Hydraulic system and method for ladder hoist control of large construction machines

Abstract

The application discloses a hydraulic system and method based on large engineering machinery escalator lifting control, and belongs to the technical field of engineering machinery equipment. An oil cylinder is hinged between the escalator and a working platform; a first power unit and a second power unit are connected to a first electromagnetic reversing valve; the first electromagnetic reversing valve is connected to a second electromagnetic reversing valve and a third check valve; one oil outlet of the second electromagnetic reversing valve is connected to a small cavity of the oil cylinder, and the other oil outlet is connected to the small cavity of the oil cylinder through a throttle valve; the third check valve is connected to a large cavity of the oil cylinder, and the third check valve is connected in parallel with a load holding valve; and a pilot control port of the load holding valve is connected to the small cavity of the oil cylinder. The hydraulic system can realize the control of the escalator without starting the host machine; the hydraulic system has relatively high power density, can reduce the space occupancy rate, and is convenient for arrangement, maintenance and installation; the hydraulic system is independent of the hydraulic system of the host machine, does not affect the flow demand of other system functions, and has excellent scalability.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery equipment technology, specifically to a hydraulic system and method for controlling the lifting of escalators in large engineering machinery. Technical Background

[0002] Large construction machinery is an important piece of equipment in engineering construction. Due to its high efficiency, its market share is continuously increasing. In large mobile construction machinery, the working platform is much higher than the ground, and ladders are usually installed to facilitate workers to get on and off the platform. Summary of the Invention

[0003] The purpose of this invention is to provide a hydraulic system and method for controlling the lifting and lowering of escalators in large-scale engineering machinery. This hydraulic system is independent of the main hydraulic system and can control the escalator's rising, falling, and stopping actions without starting the main unit.

[0004] This invention is achieved through the following technical solution: a hydraulic system for lifting and controlling the escalator of large engineering machinery, wherein the upper end of the escalator is hinged to the upper end of the work platform, and a hydraulic cylinder is hinged between the escalator and the work platform;

[0005] The first power unit and the second power unit have their oil inlets connected to the oil tank. The oil outlets of the first power unit and the second power unit are respectively connected to the oil inlet of the first solenoid directional valve. The oil outlet of the first solenoid directional valve is respectively connected to the second solenoid directional valve and the third check valve. One oil outlet of the second solenoid directional valve is connected to the small chamber of the oil cylinder, and the other oil outlet of the second solenoid directional valve is connected to the small chamber of the oil cylinder through a throttle valve.

[0006] The third check valve is connected to the large chamber of the cylinder, and a load holding valve is connected in parallel to the third check valve. The pilot control port of the load holding valve is connected to the small chamber of the cylinder.

[0007] The main hydraulic system is connected to the inlet of the third solenoid directional valve, and the outlet of the third solenoid directional valve is connected to the large chamber of the cylinder.

[0008] The large chamber of the hydraulic cylinder is connected to the oil tank via a shut-off valve.

[0009] Furthermore, the first power unit and the second power unit have the same structure, and the first power unit includes an oil pump and a DC motor for driving the oil pump.

[0010] The oil outlet of the first power unit is connected to the oil inlet of the first solenoid directional valve through a first check valve; the oil outlet of the second power unit is connected to the oil inlet of the first solenoid directional valve through a second check valve; the first check valve and the second check valve are connected to a safety valve, and the safety valve is connected to the oil tank.

[0011] The main hydraulic system is connected to the inlet of the third solenoid directional valve via a fourth check valve.

[0012] A method for controlling the lifting of escalators in large engineering machinery.

[0013] Rapid rise:

[0014] The first power unit and the second power unit work simultaneously to output high-pressure oil; at the same time, the first solenoid directional valve switches to the D-side working position, and the high-pressure oil passes through the first check valve and the second check valve respectively, and after merging, it passes through the first solenoid directional valve; then the high-pressure oil passes through the third check valve and enters the large chamber of the oil cylinder.

[0015] The oil in the small chamber of the hydraulic cylinder first passes through the second solenoid directional valve, and then returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder extends, driving the escalator to rise.

[0016] Slow ascent:

[0017] The first or second power unit works independently, outputting high-pressure oil; at the same time, the first solenoid directional valve switches to the D-side working position, and the high-pressure oil passes through the first or second check valve and then through the first solenoid directional valve; then the high-pressure oil passes through the third check valve and enters the large chamber of the oil cylinder.

[0018] The oil in the small chamber of the hydraulic cylinder first passes through the second solenoid directional valve, and then returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder extends, driving the escalator to rise.

[0019] Rise Buffer:

[0020] The first or second power unit operates independently, outputting high-pressure oil; simultaneously, the first solenoid directional valve switches to the D-side working position, and the second solenoid directional valve switches to the E-side working position; the high-pressure oil passes through the first or second check valve and then through the first solenoid directional valve; then the high-pressure oil passes through the third check valve and enters the large chamber of the oil cylinder.

[0021] The oil in the small chamber of the hydraulic cylinder first passes through the throttle valve, then through the second solenoid directional valve, and finally returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder extends, driving the escalator to rise.

[0022] Rapid decline:

[0023] The first power unit and the second power unit work simultaneously to output high-pressure oil. At the same time, the first solenoid directional valve switches to the C-side working position, and the high-pressure oil passes through the first check valve and the second check valve respectively. After merging, it passes through the first solenoid directional valve. Then, the high-pressure oil passes through the second solenoid directional valve and enters the small chamber of the oil cylinder. At the same time, the high-pressure oil also enters the pilot control port of the load holding valve, and the load holding valve opens.

[0024] The oil in the large chamber of the hydraulic cylinder first passes through the load holding valve, and then returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder retracts, driving the escalator to descend;

[0025] Slow descent:

[0026] The first or second power unit works independently, outputting high-pressure oil; at the same time, the first solenoid directional valve switches to the C-side working position, the high-pressure oil passes through the first or second check valve and then through the first solenoid directional valve, and finally the high-pressure oil passes through the second solenoid directional valve and enters the small chamber of the oil cylinder; at the same time, the high-pressure oil also enters the pilot control port of the load holding valve, and the load holding valve opens.

[0027] The oil in the large chamber of the hydraulic cylinder first passes through the load holding valve, and then returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder retracts, driving the escalator to descend;

[0028] Falling buffer:

[0029] The first or second power unit operates independently, outputting high-pressure oil. Simultaneously, the first solenoid directional valve switches to the C-side working position, and the second solenoid directional valve switches to the E-side working position. The high-pressure oil passes through the first or second check valve and then through the first solenoid directional valve. Finally, the high-pressure oil passes through the second solenoid directional valve and the throttle valve in sequence before entering the small chamber of the oil cylinder. At the same time, the high-pressure oil also enters the pilot control port of the load holding valve, and the load holding valve opens.

[0030] The oil in the large chamber of the hydraulic cylinder first passes through the load holding valve, and then returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder retracts, driving the escalator to descend.

[0031] Furthermore, it involves manual descent:

[0032] When the hydraulic system malfunctions and the escalator fails to descend automatically, the shut-off valve is manually opened. Due to the gravitational potential energy of the escalator, the oil in the large chamber of the cylinder is pressurized and returns to the oil tank through the shut-off valve. At the same time, a negative pressure is generated in the small chamber of the cylinder. The oil in the oil tank first passes through the first solenoid directional valve and then through the second solenoid directional valve before entering the small chamber of the cylinder, causing the escalator to descend.

[0033] After the main hydraulic system is started,

[0034] Rapid rise:

[0035] High-pressure oil is input into the main hydraulic system. The high-pressure oil first passes through the fourth check valve and then through the third solenoid directional valve into the large chamber of the oil cylinder.

[0036] The oil in the small chamber of the hydraulic cylinder first passes through the second solenoid directional valve, and then returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder extends, driving the escalator to rise.

[0037] Rise Buffer:

[0038] High-pressure oil is input into the main hydraulic system. At the same time, the second solenoid directional valve switches to the working position on the E side. The high-pressure oil first passes through the fourth check valve and then enters the large chamber of the oil cylinder through the third solenoid directional valve.

[0039] The oil in the small chamber of the hydraulic cylinder first passes through the throttle valve, then through the second solenoid directional valve, and finally returns to the oil tank through the first solenoid directional valve; the piston rod of the hydraulic cylinder extends, driving the escalator to rise.

[0040] Lock:

[0041] When the cylinder is fully extended, or the escalator contacts the upper mechanical limit, the third solenoid directional valve switches to side F; the high-pressure oil of the main hydraulic system first passes through the fourth check valve, and then through the third solenoid directional valve into the large chamber of the cylinder.

[0042] The oil in the small chamber of the hydraulic cylinder first passes through the second solenoid directional valve, and then returns to the oil tank through the first solenoid directional valve. The hydraulic cylinder always generates an extension force, and the escalator is in a locked state.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] The hydraulic system can achieve functions such as rapid ascent, rapid descent, buffer locking, rapid descent, slow descent, ascent buffer, descent buffer, and manual descent without starting the main unit. It can also adjust the speed to reduce mechanical shock. At the same time, it can stop, start, and lock at any position and the extreme position of ascent.

[0045] Hydraulic systems have a high power density, which can reduce space occupation, facilitate layout, maintenance and installation, and have the advantages of low cost and high reliability, making them suitable for widespread adoption.

[0046] This hydraulic system is independent of the main hydraulic system and only needs to be connected to the main system's oil tank. At the same time, the main system's pilot system can also provide a pressure source, but the required flow rate is very small and does not affect the flow rate requirements of other system functions, thus having excellent scalability. Attached Figure Description

[0047] Figure 1 The diagram shown is a structural diagram of the escalator and a schematic diagram of its hydraulic system according to the present invention.

[0048] In the diagram: 1. First power unit; 2. Second power unit; 3. First check valve; 4. Second check valve; 5. Safety valve; 6. First solenoid directional valve; 7. Second solenoid directional valve; 8. Throttle valve; 9. Third solenoid directional valve; 10. Shut-off valve; 11. Third check valve; 12. Load holding valve; 13. Hydraulic cylinder; 14. Fourth check valve; 15. Escalator; 16. Working platform. Detailed Implementation

[0049] The invention will now be further described with reference to the accompanying drawings.

[0050] Example 1

[0051] Combination Figure 1 As shown, a hydraulic system for controlling the lifting of a large engineering machinery escalator is provided. The upper end of the escalator 15 is hinged to the upper end of the work platform 16, and a hydraulic cylinder 13 is hinged between the escalator 15 and the work platform 16. The lifting of the escalator 15 is controlled by the extension and retraction of the hydraulic cylinder 13.

[0052] The first power unit 1 and the second power unit 2 have identical structures. The first power unit 1 includes an oil pump and a DC motor to drive the oil pump, which draws oil from an oil tank. The oil outlets of the first power unit 1 and the second power unit 2 are respectively connected to the first check valve 3 and the second check valve 4. The first check valve 3 is connected to the oil inlet of the first solenoid directional valve 6, and the second check valve 4 is also connected to the oil inlet of the first solenoid directional valve 6. The first check valve 3 and the second check valve 4 are also connected to the safety valve 5, which is connected to the oil tank. The safety valve 5 prevents excessive oil pressure at the power unit outlet, protecting the safety of personnel and equipment.

[0053] The oil outlet of the first solenoid directional valve 6 is connected to the second solenoid directional valve 7 and the third check valve 11 respectively. One oil outlet of the second solenoid directional valve 7 is connected to the small chamber of the oil cylinder 13, and the other oil outlet of the second solenoid directional valve 7 is connected to the small chamber of the oil cylinder 13 through the throttle valve 8.

[0054] The third check valve 11 is connected to the large chamber of the oil cylinder 13. The third check valve 11 is connected in parallel with the load holding valve 12. The pilot control port of the load holding valve 12 is connected to the small chamber of the oil cylinder 13.

[0055] The main hydraulic system is connected to the fourth check valve 14, which is connected to the inlet of the third solenoid directional valve 9. The outlet of the third solenoid directional valve 9 is connected to the large chamber of the cylinder 13.

[0056] The large chamber of cylinder 13 is connected to the oil tank through shut-off valve 10.

[0057] In this embodiment, the first and second power units output pressurized oil, which switches the flow direction through the first solenoid directional valve 6 to control the extension and retraction of the hydraulic cylinder 13, thereby controlling the ascent and descent of the escalator 15. Additionally, by controlling the working position of the second solenoid directional valve 7, the on / off state of the small chamber of the hydraulic cylinder 13 and the throttle valve 8 is controlled, changing the flow speed of the oil in the small chamber of the hydraulic cylinder 13 and adjusting the speed of the hydraulic cylinder 13, thereby controlling the speed of the escalator 15. Specifically, the first one-way valve 3, the second one-way valve 4, the third one-way valve 11, and the fourth one-way valve 14 prevent backflow of oil; the safety valve 5 prevents system overload; the solenoid directional valve 9 controls the on / off connection between the oil in the large chamber of the hydraulic cylinder 13 and the main system; the load holding valve 12 prevents the hydraulic cylinder 13 from automatically retracting under the gravitational potential energy of the escalator and can also establish back pressure to ensure smooth retraction of the hydraulic cylinder 13; the shut-off valve 10 can be manually opened, allowing the escalator to automatically descend using gravitational potential energy.

[0058] Example 2

[0059] A method for controlling the lifting of escalators in large engineering machinery, based on the above-described embodiment one, includes the following steps;

[0060] When the main hydraulic system stops,

[0061] Rapid rise:

[0062] The first power unit 1 and the second power unit 2 work simultaneously to output high-pressure oil. At the same time, the first solenoid directional valve 6 switches to the D-side working position. The high-pressure oil passes through the first check valve 3 and the second check valve 4 respectively, and after merging, it passes through the first solenoid directional valve 6. Then the high-pressure oil passes through the third check valve 11 and enters the large chamber of the oil cylinder 13.

[0063] The oil in the small chamber of cylinder 13 first passes through the second solenoid directional valve 7, and then returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 extends, driving the escalator 15 to rise. In this state, both power units output high-pressure oil simultaneously, and there is no throttling effect on the oil inlet and outlet of the cylinder, so the escalator rises at a relatively fast speed, which is a rapid ascent state.

[0064] Slow ascent:

[0065] The first power unit 1 or the second power unit 2 works independently to output high-pressure oil; at the same time, the first solenoid directional valve 6 switches to the D-side working position, and the high-pressure oil passes through the first check valve 3 or the second check valve 4 and then through the first solenoid directional valve 6; then the high-pressure oil passes through the third check valve 11 and enters the large chamber of the oil cylinder 13.

[0066] The oil in the small chamber of cylinder 13 first passes through the second solenoid directional valve 7, and then returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 extends, driving the escalator 15 to rise. In this state, only a single power unit outputs high-pressure oil, and there is no throttling effect on the oil inlet and outlet of the cylinder, so the escalator rises slowly, which is a slow-speed rising state.

[0067] Rise Buffer:

[0068] The first power unit 1 or the second power unit 2 works independently to output high-pressure oil; at the same time, the first solenoid directional valve 6 switches to the working position on the D side and the second solenoid directional valve 7 switches to the working position on the E side; the high-pressure oil passes through the first check valve 3 or the second check valve 4 and then through the first solenoid directional valve 6; then the high-pressure oil passes through the third check valve 11 and enters the large chamber of the oil cylinder 13.

[0069] The oil in the small chamber of cylinder 13 first passes through throttle valve 8, then through the second solenoid directional valve 7, and finally returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 extends, driving the escalator 15 to rise. Because only a single power unit outputs high-pressure oil in this state, and the oil output from the cylinder has a throttling effect, the escalator rises very slowly, which is a buffer state for rising.

[0070] Rapid decline:

[0071] The first power unit 1 and the second power unit 2 work simultaneously, outputting high-pressure oil. At the same time, the first solenoid directional valve 6 switches to the C-side working position, and the high-pressure oil passes through the first check valve 3 and the second check valve 4 respectively. After merging, the oil passes through the first solenoid directional valve 6. Then, the high-pressure oil passes through the second solenoid directional valve 7 and enters the small chamber of the oil cylinder 13. At the same time, the high-pressure oil also enters the pilot control port of the load holding valve 12, and the load holding valve 12 opens.

[0072] The oil in the large chamber of cylinder 13 first passes through load holding valve 12, and then returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 retracts, driving the escalator 15 to descend. In this state, both power units output high-pressure oil simultaneously, and there is no throttling effect on the oil inlet and outlet of the cylinder, so the escalator descends at a relatively fast speed, which is a rapid descent state.

[0073] Slow descent:

[0074] The first power unit 1 or the second power unit 2 works independently, outputting high-pressure oil; at the same time, the first solenoid directional valve 6 switches to the C-side working position, the high-pressure oil passes through the first check valve 3 or the second check valve 4 and then through the first solenoid directional valve 6, and finally the high-pressure oil passes through the second solenoid directional valve 7 and enters the small chamber of the oil cylinder 13; at the same time, the high-pressure oil also enters the pilot control port of the load holding valve 12, and the load holding valve 12 opens.

[0075] The oil in the large chamber of cylinder 13 first passes through load holding valve 12, and then returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 retracts, driving the escalator 15 to descend. In this state, only a single power unit outputs high-pressure oil, and there is no throttling effect on the oil inlet and outlet of the cylinder, so the escalator descends slowly, which is a slow descent state.

[0076] Falling buffer:

[0077] The first power unit 1 or the second power unit 2 operates independently, outputting high-pressure oil; simultaneously, the first solenoid directional valve 6 switches to the C-side working position, and the second solenoid directional valve 7 switches to the E-side working position; the high-pressure oil passes through the first check valve 3 or the second check valve 4, then through the first solenoid directional valve 6, and finally through the second solenoid directional valve 7 and the throttle valve 8 in sequence, entering the small chamber of the oil cylinder 13; at the same time, the high-pressure oil also enters the pilot control port of the load holding valve 12, and the load holding valve 12 opens;

[0078] The oil in the large chamber of cylinder 13 first passes through load holding valve 12, and then returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 retracts, driving the escalator 15 to descend. Because only a single power unit outputs high-pressure oil in this state, and the oil inlet of the cylinder has a throttling effect, the escalator descends very slowly, which is a descent buffer state.

[0079] Manual descent:

[0080] When the hydraulic system malfunctions and the escalator 15 fails to descend automatically, the shut-off valve 10 is manually opened. Due to the gravitational potential energy of the escalator 15, the oil in the large chamber of the cylinder 13 is pressurized and returns to the oil tank through the shut-off valve 10. At the same time, a negative pressure is generated in the small chamber of the cylinder 13. The oil in the oil tank first passes through the first solenoid directional valve 6 and then through the second solenoid directional valve 7, and enters the small chamber of the cylinder 13, causing the escalator 15 to descend.

[0081] After the main hydraulic system is started,

[0082] Rapid rise:

[0083] High-pressure oil is input into the main hydraulic system. The high-pressure oil first passes through the fourth check valve 14, and then through the third solenoid directional valve 9 to enter the large chamber of the oil cylinder 13.

[0084] The oil in the small chamber of cylinder 13 first passes through the second solenoid directional valve 7, and then returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 extends, driving the escalator 15 to rise. In this state, the high-pressure oil flow rate input to the main hydraulic system is large, and there is no throttling effect at the oil inlet and outlet of the cylinder, so the escalator rises quickly, which is a rapid ascent state.

[0085] Rise Buffer:

[0086] High-pressure oil is input into the main hydraulic system. At the same time, the second solenoid directional valve 7 switches to the working position on the E side. The high-pressure oil first passes through the fourth check valve 14, and then enters the large chamber of the oil cylinder 13 through the third solenoid directional valve 9.

[0087] The oil in the small chamber of cylinder 13 first passes through throttle valve 8, then through the second solenoid directional valve 7, and finally returns to the oil tank through the first solenoid directional valve 6; the piston rod of cylinder 13 extends, driving the escalator 15 to rise. In this state, although the main hydraulic system can input a large flow of high-pressure oil, the oil output from the cylinder has a throttling effect, and the escalator rises very slowly, which is a buffer state for rising.

[0088] Locked state:

[0089] When the cylinder 13 is fully extended, or when the escalator 13 contacts the upper mechanical limit, the third solenoid directional valve 9 switches to the F side; the high-pressure oil of the main hydraulic system first passes through the fourth check valve 14, and then through the third solenoid directional valve 9 into the large chamber of the cylinder 13.

[0090] The oil in the small chamber of the hydraulic cylinder 13 first passes through the second solenoid directional valve 7, and then through the first solenoid directional valve 6 back to the oil tank. The hydraulic cylinder 13 always generates an extension force, thereby ensuring that the escalator 15 will not descend due to the gravitational potential energy. This state is the locked state.

[0091] All power units not mentioned in the above functions cease operation, and the solenoid directional valve remains in its initial state.

[0092] In this embodiment, after the main hydraulic system stops, the battery provides power to drive two sets of DC motors, which in turn drive two power units to output high-pressure oil. The direction of the high-pressure oil flow is switched by the first solenoid directional valve 6, controlling the extension and retraction of the cylinders, and further controlling the escalator's ascent and descent. Furthermore, the second solenoid directional valve can be used to control whether the oil entering and exiting the small cylinder cavity passes through a throttle valve, thereby controlling the speed of oil entering and exiting the small cylinder cavity, and thus controlling the speed of cylinder extension and retraction. After the main hydraulic system starts, hydraulic oil can only be input to the large cylinder cavity by controlling the third solenoid directional valve 9, and the second solenoid directional valve 7 of the small cylinder cavity controls whether the output oil passes through a throttle valve, thereby controlling the oil output speed of the small cylinder cavity. At this time, the cylinders can only extend, and the escalator can only rise or lock.

[0093] This invention enables the escalator to ascend rapidly, descend rapidly, lock, descend slowly, and descend manually, while also allowing it to stop, start, and maintain its position at any location.

Claims

1. A hydraulic system for controlling the lifting of escalators in large engineering machinery. Its features are: The upper end of the escalator (15) is hinged to the upper end of the working platform (16), and a hydraulic cylinder (13) is hinged between the escalator (15) and the working platform (16). The first power unit (1) and the second power unit (2) have their oil inlets connected to the oil tank. The oil outlets of the first power unit (1) and the second power unit (2) are respectively connected to the oil inlet of the first solenoid directional valve (6). The oil outlet of the first solenoid directional valve (6) is respectively connected to the second solenoid directional valve (7) and the third check valve (11). One oil outlet of the second solenoid directional valve (7) is connected to the small chamber of the oil cylinder (13), and the other oil outlet of the second solenoid directional valve (7) is connected to the small chamber of the oil cylinder (13) through the throttle valve (8). The third check valve (11) is connected to the large chamber of the oil cylinder (13), and the third check valve (11) is connected in parallel with a load holding valve (12). The pilot control port of the load holding valve (12) is connected to the small chamber of the oil cylinder (13). The main hydraulic system is connected to the inlet of the third solenoid directional valve (9), and the outlet of the third solenoid directional valve (9) is connected to the large chamber of the cylinder (13); The large chamber of the hydraulic cylinder (13) is connected to the oil tank through the shut-off valve (10); The oil outlet of the first power unit (1) is connected to the oil inlet of the first solenoid directional valve (6) through the first check valve (3); the oil outlet of the second power unit (2) is connected to the oil inlet of the first solenoid directional valve (6) through the second check valve (4); the first check valve (3) and the second check valve (4) are connected to a safety valve (5), and the safety valve (5) is connected to the oil tank. The main hydraulic system is connected to the oil inlet of the third solenoid directional valve (9) via the fourth check valve (14).

2. The hydraulic system for lifting control of escalators in large engineering machinery according to claim 1, characterized in that: The first power unit (1) and the second power unit (2) have the same structure. The first power unit (1) includes an oil pump and a DC motor for driving the oil pump.

3. A method for controlling the lifting of escalators in large-scale engineering machinery, employing the hydraulic system for controlling the lifting of escalators in large-scale engineering machinery as described in claim 2; Rapid rise: The first power unit (1) and the second power unit (2) work simultaneously to output high-pressure oil; at the same time, the first electromagnetic reversing valve (6) switches to the working position on the D side, and the high-pressure oil passes through the first check valve (3) and the second check valve (4) respectively, and after merging, it passes through the first electromagnetic reversing valve (6); then the high-pressure oil passes through the third check valve (11) and enters the large chamber of the oil cylinder (13); The oil in the small chamber of the oil cylinder (13) first passes through the second solenoid directional valve (7), and then returns to the oil tank through the first solenoid directional valve (6); the piston rod of the oil cylinder (13) extends, driving the escalator (15) to rise; Slow ascent: The first power unit (1) or the second power unit (2) works independently and outputs high-pressure oil; at the same time, the first solenoid directional valve (6) switches to the D side working position, and the high-pressure oil passes through the first check valve (3) or the second check valve (4) and then through the first solenoid directional valve (6); then the high-pressure oil passes through the third check valve (11) and enters the large chamber of the oil cylinder (13); The oil in the small chamber of the oil cylinder (13) first passes through the second solenoid directional valve (7), and then returns to the oil tank through the first solenoid directional valve (6); the piston rod of the oil cylinder (13) extends, driving the escalator (15) to rise; Rise Buffer: The first power unit (1) or the second power unit (2) works independently and outputs high-pressure oil; at the same time, the first solenoid directional valve (6) switches to the working position on the D side and the second solenoid directional valve (7) switches to the working position on the E side; the high-pressure oil passes through the first check valve (3) or the second check valve (4) and then through the first solenoid directional valve (6); then the high-pressure oil passes through the third check valve (11) and enters the large chamber of the oil cylinder (13); The oil in the small chamber of the oil cylinder (13) first passes through the throttle valve (8), then through the second solenoid directional valve (7), and finally through the first solenoid directional valve (6) back to the oil tank; the piston rod of the oil cylinder (13) extends, driving the escalator (15) to rise; Rapid decline: The first power unit (1) and the second power unit (2) work simultaneously to output high-pressure oil. At the same time, the first solenoid directional valve (6) switches to the C-side working position. The high-pressure oil passes through the first check valve (3) and the second check valve (4) respectively, and after merging, it passes through the first solenoid directional valve (6). Then, the high-pressure oil passes through the second solenoid directional valve (7) and enters the small chamber of the oil cylinder (13). At the same time, the high-pressure oil also enters the pilot control port of the load holding valve (12), and the load holding valve (12) opens. The oil in the large chamber of the hydraulic cylinder (13) first passes through the load holding valve (12), and then returns to the oil tank through the first solenoid directional valve (6); the piston rod of the hydraulic cylinder (13) retracts, driving the escalator (15) to descend; Slow descent: The first power unit (1) or the second power unit (2) works independently and outputs high-pressure oil. At the same time, the first solenoid directional valve (6) switches to the C-side working position. The high-pressure oil passes through the first check valve (3) or the second check valve (4) and then through the first solenoid directional valve (6). Finally, the high-pressure oil passes through the second solenoid directional valve (7) and enters the small chamber of the oil cylinder (13). At the same time, the high-pressure oil also enters the pilot control port of the load holding valve (12), and the load holding valve (12) opens. The oil in the large chamber of the hydraulic cylinder (13) first passes through the load holding valve (12), and then returns to the oil tank through the first solenoid directional valve (6); the piston rod of the hydraulic cylinder (13) retracts, driving the escalator (15) to descend; Falling buffer: The first power unit (1) or the second power unit (2) works independently and outputs high-pressure oil. At the same time, the first solenoid directional valve (6) switches to the C-side working position and the second solenoid directional valve (7) switches to the E-side working position. The high-pressure oil passes through the first check valve (3) or the second check valve (4) and then through the first solenoid directional valve (6). Finally, the high-pressure oil passes through the second solenoid directional valve (7) and the throttle valve (8) in sequence and enters the small chamber of the oil cylinder (13). At the same time, the high-pressure oil also enters the pilot control port of the load holding valve (12) and the load holding valve (12) opens. The oil in the large chamber of the cylinder (13) first passes through the load holding valve (12), and then returns to the oil tank through the first solenoid directional valve (6); the piston rod of the cylinder (13) retracts, driving the escalator (15) to descend.

4. The method for controlling the lifting of escalators in large engineering machinery according to claim 3, characterized in that: Manual descent: When the hydraulic system malfunctions and the escalator (15) cannot descend automatically, the shut-off valve (10) is manually opened. Due to the gravitational potential energy of the escalator (15), the oil in the large chamber of the cylinder (13) is pressurized and returns to the oil tank through the shut-off valve (10). At the same time, the small chamber of the cylinder (13) generates negative pressure. The oil in the oil tank first passes through the first solenoid directional valve (6) and then through the second solenoid directional valve (7) to enter the small chamber of the cylinder (13), and the escalator (15) descends.

5. The method for controlling the lifting of escalators in large engineering machinery according to claim 3, characterized in that: After the main hydraulic system is started, Rapid rise: High-pressure oil is input into the main hydraulic system. The high-pressure oil first passes through the fourth check valve (14) and then through the third solenoid directional valve (9) into the large chamber of the oil cylinder (13). The oil in the small chamber of the oil cylinder (13) first passes through the second solenoid directional valve (7), and then returns to the oil tank through the first solenoid directional valve (6); the piston rod of the oil cylinder (13) extends, driving the escalator (15) to rise; Rise Buffer: High-pressure oil is input into the main hydraulic system. At the same time, the second solenoid directional valve (7) switches to the working position on the E side. The high-pressure oil first passes through the fourth check valve (14) and then enters the large chamber of the oil cylinder (13) through the third solenoid directional valve (9). The oil in the small chamber of the oil cylinder (13) first passes through the throttle valve (8), then through the second solenoid directional valve (7), and finally through the first solenoid directional valve (6) back to the oil tank; the piston rod of the oil cylinder (13) extends, driving the escalator (15) to rise; Lock: When the cylinder (13) is fully extended, or the escalator (15) contacts the upper mechanical limit, the third solenoid directional valve (9) switches to the F side; the high-pressure oil of the main hydraulic system first passes through the fourth check valve (14), and then through the third solenoid directional valve (9) into the large chamber of the cylinder (13); The oil in the small chamber of the cylinder (13) first passes through the second solenoid directional valve (7), and then returns to the oil tank through the first solenoid directional valve (6). The cylinder (13) always generates an extension force, and the escalator (15) is in a locked state.

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