Hydraulic system for hydraulic lifting bridge and control method of hydraulic system

Abstract

The invention relates to the technical field of hydraulic pressure, and discloses a hydraulic system for a hydraulic lifting bridge and a control method of the hydraulic system. A first-stage pressure control module, an overflow module and a plurality of second-stage pressure control modules are arranged in the hydraulic system, the hydraulic system is communicated with a rod cavity and a rodless cavity of a hydraulic oil cylinder of the lifting bridge, the first-stage pressure control module is communicated with a hydraulic oil tank, and the second-stage pressure control module is communicated with a hydraulic oil tank; the hydraulic oil can be conveyed in a pressurized mode, and the conveyed hydraulic oil flows into a rod cavity or a rodless cavity of the lifting bridge hydraulic oil cylinder through selective reversing of the second-stage pressure control module. When the oil pressure is too high, the overflow module enables redundant hydraulic oil to flow back to the hydraulic oil tank in a liquid separation and backflow mode, and therefore a multi-layer pressure protection system is constructed, overload can be effectively prevented, and the hydraulic system is protected against damage.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic technology, and in particular to a hydraulic system for a hydraulic lifting bridge and a control method thereof. Background Art

[0002] With the improvement of people's living standards, the demand for travel is increasing. Shipping has become one of the major means of transportation. Many ports and terminals have been added. The problem of passengers getting on and off ships is a problem that must be solved at every port and terminal. Therefore, lift bridges have been widely used.

[0003] Lifting bridge is a common port loading and unloading equipment, which is often used for transportation between islands and land. It is a port equipment connecting ro-ro terminals and large ro-ro ships, and is used to transport vehicles and personnel between islands and land. It is used in various ports, docks and other areas.

[0004] The lifting bridge consists of a movable bridge deck and a lifting system. The lifting system is connected to the lifting bridge to provide lifting force for the movable bridge to lift or lower the movable bridge deck. The movable bridge deck can be adjusted to a stable overlapping angle.

[0005] The wire rope winch lifting bridge, motor chain lifting bridge and simple hydraulic lifting bridge that are popular on the market all have the problem of easy deviation and imbalance when rising and falling, and one side is higher than the other side, which requires a lot of manpower and time to adjust. There are also hidden dangers of damage caused by bumps and passengers after the lifting bridge tilts, and safety hazards. To solve these problems, hydraulic balancing technology is used to keep the lifting bridge balanced when rising and falling, which makes it worry-free and convenient for managers, prevents equipment from being damaged by bumps, and makes it comfortable and safe for passengers to get on and off the ship.

[0006] In view of the structural characteristics of the hydraulic lift bridge, the industry has conducted relevant research and design, such as an automatic balancing hydraulic lift bridge (CN113622285A). When in use, the electronic control box starts the hydraulic station, and the hydraulic station delivers hydraulic oil to the hydraulic cylinder on the gantry. The hydraulic cylinder drives the main bridge to rise or fall, and the balance sensor promptly transmits the left and right imbalance signals generated when the main bridge rises and falls to the electronic control box. The electronic control box immediately sends information to the hydraulic station to control the left and right oil supply of the hydraulic cylinder to balance the size, so that the main bridge is always balanced. The main bridge is connected to the horizontal bridge together, thus forming a complete automatic balancing work of the hydraulic lift bridge.

[0007] However, since the pressure of the hydraulic oil of the equipment cannot be adjusted, the hydraulic lifting bridge cannot be adapted to different operating scenarios and load requirements by flexibly adjusting the pressure; secondly, the hydraulic oil pump motor of the equipment uses a direct start-up method, and the motor start-up has a large impact on the power grid, causing an instantaneous voltage drop and interference with the power system; thirdly, the hydraulic system and the electrical system may be assembled on-site by pulling wires, rather than a modular integrated structure, which can easily cause assembly confusion and further create safety hazards; fourthly, the hydraulic oil may be directly connected to the hydraulic cylinder of the movable bridge deck for input, thereby directly driving the movable bridge deck to rise and fall, resulting in large operating deviations, which will cause the movable bridge deck to twist and deform, posing a safety hazard. Summary of the invention

[0008] In order to solve the above-mentioned prior art problems, the present invention provides a hydraulic system for a hydraulic lifting bridge;

[0009] Another object of the present invention is to provide a control method for a hydraulic system of a hydraulic lifting bridge.

[0010] The hydraulic system of the present invention can be used for hydraulic cylinders of roads, islands, ships and the like where hydraulic lifting bridges are required.

[0011] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0012] A hydraulic system for a hydraulic lifting bridge, comprising a hydraulic oil tank, a primary pressure control module, an overflow module and a plurality of secondary pressure control modules; the hydraulic oil tank is connected to a plurality of lifting bridge hydraulic cylinders through a main pipeline;

[0013] The primary pressure control module is arranged on the main pipeline connecting the hydraulic oil tank and the lifting bridge, and is used to control the hydraulic oil;

[0014] The first-level pressure control module is also connected to the hydraulic oil tank through an overflow pipe, and a throttling feedback module is also provided at the connection between the first-level pressure control module and the main pipeline;

[0015] The secondary pressure control module is connected to the primary pressure control module through a main pipeline, and is used to control the hydraulic oil entering and exiting the primary pressure control module;

[0016] The overflow module is connected to the primary pressure control module and is used to reduce the high-pressure hydraulic oil to hydraulic oil of appropriate pressure;

[0017] The overflow module includes a pressure valve, an electromagnetic overflow valve, an overflow electromagnetic reversing valve and a direct-acting valve;

[0018] The pressure valve is arranged at the connection between the primary pressure control module and the main pipeline;

[0019] The electromagnetic overflow valve, the overflow electromagnetic reversing valve and the direct-acting valve are arranged on the overflow pipeline in sequence.

[0020] Preferably, the secondary pressure control module is arranged on the main pipeline connecting the primary pressure control module and the lifting bridge, and is used to control the hydraulic oil entering and exiting the primary pressure control module.

[0021] Furthermore, the primary pressure control module includes a variable piston pump and a motor; the motor is transmission-connected to the variable piston pump; the variable piston pump cooperates with an oil suction filter through a pipeline and is connected to a hydraulic oil tank.

[0022] Furthermore, the overflow pipeline also includes an overflow main pipe, a first overflow oil return pipe, a second overflow oil return pipe, a third overflow oil return pipe, and a fourth overflow oil return pipe;

[0023] The overflow main pipe is arranged between the electromagnetic overflow valve and the primary pressure control module;

[0024] The low-pressure outlet of the electromagnetic overflow valve is connected to the overflow electromagnetic reversing valve through the first overflow oil return pipe, the high-pressure outlet of the electromagnetic overflow valve is connected to the overflow electromagnetic reversing valve through the second overflow oil return pipe, and the high-pressure outlet of the electromagnetic overflow valve is also connected to the hydraulic oil tank through the fourth overflow oil return pipe;

[0025] The overflow electromagnetic reversing valve is connected to the hydraulic oil tank through a third overflow oil return pipe.

[0026] Furthermore, the secondary pressure control module includes a first electromagnetic reversing valve and a hydraulically controlled one-way valve;

[0027] The first port of the first electromagnetic reversing valve is connected to the hydraulically controlled one-way valve and connected to the rod chamber of the hydraulic cylinder of the lifting bridge;

[0028] The second port of the first electromagnetic reversing valve is connected to the rodless chamber of the lifting bridge hydraulic cylinder.

[0029] Furthermore, the secondary pressure control module also includes a pressure sensor and a ball valve;

[0030] The pressure sensor is connected to the rod chamber and the rodless chamber of the hydraulic cylinder of the lifting bridge, and the ball valve is arranged on the connecting pipeline between the hydraulic control one-way valve and the rod chamber of the hydraulic cylinder of the lifting bridge.

[0031] Further, the main pipeline includes a first main oil pipeline, a second main oil pipeline, a third main oil pipeline and a fourth main oil pipeline;

[0032] The primary pressure control module is connected to the third port of the first electromagnetic reversing valve through the first main oil pipe;

[0033] The first port of the first electromagnetic reversing valve is connected to the rod chamber of the hydraulic cylinder of the lifting bridge through the second main oil pipe;

[0034] The second port of the first electromagnetic reversing valve is connected to the rodless chamber of the lifting bridge hydraulic cylinder through the third main oil pipe;

[0035] The fourth port of the first electromagnetic reversing valve is connected to the hydraulic oil tank through a fourth main oil pipe.

[0036] Preferably, the fourth main oil pipe is arranged in the hydraulic oil tank through an oil return filter.

[0037] Furthermore, the rodless chamber of the lifting bridge hydraulic cylinder is connected to the hydraulic oil tank through an electromagnetic reversing valve and an oil return filter.

[0038] Furthermore, a displacement sensor is built into the hydraulic cylinder of the lifting bridge, and the sensor is electrically connected to the primary pressure control module, the overflow module and the secondary pressure control module.

[0039] Preferably, the test point of the displacement sensor is located in the rod cavity of the hydraulic cylinder of the lifting bridge.

[0040] Furthermore, the throttling feedback module includes a flow valve and an electromagnetic check valve; the flow valve is arranged between the first-level pressure control module and the pressure valve to detect the flow; the electromagnetic check valve is arranged between the first-level pressure control module and the pressure valve to control the on and off of the pressure oil.

[0041] A control method for a hydraulic system, the control method for the hydraulic system comprising the following steps:

[0042] S1: When the oil cylinder extends to make the hydraulic bridge descend, the primary pressure control module is started, the main pipeline is evacuated, and the hydraulic oil in the hydraulic oil tank enters the secondary pressure control module through the pressurized main pipeline under atmospheric pressure. The secondary pressure control module transmits the hydraulic oil to the rodless cavity of the hydraulic oil cylinder of the lifting bridge, and the hydraulic oil in the rod cavity of the hydraulic oil cylinder of the lifting bridge is transported back to the hydraulic oil tank through the secondary pressure control module;

[0043] S2: When the pressure valve of the overflow module detects that the oil pressure of the flowing hydraulic oil is lower than 9.5Mpa, the overflow operation is not performed;

[0044] S3: When the pressure valve of the overflow module detects that the oil pressure of the flowing hydraulic oil is higher than 9.5Mpa and lower than 22Mpa, the hydraulic oil flows out from the low-pressure outlet of the internal electromagnetic overflow valve, and the coil at one end of the overflow electromagnetic reversing valve is energized to connect the low-pressure outlet with the hydraulic oil tank, and the hydraulic oil flows back to the hydraulic oil tank through the overflow electromagnetic reversing valve and the direct-acting valve;

[0045] S4: When the pressure valve of the overflow module detects that the oil pressure of the flowing hydraulic oil is higher than 22Mpa, the electromagnetic overflow valve is activated, the hydraulic oil flows out through the high-pressure outlet, and the coil at the other end of the overflow electromagnetic reversing valve is energized to connect the high-pressure outlet with the hydraulic oil tank, and the hydraulic oil flows back / directly enters the hydraulic oil tank through the overflow electromagnetic reversing valve and the direct-acting valve;

[0046] S5: When the oil cylinder retracts and the hydraulic axle rises, the oil pipe inside the secondary pressure control module is converted, and the secondary pressure control module transmits the hydraulic oil to the rod chamber of the hydraulic cylinder of the lifting axle. The hydraulic oil in the rodless chamber of the hydraulic cylinder of the lifting axle is transported back to the hydraulic oil tank through the secondary pressure control module.

[0047] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0048] ① Setting up a primary pressure control module can pressurize the hydraulic oil to meet the pressure and flow requirements under different working conditions;

[0049] The variable piston pump is combined with a motor to connect the hydraulic oil tank through a pipeline. The variable piston pump drives the internal piston to reciprocate through the motor, compresses and pressurizes the incoming hydraulic oil, and can easily realize long-distance energy transmission. It is suitable for complex working environments and large-scale motion control. The combination of motor and plunger pump can provide a powerful and controllable power source for large-scale applications.

[0050] ② Set up a secondary pressure control module to control the flow direction of the hydraulic oil in the hydraulic cylinder of the lifting bridge and realize the switching of multiple working modes;

[0051] The solenoid reversing valve is connected with the hydraulic cylinder of the lifting bridge in conjunction with the hydraulically controlled one-way valve. The solenoid reversing valve can obtain electricity through the left and right coils to change the pipeline, quickly change the flow direction of the hydraulic oil, and change the flow direction of the rod chamber and the rodless chamber of the hydraulic cylinder, thereby controlling the lifting or lowering action of the lifting bridge, realizing precise directional control, and greatly improving the operational response speed and control accuracy of the entire hydraulic system.

[0052] ③ Set up an overflow module to maintain the system pressure within a preset safety range, thereby achieving dynamic management of the system working pressure;

[0053] The pressure valve, electromagnetic overflow valve and overflow electromagnetic reversing valve are jointly connected to the hydraulic cylinder of the lifting bridge to prevent the hydraulic oil pressure from increasing. The overflow channel can be adjusted or cut off by controlling the overflow electromagnetic reversing valve. When needed, multiple overflow channels can be quickly opened or closed to provide more precise pressure control and a fast pressure release path, thereby building a multi-level pressure protection system, which can not only effectively prevent overload, but also protect the hydraulic system from damage.

[0054] ④ Set up a throttling feedback module to achieve more precise and dynamic flow control, thereby optimizing the performance of the entire hydraulic system;

[0055] A flow valve and a solenoid check valve are set on the hydraulic oil overflow pipeline. When the system demand changes and causes pressure fluctuations, the flow output can be stabilized by adjusting the flow valve, which has a certain flow stabilization effect on the system, thereby achieving steady-state control similar to throttling feedback; the solenoid check valve can avoid oil backflow protection system. At the moment of rapid unloading or flow switching, the solenoid check valve can be quickly closed to prevent oil backflow, thereby effectively performing the throttling feedback function.

[0056] ⑤ Ball valves and pressure sensors are installed at the rod chamber and rodless chamber pipelines of the hydraulic cylinder to prevent damage to pipelines or other devices caused by sudden changes in external loads;

[0057] By adjusting the ball valve to full open or a specific opening, the ball valve is kept in a certain position, which can reduce the internal pressure of the cylinder to a minimum, making it easier for the piston to slide according to the external force, thereby achieving a "floating" state between the rod chamber and the rodless chamber. Even if the external load changes suddenly, the changing external force will not increase the load on the system and pipelines, thereby causing damage to the pipelines or other devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0059] Figure 1 It is a connection diagram of the hydraulic system for a hydraulic lift bridge;

[0060] Figure 2 It is a connection diagram of the hydraulic oil tank and the first-level pressure control module;

[0061] Figure 3 It is the connection diagram of the overflow module;

[0062] Figure 4 This is the connection diagram of the secondary voltage control module;

[0063] Figure 5 It is the connection diagram of the throttling feedback module.

[0064] The reference numerals are as follows:

[0065] 1. Hydraulic oil tank;

[0066] 2. Primary pressure control module; 201. Variable piston pump; 202. Motor;

[0067] 3. Overflow module; 301. Pressure valve; 302. Solenoid overflow valve; 303. Overflow solenoid reversing valve; 304. Direct-acting valve;

[0068] 4. Secondary pressure control module; 401. First electromagnetic reversing valve; 402. Hydraulic control check valve; 403. Pressure sensor; 404. Ball valve;

[0069] 5. Main pipeline; 501. First main oil pipeline; 502. Second main oil pipeline; 503. Third main oil pipeline; 504. Fourth main oil pipeline;

[0070] 6. Overflow pipe; 601. Overflow main pipe; 602. First overflow oil return pipe; 603. Second overflow oil return pipe; 604. Third overflow oil return pipe; 605. Fourth overflow oil return pipe;

[0071] 7. Throttle feedback module; 701. Flow valve; 702. Solenoid check valve;

[0072] 8. Oil return filter;

[0073] 9. Oil suction filter. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the described embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0075] Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. "First", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0076] Example 1

[0077] like Figure 1-5As shown, this embodiment discloses a hydraulic system for a hydraulic lifting bridge, including a hydraulic oil tank 1, a primary pressure control module 2, an overflow module 3 and a plurality of secondary pressure control modules 4; the hydraulic oil tank 1 is connected to a plurality of lifting bridge hydraulic cylinders through a main pipeline 5;

[0078] The primary pressure control module 2 is arranged on the main pipeline 5 connecting the hydraulic oil tank 1 and the lifting bridge, and is used to control the hydraulic oil;

[0079] The primary pressure control module 2 is also connected to the hydraulic oil tank 1 through an overflow pipe 6, and a throttling feedback module 7 is also provided at the connection between the primary pressure control module 2 and the main pipe 5;

[0080] The secondary pressure control module 4 is connected to the primary pressure control module 2 through the main pipeline 5, and is used to control the hydraulic oil entering and exiting the primary pressure control module 2;

[0081] The overflow module 3 is connected to the primary pressure control module 2 and is used to reduce the high-pressure hydraulic oil to hydraulic oil of appropriate pressure;

[0082] The overflow module 3 includes a pressure valve 301, an electromagnetic overflow valve 302, an overflow electromagnetic reversing valve 303 and a direct-acting valve 304;

[0083] The pressure valve 301 is arranged at the connection between the primary pressure control module 2 and the main pipeline 5;

[0084] The electromagnetic overflow valve 302 , the overflow electromagnetic reversing valve 303 and the direct-acting valve 304 are sequentially arranged on the overflow pipe 6 .

[0085] The present invention arranges a primary pressure control module 2, an overflow module 3 and several secondary pressure control modules 4 in the hydraulic system, connects the hydraulic system with the rod chamber and the rodless chamber of the hydraulic cylinder of the lifting bridge, and the primary pressure control module 2 is connected to the hydraulic oil tank 1, and can boost and transmit the hydraulic oil. The transmitted hydraulic oil flows into the rod chamber or the rodless chamber of the hydraulic cylinder of the lifting bridge through the selective switching of the secondary pressure control module 4; when the oil pressure is too high, the overflow module 3 returns the excess hydraulic oil to the hydraulic oil tank 1 by the "liquid separation reflux" method.

[0086] As a specific implementation, the primary pressure control module 2 includes a variable piston pump 201 and a motor 202; the motor 202 is transmission-connected to the variable piston pump 201; the variable piston pump 201 cooperates with the oil suction filter 9 through a pipeline and is connected to the hydraulic oil tank 1.

[0087] Specifically, a first-level pressure control module 2 is provided to increase the pressure of the hydraulic oil to meet the requirements for pressure and flow under different working conditions. The variable piston pump 201 cooperates with the motor 202 to connect to the hydraulic oil tank 1 through the main pipeline 5. The variable piston pump 201 drives the internal piston to reciprocate through the motor 202 to compress and increase the pressure of the inflowing hydraulic oil, thereby transmitting the pressurized hydraulic oil to the overflow module 3 through the main pipeline 5, and then diverting it into the hydraulic cylinder of the lifting bridge. It can conveniently realize long-distance energy transmission and is suitable for the complex working environment and large-range motion control of the lifting bridge. The combination of the motor 202 and the variable piston pump 201 can provide a powerful and controllable power source for large-scale applications.

[0088] As a specific implementation, the secondary pressure control module 4 includes a first electromagnetic reversing valve 401 and a hydraulically controlled one-way valve 402;

[0089] The first port of the first electromagnetic reversing valve 401 is connected to the hydraulically controlled one-way valve 402 and connected to the rod chamber of the hydraulic cylinder of the lifting bridge;

[0090] The second port of the first electromagnetic reversing valve 401 is connected to the rodless chamber of the hydraulic cylinder of the lifting bridge;

[0091] The secondary pressure control module 4 also includes a pressure sensor 403 and a ball valve 404;

[0092] The pressure sensor 403 is connected to the rod chamber and the rodless chamber of the hydraulic cylinder of the lifting bridge, and the ball valve 404 is arranged on the connecting pipe between the hydraulic control check valve 402 and the rod chamber of the hydraulic cylinder of the lifting bridge;

[0093] The main pipeline 5 includes a first main oil pipeline 501, a second main oil pipeline 502, a third main oil pipeline 503 and a fourth main oil pipeline 504;

[0094] The primary pressure control module 2 is connected to the third port of the first electromagnetic reversing valve 401 through the first main oil pipe 501;

[0095] The first port of the first electromagnetic reversing valve 401 is connected to the rod chamber of the hydraulic cylinder of the lifting bridge through the second main oil pipe 502;

[0096] The second port of the first electromagnetic reversing valve 401 is connected to the rodless chamber of the lifting bridge hydraulic cylinder through the third main oil pipe 503;

[0097] The fourth port of the first electromagnetic reversing valve 401 is connected to the hydraulic oil tank 1 through the fourth main oil pipe 504 .

[0098] Specifically, the first main oil pipe 501 connected to the hydraulic oil tank 1 is connected to the third port of the first electromagnetic reversing valve 401, the first port of the first electromagnetic reversing valve 401 is connected to the hydraulic control one-way valve 402 through the second main oil pipe 502 to connect to the rod chamber of the hydraulic oil cylinder of the lifting bridge, the second port of the first electromagnetic reversing valve 401 is connected to the rodless chamber of the hydraulic oil cylinder of the lifting bridge through the third main oil pipe 503, and the fourth port of the first electromagnetic reversing valve 401 is connected to the hydraulic oil tank 1 through the fourth main oil pipe 504;

[0099] Specifically, when the hydraulic lifting bridge descends, the hydraulic oil pressurized by the primary pressure control module 2 enters the first electromagnetic reversing valve 401 through the first main oil pipe 501, and the YV6 coil of the first electromagnetic reversing valve 401 is energized and moves.

[0100] The first main oil pipe 501 of the third port is connected to the third main oil pipe 503 of the second port, and the second main oil pipe 502 of the first port is connected to the fourth main oil pipe 504 of the fourth port; the pressure oil enters the first solenoid reversing valve 401 through the first main oil pipe 501, and then enters the rodless chamber of the lifting bridge hydraulic cylinder through the third main oil pipe 503; the hydraulic oil in the rod chamber of the lifting bridge hydraulic cylinder enters the first solenoid reversing valve 401 from the second main oil pipe 502, and then flows back to the hydraulic oil tank 1 through the fourth main oil pipe 504;

[0101] When the hydraulic lifting bridge rises, the YV7 coil of the first electromagnetic reversing valve 401 is energized and moves, connecting the second main oil pipe 502 with the first main oil pipe 501, and connecting the third main oil pipe 503 with the fourth main oil pipe 504; the pressure oil enters the first electromagnetic reversing valve 401 through the first main oil pipe 501, and then enters the rod chamber of the hydraulic oil cylinder of the lifting bridge through the second main oil pipe 502; the hydraulic oil in the rodless chamber of the hydraulic oil cylinder of the lifting bridge enters the first electromagnetic reversing valve 401 from the third main oil pipe 503, and then flows back to the hydraulic oil tank 1 through the fourth main oil pipe 504;

[0102] By connecting the first solenoid reversing valve 401 in conjunction with the hydraulically controlled one-way valve 402 and the hydraulic cylinder of the lifting bridge, the first solenoid reversing valve 401 can be energized through the left and right coils to change the pipeline, quickly change the flow direction of the hydraulic oil, and change the flow direction of the rod chamber and the rodless chamber of the hydraulic cylinder, thereby controlling the lifting or lowering action of the lifting bridge, achieving precise directional control, and greatly improving the operating response speed and control accuracy of the entire hydraulic system.

[0103] Specifically, ball valves 404 are provided at the third main oil pipe 503 and the fourth main oil pipe 504 connecting the rod chamber and the rodless chamber of the hydraulic cylinder, and a pressure sensor 403 is provided at the third main oil pipe 503. By adjusting the ball valve 404 to fully open or to a specific opening, the ball valve 404 is kept in a certain position, so that the internal pressure of the cylinder can be reduced to a minimum, and the piston can slide easily according to the external force, thereby achieving a "floating" state between the rod chamber and the rodless chamber. Even if the external load changes suddenly, the changing external force will not increase the load on the system and pipelines, thereby causing damage to the pipelines or other devices; the pressure sensor 403 continuously monitors the pressure changes at both ends of the hydraulic cylinder, and provides an instant feedback signal to the ball valve 404, thereby controlling the ball valve 404 to fully open or to a specific opening.

[0104] As a specific implementation method, the rodless chamber of the lifting bridge hydraulic cylinder is connected to the hydraulic oil tank 1 through the electromagnetic reversing valve 401 and the return oil filter 8; an oil suction filter 9 is provided at the connection between the first-level pressure control module 1 and the hydraulic oil tank 1, and the main pipeline 5 is arranged in the hydraulic oil tank 1 through the oil suction filter 9.

[0105] Specifically, the return oil filter 8 is located on the return oil path, and the suction oil filter 9 is located on the suction oil path. Their functions are to filter the oil returning from the rodless chamber to the hydraulic oil tank 1 and the oil sucked into the hydraulic oil tank 1, remove pollutants and particles therein, and ensure the cleanliness of the oil. This helps to extend the service life of hydraulic components, reduce the failure rate, and ensure the stable operation of the system.

[0106] As a specific implementation, a displacement sensor is also built into the hydraulic cylinder of the lifting bridge, and the sensor is also electrically connected to the primary pressure control module 2, the overflow module 3 and the secondary pressure control module 4.

[0107] Specifically, the displacement sensor can monitor the position changes of the hydraulic cylinder piston in real time, convert the mechanical displacement into an electrical signal and feed it back to the control system; the control system can automatically adjust the output pressure of the hydraulic oil by the first-level pressure control module 2, the overflow module 3 and the second-level pressure control module 4 to ensure that the movement of the hydraulic cylinder conforms to the expected trajectory and improves the stability and response speed of the system.

[0108] As a specific implementation, the throttling feedback module 7 includes a flow valve 701 and an electromagnetic check valve 702; the flow valve 701 is arranged between the first-level pressure control module 2 and the pressure valve 301 for detecting the flow; the electromagnetic check valve 702 is arranged between the first-level pressure control module 2 and the pressure valve 301 for controlling the on and off of the pressure oil.

[0109] Specifically, a flow valve 701 and an electromagnetic check valve 702 are provided on the overflow pipe 6 of the hydraulic oil. When the system demand changes and causes pressure fluctuations, the flow output can be stabilized by adjusting the flow valve 701, which has a certain flow stabilizing effect on the system, thereby realizing steady-state control similar to throttling feedback; the electromagnetic check valve 702 can avoid oil backflow protection system. At the moment of rapid unloading or flow switching, the electromagnetic check valve 702 can be quickly closed to prevent oil backflow, thereby effectively performing the throttling feedback function.

[0110] Example 2

[0111] like Figure 1-5 As shown, this embodiment discloses a hydraulic system for a hydraulic lifting bridge, including a hydraulic oil tank 1, a primary pressure control module 2, an overflow module 3 and a plurality of secondary pressure control modules 4; the hydraulic oil tank 1 is connected to a plurality of lifting bridge hydraulic cylinders through a main pipeline 5;

[0112] The primary pressure control module 2 is arranged on the main pipeline 5 connecting the hydraulic oil tank 1 and the lifting bridge, and is used to control the hydraulic oil;

[0113] The primary pressure control module 2 is also connected to the hydraulic oil tank 1 through an overflow pipe 6, and a throttling feedback module 7 is also provided at the connection between the primary pressure control module 2 and the main pipe 5;

[0114] The secondary pressure control module 4 is connected to the primary pressure control module 2 through the main pipeline 5, and is used to control the hydraulic oil entering and exiting the primary pressure control module 2;

[0115] The overflow module 3 is connected to the primary pressure control module 2 and is used to reduce the high-pressure hydraulic oil to hydraulic oil of appropriate pressure;

[0116] The overflow module 3 includes a pressure valve 301, an electromagnetic overflow valve 302, an overflow electromagnetic reversing valve 303 and a direct-acting valve 304;

[0117] The pressure valve 301 is arranged at the connection between the primary pressure control module 2 and the main pipeline 5;

[0118] The electromagnetic overflow valve 302 , the overflow electromagnetic reversing valve 303 and the direct-acting valve 304 are sequentially arranged on the overflow pipe 6 .

[0119] As a specific implementation, the overflow pipeline 6 also includes an overflow main pipe 601, a first overflow oil return pipe 602, a second overflow oil return pipe 603, a third overflow oil return pipe 604, and a fourth overflow oil return pipe 605;

[0120] The overflow main pipe 601 is arranged between the electromagnetic overflow valve 302 and the primary pressure control module 2;

[0121] The low-pressure outlet of the electromagnetic overflow valve 302 is connected to the overflow electromagnetic reversing valve 303 through the first overflow oil return pipe 602, the high-pressure outlet of the electromagnetic overflow valve 302 is connected to the overflow electromagnetic reversing valve 303 through the second overflow oil return pipe 603, and the high-pressure outlet of the electromagnetic overflow valve 302 is also connected to the hydraulic oil tank 1 through the fourth overflow oil return pipe 605;

[0122] The overflow electromagnetic reversing valve 303 is connected to the hydraulic oil tank 1 through the third overflow oil return pipe 604 .

[0123] Specifically, the electromagnetic overflow valve 302 is connected to the primary pressure control module 2 through the overflow main pipe 601, and a pressure valve 301 is also provided at the overflow main pipe 601, and the pressure valve 301 is electrically connected to the electromagnetic overflow valve 302;

[0124] When the hydraulic oil pressure is lower than 9.5Mpa, the electromagnetic overflow valve 302 is closed, and the hydraulic oil does not enter the overflow module 3;

[0125] When the oil pressure of the flowing hydraulic oil is higher than 9.5Mpa and lower than 22Mpa, the low-pressure outlet of the electromagnetic overflow valve 302 is opened, and the YV2 coil of the overflow electromagnetic reversing valve 303 is energized and moved, so that the first overflow return pipe 602 and the third overflow return pipe 604 are connected, and the hydraulic oil flows out of the first overflow return pipe 602 of the low-pressure outlet of the electromagnetic overflow valve 302 inside the hydraulic oil, and flows back to the hydraulic oil tank 1 through the first overflow return pipe 602 and the third overflow return pipe 604;

[0126] When the oil pressure of the flowing hydraulic oil is higher than 22Mpa, the high-pressure outlet of the electromagnetic overflow valve 302 is opened, and the YV3 coil of the overflow electromagnetic reversing valve 303 is energized and moved, so that the second overflow return oil pipe 603 and the third overflow return oil pipe 604 are connected; at this time, the hydraulic oil flows back to the hydraulic oil tank through the second overflow return oil pipe 603 and the third overflow return oil pipe 604 of the high-pressure outlet of the electromagnetic overflow valve 302 inside the hydraulic oil, and can also flow back to the hydraulic oil tank through the fourth overflow return oil pipe 605 of the high-pressure outlet of the electromagnetic overflow valve 302;

[0127] In order to avoid the hydraulic oil pressure increasing, the overflow channel can be adjusted or cut off by controlling the overflow solenoid reversing valve 303, and multiple overflow channels can be quickly opened or closed when needed, providing more precise pressure control and a rapid pressure release path, thereby constructing a multi-level pressure protection system, which can not only effectively prevent overload, but also protect the hydraulic system from damage.

[0128] Example 3

[0129] like Figure 1-5 As shown, this embodiment discloses a control method for a hydraulic system, and the control method for the hydraulic system includes the following:

[0130] S1: When the oil cylinder extends to make the hydraulic bridge descend, the primary pressure control module 2 is started, the main pipeline 5 is evacuated, and the hydraulic oil in the hydraulic oil tank 1 enters the secondary pressure control module 4 through the pressurized main pipeline 5 under atmospheric pressure. The secondary pressure control module 4 transmits the hydraulic oil to the rodless cavity of the hydraulic oil cylinder of the lifting bridge, and the hydraulic oil in the rod cavity of the hydraulic oil cylinder of the lifting bridge is transported back to the hydraulic oil tank 1 through the secondary pressure control module 4;

[0131] S2: When the pressure valve 301 of the overflow module 3 detects that the oil pressure of the flowing hydraulic oil is lower than 9.5Mpa, the overflow operation is not performed;

[0132] S3: When the pressure valve 301 of the overflow module 3 detects that the oil pressure of the flowing hydraulic oil is higher than 9.5Mpa and lower than 22Mpa, the hydraulic oil flows out from the low-pressure outlet of the internal electromagnetic overflow valve 302, and the coil at one end of the overflow electromagnetic reversing valve 303 is energized to connect the low-pressure outlet with the hydraulic oil tank 1, and the hydraulic oil flows back to the hydraulic oil tank 1 through the overflow electromagnetic reversing valve 303 and the direct-acting valve 304;

[0133] S4: When the pressure valve 301 of the overflow module 3 detects that the oil pressure of the flowing hydraulic oil is higher than 22Mpa, the electromagnetic overflow valve 302 is started, the hydraulic oil flows out through the high-pressure outlet, and the coil at the other end of the overflow electromagnetic reversing valve 303 is energized to connect the high-pressure outlet with the hydraulic oil tank 1, and the hydraulic oil flows back / directly enters the hydraulic oil tank 1 through the overflow electromagnetic reversing valve 303 and the direct-acting valve 304;

[0134] S5: When the oil cylinder retracts and the hydraulic bridge rises, the oil pipe inside the secondary pressure control module 4 is converted, and the secondary pressure control module 4 transmits the hydraulic oil to the rod chamber of the hydraulic cylinder of the lifting bridge. The hydraulic oil in the rodless chamber of the hydraulic cylinder of the lifting bridge is transported back to the hydraulic oil tank 1 through the secondary pressure control module 4.

[0135] Specifically, when the hydraulic bridge descends (the cylinder extends synchronously): the motor 202 rotates to drive the variable piston pump 201 to rotate, and the pipeline is evacuated; the oil in the hydraulic oil tank 1 enters the variable piston pump 201 through the oil suction filter 9 under the action of atmospheric pressure, and the variable piston pump 201 pressurizes the oil and enters the first solenoid reversing valve 401, and the coil YV1 of the first solenoid reversing valve 401 is energized. The full flow of DC24V high-pressure oil passes through the P port of the first solenoid reversing valve 401, and the YV4 and YV6 of the first solenoid reversing valve 401 are energized. The pressure oil enters the rodless chamber of the cylinder through the hydraulic control one-way valve 402. At the same time, the pressure oil opens the hydraulic control one-way valve 402, and the coil YV2 of the overflow electromagnetic reversing valve 303 is energized, so that the hydraulic oil with a low pressure of less than 9.5Mpa flows back to the hydraulic oil tank 1 from the hydraulic control one-way valve 402, thereby adjusting the extension speed of the oil rod so that it is not too fast.

[0136] When the hydraulic bridge rises (the cylinder retracts synchronously): the motor 202 rotates to drive the variable piston pump 201 to rotate, and a vacuum is drawn in the pipeline. Under the action of atmospheric pressure, the oil in the hydraulic oil tank 1 enters the variable piston pump 201 through the oil suction filter 9. The variable piston pump 201 pressurizes the oil and enters the first solenoid reversing valve 401. The high-pressure oil enters the first solenoid reversing valve 401, and YV5 and YV7 of the first solenoid reversing valve 401 are energized. The pressure oil enters the rod chamber of the cylinder through the hydraulic control one-way valve 402. At the same time, the pressure oil opens the hydraulic control one-way valve 402, and the coil YV3 of the overflow solenoid reversing valve 303 is energized, so that the hydraulic oil with a low pressure less than 22Mpa flows back to the hydraulic oil tank 1 from multiple pipes of the hydraulic control one-way valve 402, thereby realizing the operation of the high-pressure 22Mpa lifting bridge.

[0137] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A hydraulic system for a hydraulic lifting bridge, characterized in that: It comprises a hydraulic oil tank (1), a primary pressure control module (2), an overflow module (3) and a plurality of secondary pressure control modules (4); the hydraulic oil tank (1) is connected to a plurality of lifting bridge hydraulic cylinders via a main pipeline (5); The primary pressure control module (2) is arranged on a main pipeline (5) connecting the hydraulic oil tank (1) and the lifting bridge, and is used to control the hydraulic oil; The primary pressure control module (2) is also connected to the hydraulic oil tank (1) via an overflow pipe (6), and a throttling feedback module (7) is also provided at the connection between the primary pressure control module (2) and the main pipe (5); The secondary pressure control module (4) is connected to the primary pressure control module (2) via a main pipeline (5) and is used to control the hydraulic oil entering and exiting the primary pressure control module (2); The overflow module (3) is connected to the primary pressure control module (2) and is used to reduce the high-pressure hydraulic oil to hydraulic oil of appropriate pressure; The overflow module (3) comprises a pressure valve (301), an electromagnetic overflow valve (302), an overflow electromagnetic reversing valve (303) and a direct-acting valve (304); The pressure valve (301) is arranged at the connection between the primary pressure control module (2) and the main pipeline (5); The electromagnetic overflow valve (302), the overflow electromagnetic reversing valve (303) and the direct-acting valve (304) are arranged in sequence on the overflow pipe (6).

2. The hydraulic system according to claim 1, characterized in that: The primary pressure control module (2) comprises a variable piston pump (201) and a motor (202); the motor (202) is transmission-connected to the variable piston pump (201); the variable piston pump (201) cooperates with an oil suction filter (8) through a pipeline and is connected to a hydraulic oil tank (1).

3. The hydraulic system according to claim 1, characterized in that: The overflow pipeline (6) further comprises an overflow main pipe (601), a first overflow oil return pipe (602), a second overflow oil return pipe (603), a third overflow oil return pipe (604), and a fourth overflow oil return pipe (605); The overflow main pipe (601) is arranged between the electromagnetic overflow valve (302) and the primary pressure control module (2); The low-pressure outlet of the electromagnetic overflow valve (302) is connected to the overflow electromagnetic reversing valve (303) through the first overflow oil return pipe (602), the high-pressure outlet of the electromagnetic overflow valve (302) is connected to the overflow electromagnetic reversing valve (303) through the second overflow oil return pipe (603), and the high-pressure outlet of the electromagnetic overflow valve (302) is also connected to the hydraulic oil tank (1) through the fourth overflow oil return pipe (605); The overflow electromagnetic reversing valve (303) is connected to the hydraulic oil tank (1) via a third overflow oil return pipe (604).

4. The hydraulic system according to claim 1, characterized in that: The secondary pressure control module (4) comprises a first electromagnetic reversing valve (401) and a hydraulically controlled one-way valve (402); The first port of the first electromagnetic reversing valve (401) is connected to the hydraulically controlled one-way valve (402) and to the rod chamber of the hydraulic cylinder of the lifting bridge; The second port of the first electromagnetic reversing valve (401) is connected to the rodless chamber of the lifting bridge hydraulic cylinder.

5. The hydraulic system according to claim 4, characterized in that: The secondary pressure control module (4) further comprises a pressure sensor (403) and a ball valve (404); The pressure sensor (403) is connected to the rod chamber and the rodless chamber of the hydraulic cylinder of the lifting bridge, and the ball valve (404) is arranged on the connecting pipe between the hydraulic control check valve (402) and the rod chamber of the hydraulic cylinder of the lifting bridge.

6. The hydraulic system according to claim 4, characterized in that: The main pipeline (5) comprises a first main oil pipeline (501), a second main oil pipeline (502), a third main oil pipeline (503) and a fourth main oil pipeline (504); The primary pressure control module (2) is connected to the third port of the first electromagnetic reversing valve (401) through the first main oil pipe (501); The first port of the first electromagnetic reversing valve (401) is connected to the hydraulically controlled one-way valve (402) and the rod chamber of the hydraulic cylinder of the lifting bridge through the second main oil pipe (502); The second port of the first electromagnetic reversing valve (401) is connected to the rodless chamber of the lifting bridge hydraulic cylinder through the third main oil pipe (503); The fourth port of the first electromagnetic reversing valve (401) is connected to the hydraulic oil tank (1) via a fourth main oil pipe (504).

7. The hydraulic system according to claim 1, characterized in that: The rodless chamber of the lifting bridge hydraulic cylinder is connected to the hydraulic oil tank (1) through an electromagnetic reversing valve (401) and an oil return filter (8).

8. The hydraulic system according to claim 1, characterized in that: A displacement sensor is also built into the hydraulic cylinder of the lifting bridge, and the sensor is also electrically connected to the primary pressure control module (2), the overflow module (3) and the secondary pressure control module (4).

9. The hydraulic system according to claim 1, characterized in that: The throttling feedback module (7) comprises a flow valve (701) and an electromagnetic check valve (702); the flow valve (701) is arranged between the primary pressure control module (2) and the pressure valve (301) for detecting flow; the electromagnetic check valve (702) is arranged between the primary pressure control module (2) and the pressure valve (301) for controlling the on and off of pressure oil.

10. A control method using the hydraulic system according to any one of claims 1 to 9, characterized in that: The control method of the hydraulic system includes the following: S1: When the oil cylinder is extended to make the hydraulic bridge descend, the primary pressure control module (2) is started, the main pipeline (5) is evacuated, and the hydraulic oil in the hydraulic oil tank (1) enters the secondary pressure control module (4) through the pressurized main pipeline (5) under atmospheric pressure. The secondary pressure control module (4) transmits the hydraulic oil to the rodless cavity of the hydraulic oil cylinder of the lifting bridge, and the hydraulic oil in the rod cavity of the hydraulic oil cylinder of the lifting bridge is transported back to the hydraulic oil tank (1) through the secondary pressure control module (4); S2: When the pressure valve (301) of the overflow module (3) detects that the oil pressure of the flowing hydraulic oil is lower than 9.5 MPa, the overflow operation is not performed; S3: When the pressure valve (301) of the overflow module (3) detects that the oil pressure of the flowing hydraulic oil is higher than 9.5 MPa and lower than 22 MPa, the hydraulic oil flows out from the low-pressure outlet of the internal electromagnetic overflow valve (302), and the coil at one end of the overflow electromagnetic reversing valve (303) is energized to connect the low-pressure outlet with the hydraulic oil tank (1), and the hydraulic oil flows back to the hydraulic oil tank (1) through the overflow electromagnetic reversing valve (303) and the direct-acting valve (304); S4: When the pressure valve (301) of the overflow module (3) detects that the oil pressure of the flowing hydraulic oil is higher than 22 MPa, the electromagnetic overflow valve (302) is activated, the hydraulic oil flows out through the high-pressure outlet, and the coil at the other end of the overflow electromagnetic reversing valve (303) is energized to connect the high-pressure outlet with the hydraulic oil tank (1), and the hydraulic oil flows back / directly enters the hydraulic oil tank (1) through the overflow electromagnetic reversing valve (303) and the direct-acting valve (304); S5: When the oil cylinder retracts and the hydraulic bridge rises, the oil pipe inside the secondary pressure control module (4) is converted, and the secondary pressure control module (4) transmits the hydraulic oil to the rod chamber of the hydraulic cylinder of the lifting bridge, and the hydraulic oil in the rodless chamber of the hydraulic cylinder of the lifting bridge is transported back to the hydraulic oil tank (1) through the secondary pressure control module (4).

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