Variable amplitude vibration control method and hydraulic system thereof

Abstract

The invention discloses a variable amplitude vibration control method and a hydraulic system thereof, which can effectively reduce the variable amplitude vibration condition and improve the safety of the variable amplitude action of a crane, and comprises the following steps: controlling an input signal to send an instruction; the control valve is electrified to switch different working states; detecting the pressure of a rod cavity of the variable-amplitude hydraulic cylinder; judging whether the pressure value meets requirements or not; switching the working state of the electromagnetic valve; and controlling the opening of the balance valve. By means of the steps, the opening degree of the balance valve is adjusted through pressure feedback of the variable-amplitude hydraulic cylinder, and the loop flow of the hydraulic system is controlled. When the load changes or hydraulic impact is generated, the flow of a hydraulic loop can be adjusted in time, the hydraulic impact is reduced, amplitude variation vibration generated in the amplitude variation process is reduced, and safe and stable operation of the amplitude variation action of the crane is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of crane hydraulics, and more particularly to a luffing vibration control method and its hydraulic system. Background Art

[0002] As is well known, cranes play an increasingly important role in our daily lives and are used in more and more occasions. Since the working places of cranes are relatively complex, mostly in outdoor sites with harsh working conditions, crane vibration will pose serious safety hazards. How to effectively control the output vibration of cranes is one of the core issues to be considered in improving crane safety.

[0003] The working principle of the crane luffing operation is generally as follows: during the luffing upward process, by controlling the input signal, the luffing main valve is in the right position, and hydraulic oil flows out from the main pump and acts on the balance valve through the luffing main valve. At this time, the balance valve is equivalent to a check valve, and the hydraulic oil reaches the rodless cavity of the luffing cylinder through the balance valve, causing the luffing cylinder to extend and drive the load to rise. During the luffing load-bearing process, the boom of the truck crane is in a static state, the luffing main valve is in the middle position, the valve port is closed, and the hydraulic oil cannot pass through the luffing main valve, and the luffing cylinder is in a relatively stable load-bearing state. During the luffing downward process, by controlling the input signal, the luffing main valve is in the left position, the hydraulic oil enters the rod chamber of the luffing cylinder, the cylinder retracts, and at the same time, the hydraulic oil in the rodless cavity of the luffing cylinder enters the balance valve through the damping hole, enabling the load of the truck crane to descend smoothly.

[0004] Because the boom angle is constantly changing, the cylinder pressure also changes, and the pilot control pressure of the balance valve is also constantly changing, resulting in the problem of the balance valve opening - closing - opening, causing the luffing vibration phenomenon. Currently, there are two solutions to achieve stable operation of the luffing action. The first solution is to use hydrodynamic compensation, using the characteristic that the hydrodynamic force closes the spool area to reduce the throttle orifice of the balance valve; the second solution is to lead the load pressure to the spring chamber of the balance valve through a switching valve, and use the load pressure to push the balance valve spool in the opposite direction to close it.

[0005] Chinese Patent 202010650826.8 discloses a hydrodynamic compensation balance valve, which mainly designs the throttle orifice structure of the balance valve spool. When the load pressure of the luffing system increases with lowering, the hydrodynamic force generated by the throttle orifice of the spool moves the balance valve spool in the direction of reducing the flow output, reducing the spool stroke and changing the flow area of the throttle orifice, so as to achieve load-flow compensation by the action of reducing the opening of the balance valve when the load pressure is high. The disadvantage of this control method is that the compensation effect of the balance valve is not obvious, the reduction range of the flow rate with the increase of the load pressure is limited, the compensation rate and compensation inflection point are not adjustable, and the spool is prone to jitter during the commutation process, reducing safety.

[0006] Chinese Patent No. 202010655823.3 discloses a load pressure-flow compensation balance valve, which realizes load pressure-flow compensation by controlling the opening degree of the balance valve through pressure regulation and the magnitude of the flow rate. The disadvantage of this control method is that the load pressure is led to the spring chamber of the balance valve through a switching valve, which will cause the opening pressure of the balance valve to increase as the load pressure increases, and even phenomena such as the balance valve opening first and then closing during the opening process may occur, resulting in sudden changes in the flow rate. Summary of the Invention

[0007] To effectively solve the vibration problem existing in the luffing operation of traditional cranes, the present invention provides a hydraulic system for controlling luffing vibration of a crane, including an oil tank, a hydraulic pump, a three-position five-way solenoid directional valve, a main relief valve, a secondary relief valve, a flow dividing valve, a two-position two-way solenoid valve, a pressure sensor, a damping control compensation balance valve, and a luffing cylinder;

[0008] The three-position five-way solenoid directional valve has a first working oil port, a second working oil port, a third working oil port, and a fourth working oil port;

[0009] The first oil inlet is communicated with the oil outlet of the oil tank through the hydraulic pump, and the second oil outlet is communicated with the first working oil port; the third working oil port is communicated with the rodless cavity of the luffing cylinder, and the fourth working oil port is communicated with the rod chamber of the luffing cylinder;

[0010] Furthermore, the three-position five-way solenoid directional valve has a first working state and a second working state. When the three-position five-way solenoid directional valve is in the first working state, the first working oil port is communicated with the third working oil port, and the second working oil port is communicated with the fourth working oil port; when the three-position five-way solenoid directional valve is in the second working state, the first working oil port is communicated with the fourth working oil port, and the second working oil port is communicated with the third working oil port.

[0011] By adopting the above technical solution, during the process of luffing up, the three-position five-way electromagnetic directional valve is in the first working state. At this time, the first working oil port of the three-position five-way electromagnetic directional valve is communicated with the third working oil port, and the second working oil port is communicated with the fourth working oil port. The pressure oil in the fuel tank enters the rodless cavity of the luffing cylinder through the hydraulic pump into the first working oil port and the third working oil port. At the same time, the pressure oil in the rod cavity of the luffing cylinder flows back to the oil return port of the fuel tank through the fourth working oil port and the second working oil port in sequence, realizing luffing up. During the process of luffing down, the three-position five-way electromagnetic directional valve switches to the second working state. At this time, the first working oil port of the three-position five-way electromagnetic directional valve is communicated with the fourth working oil port, and the second working oil port is communicated with the third working oil port. The pressure oil in the fuel tank enters the rod cavity of the luffing cylinder through the hydraulic pump into the first working oil port and the fourth working oil port. At the same time, the pressure oil in the cylinderless cavity of the luffing cylinder flows back to the oil return port of the fuel tank through the third working oil port and the second working oil port in sequence, realizing luffing down.

[0012] The present invention provides a damping control compensation balance valve, including a pilot damping control passage. One end of the pilot damping control passage is connected to the reverse control port of the balance valve, and the other end is connected to the main spool control cavity of the balance valve, for increasing or decreasing the opening degree of the balance valve.

[0013] The pilot damping control passage includes a solenoid valve, an inlet damping, and two bypass dampings. One end of the inlet damping is connected to the reverse control port of the balance valve, and the other end is connected to the main spool control cavity of the balance valve. One end of each of the bypass dampings is connected to the passage connecting the other end of the inlet damping and the main spool control cavity of the balance valve. The other end of one bypass damping is connected to a back pressure check valve, and the other end of the other bypass damping is connected to a filter net. A two-position two-way solenoid valve is connected to the other end of the bypass damping far from the inlet damping.

[0014] The control valve includes a three-position five-way electromagnetic directional valve, a flow dividing valve, a main relief valve, and a secondary relief valve. The first working oil port of the three-position five-way electromagnetic directional valve, one end of the flow dividing valve and the main relief valve are connected to the oil inlet of the control valve. The second working oil port of the three-position five-way electromagnetic directional valve, the other end of the flow dividing valve, the main relief valve, and the secondary relief valve are connected to the oil return port of the control valve. The third working oil port of the three-position five-way electromagnetic directional valve is connected to one working oil port of the control valve. The fourth working oil port of the electromagnetic directional valve and one end of the secondary relief valve are connected to the other working oil port of the control valve.

[0015] Furthermore, the oil return port of the fuel tank is connected to the control valve, one end of the hydraulic pump is connected to the fuel tank, and the other end is connected to the oil inlet of the control valve; one working oil port of the damping control compensation balance valve is connected to one working oil port of the control valve, and the other working oil port is connected to the rodless cavity of the luffing cylinder. The other working oil port of the control valve is connected to the rod end cavity of the luffing cylinder; the reverse control port of the balance valve is connected to the passage connecting the rod end cavity of the luffing cylinder and the other working oil port of the control valve; the pressure sensor is connected to the rod end cavity of the luffing cylinder, and the on-off of the solenoid valve is controlled by the pressure feedback detected by the pressure sensor of the rod end cavity of the luffing cylinder.

[0016] The present invention provides a luffing vibration control method, and the steps are as follows:

[0017] Step 1: The control input signal issues an instruction, and the operator operates the action handle to convert the handle action into an electrical signal and input it into the hydraulic system.

[0018] Step 2: Input the control input signal into the three-position five-way solenoid directional valve, and change the working state by changing the connection mode between the first working oil port, the second working oil port and the third working oil port, the fourth working oil port of the three-position five-way solenoid directional valve, so as to change the oil flow direction of the hydraulic circuit.

[0019] Step 3: Use a pressure sensor to detect the pressure signal of the rod end cavity of the luffing hydraulic cylinder, and collect the pressure signal of the rod end cavity by a data acquisition card.

[0020] Step 4: Judge whether the pressure data of the luffing hydraulic cylinder meets less than or equal to the set pressure value. If it meets, maintain the current state for luffing action; if it does not meet, sequentially execute Step 5 and Step 6, and then return to Step 3.

[0021] Step 5: Switch the energization condition of the two-position two-way solenoid valve to switch single bypass damping oil discharge or double bypass damping parallel oil discharge.

[0022] Step 6: By changing the oil discharge method, adjust the fluid pressure, change the position of the spool, and control the change of the balance valve opening.

[0023] The beneficial effects achieved by the present invention: The present invention combines variable damping and fixed damping to form a pilot control damping network to control the opening of the balance valve spool, which can effectively filter the pilot pressure fluctuation. By adjusting the damping size through pressure feedback, the pilot output control pressure of the balance valve control end is reduced, the fluctuation of the main spool opening of the balance valve becomes smaller, and the oil return flow fluctuation under large load pressure difference also decreases accordingly, making the luffing action of the crane run smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the system block diagram of the present invention;

[0025] Figure 2Schematic diagram provided by an embodiment of the present invention;

[0026] Figure 3 Schematic diagram of a luffing hydraulic system compensated by damping control provided by an embodiment of the present invention;

[0027] Figure 4 Schematic diagram of a balance valve compensated by damping control provided by an embodiment of the present invention;

[0028] In the figure: 1 - hook; 2 - boom; 3 - luffing hydraulic cylinder; 31 - rod chamber of the luffing hydraulic cylinder; 32 - rodless chamber of the luffing hydraulic cylinder; 4 - slewing platform; 5 - motor; 6 - hydraulic pump; 7 - oil tank; 8 - control valve; 81 - main relief valve; 82 - flow dividing valve; 83 - three-position five-way solenoid directional valve; 831 - first working oil port; 832 - second working oil port; 833 - third working oil port; 834 - fourth working oil port; 84 - secondary relief valve; 9 - damping control compensated balance valve; 91 - balance valve; 92 - inlet damping; 93 - bypass damping; 94 - back pressure check valve; 95 - filter screen; 96 - bypass damping; 97 - two-position two-way solenoid valve; 10 - pressure sensor. Detailed implementation manners

[0029] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention;

[0030] In the description of the present invention, it should be understood that the terms "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations; Embodiment 1

[0031] As Figure 1 shown, the luffing vibration control method provided in this embodiment includes the following steps:

[0032] Step 1: A control input signal issues an instruction, and the operator operates the action handle to convert the handle action into an electrical signal and input it into the hydraulic system.

[0033] Step 2: The control input signal is input into the three-position five-way solenoid directional valve 83, and the working state is switched by changing the connection mode between the first working oil port 831, the second working oil port 832 and the third working oil port 833, the fourth working oil port 834 of the three-position five-way solenoid directional valve 83, so as to change the oil flow direction of the hydraulic circuit.

[0034] Step 3: Use the pressure sensor 10 to detect the pressure signal of the rod chamber 31 of the luffing hydraulic cylinder, and collect this rod chamber pressure signal by the data acquisition card.

[0035] Step 4: Determine whether the pressure data of the luffing hydraulic cylinder 3 meets the requirement of being less than or equal to the set pressure value. If it meets the requirement, maintain the current state and perform the luffing action; if it does not meet the requirement, sequentially execute Step 5 and Step 6, and then return to Step 3.

[0036] Step 5: Switch the energization condition of the two-way two-way solenoid valve 97 to switch between single bypass damping oil discharge or double bypass damping parallel oil discharge.

[0037] Step 6: Adjust the fluid pressure by changing the oil discharge method, change the position of the spool, and control the opening change of the balance valve 91.

[0038] As Figure 2 shown, the structural schematic diagram includes a hook 1, a boom 2, a luffing hydraulic cylinder 3, and a turntable 4. The luffing hydraulic cylinder 3 and the turntable 4 are connected by a hinge point. The luffing hydraulic cylinder 3 and the boom 2 are connected by a hinge point. The boom 2 and the turntable 4 are connected by a hinge point. The luffing hydraulic cylinder 2 is controlled by an external hydraulic system. When performing the luffing action, the telescopic movement of the luffing hydraulic cylinder 3 drives the boom 2 to change the angle.

[0039] As Figure 3 shown, the luffing hydraulic system includes a motor 5, a hydraulic pump 6, an oil tank 7, a control valve 8, a damping control compensation balance valve 9, a luffing hydraulic cylinder 3, and a pressure sensor 10. The oil tank 7 is connected to the oil return port of the control valve 8. One end of the hydraulic pump 6 is connected to the oil tank 7, and the other end is connected to the oil inlet of the control valve 8. One working oil port of the damping control compensation balance valve 9 is connected to one working oil port of the control valve 2, and the other working oil port is connected to the rod chamber of the luffing hydraulic cylinder 3. The other working oil port of the control valve 8 is connected to the rod chamber of the luffing hydraulic cylinder 3. The reverse control port of the balance valve 9 is connected to the passage where the rod chamber of the luffing hydraulic cylinder 3 is connected to the other working oil port of the control valve 8. The pressure sensor 10 is connected to the rod chamber of the luffing hydraulic cylinder 3. The on-off of the two-way two-way solenoid valve 97 is controlled by the pressure feedback of the rod chamber pressure of the luffing hydraulic cylinder 3 detected by the pressure sensor 10.

[0040] In this embodiment, the three-position five-way solenoid directional valve 83 has a first working state and a second working state. When the three-position five-way solenoid directional valve 83 is in the first working state, the first working oil port 831 is communicated with the third working oil port 833, and the second working oil port 832 is communicated with the fourth working oil port 834. When the three-position five-way solenoid directional valve 83 is in the second working state, the first working oil port 831 is communicated with the fourth working oil port 834, and the second working oil port 832 is communicated with the third working oil port 833.

[0041] The control valve 8 includes a three-position five-way solenoid directional valve 83, a flow dividing valve 82, a main relief valve 81 and a secondary relief valve 84; the first working oil port 831 of the three-position five-way solenoid directional valve 83, as well as one end of the flow dividing valve 82 and the main relief valve 81, are connected to the oil inlet of the control valve 8, the second working oil port of the three-position five-way solenoid directional valve 83, as well as the other ends of the flow dividing valve 82, the main relief valve 81 and the secondary relief valve 84, are connected to the oil return port of the control valve 8, the third working oil port of the three-position five-way solenoid directional valve 83 is connected to the working oil port of the control valve 8, and the fourth working oil port of the three-position five-way solenoid directional valve 83 and one end of the secondary relief valve 84 are connected to the other working oil port of the control valve 8.

[0042] During the process of boom raising, the three-position five-way solenoid directional valve 83 is in the first working state. At this time, the first working oil port 831 of the three-position five-way solenoid directional valve 83 is communicated with the third working oil port 833, and the second working oil port 832 is communicated with the fourth working oil port 834. The pressurized oil in the fuel tank 7 enters the rodless cavity 32 of the boom cylinder through the hydraulic pump 6 and the first working oil port 831 and the third working oil port 833. At the same time, the pressurized oil in the rod chamber 31 of the boom cylinder flows back to the oil return port of the fuel tank 7 through the fourth working oil port 834 and the second working oil port 832 in sequence, realizing boom raising; during the process of boom lowering, the three-position five-way solenoid directional valve 83 switches to the second working state. At this time, the first working oil port 831 of the three-position five-way solenoid directional valve 83 is communicated with the fourth working oil port 834, and the second working oil port 832 is communicated with the third working oil port 833. The pressurized oil in the fuel tank 7 enters the rod chamber 31 of the boom cylinder through the hydraulic pump 6 and the first working oil port 831 and the fourth working oil port 834. At the same time, the pressurized oil in the cylinderless cavity 32 of the boom cylinder flows back to the oil return port of the fuel tank 7 through the third working oil port 833 and the second working oil port 832 in sequence, realizing boom lowering.

[0043] The pressure value P of the rod chamber 31 of the boom cylinder is detected by the pressure sensor 10. When the pressure value P of the rod chamber 31 is less than the set value, the two-way two-way solenoid valve 97 is controlled to be energized, and only the bypass damper 93 is used for oil drainage, increasing the opening degree of the balance valve and increasing the oil return flow rate of the hydraulic circuit; when the pressure value P of the rod chamber 31 is greater than the set value, the two-way two-way solenoid valve 97 is controlled to be de-energized, and the bypass damper 93 and the bypass damper 96 drain oil in parallel, reducing the opening degree of the balance valve and reducing the oil return flow rate of the hydraulic circuit, making the boom movement proceed smoothly. Embodiment 2

[0044] As Figure 4As shown in the figure, this embodiment provides a damping control compensation balance valve. The damping control compensation balance valve 9 includes a pilot damping control passage, and the pilot damping control passage includes a balance valve 91, an inlet oil damper 92, a bypass damper 93, a back pressure check valve 94, a filter screen 95, a bypass damper 96, and a two-position two-way solenoid valve 97. One end of the inlet oil damper 92 is connected to the reverse control port of the balance valve, and the other end is connected to the main spool control chamber of the balance valve. One ends of the bypass damper 93 and the bypass damper 96 are both connected to the passage where the other end of the inlet oil damper 92 is connected to the main spool control chamber of the balance valve. The other end of the bypass damper 93 is connected to the back pressure check valve 94, and the other end of the bypass damper 96 is connected to the filter screen 95. A two-position two-way solenoid valve 97 is connected to the other end of the bypass damper 96 away from the inlet oil damper 92.

[0045] The purpose of the damping control compensation balance valve 9 is to change the control pressure value of the reverse opening-full opening of the balance valve. On the existing balance valve structure, the control end cover structure is changed, and a new pilot damping control passage is added. The change of the pilot control damping matching of the balance valve is realized by relying on the two-position two-way solenoid valve 97. Then, combined with the detection of the pressure in the rod chamber of the luffing cylinder, the on-off of the two-position two-way solenoid valve 97 is controlled in a closed loop, and further the opening of the balance valve is controlled to realize the control of the flow rate of the hydraulic system circuit and reduce the luffing vibration.

[0046] The content recorded in the description of the embodiment is only a list of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiment. The protection scope of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art according to the inventive concept of the present invention.

Claims

1. A variable amplitude vibration control hydraulic system, characterized in that: It includes an oil tank, a hydraulic pump, a three-position five-way solenoid reversing valve, a main relief valve, a secondary relief valve, a diverter valve, a two-position two-way solenoid valve, a pressure sensor, a damping control compensation balancing valve, and a variable-length oil cylinder; the oil tank is connected to the oil return port of the relief valve, one end of the hydraulic pump is connected to the oil tank, and the other end is connected to the oil inlet of the three-position five-way solenoid reversing valve; one working oil port of the balancing valve for controlling the damping size is connected to the third working oil port of the three-position five-way solenoid reversing valve, the other working oil port is connected to the rodless chamber of the variable-length oil cylinder, and the fourth working oil port of the three-position five-way solenoid reversing valve is connected to the rod chamber of the variable-length oil cylinder; the reverse control port of the balancing valve is connected to the rod chamber of the variable-length oil cylinder and the passage connected to the third working oil port of the three-position five-way solenoid reversing valve, and the other end of the bypass damping is connected to the oil tank; the pressure sensor is connected to the rod chamber of the variable-length oil cylinder, and the on-off of the solenoid valve is controlled based on the pressure feedback of the rod chamber of the variable-length oil cylinder detected by the pressure sensor.

2. The control hydraulic system according to claim 1, characterized in that: The three-position five-way solenoid directional control valve has a first working state and a second working state. When the three-position five-way solenoid directional control valve is in the first working state, the first working oil port is connected to the third working oil port, and the second working oil port is connected to the fourth working oil port; when the three-position five-way solenoid directional control valve is in the second working state, the first working oil port is connected to the fourth working oil port, and the second working oil port is connected to the third working oil port.

3. The control hydraulic system according to claim 1, characterized in that: It includes a pilot damping control passage, one end of which is connected to the reverse control port of the balancing valve, and the other end is connected to the main valve core control chamber of the balancing valve, so as to increase or decrease the opening of the balancing valve.

4. The damping control compensating balance valve according to claim 3, characterized in that: The damping control compensation balancing valve includes a pilot damping control passage, which includes a balancing valve, an oil inlet damping, a bypass damping, a back pressure check valve, a filter, a bypass damping and a two-position two-way solenoid valve; one end of the oil inlet damping is connected to the reverse control port of the balancing valve, and the other end is connected to the main valve core control chamber of the balancing valve; the bypass damping and one end of the bypass damping are both connected to the passage connecting the other end of the oil inlet damping and the main valve core control chamber of the balancing valve, the other end of the bypass damping is connected to the back pressure check valve, the other end of the bypass damping is connected to the filter, and the other end of the bypass damping away from the oil inlet damping is connected to the two-position two-way solenoid valve.

5. The control hydraulic system according to claim 1, characterized in that: The specific steps of the control hydraulic system generating an input signal through the handle to complete the process of the crane luffing action are as follows: Step 1: The control input signal issues a command, and the operator operates the action handle to convert the handle action into an electrical signal and input it into the hydraulic system. Step 2: Input the control input signal into the three-position five-way solenoid reversing valve, switch the working state by changing the connection mode of the first working oil port, the second working oil port and the third working oil port, the fourth working oil port of the three-position five-way solenoid reversing valve, and change the direction of the hydraulic circuit oil. Step 3: Use a pressure sensor to detect and obtain the rod chamber pressure signal of the variable amplitude hydraulic cylinder, and use a data acquisition card to collect the rod chamber pressure signal. Step 4: Determine whether the pressure data of the boom hydraulic cylinder satisfies the requirement of being less than or equal to the set pressure value. If so, maintain the current state and perform the boom action. If not, execute steps 5 and 6 in sequence, and then return to step 3. Step 5: Switch the power supply status of the two-position two-way solenoid valve to switch between single bypass damping oil leakage or double bypass damping parallel oil leakage. Step 6: By changing the oil leakage method, adjust the fluid pressure, change the position of the valve core, and control the change of the balance valve opening.

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