A proportional pressure relief and unloading method and system for a high-pressure and ultra-large-flow hydraulic system

Abstract

The present invention relates to a proportional pressure relief and unloading method and system for a high-pressure and extra-large flow hydraulic system. When the hydraulic system stops working, the hydraulic pump unit shuts down, and the proportional throttle valve is opened to connect the oil inlet pipeline and the return pipeline. The high-pressure oil in the high-pressure accumulator unit gradually flows to the return pipeline through the proportional throttle valve. When the pressure in the oil inlet pipeline drops to the inflation pressure of the high-pressure accumulator unit, the cartridge valve is opened, so that the high-pressure oil in the oil supply pipeline and the hydraulic pump unit all flows back to the fuel tank through the cartridge valve. This method and system can perform stable pressure relief and unloading on a high-pressure and extra-large flow hydraulic system, gradually and stably relieve the huge high-pressure liquid energy accumulated in the high-pressure pipeline and the high-pressure accumulator, effectively reduce shock vibration and noise, thereby ensuring the stable operation of the hydraulic transmission system of heavy equipment, with high reliability and long service life.

Description

Technical Field

[0001] The present invention relates to a high-pressure and extra-large flow hydraulic system, and in particular to a proportional pressure-relief unloading method and system for a high-pressure and extra-large flow hydraulic system. Background Art

[0002] With the development trend of high-end heavy equipment such as hydraulic pile hammers, forging machinery, and metallurgical machinery towards large-scale and heavy-duty, higher requirements are put forward for hydraulic transmission systems, with performance indicators of high pressure above 21 MPa and an extra-large flow of tens of thousands of liters per minute instantaneously by accumulators, so as to meet the performance requirements of high-end heavy equipment and promote the industrial upgrading of high-end heavy equipment manufacturing. The high-pressure and extra-large flow hydraulic transmission system poses new challenges to the working stability, reliability, and service life of the hydraulic pump station.

[0003] Due to the characteristics of high pressure and instantaneously extra-large flow in the hydraulic transmission systems of high-end heavy equipment such as hydraulic pile hammers, forging machinery, and metallurgical machinery, their hydraulic pump stations usually adopt the form of a combination of multiple hydraulic pumps + multiple accumulators. When these heavy equipment stop working, it is often necessary to unload the hydraulic system. If conventional unloading methods such as electromagnetic overflow valves, electro-hydraulic directional valves, and cartridge valves are used to unload the hydraulic system, at this time, the huge high-pressure liquid energy accumulated in the high-pressure pipeline and high-pressure accumulator is instantaneously released, generating strong shock vibrations and huge sound noises. The rupture of bubbles in the oil will exacerbate this effect, possibly causing the connection bolts to loosen, hydraulic components and pipe fittings to rupture, and even resulting in serious oil leakage of the equipment, thus having an important impact on the stable operation, reliability, and service life of the entire heavy equipment. Releasing the huge high-pressure liquid energy during the unloading process of the hydraulic system is an indispensable working link for the heavy equipment to stop working. In order to effectively reduce the shock vibrations and noise caused by the unloading of the high-pressure and extra-large flow hydraulic system, it is urgent to improve the existing high-pressure and extra-large flow hydraulic system. Summary of the Invention

[0004] In view of this, the present invention proposes a proportional pressure-relief unloading method and system for a high-pressure and extra-large flow hydraulic system. This method and system can perform smooth pressure-relief unloading on the high-pressure and extra-large flow hydraulic system, enabling the huge high-pressure liquid energy accumulated in the high-pressure pipeline and high-pressure accumulator to be gradually and smoothly pressure-relieved and unloaded, effectively reducing shock vibrations and noise, thereby ensuring the stable operation, high reliability, and long service life of the hydraulic transmission system of heavy equipment.

[0005] Specifically, the present invention is achieved through the following technical solutions:

[0006] A proportional pressure relief and unloading system for a high-pressure and extra-large flow hydraulic system, comprising an oil tank, a hydraulic pump set, a supply oil pipeline, a hydraulic actuator and a return oil pipeline; the oil tank is connected to the hydraulic pump set, and the high-pressure oil in the supply oil pipeline provides hydraulic energy for the hydraulic actuator and then returns to the oil tank through the return oil pipeline; a high-pressure accumulator set is arranged on the supply oil pipeline, and a proportional throttle valve communicating with the return oil pipeline and a cartridge valve communicating with the oil tank are arranged between the hydraulic pump set and the high-pressure accumulator set. The proportional throttle valve can proportionally reduce the pressure in the supply oil pipeline to the inflation pressure of the high-pressure accumulator set during pressure relief and unloading. When the pressure in the supply oil pipeline is reduced to the inflation pressure of the high-pressure accumulator set, the cartridge valve can quickly return all the high-pressure oil in the supply oil pipeline and the hydraulic pump set to the oil tank.

[0007] Further, it further comprises a control valve, which has a P port, a T port, an A port and a B port; the hydraulic pump set is connected to the P port of the control valve through a supply oil pipeline, the T port of the control valve is connected to the oil tank through a return oil pipeline; the A port of the control valve is connected to the rodless cavity of the hydraulic actuator, the B port of the control valve is connected to the rod chamber of the hydraulic actuator, and the control valve controls the hydraulic actuator to extend and retract.

[0008] Further, a pressure sensor is also arranged on the supply oil pipeline.

[0009] Further, it further comprises a directional control valve, which has an S port, an L port, a K port and an M port, and the cartridge valve has an F port, a G port and an X port; the F port of the cartridge valve is connected to the inlet oil pipeline, the G port of the cartridge valve is connected to the oil tank, the X port of the cartridge valve is connected to the S port of the directional control valve, the F port of the cartridge valve is connected to the L port of the directional control valve, and both the K port and the M port of the directional control valve are connected to the oil tank.

[0010] Further, it further comprises a controller, which controls the control valve, the proportional throttle valve and the directional control valve.

[0011] Further, both the control valve and the directional control valve are solenoid valves, and the proportional throttle valve is a proportional solenoid valve.

[0012] Further, it further comprises a relief valve, which has an H port and a Y port. The H port of the relief valve is arranged between the X port of the cartridge valve and the S port of the directional control valve, and the Y port of the relief valve is connected to the oil tank.

[0013] The present invention also provides a method for proportional pressure relief and unloading of a high-pressure and extra-large flow hydraulic system, comprising the following steps:

[0014] When the hydraulic system stops working, the hydraulic pump set shuts down, the proportional throttle valve is opened to connect the oil inlet pipeline and the return pipeline, and the high-pressure oil in the high-pressure accumulator set gradually flows to the return pipeline through the proportional throttle valve. When the pressure in the oil inlet pipeline drops to the charging pressure of the high-pressure accumulator set, the cartridge valve is opened, so that the high-pressure oil in the oil supply pipeline and the hydraulic pump set all flows back to the fuel tank through the cartridge valve.

[0015] Beneficial effects:

[0016] 1. Through the proportional pressure relief and unloading measures of the present invention, the huge high-pressure liquid energy accumulated in the high-pressure pipeline and the high-pressure accumulator can be gradually and smoothly pressure-relieved, reducing the unloading impact energy, effectively reducing the impact vibration and noise of the hydraulic system, and being applicable to high-pressure ultra-large flow hydraulic systems with a flow rate of 1000 L / min or more.

[0017] 2. The present invention ingeniously sets a proportional throttle valve between the oil inlet pipeline and the oil return pipeline, and uses the resistance of the proportional throttle valve and the conventional return pipeline to slowly reduce the high pressure in the hydraulic system to the charging pressure of the appropriate high-pressure accumulator, and then cooperates with the cartridge valve to quickly return all the high-pressure oil in the hydraulic system to the fuel tank. While effectively reducing the impact vibration and noise, it maximally saves the pressure relief and unloading time, and can return all the high-pressure oil in the pipeline to the fuel tank.

[0018] 3. The present invention controls the cartridge valve through a directional valve and the corresponding pipeline, making the pressure relief and unloading process safer and more effective; at the same time, it can also achieve the no-load operation of the hydraulic pump set, ensuring the safety of each component; in addition, an overflow valve is installed between the cartridge valve and the directional valve, which can not only save space and pipelines, but also quickly return the high-pressure oil to the fuel tank when the oil supply pipeline is overpressure overflowing, preventing the oil supply pipeline from overpressure and improving the safety of the hydraulic system. Description of the drawings

[0019] Figure 1 is the device structure diagram of the present invention;

[0020] Figure 2 is the curve graph of the unloading impact energy change in Embodiment 1 of the present invention;

[0021] Figure 3 is the curve graph of the working pressure change of the hydraulic system in Embodiment 1 of the present invention;

[0022] Figure 4 is the curve graph of the unloading impact energy change in Comparative Example 1 of the present invention;

[0023] Figure 5 is the curve graph of the working pressure change of the hydraulic system in Comparative Example 1 of the present invention;

[0024] Figure 6 It is the working pressure change curve graph of the hydraulic system of Comparative Example 2 of the present invention;

[0025] Figure 7 It is the impact energy change curve graph during unloading of Comparative Example 3 of the present invention;

[0026] Figure 8 It is the impact energy change curve graph during unloading of Comparative Example 4 of the present invention. Specific Embodiments

[0027] The present invention will be described in detail below through specific embodiments, but the scope of the present invention is not limited to the

[0028] listed embodiments. To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the

[0029] accompanying drawings and specific embodiments.

[0030] As Figure 1 shown, a proportional pressure relief and unloading system for a high-pressure and extra-large flow hydraulic system includes an oil tank 1, a hydraulic pump set 2, a supply oil pipeline 3, a hydraulic actuator 4, a return oil pipeline 5, a high-pressure accumulator set 6, a proportional valve throttle valve 7, a cartridge valve 8, a control valve 9, a pressure sensor 10, a directional control valve 11, a controller 12, and a safety valve 13.

[0031] In the hydraulic transmission system, the hydraulic pump set 2 is connected to the P port of the control valve 9, the A port of the control valve 9 is connected to the rodless cavity of the hydraulic actuator 4, the B port of the control valve 9 is connected to the rod cavity of the hydraulic actuator 4, and the T port of the control valve 9 is connected to the oil tank 1. The control valve 9 can control the extension and retraction movements of the hydraulic actuator 4.

[0032] The inlet of the high-pressure accumulator set 6 is connected between the hydraulic pump set 2 and the control valve 9, and the high-pressure accumulator set 6 can store and release hydraulic energy.

[0033] The hydraulic pump set 2 is connected to the N port of the proportional throttle valve 7 through an oil inlet pipeline, the R port of the proportional throttle valve 7 is connected to the return oil pipeline, and the proportional throttle valve 7 can relieve the high-pressure oil accumulated by the hydraulic pump set 2 and the high-pressure accumulator set 6.

[0034] The hydraulic pump unit 2 is connected to port F of the cartridge valve 8 through an oil inlet pipeline. Port G of the cartridge valve 8 is connected to the oil tank 1. Port L of the reversing valve 11 is connected between the hydraulic pump unit 2 and port F of the cartridge valve 8. Port S of the reversing valve 11 is connected to port X of the cartridge valve 8. Ports K and M of the reversing valve 11 are connected to the oil tank 1. The reversing valve 11 can control the cartridge valve 8 to unload the high-pressure oil accumulated by the hydraulic pump unit 2 and the high-pressure accumulator unit 6. Between port S of the reversing valve 11 and port X of the cartridge valve 8, port H of the overflow valve 13 is connected. Port Y of the overflow valve 13 is connected to the oil tank 1. The overflow valve 13 can set the safety pressure value of the hydraulic system and control the cartridge valve 8 to perform overpressure overflow and pressure holding on the oil supply pipeline system.

[0035] Between the hydraulic pump unit 2 and the control valve 9, the inlet of the pressure sensor 10 is connected. The pressure sensor 10 can detect the pressure of the oil supply pipeline of the hydraulic system.

[0036] The present invention also provides a proportional pressure relief and unloading method for a high-pressure and extra-large flow hydraulic system. The method is applied to the hydraulic transmission system and includes the following steps:

[0037] Step 1, the controller 12 outputs a zero-current signal to the electromagnet of the proportional throttle valve 7. The proportional throttle valve 7 operates in the right position, and ports N and R of the proportional throttle valve 7 are disconnected.

[0038] Step 2, the controller 12 outputs a control voltage signal to the electromagnet of the reversing valve 11. The reversing valve 11 operates in the left position, port L of the reversing valve 11 is connected to port K, and port S is connected to port M. Therefore, the control port X of the cartridge valve 8 is connected to the oil tank 1, the spool of the cartridge valve 8 opens, and ports F and G of the cartridge valve 8 are connected. The hydraulic pump unit 2 is started. The oil supplied by the hydraulic pump unit 2 flows back to the oil tank 1 through ports F and G of the cartridge valve 8, thereby realizing the no-load start of the hydraulic pump unit 2. The controller 12 outputs a zero-voltage signal to the electromagnet of the reversing valve 11. The reversing valve 11 operates in the right position. The oil in the oil supply pipeline flows through port L and port S of the reversing valve 11 to the control port X of the cartridge valve 8. The spool of the cartridge valve 8 closes, and ports F and G of the cartridge valve 8 are disconnected. The oil supply pipeline supplies oil to the hydraulic system.

[0039] Step 3, the hydraulic pump unit 2 supplies oil to the inlet of the high-pressure accumulator unit 6, and the high-pressure accumulator unit 6 stores energy.

[0040] Step 4, the hydraulic pump unit 2 supplies oil to port P of the control valve 9. Port T of the control valve 9 flows to the oil tank 1 through the oil return pipeline 5. The controller 12 outputs a control signal to the control valve 9, and ports A and B of the control valve 9 control the hydraulic actuator 4 to perform extension and retraction movements.

[0041] Step 5, during the operation of the hydraulic system, the reversing valve 11 works in the right position. The oil in the oil supply pipeline flows through the L port and S port of the reversing valve 11 to the H port of the overflow valve 13. When the oil pressure in the oil supply pipeline exceeds the set safety pressure value of the overflow valve 13, the overflow valve 13 opens, and the H port and Y port of the overflow valve 13 are connected. The oil at the H port of the overflow valve 13 flows through the Y port to the fuel tank 1. The pressure at the X port of the cartridge valve 8 decreases, and the cartridge valve 8 spool opens. The F port and G port of the cartridge valve 8 are connected. The oil in the oil supply pipeline flows through the F port and G port of the cartridge valve 8 to the fuel tank 1 for overflow, reducing the oil pressure in the oil supply pipeline to the set value of the overflow valve 13, thus realizing overpressure overflow protection for the oil supply pipeline.

[0042] Step 6, when the hydraulic system stops working, the hydraulic pump unit 2 stops.

[0043] Step 7, the controller 12 cuts off the control signal of the control valve 9 and outputs a control current signal to the electromagnet of the proportional throttle valve 7. The magnitude of the control current signal can control the opening size of the proportional throttle valve 7. The N port and R port of the proportional throttle valve 7 are connected. The high-pressure oil accumulated by the hydraulic pump unit 2 and the high-pressure accumulator group 6 gradually flows through the N port and R port of the proportional throttle valve 7 to the return oil pipeline 5. The resistance of the proportional throttle valve 7 and the return oil pipeline 5 causes the high-pressure oil accumulated by the high-pressure accumulator group 6 to gradually release pressure in proportion and reduce the pressure.

[0044] Step 8, when the pressure sensor 10 detects that the pressure in the oil supply pipeline of the hydraulic system has dropped to the inflation pressure of the high-pressure accumulator, the high-pressure oil accumulated by the high-pressure accumulator group 6 is gradually released. The controller 12 outputs a control voltage signal to the electromagnet of the reversing valve 11, and the reversing valve 11 works in the left position. The L port of the reversing valve 11 is connected to the K port, and the S port is connected to the M port. Therefore, the control port X of the cartridge valve 8 is connected to the fuel tank 1, the cartridge valve 8 spool opens, and the F port and G port of the cartridge valve 8 are connected. The high-pressure oil in the hydraulic pump unit 2, the high-pressure accumulator group 6, and the high-pressure pipeline all flows back to the fuel tank 1 through the F port and G port of the cartridge valve 8, and the hydraulic pump unit 2 and the high-pressure pipeline oil are unloaded, effectively reducing the impact vibration and noise during the unloading of the hydraulic system.

[0045] Example 1:

[0046] Simulation test:

[0047] The flow rate of the hydraulic pump station is 3000 L / min. Four 150-liter high-pressure accumulators are connected in parallel, and five high-pressure hoses with a diameter of 75 mm are connected in parallel for oil supply. The length of the high-pressure hose is 100 m, the inflation pressure of the accumulator is 100 bar, and the working pressure of the hydraulic system is 250 bar. The diameter of the proportional throttle valve is 25 mm, and the diameter of the cartridge valve is 100 mm.

[0048] When the proportional throttle valve reduces the working pressure of the hydraulic system from 250 bar to the charging pressure of the high-pressure accumulator, which is 100 bar, the cartridge valve is then used to unload the hydraulic system.

[0049] In Example 1, the impact energy change curve during unloading is as shown in Figure 2 and the working pressure change curve of the hydraulic system is as shown in Figure 3 . According to Figure 2 , in Example 1, the maximum impact energy is 13,500 W. The impact energy decays from 13,500 W to zero, and the action time is 2.5 seconds. According to Figure 3 , the unloading time in Example 1 is 1.03 seconds.

[0050] Comparative Example 1:

[0051] The difference from Example 1 is that the cartridge valve is directly unloaded under the working pressure of 250 bar of the hydraulic system.

[0052] In Comparative Example 1, the impact energy change curve during unloading is as shown in Figure 4 and the working pressure change curve of the hydraulic system is as shown in Figure 5 . According to Figure 4 , in Comparative Example 1, the maximum impact energy is 21,500 W. The impact energy decays from 21,500 W to zero, and the action time is 4.7 seconds. According to Figure 5 , the unloading time in Example 2 is 3.1 seconds.

[0053] Comparative Example 2:

[0054] The difference from Example 1 is that the proportional throttle valve is directly unloaded under the working pressure of 250 bar of the hydraulic system.

[0055] The working pressure change curve of the hydraulic system in Comparative Example 2 is as shown in Figure 6 . According to Figure 6 , the unloading time in Comparative Example 2 is 27.03 seconds, but the system pressure after unloading is 5.2 bar, and there is still residual pressure.

[0056] Comparative Example 3:

[0057] The difference from Example 1 is that when the proportional throttle valve reduces the working pressure of the hydraulic system from 250 bar to 200 bar, the cartridge valve is then used to unload the hydraulic system.

[0058] The impact energy change curve during unloading in Comparative Example 3 is as shown in Figure 7 . According to Figure 7 , the maximum impact energy in Comparative Example 3 is 19,000 W. The impact energy decays from 19,000 W to zero, and the action time is 4.1 seconds.

[0059] Comparative Example 4:

[0060] The difference from Embodiment 1 is that when the proportional throttle valve reduces the working pressure of the hydraulic system from 250 bar to 150 bar, the cartridge valve is used to unload the hydraulic system.

[0061] The impact energy change curve during the unloading of Comparative Example 4 is as Figure 8 shown. According to Figure 8 what is shown, the maximum impact energy of Comparative Example 4 is 16,500 w, and the impact energy decays from 16,500 w to zero, with an action time of 3.5 seconds.

[0062] It can be seen from Embodiment 1 and Comparative Examples 1-4 that the maximum impact energy and impact time of Embodiment 1 are the smallest compared to Comparative Examples 1, 3, and 4. Therefore, using the proportional throttle valve to first reduce the working pressure of the hydraulic system to the charging pressure of the accumulator and then using the cartridge valve to unload can minimize the impact vibration and noise to the greatest extent; at the same time, compared to Embodiment 1, Comparative Example 2 requires a longer unloading time, and the working pressure in the entire hydraulic system cannot be completely cleared to zero. Therefore, using the proportional throttle valve to first reduce the working pressure of the hydraulic system to the charging pressure of the accumulator and then using the cartridge valve to unload can have higher efficiency and unloading sufficiency compared to only using the proportional throttle valve, and is more in line with actual engineering applications.

[0063] The embodiments of the present invention have been introduced in detail above. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, and does not limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics, and principles described in the scope of the present invention patent should be included within the scope of the present invention's patent application. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A proportional pressure relief and unloading system for a high-pressure and extra-large flow hydraulic system, characterized in that, It includes an oil tank, a hydraulic pump unit, an oil supply pipeline, a hydraulic actuator, and an oil return pipeline; the oil tank is connected to the hydraulic pump unit, and the high-pressure oil in the oil supply pipeline provides hydraulic energy for the hydraulic actuator and then returns to the oil tank through the oil return pipeline; a high-pressure accumulator group is arranged on the oil supply pipeline, and a proportional throttle valve communicating with the oil return pipeline and a cartridge valve communicating with the oil tank are arranged between the hydraulic pump unit and the high-pressure accumulator group. The proportional throttle valve can proportionally reduce the pressure in the oil supply pipeline to the charging pressure of the high-pressure accumulator group during pressure relief and unloading. When the pressure in the oil supply pipeline drops to the charging pressure of the high-pressure accumulator group, the cartridge valve can quickly return all the high-pressure oil in the oil supply pipeline and the hydraulic pump unit to the oil tank.

2. The proportional pressure relief unloading system of the high-pressure and extra-large flow hydraulic system according to claim 1, characterized in that, It further includes a control valve, and the control valve has a P port, a T port, an A port, and a B port; the hydraulic pump unit is connected to the P port of the control valve through the oil supply pipeline, the T port of the control valve is connected to the oil tank through the oil return pipeline; the A port of the control valve is connected to the rodless cavity of the hydraulic actuator, the B port of the control valve is connected to the rod cavity of the hydraulic actuator, and the control valve controls the extension and retraction movements of the hydraulic actuator.

3. The proportional pressure relief and unloading system of the high-pressure and extra-large flow hydraulic system according to claim 1, characterized in that, A pressure sensor is also arranged on the oil supply pipeline.

4. The proportional pressure relief and unloading system of the high-pressure and extra-large flow hydraulic system according to claim 2, characterized in that It further includes a directional valve, and the directional valve has an S port, an L port, a K port, and an M port. The cartridge valve has an F port, a G port, and an X port; the F port of the cartridge valve is connected to the oil supply pipeline, the G port of the cartridge valve is connected to the oil tank, the X port of the cartridge valve is connected to the S port of the directional valve, the F port of the cartridge valve is connected to the L port of the directional valve, and both the K port and the M port of the directional valve are connected to the oil tank.

5. The proportional pressure relief unloading system of the high-pressure and extra-large flow hydraulic system according to claim 4, characterized in that, It further includes a controller, and the controller controls the control valve, the proportional throttle valve, and the directional valve.

6. The proportional pressure relief and unloading system of the high-pressure and extra-large flow hydraulic system according to claim 5, characterized in that, Both the control valve and the directional valve are solenoid valves, and the proportional throttle valve is a proportional solenoid valve.

7. The proportional pressure relief unloading system of the high-pressure and extra-large flow hydraulic system according to claim 4, characterized in that, It further includes a relief valve, and the relief valve has an H port and a Y port. The H port of the relief valve is arranged between the X port of the cartridge valve and the S port of the directional valve, and the Y port of the relief valve is connected to the oil tank.

8. A proportional pressure relief and unloading method for a high-pressure and super-large flow hydraulic system, which uses the proportional pressure relief and unloading system for the high-pressure and super-large flow hydraulic system according to any one of claims 1-7, characterized in that, It includes the following steps: When the hydraulic system stops working, the hydraulic pump unit stops running, the proportional throttle valve is opened to connect the oil supply pipeline and the oil return pipeline, and the high-pressure oil in the high-pressure accumulator group gradually flows to the oil return pipeline through the proportional throttle valve. When the pressure in the oil supply pipeline drops to the charging pressure of the high-pressure accumulator group, the cartridge valve is opened, so that all the high-pressure oil in the oil supply pipeline and the hydraulic pump unit returns to the oil tank through the cartridge valve.

Images