuit, 25 - second on-off valve, 26 - control oil reversing unit; 27 - power-off protection control oil circuit, 28 - electro-hydraulic reversing valve;

[0059] 261 - control oil reversing valve, 262 - first control oil circuit, 263 - second control oil circuit, 264 - third control oil circuit, 265 - fourth control oil circuit, 266 - first one-way valve, 267 - second one-way valve, 268 - first throttle damper, 269 - second throttle damper;

[0060] A- oil inlet, B- first oil outlet, C- second oil outlet. DETAILED DESCRIPTION

[0061] The present application provides a hydraulic system and also provides a crane having the hydraulic system.

[0062] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0063] like Figure 1-Figure 3 As shown, a hydraulic system includes: a telescopic cylinder 1, a hydraulic valve group 2, a first working oil circuit 3 and a second working oil circuit 4; the telescopic cylinder 1 includes a rod chamber 11 and a rodless chamber 12; the hydraulic valve group 2 includes: an oil supply port P, an oil return port T, a first working oil port 21 and a second working oil port 22.

[0064] One end of the first working oil passage 3 is connected to the first working oil port 21 , and the other end is connected to the rod chamber 11 ;

[0065] One end of the second working oil passage 4 is connected to the second working oil port 22 , and the other end is connected to the rodless chamber 12 .

[0066] The hydraulic valve group 2 can connect the first hydraulic oil passage 3 and the second hydraulic oil passage 4 .

[0067] The oil supply port P and the oil return port T are respectively connected to the oil tank. The hydraulic valve group 2 can control the flow direction of the hydraulic oil. Under the control of the hydraulic valve group 2, the oil supply port P can selectively connect to the first working oil port 21 or the second working oil port 22. When the oil supply port P is connected to the first working oil port 21, the oil tank supplies oil to the first working oil port 21. At this time, the oil return port T is connected to the second working oil port 22, and the second working oil port 22 returns oil to the oil tank through the oil return port T. When the oil supply port P is connected to the second working oil port 22, the oil tank supplies oil to the second working oil port 22. At this time, the oil return port T is connected to the first working oil port 21, and the first working oil port 21 returns oil to the oil tank through the oil return port T.

[0068] Under the control of hydraulic valve group 2, different hydraulic oil flow directions can be selected under different working conditions:

[0069] When the telescopic cylinder is extended with the arm extended, hydraulic valve assembly 2 connects the oil supply port P with the second working oil port 22 and the oil return port T with the first working oil port 21. Hydraulic oil in the tank flows from the oil supply port P to the second working oil port 22, through the second working oil passage 4, and into the rodless chamber 12. Simultaneously, hydraulic oil in the rod chamber 11 flows through the first working oil passage 3, from the first working oil port 21, and back to the tank through the oil return port T.

[0070] When the telescopic cylinder is retracted, the hydraulic valve assembly 2 connects the oil supply port P to the first working oil port 21 and the oil return port T to the second working oil port 22. Hydraulic oil in the tank flows out of the oil supply port P to the first working oil port 21, then flows into the rod chamber 11 through the first working oil passage 3. Simultaneously, hydraulic oil in the rodless chamber 12 flows through the second working oil passage 4, from the second working oil port 22, and back to the tank through the oil return port T.

[0071] When the telescopic cylinder's arm is extended, the hydraulic valve assembly 2 connects the first working oil circuit 3 with the second working oil circuit 4. It also connects the oil supply port P with the second working oil port 22, and the oil return port T with the first working oil port 21. Hydraulic oil in the tank flows through the oil supply port P to the second working oil port 22, then flows through the second working oil circuit 4 into the rodless chamber 12. Simultaneously, the hydraulic oil in the rod chamber 11 flows from the first working oil circuit 3 to the second working oil circuit 4 and into the rodless chamber 12.

[0072] The hydraulic system provided by this application can select the hydraulic oil flow direction of the telescopic cylinder according to the operating conditions: when the telescopic cylinder extends without an arm, hydraulic valve group 2 controls the hydraulic oil circuit to achieve differential connection. This differential principle allows for unassisted extension, increasing the extension speed of the telescopic cylinder. When the telescopic cylinder extends / retracts with the arm, hydraulic valve group 2 controls the hydraulic oil circuit to no longer use differential connection, allowing the hydraulic oil to circulate through the tank, ensuring sufficient thrust for the telescopic cylinder and a strong load capacity for extension / retraction. This application can flexibly select the optimal hydraulic oil flow direction under all three operating conditions, offering high overall cost-effectiveness and highly flexible applicability.

[0073] In certain embodiments of the present application, the hydraulic valve assembly 2 includes an electro-hydraulic directional control valve 28, a first on-off valve 23, a connecting working oil circuit 24, a second on-off valve 25, and an on-off valve control unit. The electro-hydraulic directional control valve 28 is provided with a first working oil port 21 and a second working oil port 22, for controlling oil supply to the first working oil port and oil return through the second working oil port, or for controlling oil supply to the second working oil port and oil return through the first working oil port. The first on-off valve 23 is connected to the first working oil circuit 3, and the on-off valve control unit controls the on-off state of the first working oil circuit 3, thereby controlling whether the rod chamber 11 is connected to the first working oil port 21. The connecting working oil circuit 24 connects the first oil circuit 3 with the second oil circuit 4. The second on-off valve 25 is connected to the connecting working oil circuit 24, and the on-off valve control unit controls the on-off state of the connecting working oil circuit 24, thereby controlling whether the first working oil circuit 3 and the second working oil circuit 4 are connected.

[0074] When the telescopic cylinder is extended with its arm, and when the telescopic cylinder is retracted, the on-off valve control unit controls the first on-off valve 23 to be in the open state and the second on-off valve 25 to be in the closed state, thereby ensuring that the first oil circuit 3 is always connected to the rod chamber 11 and the first working oil port 21, while the first working oil circuit 3 is disconnected from the second working oil circuit 4; at this time, the rod chamber 11 and the rodless chamber 12 both realize the oil inlet or return of hydraulic oil through the oil tank.

[0075] When the empty arm of the telescopic cylinder is extended, the on-off valve control unit controls the first on-off valve 23 to be in a closed state and the second on-off valve 25 to be in an open state, ensuring that the rod chamber 11 is no longer connected to the first working oil port 21 through the first working oil circuit, and the first oil circuit 3 is connected to the second oil circuit 4; at this time, the oil circuits of the rod chamber 11 and the rodless chamber 12 are connected, so that the hydraulic oil in the rod chamber 11 flows to the rodless chamber 12, and the hydraulic oil circuit realizes differential connection.

[0076] Furthermore, the electro-hydraulic reversing valve 28 is provided with an oil supply port P, an oil return port T, a first working oil port 21, and a second working oil port 22. The electro-hydraulic reversing valve 28 includes: a DT01 potential, a neutral position, and a DT02 potential. When DT01 is energized, the oil supply port P is connected to the second working oil port 22, and the oil return port T is connected to the first working oil port 21. When DT02 is energized, the oil supply port P is connected to the first working oil port 21, and the oil return port T is connected to the second working oil port 22. The structure of the electro-hydraulic reversing valve 28 is simple, and the switching of oil supply to different working oil ports can be achieved only by changing different potentials; at the same time, the selection of different hydraulic oil circuit directions can be achieved only by controlling the opening or closing of the first on-off valve 23 and the second on-off valve 25 through the on-off valve control unit.

[0077] In certain embodiments of the present application, the first on-off valve 23 is a first cartridge valve; and the second on-off valve 25 is a second cartridge valve.

[0078] Furthermore, the first cartridge valve and the second cartridge valve in the present application are both two-way cartridge valves (ie logic valves).

[0079] Cartridge valves offer simple structure, reliable operation, and a high degree of standardization. They can significantly reduce size and weight for high-flow, high-pressure, and complex hydraulic systems. Two-way cartridge valves can control the flow or shutoff of a single hydraulic circuit, making them the most cost-effective option.

[0080] Furthermore, the on-off valve control unit is a control oil reversing unit 26 .

[0081] It should be noted that the two-way cartridge valve includes two working oil ports and one control oil port; when no control oil flows into the control oil port of the two-way cartridge valve, the two working oil ports of the two-way cartridge valve are always connected, and the oil circuit connecting the two-way cartridge valve is always connected; when control oil flows into the control oil port of the two-way cartridge valve, the two working oil ports of the two-way cartridge valve are closed, and the oil circuit connecting the two-way cartridge valve is closed.

[0082] The control oil reversing unit 26 can control whether the control oil flows to the control oil port of the first two-way cartridge valve, and at the same time control whether the control oil flows to the control oil port of the second two-way cartridge valve.

[0083] By setting the control oil reversing unit 26, it is possible to flexibly and cleverly control whether the control oil enters the control oil port of the first two-way cartridge valve or the control oil port of the second two-way cartridge valve, thereby controlling the closing of the first two-way cartridge valve or the second two-way cartridge valve.

[0084] In certain embodiments of the present application, the control oil reversing unit 26 includes: a control oil reversing valve 261, a first control oil circuit 262, a second control oil circuit 263, a third control oil circuit 264, a fourth control oil circuit 265, a first one-way valve 266 and a second one-way valve 267.

[0085] The control oil reversing valve 261 includes: an oil inlet A, a first oil outlet B and a second oil outlet C;

[0086] The first control oil circuit 262 connects the first working oil port 21 to the oil inlet A;

[0087] The second control oil circuit 263 connects the second working oil port 22 to the oil inlet A;

[0088] The third control oil circuit 264 connects the first oil outlet B to the control oil port of the first two-way cartridge valve;

[0089] The fourth control oil circuit 265 connects the second oil outlet C to the control oil port of the second two-way cartridge valve;

[0090] The first one-way valve 266 is provided on the first control oil circuit 262 to control the control oil in the first control oil circuit 262 to flow only toward the control oil reversing valve 261 ;

[0091] The second one-way valve 267 is provided on the second control oil circuit 263 to control the control oil in the second control oil circuit 263 to flow only toward the control oil reversing valve 261 ;

[0092] The control oil reversing valve 261 can control whether the control oil flows out from the first oil outlet B, and at the same time control whether the control oil flows out from the second oil outlet C.

[0093] By setting up the first control oil circuit 262 and the second control oil circuit 263, it is ensured that only one set of oil supply system can be used to achieve the synchronous delivery of the hydraulic oil flowing through the rod chamber 11 or the rodless chamber 12 and the control oil flowing to the two-way cartridge valve. The layout of the entire hydraulic system is simple, stable and reliable.

[0094] In certain embodiments of the present application, the control oil reversing valve 261 is a three-position, four-way solenoid reversing valve. The three-position, four-way reversing valve has a simple structure. By simply changing the voltage, it can determine whether the control oil flowing into the oil inlet A flows out of the first oil outlet B or the second oil outlet C, thereby closing the first or second two-way cartridge valve.

[0095] Furthermore, the three-position, four-way solenoid directional valve includes: DT03 is energized, the neutral position, and DT04 are energized; when DT03 is energized, the oil inlet A is connected to the second oil outlet C, at which point oil flows into the control oil port of the second two-way cartridge valve, the second two-way cartridge valve closes, and the first two-way cartridge valve opens. When DT04 is energized, the oil inlet A is connected to the first oil outlet B, at which point oil flows into the control oil port of the first two-way cartridge valve, the first two-way cartridge valve closes, and the second two-way cartridge valve opens.

[0096] In certain embodiments of the present application, the control oil reversing valve 261 includes: a first reversing valve and a second reversing valve; the first reversing valve and the second reversing valve are both two-position four-way electromagnetic reversing valves;

[0097] The oil inlet of the first reversing valve and the oil inlet of the second reversing valve are both connected to the oil inlet A;

[0098] The first reversing valve includes a first oil outlet B;

[0099] The second reversing valve includes a second oil outlet C;

[0100] The control oil flows out from the first oil outlet B and the second oil outlet C by simultaneously controlling the potential transformation of the first reversing valve and the potential transformation of the second reversing valve.

[0101] Furthermore, the first two-position four-way electromagnetic directional control valve includes: DT03 with an on potential and an off potential; the second two-position four-way electromagnetic directional control valve includes: DT04 with an on potential and an off potential.

[0102] When DT03 of the first two-position four-way solenoid reversing valve is energized and the second two-position four-way solenoid reversing valve is at the off-state potential, the oil inlet (i.e., oil inlet A) of the first reversing valve is disconnected from the first oil outlet B, and the oil inlet (i.e., oil inlet A) of the second reversing valve is connected to the second oil outlet C; at this time, the control oil port of the first two-way cartridge valve does not flow with oil, while the control oil port of the second two-way cartridge valve flows with oil, that is, the first two-way cartridge valve is opened and the second two-way cartridge valve is closed.

[0103] When the first two-position four-way solenoid directional control valve is at the off-state and DT04 of the second two-position four-way solenoid directional control valve is energized, the oil inlet (i.e., oil inlet A) of the first reversing valve is connected to the first oil outlet B, and the oil inlet (i.e., oil inlet A) of the second reversing valve is disconnected from the second oil outlet C; at this time, oil flows into the control oil port of the first two-way cartridge valve, and oil does not flow into the control oil port of the second two-way cartridge valve, that is, the first two-way cartridge valve is closed and the second two-way cartridge valve is open.

[0104] In addition to selecting a three-position four-way electromagnetic reversing valve, the control oil reversing valve 261 can also select two two-position four-way reversing valves; the selection of the control oil reversing valve 261 is flexible and varied, and the most cost-effective structural type can be selected according to different application scenarios.

[0105] In certain embodiments of the present application, the hydraulic valve assembly 2 includes: a power-off protection control oil circuit 27 ; the power-off protection control oil circuit 27 connects the rod chamber 11 to the third control oil circuit 264 .

[0106] When the control oil reversing valve 261 is at the off position, the third control oil circuit 264 is connected to the fourth control oil circuit 265 .

[0107] When the oil cylinder is in a stopped state and all the electromagnets in the hydraulic valve group 2 are in a de-energized state, that is, when the control oil reversing valve 261 is in the middle position (off potential), the hydraulic oil in the rod chamber 11 will flow from the first working oil circuit 3 to the third control oil circuit 264. At this time, the control oil port of the first two-way cartridge valve is filled with oil, and the first two-way cartridge valve is closed; at the same time, the hydraulic oil flows from the third control oil circuit 264 to the fourth control oil circuit. At this time, the control oil port of the second two-way cartridge valve is filled with oil, and the second two-way cartridge valve is closed. When the first two-way cartridge valve and the second two-way cartridge valve are both in a closed state, the hydraulic oil in the rod chamber 11 and the rodless chamber 12 of the telescopic oil cylinder are both in a closed state, which can prevent the telescopic oil cylinder from moving forward.

[0108] It should be noted that the power-off protection control oil circuit 27 is connected to a third throttle damper. By setting the throttle damper, the flow rate flowing through the oil circuit can be kept stable, thereby improving the stability of the hydraulic system flow circuit.

[0109] In certain embodiments of the present application, the third control oil circuit 264 is connected to a first throttle damper 268, and the fourth control oil circuit 265 is connected to a second throttle damper 269. The provision of throttle dampers ensures a steady flow through the control oil circuits, improving the stability of the hydraulic system flow path.

[0110] In some embodiments of the present application, the first working oil circuit 3 is provided with a relief valve 5. The relief valve 5 can play a safety protection role in the hydraulic system. When the hydraulic system pressure exceeds a specified value, the valve of the relief valve 5 opens to prevent the system pressure from exceeding the specified value.

[0111] The second working oil circuit 4 is equipped with a balancing valve 6, whose control oil circuit is connected to the first working oil circuit 3. When hydraulic oil flows from the tank through the first working oil circuit 3 to the rod chamber 11, the hydraulic oil is diverted from the first working oil circuit 3 to the control oil circuit of the balancing valve 6, causing the balancing valve 6 to open. This allows the hydraulic oil in the rodless chamber 12 to flow back to the tank through the second working oil circuit 4. The balancing valve 6 has a simple structure and stable flow rate, allowing the second working oil circuit 4 to be opened or closed under different operating conditions.

[0112] A crane is provided with the above hydraulic system and is used for controlling the extension and retraction of the crane's boom.

[0113] Since the crane includes the above-mentioned hydraulic system, the beneficial effects brought about by the hydraulic system of this crane can be found in the above content and will not be repeated here.

[0114] Working process:

[0115] 1. When the telescopic cylinder is extended with the arm:

[0116] ① DT01 of the electro-hydraulic directional control valve 28 is energized, the oil supply port P is connected to the second working oil port 22, and the oil return port is connected to the first working oil port 21;

[0117] ② The hydraulic oil is divided into control oil from the second working oil circuit 4, and the control oil enters the oil inlet A of the control oil reversing valve 261 from the second control oil circuit 263 through the second one-way valve 267;

[0118] ③ DT03 of the control oil reversing valve 261 is energized, connecting the oil inlet A to the second oil outlet C. The control oil flows into the control oil port of the second two-way cartridge valve through the fourth control oil passage 265. At this time, the second two-way cartridge valve is closed and the first two-way cartridge valve is open. That is, the first working oil passage 3 is disconnected from the second working oil passage 4. The first working oil passage 3 connects the rod chamber 11 to the first working oil port 21.

[0119] ④ The hydraulic oil flows out from the second working oil port 22, flows through the second working oil circuit 4 to the rodless chamber 12, the hydraulic oil enters the rodless chamber 12, and the telescopic cylinder extends; at the same time, the hydraulic oil in the rod chamber 11 flows back to the oil tank through the first working oil circuit 3 and the first two-way cartridge valve 23 through the first working oil port 21.

[0120] Under this working condition, the telescopic cylinder has a sufficiently large thrust to ensure that the arm has a strong load capacity.

[0121] 2. When the telescopic cylinder is extended with its empty arm:

[0122] ① DT01 of the electro-hydraulic directional control valve 28 is energized, the oil supply port P is connected to the second working oil port 22, and the oil return port is connected to the first working oil port 21;

[0123] ② The hydraulic oil is divided into control oil from the second working oil circuit 4, and the control oil enters the oil inlet A of the control oil reversing valve 261 from the second control oil circuit 263 through the second one-way valve 267;

[0124] ③ DT04 of the control oil reversing valve 261 is energized, connecting the oil inlet A with the first oil outlet B. The control oil flows into the control oil port of the first two-way cartridge valve through the third control oil passage 264. At this time, the first two-way cartridge valve is in the closed state, and the second two-way cartridge valve is in the open state. That is, the rod chamber 11 is no longer connected to the first working oil port 21 through the first working oil passage 3. Instead, the first working oil passage 3 and the second working oil passage 4 are connected through the connecting working oil passage 24.

[0125] ④ The hydraulic oil flows out from the second working oil port 22, flows through the second working oil circuit 4 to the rodless chamber 12, the hydraulic oil enters the rodless chamber 12, and the telescopic cylinder extends; at the same time, the hydraulic oil in the rod chamber 11 flows through the first working oil circuit and the second two-way cartridge valve 23 to the second working oil circuit 4 and flows into the rodless chamber 12.

[0126] Under this working condition, the hydraulic oil circuits in the rodless cavity 11 and the rod cavity 12 are differentially connected, and the extension speed of the telescopic cylinder is improved through the differential principle.

[0127] 3. When the telescopic cylinder is retracted:

[0128] ① DT02 of the electro-hydraulic directional control valve 28 is energized, the oil supply port P is connected to the first working oil port 22, and the oil return port is connected to the second working oil port 22;

[0129] ② The hydraulic oil is divided into control oil from the first working oil circuit 3, and the control oil enters the oil inlet A of the control oil reversing valve 261 from the first control oil circuit 262 through the first one-way valve 266;

[0130] ③ DT03 of the control oil reversing valve 261 is energized, connecting the oil inlet A to the second oil outlet C. The control oil flows into the control oil port of the second two-way cartridge valve through the fourth control oil passage 265. At this time, the second two-way cartridge valve is closed and the first two-way cartridge valve is open. That is, the first working oil passage 3 is disconnected from the second working oil passage 4. The first working oil passage 3 connects the rod chamber 11 to the first working oil port 21.

[0131] ④ The hydraulic oil flows out from the first working oil port 21, flows through the first working oil circuit 3 and the first two-way cartridge valve to the rod chamber 11, hydraulic oil enters the rod chamber 11, and the telescopic cylinder retracts; at the same time, the control oil circuit is diverted to the control oil circuit of the balancing valve 6, the balancing valve 6 is opened, and the hydraulic oil in the rodless chamber 12 flows back to the oil tank through the balancing valve 6 and the second working oil circuit 4 through the second working oil port 21.

[0132] The hydraulic system provided by the present application can flexibly select the optimal hydraulic oil flow direction under three working conditions, and has high comprehensive cost-effectiveness and extremely flexible applicability; in addition, when the hydraulic valve group is in the power-off state, when the first two-way cartridge valve and the second two-way cartridge valve are both in the closed state, the hydraulic oil in the rod chamber and the rodless chamber of the telescopic cylinder are both in a closed state, which can prevent the telescopic cylinder from rushing forward; the hydraulic system of the present application has a simple structure, low cost, and great market promotion and application value.

[0133] The components and devices involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the accompanying drawings. As will be appreciated by those skilled in the art, these components and devices can be connected, arranged, or configured in any manner. Words such as "including," "comprising," "having," and the like are open-ended words that mean "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0134] It should also be noted that in the device of the present application, each component can be decomposed and / or reassembled, and such decomposition and / or reassembly should be regarded as equivalent solutions of the present application.

[0135] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0136] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

[0137] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A hydraulic system, characterized in that: The invention comprises a telescopic oil cylinder having a rod chamber and a rodless chamber and a hydraulic valve group, wherein the hydraulic valve group comprises: a first working oil port, connected to the rod chamber through a first working oil passage; a second working oil port, connected to the rodless chamber through a second working oil passage; a first cartridge valve connected to the first working oil circuit; connecting the working oil circuits to connect the first working oil circuit with the second working oil circuit; a second cartridge valve connected to the communicating working oil path; a control oil reversing unit, comprising a control oil reversing valve, a third control oil circuit, and a fourth control oil circuit, wherein the control oil reversing valve comprises an oil inlet A, a first oil outlet, and a second oil outlet, the third control oil circuit connecting the first oil outlet to the control oil port of the first cartridge valve, and the fourth control oil circuit connecting the second oil outlet to the control oil port of the second cartridge valve; a power-off protection control oil circuit, connecting the rod chamber to the third control oil circuit, and when the control oil reversing valve is in the off position, the third control oil circuit is connected to the fourth control oil circuit; Among them, the control oil reversing unit can control whether the control oil flows to the control oil port of the first cartridge valve, and at the same time control whether the control oil flows to the control oil port of the second cartridge valve, so as to achieve: the hydraulic oil flows into the rodless chamber through the second working oil circuit, and at the same time the hydraulic oil in the rod chamber flows out through the first working oil circuit; or, the hydraulic oil flows into the rod chamber through the first working oil circuit, and at the same time the hydraulic oil in the rodless chamber flows out through the second working oil circuit; or, the hydraulic oil flows into the rodless chamber through the second working oil circuit, and at the same time the hydraulic oil in the rod chamber merges into the rodless chamber through the first working oil circuit.

2. The hydraulic system according to claim 1, characterized in that The hydraulic valve group includes an electro-hydraulic reversing valve, and the electro-hydraulic reversing valve is provided with the first working oil port and the second working oil port.

3. The hydraulic system according to claim 2, characterized in that The control oil reversing unit includes: a first control oil circuit, connecting the first working oil port to the oil inlet A; a second control oil circuit, connecting the second working oil port to the oil inlet A; Wherein, a first one-way valve is provided on the first control oil circuit to control the control oil in the first control oil circuit to flow only to the control oil reversing valve; A second one-way valve is provided on the second control oil circuit to control the control oil in the second control oil circuit to flow only toward the control oil reversing valve; The control oil reversing valve can control whether the control oil flows out from the first oil outlet and simultaneously control whether the control oil flows out from the second oil outlet.

4. The hydraulic system according to claim 3, characterized in that The control oil reversing valve is a three-position four-way electromagnetic reversing valve.

5. The hydraulic system according to claim 3, characterized in that: The control oil reversing valve includes: a first reversing valve and a second reversing valve; the first reversing valve and the second reversing valve are both two-position four-way electromagnetic reversing valves; The oil inlet of the first reversing valve and the oil inlet of the second reversing valve are both connected to the oil inlet A; The first reversing valve includes the first oil outlet; The second reversing valve includes the second oil outlet; The control oil flows out from the first oil outlet and the second oil outlet by controlling the potential transformation of the first reversing valve and the potential transformation of the second reversing valve.

6. The hydraulic system according to claim 3, characterized in that The third control oil circuit is connected to a first throttling damper; The fourth control oil circuit is connected to a second throttling damper.

7. The hydraulic system according to claim 1, characterized in that The first working oil circuit is provided with a relief valve; and / or, The second working oil circuit is provided with a balancing valve, and a control oil circuit of the balancing valve is connected to the first working oil circuit.

8. A crane, characterized in that: A hydraulic system according to any one of claims 1 to 7 is provided for controlling the extension and retraction of the boom of the crane.

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