Working platform hydraulic system and electric aerial work platform

Abstract

A working platform hydraulic system and an electric aerial work platform. The working platform hydraulic system comprises a platform oil cylinder hydraulic circuit and a platform power unit, wherein the platform power unit is arranged on a working platform and independently supplies oil to the platform oil cylinder hydraulic circuit. In an electric aerial work platform using the working platform hydraulic system, a lower vehicle oil pump supplying oil to main boom work circuits and the platform power unit on the working platform are arranged in an independent and distributed manner. Distributed arrangement of hydraulic power enables the platform oil cylinder hydraulic circuit to be independently supplied with oil by the platform power unit additionally provided on the working platform, such that the working platform hydraulic system is separated from other motion hydraulic systems, and when low-flow and high-pressure platform motions are combined with large-flow and low-pressure motions, pressure redundancy and waste is avoided, thereby improving energy efficiency. Moreover, complex connection of hydraulic pipelines is avoided, energy consumption is reduced, and long-distance transfer of energy is achieved.

Description

Work platform hydraulic systems and electric aerial work platforms

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202410154055.1 filed on February 2, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the field of aerial work machinery, and specifically relates to an electric aerial work platform and a hydraulic system for its working platform. Background Art

[0004] As the electrification process of aerial work platforms is completed and advanced, the problem of product endurance has gradually become prominent, and the market has put forward higher requirements for energy conservation and consumption reduction. In the existing technology, the driving oil source for the three actions of the work platform (swing, amplitude adjustment, and leveling) all comes from the off-board oil pump, which is controlled by the main valve and transported to the platform control valve through a long pipeline around the boom drag chain. The loss of the long pipeline, coupled with the structural limitations of the boom drag chain, makes it impossible to use a large specification for the pipeline, resulting in greater loss along the pipeline and increased energy waste. Usually, in the summer when the oil viscosity is low, the energy consumption wasted due to loss along the way will account for 10-20% of the total energy consumption of the platform action, while in the winter when the oil viscosity is high, this value will be as high as 20-30%.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide a working platform hydraulic system and an electric aerial work platform to achieve energy saving and consumption reduction.

[0007] In order to achieve the above-mentioned object, the first aspect of the present application provides a working platform hydraulic system, the working platform hydraulic system comprising:

[0008] Platform cylinder hydraulic circuits, including the fly arm luffing cylinder circuit, platform swing cylinder circuit, and platform leveling cylinder circuit; and

[0009] The platform power unit is arranged on the working platform and independently supplies oil to the hydraulic circuit of the platform cylinder. The platform power unit includes a motor pump and a platform hydraulic oil tank placed on the working platform. The motor pump pumps hydraulic oil from the platform hydraulic oil tank and pumps it to the oil circuit of the fly arm luffing cylinder, the oil circuit of the platform swing cylinder and the oil circuit of the platform leveling cylinder.

[0010] Optionally, the platform power unit further includes an electric emergency pump and / or a manual emergency pump.

[0011] Optionally, the platform leveling cylinder oil circuit includes:

[0012] Platform leveling cylinder and leveling proportional reversing valve;

[0013] A leveling compensator, wherein the hydraulic control end of the leveling compensator is connected to the oil outlet of the leveling shuttle valve, and the two oil inlets of the leveling shuttle valve are respectively connected to the rod chamber working oil circuit and the rodless chamber working oil circuit between the leveling proportional reversing valve and the platform leveling cylinder.

[0014] Optionally, the platform swing cylinder oil circuit includes:

[0015] Platform swing cylinder and swing proportional reversing valve;

[0016] A fixed flow valve is arranged at the oil inlet of the swing proportional reversing valve.

[0017] Optionally, the fly arm luffing cylinder oil circuit includes:

[0018] Flying boom luffing cylinder and luffing proportional reversing valve;

[0019] A luffing compensator, the hydraulic control end of the luffing compensator is connected to the oil outlet of the luffing shuttle valve, and the two oil inlets of the luffing shuttle valve are respectively connected to the rod chamber working oil circuit and the rodless chamber working oil circuit between the luffing proportional reversing valve and the flying arm luffing cylinder.

[0020] Optionally, the working platform hydraulic system includes:

[0021] A load-sensing valve, the hydraulic control end of which is connected to the rod chamber working oil circuit and the rodless chamber working oil circuit of the platform leveling cylinder, the boom luffing cylinder, and the platform swing cylinder through a shuttle valve.

[0022] Optionally, an exhaust joint is provided in the platform hydraulic oil tank, the exhaust joint is connected to an air duct, and the air duct extends out of the platform hydraulic oil tank.

[0023] Optionally, the exhaust joint is connected to a float for floating on the liquid surface, and the float includes a hollow body and a gravity block arranged in the cavity of the hollow body.

[0024] Optionally, an air filter is installed at the protruding end of the air duct.

[0025] A second aspect of the present application provides an electric aerial work platform, which includes the above-mentioned work platform hydraulic system.

[0026] Optionally, the electric aerial work platform further includes a main arm working circuit and an off-board oil pump for supplying oil to the main arm working circuit, and the off-board oil pump and the platform power unit on the work platform are independently distributed and arranged.

[0027] The work platform hydraulic system of this application, and the electric aerial work platform employing this hydraulic system, utilizes a distributed layout of hydraulic power. The platform cylinder hydraulic circuit is independently supplied with oil by a platform power unit added to the work platform. Compared to traditional centralized, long-distance oil supply, this avoids complex hydraulic piping connections, reduces hydraulic transmission energy consumption, and enables long-distance electrical transmission of energy for the aerial work platform's actuators. Furthermore, the work platform hydraulic system is separated from the electric aerial work platform's other hydraulic systems. This eliminates redundant pressure waste when combining low-flow, high-pressure platform movements with high-flow, low-pressure movements, thereby improving energy efficiency.

[0028] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without inventive work. In the drawings:

[0030] FIG1 is a control schematic diagram of an electro-hydraulic drive system of an existing electric aerial work platform;

[0031] FIG2 is a schematic structural diagram of an electric aerial work platform according to a specific embodiment of the present application;

[0032] FIG3 is a hydraulic principle diagram of a hydraulic system of a working platform according to a specific embodiment of the present application;

[0033] FIG4 is a schematic diagram of a state of a platform hydraulic oil tank in an electric aerial work platform in a tilted state according to a specific embodiment of the present application; and

[0034] FIG5 and FIG6 are schematic diagrams showing the hydraulic oil tank of the platform in FIG4 in a horizontal state and an inverted state, respectively.

[0035] LIST OF REFERENCE NUMERALS 1 Motor pump 2 Electric emergency pump 3 Manual emergency pump 4 High-pressure filter 5 Main relief valve 6 Unloading valve 7 Load sensing valve 8 Luffing compensator 9 Luffing proportional directional control valve 10 Fixed flow valve 11 Swing proportional directional control valve 12 Leveling compensator 13 Leveling proportional directional control valve 14 First relief valve 15 Second relief valve 16 Third relief valve 17 Fourth relief valve 18 First balancing valve 19 Fly boom luffing cylinder 20 Second balancing valve 21 Platform swing cylinder 22 Third balancing valve 23 Platform leveling cylinder 24 Platform hydraulic oil tank 100 Platform power unit 200 Working platform 101 Gravity block 102 Float 103 Exhaust connector 104 Air duct 105 Air filter DETAILED DESCRIPTION

[0036] The following describes the specific embodiments of the present application in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0037] The following describes the working platform hydraulic system and the electric aerial work platform according to the present application with reference to the accompanying drawings.

[0038] As shown in Figure 1, in the electro-hydraulic drive system of the prior art electric aerial work platform, the travel hydraulic system of the lower vehicle supplies oil to the upper vehicle, that is, the lower vehicle oil pump controls the output through the main valve (i.e., multi-way valve), and is transported to the platform control valve through a long pipeline around the boom drag chain. However, there is loss along the long pipeline when transporting hydraulic oil. In actual applications, for products with electronically controlled leveling, during the operation of the main boom luffing cylinder, the leveling cylinder also needs to be linked and driven by the system oil supply. Under small load luffing conditions, the oil pressure of the main boom luffing cylinder is generally low, usually around half of the system's maximum pressure; while the oil pressure of the leveling oil is at around 2 / 3 of the system's maximum pressure for a long time; this will cause the main boom luffing with large flow and low pressure requirements to cause the entire system pressure to rise by about 15% due to the participation of leveling, resulting in energy waste.

[0039] In view of this, the present application proposes a new type of working platform hydraulic system, which includes:

[0040] Platform cylinder hydraulic circuits; and

[0041] The platform power unit 100 is installed on the working platform 200 and independently supplies oil to the hydraulic circuit of the platform cylinder.

[0042] Among them, the inventors of this application deeply realized that, from the perspective of energy utilization, the efficiency of electric transmission and electric drive is much higher than that of hydraulic transmission and hydraulic drive. Based on the existing technology and the characteristics of transmission and drive of aerial work platforms, feasible paths to energy saving and consumption reduction include reducing the energy loss of components and pipelines, improving energy conversion and transmission efficiency, and effective measures such as reducing the length of hydraulic control components and pipelines, adopting high-efficiency electro-hydraulic components, and improving the system's energy distribution efficiency and effective energy utilization rate.

[0043] To this end, the present application separately provides a platform power unit 100 to independently supply oil to each platform cylinder, eliminating the need to draw oil from a multi-way valve as shown in Figure 1. This utilizes a distributed electric drive arrangement and a hydraulic system combined with hydraulic control valves and actuators. This distributed power unit arrangement eliminates the need for long pipelines to transport hydraulic oil, eliminating the problem of loss along the way. This avoids complex hydraulic pipeline connections and reduces hydraulic transmission energy consumption. Furthermore, because the platform oil source and the main arm's amplitude adjustment are independent of each other, there is no wasted energy due to increased system pressure caused by leveling pressure, thereby improving energy efficiency.

[0044] Figure 2 is a schematic diagram of the structure of an electric aerial work platform according to a specific embodiment of the present application; Figure 3 is a hydraulic principle diagram of the working platform hydraulic system according to a specific embodiment of the present application. As an example, the platform power unit 100 in Figures 2 and 3 may include a motor pump 1 and a platform hydraulic oil tank 24 located on the working platform 200. The platform cylinder hydraulic circuit includes a fly boom luffing cylinder oil circuit, a platform swing cylinder oil circuit, and a platform leveling cylinder oil circuit. The motor pump 1 draws hydraulic oil from the platform hydraulic oil tank 24 and pumps it to the fly boom luffing cylinder oil circuit, the platform swing cylinder oil circuit, and the platform leveling cylinder oil circuit. In this way, the platform power unit 100 is placed on the working platform 200, and the working platform hydraulic system is powered by an independent power unit. This not only isolates the work platform from other low-pressure, high-flow actuators, reduces overall system energy consumption, but also avoids the problems of long hydraulic oil pipelines, slow response over long distances, and high pressure loss.

[0045] For emergency use, the platform power unit 100 may also include an electric emergency pump 2 and / or a manual emergency pump 3. If the motor of the platform power unit 100 fails or becomes unusable due to a power outage, the electric emergency pump 2 or the manual emergency pump 3 can be activated to ensure continuous oil supply to the fly boom luffing cylinder, platform swing cylinder, and platform leveling cylinder circuits, thereby ensuring cylinder operation and safety.

[0046] Referring to Figure 3 , the boom luffing, platform swing, and platform leveling actions of the electric aerial work platform are directly driven by the platform power unit 100. The hydraulic power and hydraulic system of the work platform 200 are shown in Figure 3 . The components that make up the complete hydraulic control system include hydraulic cylinders, power units, control valves, counterbalance valves, filters, connecting lines, and the platform hydraulic oil tank 24.

[0047] The platform leveling cylinder oil circuit may include:

[0048] Platform leveling cylinder 23 and leveling proportional reversing valve 13;

[0049] Leveling compensator 12, the hydraulic control end of the leveling compensator 12 is connected to the oil outlet of the leveling shuttle valve, and the two oil inlets of the leveling shuttle valve are respectively connected to the rod chamber working oil circuit and the rodless chamber working oil circuit between the leveling proportional reversing valve 13 and the platform leveling cylinder 23.

[0050] The platform leveling cylinder oil circuit requires a relatively high oil pressure, consistently maintaining approximately two-thirds of the system's maximum pressure. When the drive cylinder is extended, the platform power unit 100 outputs flow. The oil passes through the high-pressure filter 4, which closes the unloading valve 6. The oil then flows through the leveling compensator 12, the leveling proportional reversing valve 13, and the third balancing valve 22 before entering the rodless chamber of the platform leveling cylinder 23. The oil in the rod chamber then flows through the third balancing valve 22 and the leveling proportional reversing valve 13 into the main return oil circuit, returning to the platform hydraulic oil tank 24 within the platform power unit 100.

[0051] Similarly, when the driving cylinder is recovered, the platform power unit 100 outputs flow, the oil passes through the high-pressure filter 4, the unloading valve 6 is powered on and closed, and the oil passes through the leveling compensator 12, the leveling proportional reversing valve 13, and the third balancing valve 22 and then enters the rod chamber of the platform leveling cylinder 23. The oil in the rodless chamber of the cylinder passes through the third balancing valve 22 and the leveling proportional reversing valve 13 and flows into the main return oil circuit and returns to the platform hydraulic oil tank 24 in the platform power unit 100.

[0052] The leveling compensator 12 receives a relatively high-pressure pilot signal from the leveling shuttle valve to ensure that the system flow and pressure are output to the platform leveling cylinder 23 as required. Under normal conditions, the compensator valve is open. When the platform leveling cylinder 23 is working under load, the relatively high-pressure pilot oil in the rod chamber working oil circuit and the rodless chamber working oil circuit drives the compensator valve core to move, reducing the valve opening. As the cylinder load increases, the valve opening decreases, the supply flow decreases, and the piston rod extension speed decreases. Similarly, when the load decreases, the valve opening increases, the supply flow increases, and the piston rod extension speed increases. As an example, the leveling compensator 12 can be a hydraulically controlled on-off valve with a continuously adjustable valve opening.

[0053] In addition, the platform swing cylinder oil circuit may include:

[0054] Platform swing cylinder 21 and swing proportional reversing valve 11;

[0055] The fixed flow valve 10 is arranged at the oil inlet of the swing proportional reversing valve 11 .

[0056] Among them, when the platform swings to the left, the platform power unit 100 outputs flow, the oil flows through the high-pressure filter 4, the unloading valve 6 is powered on and closed, and the oil passes through the fixed flow valve 10, the swing proportional reversing valve 11, and the second balancing valve 20 and enters the left chamber of the platform swing cylinder 21. The oil in the right chamber passes through the second balancing valve 20 and the swing proportional reversing valve 11 and flows into the main return oil circuit and returns to the platform hydraulic oil tank 24 in the platform power unit 100.

[0057] When the platform swings right, the platform power unit 100 outputs flow, the oil passes through the high-pressure filter 4, the unloading valve 6 is powered and closed, and the oil passes through the fixed flow valve 10, the swing proportional reversing valve 11, and the second balancing valve 20 and enters the right chamber of the platform swing cylinder 21. The oil in the left chamber passes through the second balancing valve 20 and the swing proportional reversing valve 11 and flows into the main return oil circuit and returns to the platform hydraulic oil tank 24 in the platform power unit 100.

[0058] The action of the platform leveling cylinder 21 should be smooth, so a fixed flow valve 10 is provided to supply a stable flow to the leveling cylinder so that the leveling action is slow and smooth.

[0059] In addition, the fly boom luffing cylinder oil circuit may include:

[0060] Flying boom luffing cylinder 19 and luffing proportional reversing valve 9;

[0061] The amplitude compensator 8, the hydraulic control end of the amplitude compensator 8 is connected to the oil outlet of the amplitude shuttle valve, and the two oil inlets of the amplitude shuttle valve are respectively connected to the rod chamber working oil circuit and the rodless chamber working oil circuit between the amplitude proportional reversing valve 9 and the flying arm amplitude cylinder 19.

[0062] When the boom is raised, the platform power unit 100 outputs flow, the oil passes through the high-pressure filter 4, the unloading valve 6 is powered on and closed, and the oil passes through the boom compensator 8, the boom proportional reversing valve 9, and the first balancing valve 18, and then enters the rodless chamber of the boom boom cylinder 19. The oil in the rod chamber passes through the first balancing valve 18 and the boom proportional reversing valve 9, and flows into the main return oil circuit and returns to the platform hydraulic oil tank 24 in the platform power unit 100.

[0063] When the boom is lowered, the platform power unit 100 outputs flow, the oil passes through the high-pressure filter 4, the unloading valve 6 is powered and closed, and the oil passes through the boom compensator 8, the boom proportional reversing valve 9, and the first balancing valve 18, and then enters the rod chamber of the boom boom cylinder 19. The oil in the rodless chamber passes through the first balancing valve 18 and the boom proportional reversing valve 9, and flows into the main return oil circuit and returns to the platform hydraulic oil tank 24 in the platform power unit 100.

[0064] The function of the boom compensator 8 is essentially the same as that of the leveling compensator 12. By receiving a relatively high-pressure pilot signal from the boom shuttle valve in the rod and rodless working oil circuits, the boom compensator 8 ensures that the system flow and pressure are output to the boom proportional reversing valve 9 as required. Under normal conditions, the compensator's valve port is open. When the boom boom cylinder 19 is operating under load, the relatively high-pressure pilot oil in the rod and rodless working oil circuits drives the compensator's valve core, reducing the valve opening. As the cylinder load increases, the valve opening decreases, the supply flow decreases, and the piston rod extension speed decreases. Similarly, as the load decreases, the valve opening increases, the supply flow increases, and the piston rod extension speed increases.

[0065] In the embodiment of FIG3 , the working platform hydraulic system may further include:

[0066] The load sensing valve 7, the hydraulic control end of the load sensing valve 7 is connected to the rod chamber working oil circuit and the rodless chamber working oil circuit of the platform leveling cylinder 23, the flying arm luffing cylinder 19, and the platform swing cylinder 21 through a shuttle valve.

[0067] It can be seen that the hydraulic control end of the load sensing valve 7 obtains the highest pressure in each load working oil circuit. On this basis, it relieves pressure or replenishes oil according to the load requirements to ensure that the flow and pressure of the main oil inlet circuit are output according to the system requirements.

[0068] The hydraulic system in Figure 3 also features a main relief valve 5. Its relief pressure serves as the system's maximum pressure. When pressure exceeds the main relief valve's relief pressure, the main oil inlet circuit releases pressure through the main relief valve 5. Furthermore, the working oil circuits of the boom luffing cylinder 19 and platform leveling cylinder 23 are equipped with a first relief valve 14, a second relief valve 15, a third relief valve 16, and a fourth relief valve 17 to relieve excess pressure and ensure the safety of the actuators.

[0069] In addition, since the platform power unit 100 is composed of the platform hydraulic oil tank 24 and the motor pump 1, and is arranged on the work platform 200, during leveling, the hydraulic oil tank may be tilted, horizontal, or inverted. If a conventional oil tank is used, when the oil tank is tilted or inverted, the oil may leak through the air filter 105.

[0070] To address this issue, the present application has specifically designed the internal structure of the hydraulic oil tank. Referring to Figure 4 , the platform hydraulic oil tank 24 in this embodiment is equipped with an exhaust connector 103, which is connected to an air duct 104, which extends out of the platform hydraulic oil tank 24. Exhaust connector 103 and air duct 104 allow for the timely removal or replenishment of air from the tank.

[0071] However, when the fuel tank is not in the correct position, it is necessary to ensure that the exhaust connector 103 is always in the air cavity inside the fuel tank to allow the fuel tank to breathe smoothly. Since the fuel tank may be inverted, it is impossible to fix the exhaust connector 103 on the inner wall of the fuel tank or arrange it in the center. These fixing methods are not feasible and can easily cause the exhaust connector 103 to be submerged in oil, resulting in the fuel tank being unable to breathe.

[0072] Specifically, the exhaust connector 103 shown in Figure 4 is connected to a float 102 designed to float on the liquid surface. Float 102 comprises a hollow body and a weight block 101 positioned within the hollow body. The weight block 101, which can freely move within the cavity, ensures that float 102 remains afloat above the liquid surface in the fuel tank, regardless of the tank's position, as shown in Figures 5 and 6. Float 102 can be a sphere, as shown, or a square box. Weight block 101 can be a metal ball, square metal block, or any other shape. This arrangement eliminates the problem of oil leaks from the fuel tank air filter when the platform is tilted or inverted.

[0073] An air filter 105 can also be installed at the protruding end of the air duct 104 to prevent external contaminants from entering the oil tank. The function of the air duct 104 is to connect the exhaust connector 103 and the air filter 105. The weight block 101, the float 102, and the exhaust connector 103 can be separate parts that are assembled to form a whole, or they can be an integrated structure. The purpose is to ensure that the exhaust port of the exhaust connector 103 can remain in the air of the oil tank body outside the hydraulic oil level when the platform hydraulic oil tank 24 is in any posture. When the platform power unit 100 is working and the oil in the tank becomes less, the outside air can enter the interior of the oil tank through the air filter 105, the air duct 104, and the exhaust connector 103; when the oil in the platform hydraulic oil tank 24 increases, the air inside the oil tank is discharged from the oil tank through the exhaust connector 103, the air duct 104, and the air filter 105.

[0074] The above-mentioned intake and exhaust design of the platform hydraulic oil tank 24 can ensure smooth intake and exhaust of the oil tank; it can also ensure that no matter what posture or angle the platform is in, the hydraulic oil will not leak out through the air filter 105.

[0075] The above-mentioned work platform hydraulic system can be applied to various aerial work platforms, especially electric aerial work platforms, to save energy and reduce consumption, and simplify the layout of hydraulic pipelines.

[0076] When the above-mentioned independent oil supply working platform hydraulic system is adopted, other actuators of the electric aerial work platform, such as the main arm working circuits of the main arm, can be supplied with oil through an off-board oil pump (not shown), and the off-board oil pump and the platform power unit 100 on the working platform 200 are distributed and arranged independently of each other.

[0077] By designing a distributed work platform hydraulic power and control system, the work platform hydraulic system is separated from the other hydraulic systems of the electric aerial work platform. This eliminates redundant pressure waste when combining low-flow, high-pressure platform movements with high-flow, low-pressure movements, thereby improving energy efficiency. The hydraulic tank's intake and exhaust design ensures smooth intake and exhaust, and prevents hydraulic oil from leaking through the air filter, regardless of the platform's posture or angle.

[0078] In summary, in the working platform hydraulic system of the present application and the electric aerial work platform using the hydraulic system, distributed working platform hydraulic power and control are used to replace the centralized long-distance oil supply of the existing technology, avoiding complicated hydraulic pipeline connections, reducing hydraulic transmission energy consumption, realizing long-distance electrical transmission of energy of the aerial work platform actuator, and improving energy efficiency; distributed working platform hydraulic power and control separates the platform hydraulic system from other action hydraulic systems of the aerial work platform, and when the small-flow, high-pressure platform action and the large-flow, low-pressure action are combined, it will not cause redundant pressure waste, thereby improving energy efficiency.

[0079] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0080] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0081] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0082] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. The hydraulic system of the working platform is characterized by: The working platform hydraulic system includes: Platform cylinder hydraulic circuits, including the fly arm luffing cylinder circuit, platform swing cylinder circuit, and platform leveling cylinder circuit; and A platform power unit (100) is arranged on a working platform (200) and independently supplies oil to the platform cylinder hydraulic circuit. The platform power unit (100) comprises a motor pump (1) and a platform hydraulic oil tank (24) placed on the working platform (200). The motor pump (1) pumps hydraulic oil from the platform hydraulic oil tank (24) and pumps the oil to the fly arm luffing cylinder oil circuit, the platform swing cylinder oil circuit, and the platform leveling cylinder oil circuit.

2. The working platform hydraulic system according to claim 1, characterized in that: The platform power unit (100) further comprises an electric emergency pump (2) and / or a manual emergency pump (3).

3. The working platform hydraulic system according to claim 1, characterized in that: The platform leveling cylinder oil circuit includes: Platform leveling oil cylinder (23) and leveling proportional reversing valve (13); A leveling compensator (12), wherein the hydraulic control end of the leveling compensator (12) is connected to the oil outlet of the leveling shuttle valve, and the two oil inlets of the leveling shuttle valve are respectively connected to the rod chamber working oil circuit and the rodless chamber working oil circuit between the leveling proportional reversing valve (13) and the platform leveling oil cylinder (23).

4. The working platform hydraulic system according to claim 3, characterized in that: The platform swing cylinder oil circuit includes: Platform swing oil cylinder (21) and swing proportional reversing valve (11); A fixed flow valve (10) is arranged at the oil inlet of the swing proportional reversing valve (11).

5. The working platform hydraulic system according to claim 4, characterized in that: The fly arm luffing cylinder oil circuit includes: Flying arm luffing oil cylinder (19) and luffing proportional reversing valve (9); A variable amplitude compensator (8), wherein the hydraulic control end of the variable amplitude compensator (8) is connected to the oil outlet of the variable amplitude shuttle valve, and the two oil inlets of the variable amplitude shuttle valve are respectively connected to the rod chamber working oil circuit and the rodless chamber working oil circuit between the variable amplitude proportional reversing valve (9) and the flying arm variable amplitude cylinder (19).

6. The working platform hydraulic system according to claim 5, characterized in that: The working platform hydraulic system includes: A load-sensing valve (7) is provided, wherein the hydraulic control end of the load-sensing valve (7) is connected to the rod chamber working oil circuit and the rodless chamber working oil circuit of the platform leveling cylinder (23), the boom luffing cylinder (19), and the platform swing cylinder (21) through a shuttle valve.

7. The working platform hydraulic system according to any one of claims 1 to 6, characterized in that: An exhaust joint (103) is provided in the platform hydraulic oil tank (24), the exhaust joint (103) is connected to an air guide pipe (104), and the air guide pipe (104) extends out of the platform hydraulic oil tank (24).

8. The working platform hydraulic system according to claim 7, characterized in that: The exhaust joint (103) is connected to a float (102) for floating on the liquid surface, and the float (102) comprises a hollow body and a gravity block (101) arranged in the cavity of the hollow body.

9. The working platform hydraulic system according to claim 7, characterized in that: An air filter (105) is installed at the protruding end of the air guide tube (104).

10. Electric aerial work platform, characterized in that, The electric aerial work platform comprises a work platform hydraulic system according to any one of claims 1 to 9.

11. The electric aerial work platform according to claim 10, characterized in that: The electric aerial work platform further comprises a main arm working circuit and an off-board oil pump for supplying oil to the main arm working circuit. The off-board oil pump and the platform power unit (100) on the working platform (200) are independently distributed and arranged.

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