Hydraulic systems for cranes

Abstract

The present disclosure provides a hydraulic system for a crane, belonging to the field of hydraulic technology. The hydraulic system includes a power module, a first three-position four-way reversing valve, a first shuttle valve, an on-off valve, an actuator and a two-position four-way reversing valve; the oil inlet and the oil return port of the first three-position four-way reversing valve are respectively connected to the first oil outlet and the oil return port of the power module, the first working oil port of the first three-position four-way reversing valve is respectively connected to the first oil inlet of the first shuttle valve, the first working oil port of the on-off valve, and the first oil port of the actuator, the second working oil port of the first three-position four-way reversing valve is respectively connected to the second oil inlet of the first shuttle valve, the second working oil port of the on-off valve, and the second oil port of the actuator; the first oil inlet and the second oil inlet of the two-position four-way reversing valve are respectively connected to the first oil outlet of the power module and the oil outlet of the first shuttle valve, and the oil outlet of the two-position four-way reversing valve is connected to the control oil port of the power module. The present disclosure solves the problem of complex flushing process.

Description

Technical Field

[0001] The present disclosure belongs to the field of hydraulic technology, and in particular relates to a hydraulic system for a crane. Background Art

[0002] The hydraulic system belongs to the field of hydraulic transmission and control technology. The cleanliness of the hydraulic system directly affects the reliability of the hydraulic system.

[0003] In the related technology, the common hydraulic system includes a hydraulic oil tank, a main pump, and an actuator. The main pump and the actuator form a closed circuit. The main pump pumps the hydraulic oil in the hydraulic oil tank to provide power for the actuator. The cleaning of the hydraulic system is generally done by flushing the hydraulic system pipelines with oil through external hydraulic pump stations and pipelines.

[0004] However, the above-mentioned oil flushing method is complicated and time-consuming. Summary of the invention

[0005] The embodiment of the present disclosure provides a hydraulic system for a crane, which can solve the problem that the oil flushing process is complicated and requires a lot of time and cost. The technical solution is as follows:

[0006] The embodiment of the present disclosure provides a hydraulic system for a crane, comprising a power module, a first three-position four-way reversing valve, a first shuttle valve, an on-off valve, an actuator, and a two-position four-way reversing valve;

[0007] The oil inlet and oil return port of the first three-position four-way reversing valve are respectively connected to the first oil outlet and oil return port of the power module, the first working oil port of the first three-position four-way reversing valve is respectively connected to the first oil inlet of the first shuttle valve, the first working oil port of the on-off valve, and the first oil port of the actuator, and the second working oil port of the first three-position four-way reversing valve is respectively connected to the second oil inlet of the first shuttle valve, the second working oil port of the on-off valve, and the second oil port of the actuator;

[0008] The first oil inlet and the second oil inlet of the two-position four-way reversing valve are respectively connected to the first oil outlet of the power module and the oil outlet of the first shuttle valve, and the oil outlet of the two-position four-way reversing valve is connected to the control oil port of the power module;

[0009] When the power module is in the first state, the oil pressure at the first oil outlet of the power module and the oil pressure at the first working oil port of the first three-position four-way reversing valve are set to a first set pressure difference value; when the power module is in the second state, the oil pressure at the first oil outlet of the power module and the oil pressure at the first working oil port of the first three-position four-way reversing valve are set to a second set pressure difference value, and the second set pressure difference value is greater than the first set pressure difference value.

[0010] In one implementation of the present disclosure, the hydraulic system further includes a handle;

[0011] The oil inlet and return port of the handle are respectively connected to the second oil outlet and return port of the power module, and the first working oil port and second working oil port of the handle are respectively connected to the first control oil port and second control oil port of the first three-position four-way reversing valve.

[0012] In another implementation of the present disclosure, the hydraulic system further includes a second three-position four-way reversing valve;

[0013] The oil inlet and the oil return port of the second three-position four-way reversing valve are respectively connected to the second oil outlet and the oil return port of the power module, and the first working oil port and the second working oil port of the second three-position four-way reversing valve are respectively connected to the first control oil port and the second control oil port of the first three-position four-way reversing valve;

[0014] The on-off valve, the two-position four-way directional valve and the second and third-position four-way directional valve are all solenoid valves.

[0015] In yet another implementation of the present disclosure, the hydraulic system further includes a second shuttle valve and a third shuttle valve;

[0016] The first oil inlet and the second oil inlet of the second shuttle valve are respectively connected to the first working oil port of the handle and the first working oil port of the second three-position four-way reversing valve, and the oil outlet of the second shuttle valve is connected to the first control oil port of the first three-position four-way reversing valve;

[0017] The first oil inlet and the second oil inlet of the third shuttle valve are respectively connected to the second working oil port of the handle and the second working oil port of the second three-position four-way reversing valve, and the oil outlet of the third shuttle valve is connected to the second control oil port of the first three-position four-way reversing valve.

[0018] In yet another implementation of the present disclosure, the power module includes a variable pump, a constant pressure control valve, and a load sensing control valve;

[0019] The oil outlet of the variable pump is connected to the oil inlet of the constant pressure control valve, the control oil port of the constant pressure control valve, the oil inlet of the load sensing control valve, and the first control oil port of the load sensing control valve;

[0020] The working oil port and the second control oil port of the load-sensing control valve are respectively connected to the first working oil port of the constant pressure control valve and the oil outlet of the two-position four-way reversing valve;

[0021] The second working oil port of the constant pressure control valve is connected to the control oil port of the variable pump.

[0022] In yet another implementation of the present disclosure, the power module further includes a metering pump;

[0023] The oil outlet of the metering pump is connected with the oil inlet of the handle and the oil inlet of the second, third and fourth position four-way reversing valve.

[0024] In yet another implementation of the present disclosure, the power module further includes a relief valve;

[0025] The oil inlet of the relief valve is connected to its own control oil port and the oil outlet of the metering pump.

[0026] In yet another implementation of the present disclosure, the hydraulic system further includes a hydraulic lock;

[0027] The hydraulic lock includes a first hydraulically controlled one-way valve and a second hydraulically controlled one-way valve;

[0028] The first oil port, the second oil port and the control oil port of the first hydraulically controlled one-way valve are respectively connected to the first working oil port of the first three-position four-way reversing valve, the first oil port of the actuator and the second working oil port of the first three-position four-way reversing valve;

[0029] The first oil port, the second oil port and the control oil port of the second hydraulically controlled one-way valve are respectively connected to the second working oil port of the first three-position four-way reversing valve, the second oil port of the actuator and the first working oil port of the first three-position four-way reversing valve.

[0030] In yet another implementation of the present disclosure, the hydraulic system further includes a filter;

[0031] The oil inlet of the filter is connected to the oil return port of the first three-position four-way reversing valve.

[0032] In yet another implementation of the present disclosure, the hydraulic system further includes a one-way valve;

[0033] The oil inlet of the one-way valve is connected to the oil inlet of the filter, and the oil return port of the one-way valve is connected to the oil return port of the filter.

[0034] The technical solution provided by the embodiments of the present disclosure has the following beneficial effects:

[0035] The first set pressure difference value can ensure the constant pressure when the pipeline is working normally. The second set pressure difference value is greater than the first set pressure difference value, so that the pipeline pressure is greater than the first set pressure difference value. When it is less than the second set pressure difference value, it always works at the maximum flow rate. The on-off valve short-circuits the actuator to prevent the hydraulic oil from contaminating the actuator during oil cross-contamination. The pressure difference between the first oil outlet and the control oil port of the power module is 0. At this time, the maximum displacement of hydraulic oil passes through the oil circuit, which can increase the oil cross-contamination efficiency.

[0036] That is to say, by setting the hydraulic system to two states, the hydraulic system can achieve oil flushing without an external hydraulic pump station, saving a lot of time costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 is a structural schematic diagram of a hydraulic system for a crane provided in an embodiment of the present disclosure;

[0039] Figure 2 It is a schematic diagram of the structure of the power module provided in the embodiment of the present disclosure.

[0040] The symbols in the figure mean the following:

[0041] 1. Power module;

[0042] 101, variable displacement pump; 102, constant pressure control valve; 103, load sensing control valve; 104, fixed displacement pump; 105, relief valve;

[0043] 2. The first three-position four-way reversing valve;

[0044] 3. The first shuttle valve;

[0045] 4. On-off valve;

[0046] 5. Actuator;

[0047] 6. Two-position four-way reversing valve;

[0048] 7. Handle;

[0049] 8. Second and third position four-way reversing valve;

[0050] 9. Second shuttle valve;

[0051] 10. The third shuttle valve;

[0052] 11. Fuel tank;

[0053] 12. Hydraulic lock;

[0054] 121, first hydraulically controlled one-way valve; 122, second hydraulically controlled one-way valve;

[0055] 13. Filter;

[0056] 14. Check valve;

[0057] 15. Differential pressure sensor;

[0058] 16. Controller. DETAILED DESCRIPTION

[0059] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0060] The hydraulic system can convert the mechanical energy of the pump into the pressure energy of the hydraulic oil. The hydraulic oil is controlled by various valves in the pipeline to drive the hydraulic machinery to do work. It can be used in various marine machinery, engineering machinery, etc. that require hydraulic drive.

[0061] An embodiment of the present disclosure provides a hydraulic system for a crane. Figure 1 A schematic diagram of a hydraulic system according to an embodiment of the present disclosure is shown in FIG. Figure 1 The hydraulic system includes a power module 1, a first three-position four-way reversing valve 2, a first shuttle valve 3, an on-off valve 4, an actuator 5 and a two-position four-way reversing valve 6.

[0062] The oil inlet P and the oil return port T of the first three-position four-way reversing valve 2 are respectively connected to the first oil outlet P1 and the oil return port T of the power module 1, the first working oil port A of the first three-position four-way reversing valve 2 is respectively connected to the first oil inlet A of the first shuttle valve 3, the first working oil port A of the on-off valve 4, and the first oil port A of the actuator 5, and the second working oil port B of the first three-position four-way reversing valve 2 is respectively connected to the second oil inlet B of the first shuttle valve 3, the second working oil port B of the on-off valve 4, and the second oil port B of the actuator 5.

[0063] The first oil inlet A and the second oil inlet B of the two-position four-way reversing valve 6 are respectively connected to the first oil outlet P1 of the power module 1 and the oil outlet C of the first shuttle valve 3 , and the oil outlet T of the two-position four-way reversing valve 6 is connected to the control oil port X of the power module 1 .

[0064] When the power module is in the first state, the oil pressure at the first oil outlet P1 of the power module 1 and the oil pressure at the first working oil port A of the first three-position four-way reversing valve 2 are equal to a first set pressure difference value. When the power module 1 is in the second state, the oil pressure at the first oil outlet P1 of the power module 1 and the oil pressure at the first working oil port A of the first three-position four-way reversing valve are equal to a second set pressure difference value. The second set pressure difference value is greater than the first set pressure difference value.

[0065] In this embodiment, the actuator 5 is a motor.

[0066] In a hydraulic system provided by an embodiment of the present disclosure, when the hydraulic system works normally, the power module 1 is in the first state, and the first working oil port A and the second working oil port B of the on-off valve 4 are disconnected. The hydraulic oil passes through the oil inlet S and the first oil outlet P1 of the power module 1 in sequence. Since it is necessary to drive the actuator 5 to rotate forward, the first three-position four-way reversing valve 2 works in the left position at this time, the oil inlet P of the first three-position four-way reversing valve 2 is connected to the first working oil port A, and the oil return port T of the first three-position four-way reversing valve 2 is connected to the second working oil port B. The hydraulic oil passes through the oil inlet P and the first working oil port A of the first three-position four-way reversing valve 2, the first oil port A and the second oil port B of the actuator 5, and the second working oil port B and the oil return port T of the first three-position four-way reversing valve 2 in sequence, thereby driving the actuator 5 to rotate forward. At the same time, the two-position four-way reversing valve 6 works in the right position, and the first oil inlet A and the oil outlet T of the two-position four-way reversing valve 6 are connected. The hydraulic oil flowing out of the first working oil port A of the first three-position four-way reversing valve 2 also passes through the first oil inlet A and oil outlet C of the first shuttle valve 3, the first oil inlet A and oil outlet T of the two-position four-way reversing valve 6, and finally enters the control oil port X of the power module 1, so that the pressure difference between the first oil outlet P1 of the power module 1 and the first working oil port A of the first three-position four-way reversing valve 2 is always equal to the first set pressure difference value. Similarly, when it is necessary to drive the actuator 5 to reverse, the first three-position four-way reversing valve 2 works in the right position. At this time, the oil inlet P of the first three-position four-way reversing valve 2 is connected to the second working oil port B, and the oil return port T of the first three-position four-way reversing valve 2 is connected to the first working oil port A. The flow mode of the hydraulic oil is similar to that when the actuator 5 rotates forward, which will not be repeated here. Similarly, when the actuator 5 stops working, the first three-position four-way reversing valve 2 works in the middle position, the oil inlet P of the first three-position four-way reversing valve 2 is blocked, the pressure of the control oil port X of the power module 1 is basically zero, the pressure of the first oil outlet P1 of the power module 1 is the first set pressure difference value, and the output flow of the power module 1 only maintains its own leakage and is in standby state.

[0067] In the above implementation, the working direction and working state of the actuator 5 can be adjusted according to the working state of the first three-position four-way reversing valve 2. The hydraulic oil flows into the control oil port X of the power module 1, and the pressure in the control line will not be higher than the first set pressure difference value.

[0068] Optionally, the first set pressure difference value is 2.5 MPa.

[0069] In a hydraulic system provided by an embodiment of the present disclosure, when the hydraulic system is being flushed with oil, the power module 1 is in the second state, the first working oil port A and the second working oil port B of the on-off valve 4 are connected, the hydraulic oil does not pass through the actuator 5, and the actuator 5 does not work. The two-position four-way reversing valve 6 works in the left position, the second oil inlet B and the oil outlet T of the two-position four-way reversing valve 6 are connected, and in order to make the hydraulic oil flow forward in the pipeline, the first three-position four-way reversing valve 2 works in the left position, the oil inlet P of the first three-position four-way reversing valve 2 is connected to the first working oil port A, the first three-position four-way reversing valve 2 is connected to the oil return port T and the second working oil port B, and the hydraulic oil successively passes through the oil inlet S and the first oil outlet P1 of the power module 1, the oil inlet P and the first working oil port A of the first three-position four-way reversing valve 2, the first working oil port A and the second working oil port B of the on-off valve 4, and the second working oil port B and the oil return port T of the first three-position four-way reversing valve 2. At the same time, the hydraulic oil flowing out from the first oil outlet P1 of the power module 1 also passes through the second oil inlet B and oil outlet T of the two-position four-way reversing valve 6, and finally flows into the control oil port X of the power module 1, so that the pressure difference between the first oil outlet P1 of the power module 1 and the first working oil port A of the first three-position four-way reversing valve 2 is always equal to the second set pressure difference value. Similarly, in order to make the hydraulic oil flow in the pipeline in the reverse direction, the first three-position four-way reversing valve 2 works in the right position. At this time, the oil inlet P of the first three-position four-way reversing valve 2 is connected to the second working oil port B, and the return oil port T of the first three-position four-way reversing valve 2 is connected to the first working oil port A. The flow mode of the hydraulic oil is similar to that when the actuator 5 rotates forward, which will not be repeated here. When the first three-position four-way reversing valve 2 works in the middle position, the hydraulic oil passes through the second oil inlet B and oil outlet T of the two-position four-way reversing valve 6, and finally flows into the control oil port X of the power module 1.

[0070] Optionally, the second set pressure difference value is 28 MPa.

[0071] In the above implementation, the first set pressure difference value can ensure the constant pressure when the pipeline is working normally, and the second set pressure difference value is greater than the first set pressure difference value, so that the pipeline pressure is greater than the first set pressure difference value and less than the second set pressure difference value, and the pipeline always maintains the maximum flow rate. The on-off valve 4 short-circuits the actuator 5 to prevent the hydraulic oil from contaminating the actuator 5 during oil cross-contamination. The pressure difference between the first oil outlet P1 and the control oil port X of the power module 1 is 0. At this time, the maximum displacement of hydraulic oil passes through the oil circuit, which can increase the oil cross-contamination efficiency.

[0072] That is to say, by setting the hydraulic system to two states, the hydraulic system can achieve oil flushing without an external hydraulic pump station, saving a lot of time costs.

[0073] The hydraulic system further includes an oil tank 11 , and the hydraulic oil in the pipeline flows out of the oil tank 11 and finally returns to the oil tank 11 .

[0074] In order to realize the switching between the above two hydraulic system states, the hydraulic system has two control methods. The implementation process of the two control methods is introduced below.

[0075] Continue to see Figure 1 In this embodiment, the hydraulic system also includes a handle 7, the oil inlet P and the oil return port T of the handle 7 are respectively connected to the second oil outlet P2 and the oil return port t of the power module 1, and the first working oil port A and the second working oil port B of the handle 7 are respectively connected to the first control oil port C1 and the second control oil port C2 of the first three-position four-way reversing valve 2.

[0076] In order to make the first three-position four-way reversing valve 2 work in the left position, the handle 7 is in the first working state at this time, the oil inlet P of the handle 7 is connected with the first working oil port A, and the hydraulic oil flows in from the oil inlet P of the handle 7, and flows into the first control oil port C1 of the first three-position four-way reversing valve 2 through the first working oil port A of the handle 7. Similarly, in order to make the first three-position four-way reversing valve 2 work in the right position, the handle 7 is in the second working state at this time, the oil inlet P of the handle 7 is connected with the second working oil port B, and the hydraulic oil flows in from the oil inlet P of the handle 7, and flows into the second control oil port C2 of the first three-position four-way reversing valve 2 through the second working oil port B of the handle 7.

[0077] In the above implementation, the pressure at the first working oil port A and the second working oil port B of the handle 7 can be changed by adjusting the state of the handle 7, thereby adjusting the pressure of the first control oil port C1 and the second control oil port C2 of the first three-position four-way reversing valve 2, thereby controlling the state of the first three-position four-way reversing valve 2.

[0078] Optionally, the hydraulic system also includes a second three-position four-way reversing valve 8, the oil inlet P and the oil return port T of the second three-position four-way reversing valve 8 are respectively connected to the second oil outlet P2 and the oil return port T of the power module 1, the first working oil port A and the second working oil port B of the second three-position four-way reversing valve 8 are respectively connected to the first control oil port C1 and the second control oil port C2 of the first three-position four-way reversing valve 2, and the on-off valve 4, the two-position four-way reversing valve 6 and the second three-position four-way reversing valve 8 are all solenoid valves.

[0079] The second three-position four-way reversing valve 8 is a solenoid valve. The change of the power-on and power-off state of the second three-position four-way reversing valve 8 can change the flow direction of the hydraulic oil in the second three-position four-way reversing valve 8, thereby adjusting the working state of the first three-position four-way reversing valve 2.

[0080] In order to make the first three-position four-way reversing valve 2 work in the left position, the second three-position four-way reversing valve 8 works in the left position at this time, the oil inlet P of the second three-position four-way reversing valve 8 is connected with the first working oil port A, the second working oil port B of the second three-position four-way reversing valve 8 is connected with the oil return port T, and the hydraulic oil flows in from the oil inlet P of the second three-position four-way reversing valve 8, passes through the first working oil port A of the second three-position four-way reversing valve 8 and flows into the first control oil port C1 of the first three-position four-way reversing valve 2.

[0081] Similarly, in order to make the first three-position four-way reversing valve 2 work in the right position, the second three-position four-way reversing valve 8 works in the right position at this time, the oil inlet P of the second three-position four-way reversing valve 8 is connected with the second working oil port B, the first working oil port A of the second three-position four-way reversing valve 8 is connected with the oil return port T, the hydraulic oil flows in from the oil inlet P of the second three-position four-way reversing valve 8, passes through the second working oil port B of the second three-position four-way reversing valve 8 and flows into the second control oil port C2 of the first three-position four-way reversing valve 2.

[0082] Optionally, the hydraulic system also includes a second shuttle valve 9 and a third shuttle valve 10, the first oil inlet A and the second oil inlet B of the second shuttle valve 9 are respectively connected to the first working oil port A of the handle 7 and the first working oil port A of the second three-position four-way reversing valve 8, the oil outlet C of the second shuttle valve 9 is connected to the first control oil port C1 of the first three-position four-way reversing valve 2, the first oil inlet A and the second oil inlet B of the third shuttle valve 10 are respectively connected to the second working oil port B of the handle 7 and the second working oil port B of the second three-position four-way reversing valve 8, and the oil outlet C of the third shuttle valve 10 is connected to the second control oil port C2 of the first three-position four-way reversing valve 2.

[0083] The hydraulic oil flows in from the first oil inlet A or the second oil inlet B of the second shuttle valve 9 where the pressure is higher, and flows out from the oil outlet C of the second shuttle valve 9. Similarly, the hydraulic oil flows in from the first oil inlet A or the second oil inlet B of the third shuttle valve 10 where the pressure is higher, and flows out from the oil outlet C of the third shuttle valve 10.

[0084] In the above implementation, the oil outlets C of the first shuttle valve 3 and the second shuttle valve 9 are respectively connected to the first control oil port C1 and the second control oil port C2 of the first three-position four-way reversing valve 2, so that the hydraulic oil in the pipeline with higher pressure can control the first three-position four-way reversing valve 2. When the power module 1 is in the first state, the first three-position four-way reversing valve 2 is manually controlled by the handle 7, and the speed is manually variable; when the power module 1 is in the second state, the second three-position four-way reversing valve 8 is used to automatically control the first three-position four-way reversing valve 2 directly to full open for oil cross-talk.

[0085] That is to say, the handle 7 and the second three-position four-way reversing valve 8 will not work at the same time, so as to prevent the handle 7 and the second three-position four-way reversing valve 8 from affecting each other due to their working at the same time.

[0086] Figure 2 is a schematic diagram of the structure of the power module 1, such as Figure 2 As shown, in this embodiment, the power module 1 includes a variable pump 101, a constant pressure control valve 102 and a load sensing control valve 103, the oil outlet S of the variable pump 101 is connected to the oil inlet P of the constant pressure control valve 102, the control oil port C of the constant pressure control valve 102, the oil inlet P of the load sensing control valve 103, and the first control oil port C1 of the load sensing control valve 103, the working oil port A and the second control oil port C2 of the load sensing control valve 103 are respectively connected to the first working oil port A of the constant pressure control valve 102 and the oil outlet T of the two-position four-way reversing valve 6, and the second working oil port B of the constant pressure control valve 102 is connected to the control oil port C of the variable pump 101.

[0087] Optionally, the spring pressure of the load sensing control valve 103 is a first set pressure difference value, and the spring pressure of the constant pressure control valve 102 is a second set pressure difference value.

[0088] When the two-position four-way reversing valve 6 works in the right position, the first oil inlet A and the oil outlet T of the two-position four-way reversing valve 6 are connected. At this time, the pressure difference between the oil outlet P of the variable pump 101 and the second control oil port C2 of the load sensing control valve 103 is equal to the first set pressure difference. The constant pressure control valve 102 works in the right position, the first working oil port A of the constant pressure control valve 102 is connected to the second working oil port B, and the working position of the load sensing control valve 103 is determined by the pressure difference between the first control oil port C1 and the second control oil port. Before starting, the constant pressure control valve 102 and the load sensing control valve 103 work in the right position under the action of the spring force, and the hydraulic oil flows out from the C port of the variable pump 101, flows through the second working oil port B and the first working oil port A of the constant pressure control valve 102, the first working oil port A and the return oil port T of the load sensing control valve 103, and finally flows into the oil tank 11, and the variable pump works at the maximum displacement. After starting, when the first three-position four-way reversing valve 2 does not reverse, the pressure difference between the first control oil port C1 of the load sensing control valve 103 and the second control oil port C2 increases to a value slightly larger than the first set pressure difference, the load sensing control valve 103 works in the left position, the oil inlet P of the load sensing control valve 103 is connected to the first working oil port A, and the hydraulic oil flows through the oil inlet P and the first working oil port A of the load sensing control valve 103, the first working oil port A and the second working oil port B of the constant pressure control valve 102 in sequence, and finally flows into the C port of the variable pump 101, so that the displacement of the variable pump 101 is reduced and the pressure is maintained. After starting, when the first three-position four-way reversing valve 2 is half-open, the outlet pressure of the variable pump 101 decreases, the pressure difference between the first control oil port C1 of the load sensing control valve 103 and the second control oil port C2 is less than the first set pressure difference value, the load sensing control valve 103 works in the right position, the displacement of the variable pump 101 increases, and the outlet pressure of the variable pump 101 increases until the pressure difference between the first control oil port C1 of the load sensing control valve 103 and the second control oil port C2 is equal to the first set pressure difference value, and a balanced state is reached. After starting, when the first three-position four-way reversing valve 2 changes from half-open to fully open, due to the unchanged instantaneous flow, the pressure of the oil inlet P of the first three-position four-way reversing valve 2 becomes smaller, and the pressure difference between the first control oil port C1 of the load-sensitive control valve 103 and the second control oil port C2 is less than the first set pressure difference value, the load-sensitive control valve 103 works in the right position, the displacement of the variable pump 101 increases, and the outlet pressure of the variable pump 101 increases until the pressure difference between the first control oil port C1 of the load-sensitive control valve 103 and the second control oil port C2 is equal to the first set pressure difference value, and the equilibrium state is reached again.

[0089] When the two-position four-way reversing valve 6 works in the left position, the second oil inlet B and the oil outlet T of the two-position four-way reversing valve 6 are connected. At this time, the pressure difference between the oil outlet P of the variable pump 101 and the second control oil port C2 of the load sensing control valve 103 is 0, the load sensing control valve 103 and the constant pressure control valve 102 both work in the right position, the oil return port T of the load sensing control valve 103 is connected to the working oil port A, the first working oil port A and the second working oil port B of the constant pressure control valve 102 are connected, and the variable pump 101 works at the maximum flow rate.

[0090] In the above implementation, when the two-position four-way directional valve 6 works in the left position or the right position, even if the working pressure of the actuator 5 changes, the load-sensitive control valve 103 causes the variable pump 101 to automatically change the displacement, so that the pressure at the oil inlet P of the first three-position four-way directional valve 2 is always higher than the pressure at the first working oil port A or the second working oil port B by a first set pressure difference value, so that the oil inlet flow of the first three-position four-way directional valve 2 is only related to the valve core opening size of the first three-position four-way directional valve 2, and has nothing to do with the working pressure of the actuator 5.

[0091] Optionally, continue to see Figure 2 The power module 1 further includes a metering pump 104 , an oil outlet P of the metering pump 104 is connected to an oil inlet P of the handle 7 and an oil inlet P of the second three-position four-way reversing valve 8 .

[0092] The hydraulic oil flows out from the oil outlet P of the metering pump 104 and flows into the oil inlet P of the handle 7 or the second three-position four-way reversing valve 8 .

[0093] In the above implementation, the metering pump 104 supplies oil to the handle 7 and the second three-position four-way reversing valve 8 to adjust the state of the first three-position four-way reversing valve 2 .

[0094] Optionally, continue to see Figure 2 The power module 1 further includes a relief valve 105 , an oil inlet P of the relief valve 105 is connected to its own control oil port A and an oil outlet P of the metering pump 104 .

[0095] In the above implementation, when the pressure of the oil outlet P of the metering pump 104 reaches the pressure threshold of the relief valve 105, the oil inlet P and the oil return port T of the relief valve 105 are connected, and the pressure is automatically released, so that the pressure of the oil outlet P of the metering pump 104 is always the same as the pressure threshold of the relief valve 105, thereby providing a stable pressure oil source for the handle 7 and the second three-position four-way reversing valve 8.

[0096] In this embodiment, the pressure threshold of the relief valve 105 is 3.5 MPa.

[0097] Optionally, the hydraulic system also includes a hydraulic lock 12, which includes a first hydraulically controlled one-way valve 121 and a second hydraulically controlled one-way valve 122. The first oil port A, the second oil port B, and the control oil port C of the first hydraulically controlled one-way valve 121 are respectively connected to the first working oil port A of the first three-position four-way reversing valve 2, the first oil port A of the actuator 5, and the second working oil port B of the first three-position four-way reversing valve 2. The first oil port A, the second oil port B, and the control oil port C of the second hydraulically controlled one-way valve 122 are respectively connected to the second working oil port B of the first three-position four-way reversing valve 2, the second oil port B of the actuator 5, and the first working oil port A of the first three-position four-way reversing valve 2.

[0098] When the hydraulic lock 12 is required to positively lock the hydraulic oil in the pipeline with a low pressure, the flow trend of the hydraulic oil is from the first oil port A of the first hydraulically controlled one-way valve 121 to the second oil port B, the first oil port A and the second oil port B of the actuator 5, the second oil port B and the first oil port A of the second hydraulically controlled one-way valve 122. At this time, the pressure at the control oil port C of the second hydraulically controlled one-way valve 122 is relatively low, and the second hydraulically controlled one-way valve 122 is blocked. When the pressure at the control oil port C of the second hydraulically controlled one-way valve 122 is greater than the control threshold of the second hydraulically controlled one-way valve 122, the second hydraulically controlled one-way valve 122 is connected, and the hydraulic oil flows from the first oil port A of the second hydraulically controlled one-way valve 122 to the second working oil port B of the first three-position four-way reversing valve 2. Similarly, when the hydraulic lock 12 is needed to reverse and perform a low-pressure locking effect on the hydraulic oil in the pipeline, the flow trend of the hydraulic oil is from the first oil port A of the second hydraulically controlled one-way valve 122 to the second oil port B, the second oil port B and the first oil port A of the actuator 5, the second oil port B and the first oil port A of the first hydraulically controlled one-way valve 121, the pressure at the control oil port C of the first hydraulically controlled one-way valve 121 is low, and the first hydraulically controlled one-way valve 121 is blocked. When the pressure at the control oil port C of the first hydraulically controlled one-way valve 121 is greater than the control threshold of the first hydraulically controlled one-way valve 121, the first hydraulically controlled one-way valve 121 is connected, and the hydraulic oil flows from the first oil port A of the first hydraulically controlled one-way valve 121 to the first working oil port A of the first three-position four-way reversing valve 2.

[0099] In the above implementation, the hydraulic lock 12 can lock the actuator 5 when the pressure is low, thereby preventing the actuator 5 from working.

[0100] Optionally, the hydraulic system includes a filter 13 , and an oil inlet P of the filter 13 is connected to an oil return port T of the first three-position four-way reversing valve 2 .

[0101] When the hydraulic oil in the pipeline flows in from the oil inlet P of the filter 13 and flows out from the oil return port T of the filter 13, impurities in the hydraulic oil are filtered to prevent the hydraulic oil from contaminating the pipeline.

[0102] Optionally, the hydraulic system includes a one-way valve 14 , an oil inlet P of the one-way valve 14 is connected to an oil inlet P of the filter 13 , and an oil return port T of the one-way valve 14 is connected to an oil return port T of the filter 13 .

[0103] When the filter 13 is not blocked, the pressure at the oil inlet P of the one-way valve 14 does not reach the pressure threshold of the one-way valve 14, and the one-way valve 14 is disconnected. When the filter 13 is blocked, the pressure at the oil inlet P of the one-way valve 14 reaches the pressure threshold of the one-way valve 14, the one-way valve 14 is connected, and the hydraulic oil flows out from the oil return port T of the one-way valve 14.

[0104] In the above implementation, the one-way valve 14 can prevent the filter element from being damaged when the filter 13 is blocked, thereby preventing secondary pollution.

[0105] Optionally, there are pressure difference sensors 15 on both sides of the filter 13. The pressure difference sensor 15 is connected to the controller 16 to detect whether the filter 13 is blocked and to issue an alarm when the filter 13 is blocked.

[0106] In this embodiment, the solenoid valves are all controlled by the controller 16, and automatic control of the solenoid valves can be achieved by changing the set program.

[0107] The working principle of the hydraulic system provided by the present disclosure is briefly described below:

[0108] The hydraulic system has two modes: working mode and oil flow mode.

[0109] When the hydraulic system is in working mode, the power module 1 is in the first state, the two-position four-way reversing valve 6 works in the right position, the first oil inlet A and the oil outlet T of the two-position four-way reversing valve 6 are connected, the first working oil port A and the second working oil port B of the on-off valve 4 are disconnected, the second three-position four-way reversing valve 8 works in the middle position, and the first three-position four-way reversing valve 2 is manually controlled by the handle 7. When the handle controls the first three-position four-way reversing valve 2 to work in the left position, the oil inlet P of the first three-position four-way reversing valve 2 is connected to the first working oil port A. The return oil port T of the first three-position four-way reversing valve 2 is connected to the second working oil port B, and the hydraulic oil flows out of the oil tank 11, and passes through the oil inlet S and the oil outlet P of the variable pump 101, the oil inlet P and the first working oil port A of the first three-position four-way reversing valve 2, the first oil port A and the second oil port B of the actuator 5, the second working oil port B and the return oil port T of the first three-position four-way reversing valve 2, and the second control oil port C2 of the load-sensitive control valve 103, and finally flows into the oil tank 11, thereby driving the actuator 5 to rotate forward. When the handle controls the first three-position four-way reversing valve 2 to work in the right position, the flow direction of the hydraulic oil is similar and will not be repeated. At this time, since the pressure of the oil outlet P of the variable pump 101 is always higher than the second control oil port C2 of the load-sensitive control valve 103 by the first set pressure difference value. The flow rate of the hydraulic oil and the direction of flowing through the actuator 5 can be adjusted by adjusting the first three-position four-way reversing valve 2.

[0110] When the hydraulic system is in oil-series mode, the power module 1 is in the second state, the two-position four-way reversing valve 6 works in the left position, the second oil inlet B and the oil outlet T of the two-position four-way reversing valve 6 are connected, and the first working oil port A and the second working oil port B of the on-off valve 4 are connected to prevent the actuator 5 from being contaminated by the hydraulic oil, and the second three-position four-way reversing valve 8 works in the right position or the left position to change the direction of the hydraulic oil in the pipeline. When the second three-position four-way reversing valve 8 works in the left position, the first three-position four-way reversing valve 2 works in the left position, the oil inlet P of the first three-position four-way reversing valve 2 is connected to the first working oil port A, the oil return port T of the first three-position four-way reversing valve 2 is connected to the second working oil port B, and the hydraulic oil flows out of the oil tank 11, passes through the oil inlet S and oil outlet P of the variable pump 101, the oil inlet P and the first working oil port A of the first three-position four-way reversing valve 2, the first working oil port A and the second working oil port B of the on-off valve 4, the second working oil port B and the oil return port T of the first three-position four-way reversing valve 2, the second control oil port C2 of the load-sensitive control valve 103, and finally flows into the oil tank 11. When the second three-position four-way reversing valve 8 works in the right position, the first three-position four-way reversing valve 2 works in the right position, and the flow direction of the hydraulic oil is similar, which will not be repeated. At this time, the hydraulic oil flow in the pipeline is the largest to improve the oil cross-linking efficiency. During the oil leakage process, when the filter 13 is blocked, the system automatically sends out an alarm signal to prompt the replacement of the filter 13.

[0111] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A hydraulic system for a crane, characterized in that: It comprises a power module (1), a first three-position four-way reversing valve (2), a first shuttle valve (3), an on-off valve (4), an actuator (5), a two-position four-way reversing valve (6), a handle (7), a second three-position four-way reversing valve (8), a second shuttle valve (9) and a third shuttle valve (10); The oil inlet and oil return port of the first three-position four-way reversing valve (2) are respectively connected to the first oil outlet and oil return port of the power module (1); the first working oil port of the first three-position four-way reversing valve (2) is respectively connected to the first oil inlet of the first shuttle valve (3), the first working oil port of the on-off valve (4), and the first oil port of the actuator (5); the second working oil port of the first three-position four-way reversing valve (2) is respectively connected to the second oil inlet of the first shuttle valve (3), the second working oil port of the on-off valve (4), and the second oil port of the actuator (5); The first oil inlet and the second oil inlet of the two-position four-way reversing valve (6) are respectively connected to the first oil outlet of the power module (1) and the oil outlet of the first shuttle valve (3), and the oil outlet of the two-position four-way reversing valve (6) is connected to the control oil port of the power module (1); When the power module (1) is in a first state, the oil pressure at the first oil outlet of the power module (1) and the oil pressure at the first working oil outlet of the first three-position four-way reversing valve (2) are at a first set pressure difference value; when the power module (1) is in a second state, the oil pressure at the first oil outlet of the power module (1) and the oil pressure at the first working oil outlet of the first three-position four-way reversing valve (2) are at a second set pressure difference value, and the second set pressure difference value is greater than the first set pressure difference value; The oil inlet and the oil return port of the handle (7) are respectively connected to the second oil outlet and the oil return port of the power module (1); the first working oil port and the second working oil port of the handle (7) are respectively connected to the first control oil port and the second control oil port of the first three-position four-way reversing valve (2); The oil inlet and the oil return port of the second three-position four-way reversing valve (8) are respectively connected to the second oil outlet and the oil return port of the power module (1); the first working oil port and the second working oil port of the second three-position four-way reversing valve (8) are respectively connected to the first control oil port and the second control oil port of the first three-position four-way reversing valve (2); the on-off valve (4), the two-position four-way reversing valve (6) and the second three-position four-way reversing valve (8) are all solenoid valves; The first oil inlet and the second oil inlet of the second shuttle valve (9) are respectively connected to the first working oil port of the handle (7) and the first working oil port of the second three-position four-way reversing valve (8), and the oil outlet of the second shuttle valve (9) is connected to the first control oil port of the first three-position four-way reversing valve (2); the first oil inlet and the second oil inlet of the third shuttle valve (10) are respectively connected to the second working oil port of the handle (7) and the second working oil port of the second three-position four-way reversing valve (8), and the oil outlet of the third shuttle valve (10) is connected to the second control oil port of the first three-position four-way reversing valve (2); The oil outlets of the first shuttle valve (3) and the second shuttle valve (9) are respectively connected to the first control oil outlet and the second control oil outlet of the first three-position four-way reversing valve (2), so that the hydraulic oil in the pipeline with a relatively high pressure can control the first three-position four-way reversing valve (2). When the power module (1) is in the first state, the first three-position four-way reversing valve (2) is manually controlled by the handle (7) for manual stepless speed regulation; when the power module (1) is in the second state, the first three-position four-way reversing valve (2) is automatically controlled by the second three-position four-way reversing valve (8) to be directly fully opened for oil cross-talk.

2. The hydraulic system according to claim 1, characterized in that: The power module (1) comprises a variable displacement pump (101), a constant pressure control valve (102) and a load sensitive control valve (103); The oil outlet of the variable pump (101) is connected to the oil inlet of the constant pressure control valve (102), the control oil port of the constant pressure control valve (102), the oil inlet of the load sensing control valve (103), and the first control oil port of the load sensing control valve (103); The working oil port and the second control oil port of the load-sensing control valve (103) are respectively connected to the first working oil port of the constant pressure control valve (102) and the oil outlet of the two-position four-way reversing valve (6); The second working oil port of the constant pressure control valve (102) is connected to the control oil port of the variable pump (101).

3. The hydraulic system according to claim 2, characterized in that: The power module (1) further comprises a metering pump (104); The oil outlet of the metering pump (104) is connected to the oil inlet of the handle (7) and the oil inlet of the second three-position four-way reversing valve (8).

4. The hydraulic system according to claim 3, characterized in that: The power module (1) further comprises a relief valve (105); The oil inlet of the overflow valve (105) is connected to its own control oil port and the oil outlet of the metering pump (104).

5. The hydraulic system according to claim 1, characterized in that: The hydraulic system also includes a hydraulic lock (12); The hydraulic lock (12) comprises a first hydraulically controlled one-way valve (121) and a second hydraulically controlled one-way valve (122); The first oil port, the second oil port and the control oil port of the first hydraulically controlled one-way valve (121) are respectively connected to the first working oil port of the first three-position four-way reversing valve (2), the first oil port of the actuator (5) and the second working oil port of the first three-position four-way reversing valve (2); The first oil port, the second oil port and the control oil port of the second hydraulically controlled one-way valve (122) are respectively connected to the second working oil port of the first three-position four-way reversing valve (2), the second oil port of the actuator (5) and the first working oil port of the first three-position four-way reversing valve (2).

6. The hydraulic system according to claim 1, characterized in that: The hydraulic system further comprises a filter (13); The oil inlet of the filter (13) is connected to the oil return port of the first three-position four-way reversing valve (2).

7. The hydraulic system according to claim 6, characterized in that: The hydraulic system further comprises a one-way valve (14); The oil inlet of the one-way valve (14) is connected to the oil inlet of the filter (13), and the oil return port of the one-way valve (14) is connected to the oil return port of the filter (13).

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