Variable amplitude hydraulic system, engineering machinery and variable amplitude control method

Abstract

The invention relates to the technical field of engineering machinery, and discloses a variable-amplitude hydraulic system, engineering machinery and a variable-amplitude control method. The variable-amplitude hydraulic system comprises a variable-amplitude oil cylinder, a pressure detection module, an oil way module, a first pilot oil way module and a control module. The pressure detection module is used for detecting the oil pressure of the rod cavity; the oil way module comprises a first oil way module and a first balance valve, the first oil way module is connected with a rod cavity of the variable-amplitude oil cylinder, and the first balance valve is arranged on a first oil way; the first pilot oil way module is connected with the control end of the first balance valve. The control module is configured to send out a stop signal used for controlling stopping of current work under the condition that the oil pressure detected by the pressure detection module is larger than a preset safety value, and / or control the pilot oil way module to open an oil return working position of the first balance valve for oil return. According to the variable-amplitude hydraulic system, when the pressure of a variable-amplitude oil cylinder rod cavity is larger than a preset safety value, oil return is actively started, equipment safety is protected, and the service life is prolonged.

Description

Technical Field

[0001] This application belongs to the technical field of construction machinery, and specifically relates to a luffing hydraulic system, a construction machinery, and a luffing control method. Background Art

[0002] With the development trend of the large-scale of cranes, significant structural evolutions have occurred in their core components: the cylinder diameter of the luffing cylinder continues to increase to meet the high-load requirements; the mast structure adopts a super-lifting device and is combined with a variable luffing boom design, significantly expanding the operating elevation angle range. Although such structural innovations have improved the operating performance, they have also increased the safety risks of the luffing system, especially the risk of the luffing cylinder tilting backward being the most prominent. The existing technology uses a hydraulic valve lock in the rod chamber for passive protection, but it cannot adapt to new complex working conditions. In the traditional design of the luffing cylinder, the rodless chamber is used as the main pressure-bearing chamber to bear high-pressure loads, while the rod chamber is designed to bear low pressure due to structural and operating conditions limitations.

[0003] In the working condition of hoisting a heavy object: the deformation of the main boom causes the rodless chamber of the luffing cylinder to be pressurized, the oil is compressed, causing the piston rod to retract, and the rod chamber is passively refilled with oil; in the lowering condition, the release of the load causes the pressure in the rodless chamber to drop suddenly, and the rebound of the oil forces the piston rod to extend. At this time, the rod chamber forms a locked cavity due to the lock of the balance valve, and the pressure rises sharply.

[0004] However, there are key defects in the existing hydraulic control strategy: the pressure regulation of the rod chamber completely relies on the passive compensation mechanism and lacks the active linkage control with the hoisting action. Especially when the tension of the hoisting system is quickly unloaded at the moment when the heavy object touches the ground, the luffing system cannot actively release the pressure accumulated in the rod chamber, resulting in the pressure peak far exceeding the design threshold of low-pressure components such as the cylinder head, causing safety accidents such as seal failure, thread slipping, even cylinder head bursting, and piston rod ejection. Summary of the Invention

[0005] The purpose of this application is to provide a luffing hydraulic system, a construction machinery, and a luffing control method, which are used to solve the problem that when the tension of the hoisting system is quickly unloaded in the existing technology, the luffing system cannot actively release the pressure accumulated in the rod chamber, which is likely to lead to safety accidents such as seal failure, thread slipping, even cylinder head bursting, and piston rod ejection.

[0006] To achieve the above purpose, in the first aspect of this application, a luffing hydraulic system is provided, which is applied to construction machinery. The luffing hydraulic system includes:

[0007] A luffing cylinder, having a rodless chamber and a rod chamber, and is used to drive the boom assembly to perform pitching and luffing actions;

[0008] A pressure detection module, which is used to detect the oil pressure of the rod chamber;

[0009] The oil circuit module includes a first oil circuit module and a first balance valve. The first oil circuit module is connected to the rod chamber and is used for supplying oil and returning oil to the rod chamber. The first balance valve is arranged on the first oil circuit;

[0010] A first pilot oil circuit module is connected to the control end of the first balance valve and is used for controlling the opening of the oil return working position of the first balance valve through pilot oil; and

[0011] The control module is configured to issue a stop signal for controlling the stop of the current work and / or control the first pilot oil circuit module to open the oil return working position of the first balance valve for oil return when the oil pressure detected by the pressure detection module is greater than a preset safety value.

[0012] As a further improvement of the above technical solution:

[0013] In some embodiments, the oil circuit module further includes a second oil circuit module. The second oil circuit module is connected to the rodless chamber and is used for supplying oil and returning oil to the rodless chamber;

[0014] The first pilot oil circuit module is provided with a pilot oil control oil port and two oil inlets. One of the oil inlets is connected to the second oil circuit module, and the other oil inlet is externally connected to a control oil source. The pilot oil control oil port is connected to the control end of the first balance valve through a pipeline;

[0015] Wherein, when the second oil circuit module supplies oil, the first pilot oil circuit module is used to directly convert the pressure oil in the second oil circuit module into pilot oil for controlling the first balance valve under the control of the control module; when the second oil circuit module switches to oil return or pressure holding, the first pilot oil circuit module is used to convert the externally connected control oil source into pilot oil for controlling the first balance valve under the control of the control module.

[0016] In some embodiments, the first pilot oil circuit module includes:

[0017] A shuttle valve is provided with the pilot oil control oil port and the two oil inlets; and

[0018] A control valve is arranged on the pipeline connecting the shuttle valve and the external control oil source;

[0019] Wherein, the control valve is an electric control valve. The electric control valve is electrically connected to the control module. When the second oil circuit module switches to oil return or pressure holding and when the oil pressure detected by the pressure detection module is greater than a preset safety value, the control module controls the control valve to open for oil supply;

[0020] Alternatively, the control valve is a hydraulically controlled valve, and the control end of the hydraulically controlled valve is used to externally connect a control oil source, and the control oil source is the pressure oil used to drive the hoisting mechanism to descend in the construction machinery.

[0021] In some embodiments, the first pilot oil circuit module includes a first reversing valve, the first reversing valve is provided with an oil return port, the pilot oil control oil port and two of the oil inlet ports, the first reversing valve further includes a first working position, a second working position and a third working position, and the control module is used to control the spool of the first reversing valve to switch between the first working position, the second working position and the third working position;

[0022] Wherein, in the first working position, the second oil circuit module is communicated with the pilot oil control oil port through the corresponding oil inlet port of the first reversing valve; in the second working position, the externally connected control oil source is communicated with the pilot oil control oil port through the corresponding oil inlet port of the first reversing valve; in the third working position, the pilot oil control oil port is communicated with the oil return port.

[0023] In some embodiments, the first pilot oil circuit module further includes a control oil supply module for providing a control oil source;

[0024] Alternatively, the control oil source is provided by an oil supply module of the hydraulic system of the construction machinery.

[0025] In some embodiments, the oil circuit module further includes:

[0026] A second oil circuit module, connected to the rodless chamber, for supplying oil and returning oil to the rodless chamber; and

[0027] A second reversing valve, connected to the second oil circuit module and the first oil circuit module, and the second reversing valve is further used to connect an oil supply module in the hydraulic system of the construction machinery;

[0028] The control module is electrically connected to the second reversing valve, and the control module is configured to control the switching of the working position of the second reversing valve so that the oil supply module selects to be connected to the first oil circuit module or the second oil circuit module.

[0029] In some embodiments, the oil circuit module further includes a second balance valve, and the second balance valve is arranged on the second oil circuit module;

[0030] The luffing hydraulic system further includes a second pilot oil circuit module, connected to the control end of the second balance valve, for controlling the opening of the oil return working position of the second balance valve through pilot oil.

[0031] In some embodiments, overflow valves are further provided on both the first oil circuit module and the second oil circuit module.

[0032] The second aspect of the present application further provides a construction machinery, including a boom assembly, a hoisting mechanism, and a luffing hydraulic system provided according to the first aspect above.

[0033] The third aspect of the present application further provides a luffing control method, which is applied to the construction machinery provided according to the second aspect above. The luffing control method includes:

[0034] Luffing arm-lifting working condition control method: Control the rodless cavity of the luffing cylinder to be filled with oil, control the return oil working position of the first balance valve to be opened through the pilot oil in the first pilot oil circuit module, and detect the oil pressure of the rod cavity in real time through the pressure detection module. When the oil pressure of the rod cavity is greater than a preset safety value, a stop signal is issued to stop the luffing arm-lifting action;

[0035] Luffing arm-lowering working condition control method: Control the rod cavity of the luffing cylinder to be filled with oil, and the rodless cavity to return oil, and detect the oil pressure of the rod cavity in real time through the pressure detection module. When the oil pressure of the rod cavity is greater than a preset safety value, a stop signal is issued to stop the luffing arm-lowering action;

[0036] Hoisting mechanism lowering target object working condition control method: Detect the oil pressure of the rod cavity in real time through the pressure detection module. When the oil pressure of the rod cavity is greater than a preset safety value, a stop signal is issued to stop the operation of the hoisting mechanism, and at the same time, control the pilot oil circuit module to open the return oil working position of the first balance valve for active oil return.

[0037] Compared with the prior art, a luffing hydraulic system, a construction machinery, and a luffing control method provided by the present application have at least the following technical effects:

[0038] The luffing hydraulic system provided by this application uses a pressure detection module to detect the oil pressure in the rod chamber in real time, and connects the control end of the first balance valve through the first pilot oil circuit module to control the opening of the oil return working position of the first balance valve through pilot oil. When the oil pressure detected by the pressure detection module is greater than the preset safety value, the control module issues a stop signal for controlling the stop of the current operation, and / or controls the pilot oil circuit module to open the oil return working position of the first balance valve for oil return. When applied to construction machinery, when dealing with the rapid unloading of the pulling force of the hoisting system, the oil in the rodless chamber of the luffing cylinder rebounds, the piston rod extends, and the oil pressure in the rod chamber increases instantaneously. At this time, the pressure detection module detects that the oil pressure in the rod chamber is greater than the preset safety value, and the control module issues a stop signal to stop the action of the hoisting mechanism. At the same time, it controls the pilot oil circuit module to open the oil return working position of the first balance valve for active oil return, realizing the active pressure relief of the rod chamber, effectively preventing the damage of the seals and connection structures of the cylinder head on the rod chamber side due to the excessive pressure accumulated in the rod chamber in a short time, and preventing the damage of other low-pressure-resistant parts, further avoiding safety hazards such as cylinder head bursting and piston rod ejection, thereby improving reliability and extending service life.

[0039] In addition, in the luffing arm lifting control condition and the luffing arm lowering control condition, the oil pressure in the rod chamber can also be detected in real time through the pressure detection module. When the oil pressure in the rod chamber is greater than the preset safety value, a stop signal is issued to stop the luffing action to ensure the safety and reliability of the operation.

[0040] Other features and advantages of the embodiments of this application will be described in detail in the subsequent specific implementation part. Brief Description of the Drawings

[0041] The drawings are used to provide a further understanding of the embodiments of this application, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the embodiments of this application, but do not constitute a limitation to the embodiments of this application. For those of ordinary skill in the art, other drawings can also be obtained based on the structures shown in these drawings without creative efforts. In the drawings:

[0042] Figure 1 is a schematic diagram of the oil circuit of a luffing hydraulic system provided by an embodiment of this application;

[0043] Figure 2 is Figure 1 a schematic diagram of the oil circuit of the first type of first pilot oil circuit module in the shown luffing hydraulic system;

[0044] Figure 3 is Figure 1 a schematic diagram of the oil circuit of the second type of first pilot oil circuit module in the shown luffing hydraulic system;

[0045] Figure 4 is Figure 1 a schematic diagram of the oil circuit of the third first pilot oil circuit module in the luffing hydraulic system shown;

[0046] Figure 5 a schematic diagram of the oil circuit of a luffing hydraulic system provided by another embodiment of the present application;

[0047] Figure 6 is Figure 5 a schematic diagram of the oil circuit of a first pilot oil circuit module in the luffing hydraulic system shown.

[0048] Description of the reference numerals

[0049] 10. Boom assembly;

[0050] 100. Luffing cylinder; 110. Rodless cavity; 120. Rod chamber;

[0051] 200. Pressure detection module;

[0052] 300. Oil circuit module; 310. First oil circuit module; 320. First balance valve; 330. Second oil circuit module; 340. Second reversing valve; 350. Second balance valve; 360. Relief valve;

[0053] 400. First pilot oil circuit module; 410. Shuttle valve; 420. Control valve; 430. First reversing valve; 440. Control oil supply module;

[0054] 500. Control module;

[0055] 600. Second pilot oil circuit module; 610. Third reversing valve;

[0056] 700. Pilot oil supply module. Detailed description of the specific embodiments

[0057] The following will describe in detail the specific embodiments of the present application with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present application, and are not intended to limit the present application.

[0058] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with exemplary embodiments.

[0059] Embodiment 1

[0060] Please refer to Figure 1 , this embodiment provides a luffing hydraulic system, which can be applied to construction machinery, such as a crane. The crane includes a telescopic boom assembly 10 and a hoisting mechanism. Particularly for large cranes, a superlift device is provided on the boom assembly 10.

[0061] The luffing hydraulic system provided in this embodiment includes: a luffing oil cylinder 100, a pressure detection module 200, an oil circuit module 300, a first pilot oil circuit module 400, and a control module 500. The luffing oil cylinder 100 has a rodless cavity 110 and a rod cavity 120, and the luffing oil cylinder 100 is used to drive the boom assembly 10 to perform pitching luffing actions; the pitching luffing actions include raising the boom and lowering the boom.

[0062] Among them, for the raising boom action: the rodless cavity 110 is filled with oil, and the pressure oil pushes the piston rod of the luffing oil cylinder 100 to extend, and the oil in the rod cavity 120 returns to the fuel tank of the hydraulic system of the construction machinery; for the lowering boom action: the rod cavity 120 is filled with oil (the piston rod retracts), and the oil in the rodless cavity 110 returns to the fuel tank.

[0063] The pressure detection module 200 is used to detect the oil pressure in the rod cavity 120; the pressure detection module 200 can be arranged at the oil outlet of the rod cavity 120 of the luffing oil cylinder 100 and is electrically connected to the control module 500. In this way, it is used to detect the oil pressure in the rod cavity 120 in real time, and convert the detected oil pressure into an electrical signal and feedback it to the control module 500. Thus, it provides basic data support for the safe operation of the system through the real-time monitoring mechanism, ensuring timely response when the oil pressure is abnormal.

[0064] Optionally, the pressure detection module 200 can be selected as a pressure sensor or a pressure gauge. It is installed at the flange of the oil outlet of the rod cavity 120 and is connected to the control module 500 through a shielded cable to reduce signal interference.

[0065] The oil circuit module 300 includes a first oil circuit module 310 and a first balance valve 320. The first oil circuit module 310 is connected to the rod cavity 120 and is used for the oil supply and return of the rod cavity 120. The first balance valve 320 is arranged on the first oil circuit. By setting the first balance valve 320, the stability of the oil pressure in the rod cavity 120 is effectively ensured, preventing the phenomenon of out-of-control actions due to the influence of load changes. Among them, the pressure oil in the oil circuit module 300 comes from the hydraulic system of the construction machinery.

[0066] The first pilot oil circuit module 400 is connected to the control end of the first balance valve 320 and is used to control the opening of the oil return working position of the first balance valve 320 through the pilot oil, that is to say, the pilot oil drives the spool of the first balance valve 320 to move to switch to the oil return working position for operation. Among them, the default initial working position of the first balance valve 320 is the cut-off working position, and only allows the pressure oil to enter the rod cavity 120 through the first balance valve 320.

[0067] The control module 500 can be electrically connected to the control components in the pressure detection module 200, the oil circuit module 300, and the first pilot oil circuit module 400. In this embodiment, the control module 500 is configured as:

[0068] When the oil pressure detected by the pressure detection module 200 is greater than the preset safety value, a stop signal for controlling the stop of the current operation is issued, or the pilot oil circuit module 300 is controlled to open the oil return working position of the first balance valve 320 for oil return;

[0069] When the oil pressure detected by the pressure detection module 200 is greater than the preset safety value, a stop signal for controlling the stop of the current operation and the pilot oil circuit module 300 is controlled to open the oil return working position of the first balance valve 320 for oil return.

[0070] It can be understood that the above lists three control strategies for the control module 500. Specifically, it can be correspondingly configured according to different working conditions of the construction machinery, ensuring the safety of the luffing cylinder 100 on the one hand and providing a safe and reliable guarantee for the operation of the construction machinery on the other hand.

[0071] Optionally, the control module 500 includes a PLC controller.

[0072] It should be noted that when the construction machinery hoists the target object through the hoisting mechanism, during the process of the target object lifting off the ground, the main arm of the boom assembly 10 is stressed and deformed. At this time, the luffing cylinder 100 is pressurized, the pressure in the rodless cavity 110 increases, the oil in the rodless cavity 110 is compressed, the piston rod retracts, and the rodless cavity 110 of the luffing cylinder 100 is supplemented with suction pressure oil from the system return oil circuit through the first oil circuit module 310 until the target object leaves the ground and reaches equilibrium;

[0073]

[0074] β: Elastic modulus of pressure oil (constant: 1.2 - 2.0 GPa); V1: Volume of the rod chamber 120 of the cylinder; V2: Volume of the rodless chamber 110 of the cylinder; ΔV1: Change in volume of the rod chamber 120 of the cylinder; ΔV2: Change in volume of the rodless chamber 110 of the cylinder; ΔP1: Change in pressure in the rod chamber 120; ΔP2: Change in pressure in the rodless chamber 110.

[0075] After the hoisting mechanism lowers the hoisted target object to the ground or the installation position, the hoisting mechanism pays out the rope, the tension of the target object on the steel wire rope is released, the main arm of the boom assembly 10 and the luffing cylinder 100 are released from the pressure of the target object, the pressure in the rodless chamber 110 of the luffing cylinder 100 decreases, the compressed oil in the rodless chamber 110 rebounds, the piston rod extends, and since the rod chamber 120 is locked by the first balance valve 320, the pressure in the rod chamber 120 increases until the tension generated by the target object on the steel wire rope is completely removed and a new equilibrium is reached, and the pressure increase in the rod chamber 120 stops (in some working conditions, the pressure increase value will exceed 15 MPa).

[0076] In view of the above situation, the pressurization of the rod chamber 120 of the existing technology is passive, and it is impossible to actively control the pressure relief of the rod chamber 120 of the boom cylinder 100 by combining with the action of the hoisting mechanism, which will cause the pressure in the rod chamber 120 to increase too high, damaging the cylinder head of the rod chamber 120 and the components that are resistant to low pressure in the rod chamber 120. Seriously, it may cause the cylinder head to burst and the piston rod to rush out, ultimately leading to serious safety accidents.

[0077] For the boom hydraulic system provided in this embodiment, when the oil pressure detected by the pressure detection module 200 is greater than the preset safety value, the control module 500 issues a stop signal for controlling the stop of the current operation, and / or controls the pilot oil circuit module 300 to open the oil return working position of the first balance valve 320 for oil return. When applied to construction machinery, when the pulling force of the hoisting system is quickly unloaded, the oil in the rodless chamber 110 of the boom cylinder 100 rebounds by compressing the oil, and the piston rod extends. At this time, the oil pressure in the rod chamber 120 increases instantaneously. At this time, the pressure detection module 200 detects that the oil pressure in the rod chamber 120 is greater than the preset safety value, and the control module 500 issues a stop signal to stop the action of the hoisting mechanism. At the same time, the control module 500 controls the pilot oil circuit module 300 to open the oil return working position of the first balance valve 320 for active oil return, realizing the active pressure relief of the rod chamber 120, thereby effectively preventing the damage of the sealing and connection structure of the cylinder head on the side of the rod chamber 120 due to the excessive pressure accumulated in the rod chamber 120 in a short time, and at the same time preventing the damage of other components resistant to low pressure, further avoiding safety hazards such as cylinder head explosion and piston rod ejection, thereby improving the reliability and extending the service life.

[0078] Embodiment 2

[0079] Please refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4 , in this embodiment, a boom hydraulic system is provided, which can be applied to construction machinery, such as a crane. This embodiment is an improvement based on the technical solution of the above Embodiment 1. Compared with the above Embodiment 1, the difference is as follows:

[0080] In this embodiment, the oil circuit module 300 further includes a second oil circuit module 330, a second reversing valve 340 and a second balance valve 350. The second oil circuit module 330 is connected to the rodless chamber 110 of the boom cylinder 100 and is used for supplying oil and returning oil to the rodless chamber 110.

[0081] The second reversing valve 340 is connected to the second oil circuit module 330 and the first oil circuit module 310. The second reversing valve 340 is also connected to the oil supply module of the hydraulic system. The oil supply module includes an oil tank and an oil pump. The oil pump is used to extract the pressurized oil in the oil tank and deliver it to the second reversing valve 340.

[0082] The second reversing valve 340 is electrically connected to the control module 500. The control module 500 can control the movement of the spool in the second reversing valve 340, thereby controlling whether the oil supply module supplies oil to the first oil circuit module 310 or the second oil circuit module 330.

[0083] Specifically, in this embodiment, the second reversing valve 340 is a three-position five-way solenoid valve. The second reversing valve 340 has three working positions, which can be respectively defined as the left working position, the middle working position, and the right working position. The second reversing valve 340 has five oil ports, namely oil port P, oil port T1, oil port T2, oil port A1, and oil port B1. Oil port P, oil port T1, and oil port T2 are respectively connected to the oil supply module. Oil port A1 is connected to the second oil circuit module 330, and oil port B1 is connected to the first oil circuit module 310.

[0084] Among them, the working principle of the second reversing valve 340 is as follows: when the spool of the second reversing valve 340 is switched to the left working position, oil port T1 is communicated with oil port A1 for the second oil supply module to return oil to the fuel tank, and oil port P is communicated with oil port B1 for the oil supply module to supply oil to the first oil supply module; when the spool of the second reversing valve 340 is switched to the right working position, oil port P is communicated with oil port A1 for the oil supply module to supply oil to the second oil supply module, and oil port T2 is communicated with oil port B1 for the first oil supply module to return oil to the fuel tank.

[0085] The second balance valve 350 is arranged on the second oil circuit module 330. By setting the second balance valve 350, the oil pressure stability of the rodless cavity 110 is effectively ensured, and the phenomenon of out-of-control operation due to the influence of load change is prevented. Among them, the pressure oil in the oil circuit module 300 comes from the hydraulic system of the construction machinery.

[0086] In this embodiment, the luffing hydraulic system further includes a second pilot oil circuit module 600 that is electrically connected to the control module 500. The second pilot oil circuit module is connected to the control end of the second balance valve 350 and is used to control the opening of the oil return working position of the second balance valve 350 through pilot oil.

[0087] In this embodiment, the second pilot oil circuit module 600 includes a third reversing valve 610 that is electrically connected to the control module 500. The third reversing valve 610 is used to externally connect a pilot oil supply module 700 for supplying a pilot oil source. The third reversing valve 610 is also connected to the control end of the second balance valve 350 and is used to control the opening and oil return of the second balance valve 350 through pilot oil.

[0088] Specifically, the third reversing valve 610 has an oil inlet working position and an oil return working position. In this way, the control module 500 can control the switching of the spool of the third reversing valve 610 between the oil inlet working position and the oil return working position according to the actual situation. When the third reversing valve 610 is controlled to switch to the oil inlet working position, the pressure oil in the pilot oil source opens the oil return of the second balance valve 350 through the third reversing valve 610. When the control module 500 controls the third reversing valve 610 to switch to the oil return working position, the pilot oil at the control end of the second balance valve 350 returns to the fuel tank through the third reversing valve 610.

[0089] Optionally, the third reversing valve 610 can be selected as a two-position three-way hydraulic control valve.

[0090] Overflow valves 360 are also provided on both the first oil circuit module 310 and the second oil circuit module 330 to prevent the pressure oil in the pipelines of the first oil circuit module 310 and the second oil circuit module 330 from overpressuring.

[0091] In this embodiment, the first pilot oil circuit module 400 is provided with a pilot oil control oil port and two oil inlet ports. One of the oil inlet ports is connected to the second oil circuit module 330, and the connection point is located between the second balance valve 350 and the second reversing valve 340. The other oil inlet port is externally connected to a control oil source, and the pilot oil control oil port is connected to the control end of the first balance valve 320 through a pipeline.

[0092] Among them, when the second oil circuit module 330 supplies oil, the first pilot oil circuit module 400 is used to directly convert the pressure oil in the second oil circuit module 330 into the pilot oil for controlling the first balance valve 320 under the control of the control module 500; when the second oil circuit module 330 switches to oil return or pressure holding, the first pilot oil circuit module 400 is used to convert the externally connected control oil source into the pilot oil for controlling the first balance valve 320 under the control of the control module 500. In this way, it is ensured that when the rodless cavity 110 of the luffing cylinder 100 is filled with oil, the first balance valve 320 can be quickly opened through the converted pilot oil in the second oil circuit module 330 to realize the oil return of the rodless cavity 110, ensuring the timeliness of the oil return and the more stable operation of the luffing cylinder 100.

[0093] Specifically, in this embodiment, the first pilot oil circuit module 400 includes: a shuttle valve 410 and a control valve 420. The shuttle valve 410 is provided with a pilot oil control oil port P3-1 and two oil inlet ports P1-1, P2-1. One of the oil inlet ports P1-1 is connected to the second oil circuit module 330, and the connection point of the oil inlet port P1-1 and the second oil circuit module 330 is located between the second balance valve 350 and the second reversing valve 340. The other oil inlet port P2-1 is externally connected to a control oil source, and the pilot oil control oil port P3-1 is connected to the control end of the first balance valve 320 through a pipeline.

[0094] The control valve 420 is disposed on the pipeline connecting the oil inlet P2-1 of the shuttle valve 410 and an external control oil source. The control valve 420 is electrically connected to the control module 500.

[0095] Please refer to Figure 2 and Figure 3 , in some embodiments, the control valve 420 can be selected as an electrically controlled valve. Among them, the electrically controlled valve can preferably be an electromagnetic reversing valve (such as a two-position three-way solenoid valve, as shown in Figure 2 ) or an electro-hydraulic proportional pressure reducing valve (as shown in Figure 3 ).

[0096] Specifically, the electrically controlled valve has an oil inlet working position and an oil return working position. In this way, the control module 500 can control the opening of the electrically controlled valve according to the actual situation, that is, control the electrically controlled valve to switch to the oil inlet working position. At this time, the pressure oil in the control oil source enters the oil inlet P2-1 of the shuttle valve 410 to be converted into pilot oil to control the first balance valve 320. When the control module 500 controls the electrically controlled valve to switch to the oil return working position, the pilot oil at the control end of the first balance valve 320 returns to the fuel tank through the oil inlet P2-1 of the shuttle valve 410.

[0097] Among them, when the second oil circuit module 330 supplies oil, the direction from the oil inlet P1-1 to the pilot oil control oil port P3-1 of the shuttle valve 410 is in a conducting state, and the direction from the pilot oil control oil port P3-1 to the oil inlet P2-1 of the shuttle valve 410 is in a cut-off state. In this way, the pressure oil in the second oil circuit module 330 is directly converted into pilot oil for controlling the first balance valve 320 through the shuttle valve 410. At this time, the electrically controlled valve is in the oil return working position, ensuring that there is no back pressure at the oil inlet P2-1 end of the shuttle valve 410, and the shuttle valve 410 switches more smoothly.

[0098] When the second oil circuit module 330 switches to oil return or pressure holding, no pressure oil enters the oil inlet P1-1 of the shuttle valve 410 (in other words, there is no back pressure at the oil inlet P1-1 of the shuttle valve 410), and at this time, the direction from the pilot oil control oil port P3-1 to the oil inlet P1-1 is in a cut-off state. At this time, if the oil pressure detected by the pressure detection module 200 is greater than the preset safety value, the control module 500 controls the electrically controlled valve to open to switch to the oil inlet working position, so as to introduce the external control oil source into the shuttle valve 410 to control the first balance valve 320 to open and return oil.

[0099] Please refer to Figure 4, in some embodiments, the control valve 420 can be selected as a hydraulic control valve, and the control end of the hydraulic control valve is used to externally connect to a control oil source, which is the pressure oil used in construction machinery to drive the hoisting mechanism to lower. Among them, by connecting the pressure oil for driving the hoisting mechanism to lower to the control end of the hydraulic control valve, it is possible to drive the hoisting mechanism to lower (lower the hoist) while automatically controlling the opening of the hydraulic control valve to supply oil, so as to synchronously open the oil return working position of the first balance valve 320 for oil return, achieving the purpose of synchronously opening the pressure relief of the rod chamber 110 of the boom cylinder 100, further reducing the electronic control logic and making the structure simpler.

[0100] In some embodiments, the first pilot oil circuit module 400 further includes a control oil supply module 440, and the control oil supply module 440 is used to provide pressure oil (pilot oil) for control. The control oil supply module 440 includes a separately provided oil pump, and the oil pump can be connected to the main fuel tank of the hydraulic system of the construction machinery, or an independent fuel tank can be configured separately.

[0101] In some other embodiments, the control oil source is provided by the oil supply module of the hydraulic system of the construction machinery.

[0102] It can be understood that the boom hydraulic system provided in this embodiment is applied to construction machinery. When dealing with the rapid unloading of the pulling force of the hoisting system, the oil in the rodless chamber 110 of the boom cylinder 100 rebounds under compression, and the piston rod extends. At this time, the oil pressure in the rod chamber 120 increases instantaneously. At this time, the pressure detection module 200 detects that the oil pressure in the rod chamber 120 is greater than the preset safety value, and the control module 500 issues a stop signal to stop the operation of the hoisting mechanism. At the same time, the control valve 420 is switched to the oil inlet working position. At this time, the pressure oil in the control oil source enters the oil inlet P2-1 of the shuttle valve 410 to be converted into pilot oil to control the first balance valve 320, so as to open the oil return working position of the first balance valve 320 for active oil return and achieve active pressure relief of the rod chamber 120.

[0103] In this way, the boom hydraulic system provided in this embodiment can effectively prevent the damage of the seals and connection structures of the cylinder head on the rod chamber 120 side due to the excessive pressure accumulated in the rod chamber 120 in a short time, and at the same time prevent the damage of other low-pressure-resistant parts, further avoiding the occurrence of safety hazards such as cylinder head explosion and piston rod ejection, thereby improving the reliability and extending the service life.

[0104] Embodiment Three

[0105] Please refer to Figure 5 and Figure 6 , in this embodiment, a boom hydraulic system is provided, which can be applied to construction machinery, such as a crane. This embodiment is an improvement based on the technical solution of the above Embodiment Two. Compared with the above Embodiment Two, the difference lies in:

[0106] In this embodiment, the first pilot oil circuit module 400 includes a first reversing valve 430. In other words, in this embodiment, the shuttle valve 410 and the solenoid valve in the second embodiment above are replaced by the first reversing valve 430.

[0107] Among them, the first reversing valve 430 is provided with a pilot oil control oil port P3-2, an oil return port P4, and two oil inlet ports (P1-2, P2-2). The first reversing valve 430 further includes a first working position, a second working position, and a third working position. The control module 500 is used to control the spool of the first reversing valve 430 to switch between the first working position, the second working position, and the third working position, and the third working position is the neutral position. Optionally, the first reversing valve 430 can be selected as a three-position four-way valve.

[0108] Among them, in the first working position, the second oil circuit module 330 is communicated with the pilot oil control oil port P3-2 through the corresponding oil inlet port P1-2 of the first reversing valve 430; in the second working position, the external control oil source is communicated with the pilot oil control oil port P3-2 through the corresponding oil inlet port P2-2 of the first reversing valve 430; in the third working position, the pilot oil control oil port P3-2 of the first reversing valve 430 is communicated with the oil return port P4.

[0109] It can be understood that the luffing hydraulic system provided in this embodiment is applied to construction machinery. When dealing with the rapid unloading of the pulling force of the hoisting system, the oil in the rodless cavity 110 of the luffing cylinder 100 is compressed and rebounds, and the piston rod extends. At this time, the oil pressure in the rod cavity 120 increases instantaneously. At this time, the pressure detection module 200 detects that the oil pressure in the rod cavity 120 is greater than the preset safety value, and the control module 500 issues a stop signal to stop the action of the hoisting mechanism. At the same time, the control module 500 controls the first reversing valve 430 to switch to the second working position. At this time, the pressure oil in the control oil source enters the oil inlet port P2-2 of the first reversing valve 430 to be converted into pilot oil to control the first balance valve 320, so as to open the oil return working position of the first balance valve 320 for active oil return, and realize the active pressure relief of the rod cavity 120.

[0110] In this way, the luffing hydraulic system provided in this embodiment can effectively prevent the sealing and connection structure of the cylinder head on the rod cavity 120 side from being damaged due to the excessive pressure accumulated in the rod cavity 120 in a short time, and at the same time prevent the damage of other low-pressure-resistant parts, and further avoid the occurrence of safety hazards such as cylinder head explosion and piston rod ejection, thereby improving the reliability and extending the service life.

[0111] Embodiment 4

[0112] Please refer to Figures 1 to 6 , in this embodiment, a construction machinery is provided. The construction machinery includes a boom assembly 10, a hoisting mechanism, and a luffing hydraulic system provided according to any one of the above embodiments. The construction machinery can be selected as a crane.

[0113] The luffing oil cylinder 100 is used to drive the boom assembly 10 to perform pitching luffing actions; the pitching luffing actions include raising the boom and lowering the boom.

[0114] Among them, for the boom raising action: the rodless cavity 110 is filled with oil, and the pressure oil pushes the piston rod of the luffing oil cylinder 100 to extend, and the oil in the rod chamber 120 returns to the fuel tank of the hydraulic system of the construction machinery; for the boom lowering action: the rod chamber 120 is filled with oil (the piston rod retracts), and the oil in the rodless cavity 110 returns to the fuel tank. The hoisting mechanism realizes the hoisting of the target object by winding in and out the rope.

[0115] Furthermore, this embodiment also provides a luffing control method, which is applied to the above-mentioned construction machinery. Among them, the luffing control method includes:

[0116] Luffing boom raising condition control method: Control the rodless cavity 110 of the luffing oil cylinder 100 to be filled with oil, control the return oil working position of the first balance valve 320 to open through the pilot oil in the first pilot oil circuit module 400, and detect the oil pressure in the rod chamber 120 in real time through the pressure detection module 200. When the oil pressure in the rod chamber 120 is greater than the preset safety value, send a stop signal to stop the luffing boom raising action (stop the oil supply module from supplying oil and control the second reversing valve 340 to switch to the neutral position);

[0117] Luffing boom lowering condition control method: Control the rod chamber 120 of the luffing oil cylinder 100 to be filled with oil, the rodless cavity 110 returns oil, and detect the oil pressure in the rod chamber 120 in real time through the pressure detection module 200. When the oil pressure in the rod chamber 120 is greater than the preset safety value, send a stop signal to stop the luffing boom lowering action (stop the oil supply module from supplying oil and control the second reversing valve 340 to switch to the neutral position);

[0118] Hoisting the target object condition control method of the hoist: The pressure detection module 200 does not feedback signals; of course, in some embodiments, the pressure detection module 200 can also participate in the work and perform signal feedback to judge whether the first balance opens the return oil normally.

[0119] Lowering the target object condition control method of the hoist: Detect the oil pressure in the rod chamber 120 in real time through the pressure detection module 200. When the oil pressure in the rod chamber 120 is greater than the preset safety value, send a stop signal to stop the hoisting mechanism action, and at the same time control the pilot oil circuit module 300 to open the return oil working position of the first balance valve 320 for active oil return.

[0120] In this way, the luffing hydraulic system provided by this embodiment can effectively prevent the sealing and connection structure of the cylinder head on the rod chamber 120 side from being damaged due to the excessive pressure accumulated in the rod chamber 120 in a short time, and at the same time prevent the damage of other low-pressure resistant parts, and further avoid the occurrence of safety hazards such as cylinder head bursting and piston rod ejection, thereby improving the reliability and extending the service life.

[0121] In addition, in the boom raising control condition and the boom lowering control condition, the oil pressure of the rod chamber 120 can also be detected in real time by the pressure detection module 200. When the oil pressure of the rod chamber 120 is greater than the preset safety value, a stop signal is issued to stop the luffing operation, so as to ensure the safety and reliability of the operation.

[0122] It should be noted that in this application, unless otherwise stated, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to this application.

[0123] In this application, the boom assembly 10 and the hoisting mechanism are well known to those skilled in the art and do not belong to the core improvement part of this application, so they will not be described in detail here.

[0124] In the description of this application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0125] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or communicable with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0126] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0127] Although the embodiments of this application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on this application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A luffing hydraulic system, applied to construction machinery, is characterized in that, The luffing hydraulic system includes: A luffing oil cylinder (100) having a rodless chamber (110) and a rod chamber (120), and is used to drive the boom assembly (10) to perform pitching and luffing actions; A pressure detection module (200) for detecting the oil pressure in the rod chamber (120); An oil circuit module (300) including a first oil circuit module (310) and a first balance valve (320). The first oil circuit module (310) is connected to the rod chamber (120) and is used for supplying oil and returning oil to the rod chamber (120). The first balance valve (320) is arranged on the first oil circuit; A first pilot oil circuit module (400) connected to the control end of the first balance valve (320) and is used to control the opening of the oil return working position of the first balance valve (320) through pilot oil; and A control module (500) configured to issue a stop signal for controlling the stop of the current operation and / or control the pilot oil circuit module (300) to open the oil return working position of the first balance valve (320) for oil return when the oil pressure detected by the pressure detection module (200) is greater than a preset safety value.

2. The luffing hydraulic system according to claim 1, wherein The oil circuit module (300) further includes a second oil circuit module (330). The second oil circuit module (330) is connected to the rodless chamber (110) and is used for supplying oil and returning oil to the rodless chamber (110); The first pilot oil circuit module (400) is provided with a pilot oil control oil port and two oil inlets. One of the oil inlets is connected to the second oil circuit module (330), and the other oil inlet is externally connected to a control oil source. The pilot oil control oil port is connected to the control end of the first balance valve (320) through a pipeline; Wherein, when the second oil circuit module (330) supplies oil, the first pilot oil circuit module (400) is used to directly convert the pressure oil in the second oil circuit module (330) into pilot oil for controlling the first balance valve (320) under the control of the control module (500); when the second oil circuit module (330) switches to oil return or pressure holding, the first pilot oil circuit module (400) is used to convert the externally connected control oil source into pilot oil for controlling the first balance valve (320) under the control of the control module (500).

3. The luffing hydraulic system according to claim 2, wherein The first pilot oil circuit module (400) includes: A shuttle valve (410) provided with the pilot oil control oil port and the two oil inlets; and A control valve (420) arranged on the pipeline connecting the shuttle valve (410) and the external control oil source; Wherein, the control valve (420) is an electric control valve, and the electric control valve is electrically connected to the control module (500). When the second oil circuit module (330) switches to oil return or pressure holding and the oil pressure detected by the pressure detection module (200) is greater than a preset safety value, the control module (500) controls the control valve (420) to open for oil supply; Alternatively, the control valve (420) is a hydraulic control valve, and the control end of the hydraulic control valve is used to be externally connected to a control oil source, and the control oil source is the pressure oil used to drive the hoisting mechanism of the construction machinery to descend.

4. The luffing hydraulic system according to claim 2, characterized in that, The first pilot oil circuit module (400) includes a first reversing valve (430). The first reversing valve (430) is provided with an oil return port, the pilot oil control oil port, and two of the oil inlet ports. The first reversing valve (430) further includes a first working position, a second working position, and a third working position. The control module (500) is configured to control the spool of the first reversing valve (430) to switch between the first working position, the second working position, and the third working position; Wherein, in the first working position, the second oil circuit module (330) is in communication with the pilot oil control oil port through the corresponding oil inlet port of the first reversing valve (430); in the second working position, an external control oil source is in communication with the pilot oil control oil port through the corresponding oil inlet port of the first reversing valve (430); in the third working position, the pilot oil control oil port is in communication with the oil return port.

5. The luffing hydraulic system according to any one of claims 2-4, characterized in that, The first pilot oil circuit module (400) further includes a control oil supply module (440) for providing a control oil source; Alternatively, the control oil source is provided by an oil supply module of a hydraulic system of a construction machine.

6. The luffing hydraulic system according to claim 1, characterized in that, The oil circuit module (300) further includes: A second oil circuit module (330) connected to the rodless chamber (110) for supplying oil to and returning oil from the rodless chamber (110); and A second reversing valve (340) connected to the second oil circuit module (330) and the first oil circuit module (310). The second reversing valve (340) is further configured to connect to an oil supply module in the hydraulic system of the construction machine; The control module (500) is electrically connected to the second reversing valve (340). The control module (500) is configured to control the switching of the working position of the second reversing valve (340) so that the oil supply module is selectively connected to the first oil circuit module (310) or the second oil circuit module (330).

7. The luffing hydraulic system according to claim 6, characterized in that, The oil circuit module (300) further includes a second balance valve (350). The second balance valve (350) is disposed on the second oil circuit module (330); The luffing hydraulic system further includes a second pilot oil circuit module (600) connected to the control end of the second balance valve (350) for controlling the opening of the oil return working position of the second balance valve (350) through pilot oil.

8. The luffing hydraulic system according to claim 7, characterized in that, Overflow valves (360) are also provided on both the first oil circuit module (310) and the second oil circuit module (330).

9. An engineering machinery, characterized in that, It includes a boom assembly (10), a hoisting mechanism, and the luffing hydraulic system according to any one of claims 1-8.

10. A luffing control method, characterized in that, Applied to the construction machine according to claim 9, the luffing control method includes: Luffing up-arm working condition control method: Control the rodless chamber (110) of the luffing cylinder (100) to intake oil. Control the oil return working position of the first balance valve (320) to open through the pilot oil in the first pilot oil circuit module (400), and detect the oil pressure of the rod chamber (120) in real time through the pressure detection module (200). When the oil pressure in the rod chamber (120) is greater than a preset safety value, send a stop signal to stop the luffing up-arm action; Luffing and lowering boom condition control method: Control the rod chamber (120) of the luffing cylinder (100) to intake oil, and the rodless chamber (110) to return oil, and use the pressure detection module (200) to detect the oil pressure in the rod chamber (120) in real time. When the oil pressure in the rod chamber (120) is greater than the preset safety value, send a stop signal to stop the luffing and lowering boom action; Hoisting and lowering the target condition control method: Use the pressure detection module (200) to detect the oil pressure in the rod chamber (120) in real time. When the oil pressure in the rod chamber (120) is greater than the preset safety value, send a stop signal to stop the hoisting mechanism action, and at the same time control the pilot oil circuit module (300) to open the oil return working position of the first balance valve (320) for active oil return.

Images