Electrically-driven aerial work platform and hydraulic system thereof

Abstract

An electrically-driven aerial work platform and a hydraulic system thereof. The hydraulic system comprises: an upper hydraulic system, comprising a derricking oil cylinder and a telescopic oil cylinder that are used for driving a boom, and an upper hydraulic pump for supplying oil to the derricking oil cylinder and the telescopic oil cylinder; and a lower hydraulic system, comprising a turning oil cylinder for driving a vehicle body to turn, a floating oil cylinder assembly, and a lower hydraulic pump for supplying oil to the turning oil cylinder and the floating oil cylinder assembly; wherein the upper hydraulic system and the lower hydraulic system are independent of each other, and the rated displacement of the upper hydraulic pump is greater than the rated displacement of the lower hydraulic pump. By means of the independent distributed arrangement of the upper hydraulic system and the lower hydraulic system, the hydraulic system of the electrically-driven aerial work platform well solves the problem in the prior art of large pressure loss caused as a result of an upper hydraulic pump needing to pump oil in a high-pressure mode to transfer the oil to a turning oil cylinder and a floating oil cylinder of a lower hydraulic system by means of a central rotary joint, and can reduce energy consumption, save energy and improve the efficiency, and meet the requirements of energy saving and emission reduction.

Description

Electric-driven aerial work platform and its hydraulic system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202410065276.1 filed on January 16, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present application belongs to the technical field of aerial work platforms, and specifically relates to an electric-driven aerial work platform and a hydraulic system thereof. Background Art

[0004] Electric aerial work platforms use travel motors to drive tires. Steering and floating functions are frequently required during the vehicle's movement. Conventional technology uses a shared hydraulic oil source for vehicle steering and floating, as well as for boom arm adjustment, telescoping, and rotational movements. Therefore, steering is driven by a pump motor driving a main pump, which then controls the direction of the oil circuit via a reversing valve and transfers the oil to the lower vehicle's steering cylinder via a center rotary joint. Similarly, floating is driven by a pump motor driving a main pump, which then transfers the oil through a float control valve and a center rotary joint to the lower vehicle's floating cylinder. Current electric aerial work platform hydraulic systems are relatively complex and energy-intensive. With increasing energy-efficiency requirements for electric vehicles, these systems are increasingly unable to meet design energy requirements.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide an electric-driven aerial work platform and its hydraulic system to achieve the functions of reducing energy consumption, saving energy and increasing efficiency.

[0007] In order to achieve the above objectives, the present application provides, on one hand, a hydraulic system for an electric-driven aerial work platform, comprising:

[0008] The vehicle hydraulic system includes a luffing cylinder and a telescopic cylinder for driving the boom, and a vehicle hydraulic pump for supplying oil to the luffing cylinder and the telescopic cylinder; and

[0009] The vehicle disembarkation hydraulic system includes a steering cylinder for driving the vehicle body to steer, a floating cylinder assembly, and a vehicle disembarkation hydraulic pump for supplying oil to the steering cylinder and the floating cylinder assembly;

[0010] The onboard hydraulic system and the offboard hydraulic system are independent of each other, and the rated displacement of the onboard hydraulic pump is greater than the rated displacement of the offboard hydraulic pump.

[0011] Optionally, the vehicle disembarking hydraulic system includes a steering control hydraulic circuit, and the steering control hydraulic circuit includes:

[0012] A steering reversing valve, used for reversing control of the steering cylinder and comprising a first working oil port and a second working oil port connected to the large and small chambers of the steering cylinder, respectively; the oil inlet of the steering reversing valve is connected to the main oil inlet circuit, and the oil return port is connected to the main oil return circuit;

[0013] A shuttle valve, wherein the two comparison oil ports are connected to the first working oil port and the second working oil port respectively;

[0014] A compensator is connected between the main oil inlet circuit and the main oil return circuit, and a control oil port is hydraulically connected to the oil outlet of the shuttle valve through a pilot control oil circuit.

[0015] Optionally, the compensator is a hydraulically controlled stop valve with a continuously adjustable valve opening, and the control oil port of the compensator includes a first control end and a second control end at both ends, the first control end is a spring end and is connected to the pilot control oil circuit, and the second control end is hydraulically connected to the main oil inlet circuit.

[0016] Optionally, the steering control hydraulic circuit includes:

[0017] a one-way valve, disposed in the pilot control oil circuit of the compensator;

[0018] The one-way valve is configured to allow hydraulic oil to flow from the oil outlet of the shuttle valve to the control oil port of the compensator and to cut off the reverse flow.

[0019] Optionally, the steering control hydraulic circuit includes:

[0020] A throttle valve is provided in the connecting oil circuit between the pilot control oil circuit and the main oil return oil circuit.

[0021] Optionally, the steering control hydraulic circuit includes:

[0022] A pressure compensating flow valve is arranged in the main oil inlet circuit adjacent to the oil inlet of the steering reversing valve.

[0023] Optionally, the vehicle disembarking hydraulic system includes a floating control hydraulic circuit, and the floating control hydraulic circuit includes:

[0024] A floating control valve, used to control the floating cylinder assembly, wherein the oil inlet of the floating control valve is connected to the main oil inlet circuit via a bypass oil inlet circuit;

[0025] a pressure reducing valve, arranged in the bypass oil inlet line;

[0026] The bypass oil inlet circuit forms a first hydraulic connection point on the main oil inlet circuit, and the compensator forms a second hydraulic connection point on the main oil inlet circuit, and the first hydraulic connection point is located at the downstream end of the second hydraulic connection point.

[0027] Optionally, the vehicle disembarking hydraulic system includes:

[0028] a floating relief valve, provided between the bypass oil inlet circuit and the main oil return circuit between the pressure reducing valve and the floating control valve; and

[0029] A main overflow valve is arranged between the main oil inlet oil circuit and the main oil return oil circuit.

[0030] Optionally, the vehicle disembarking hydraulic system includes:

[0031] A power unit assembly, including the integrated dismounting hydraulic pump, motor, and hydraulic oil tank;

[0032] The control valve group at least includes the steering reversing valve, the shuttle valve, the compensator, the floating control valve and the pressure reducing valve that are integrated.

[0033] Optionally, the getting-off hydraulic pump and the getting-on hydraulic pump are both motor-driven hydraulic pumps.

[0034] On the other hand, the present application further provides an electric-driven aerial work platform, which includes the hydraulic system of the above-mentioned electric-driven aerial work platform.

[0035] The hydraulic system of the electric-driven aerial work platform of this application utilizes an independent and distributed arrangement of the upper and lower hydraulic systems. This effectively solves the problem of high pressure loss caused by the lower steering cylinder and floating cylinder requiring the upper hydraulic pump to pump high-pressure oil through a central rotary joint in the prior art. This reduces energy consumption, increases energy efficiency, and meets the needs of energy conservation and emission reduction.

[0036] 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

[0037] 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:

[0038] FIG1 is a hydraulic principle diagram of a portion of the hydraulic system of an electric-driven aerial work platform in the prior art;

[0039] FIG2 is a hydraulic principle diagram of a dismounting hydraulic system in a hydraulic system of an electric-driven aerial work platform according to a specific embodiment of the present application, wherein the travel motor hydraulic circuit and the like are omitted; and

[0040] FIG3 is a hydraulic principle diagram of the integrated control valve group used in the hydraulic system of FIG2 .

[0041] LIST OF REFERENCE NUMERALS 1 Hydraulic oil tank 2 Lowering hydraulic pump 3 High-pressure filter 4 Control valve group 5 Pressure measuring joint 6 Floating cylinder assembly 7 Steering cylinder 41 Compensator 42 Main relief valve 43 Pressure reducing valve 44 Floating relief valve 45 Floating control valve 46 Shuttle valve 47 Steering reversing valve 48 Pressure-compensating flow valve 49 Check valve 410 Throttle valve L0 Main return oil line L1 Main oil supply line L' Pilot control oil line L1' Bypass oil supply line A1 First working oil port A2 Second working oil port V1 First hydraulic connection point V2 Second hydraulic connection point DETAILED DESCRIPTION

[0042] 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.

[0043] The following describes the electric-driven aerial work platform and its hydraulic system according to the present application with reference to the accompanying drawings.

[0044] As previously mentioned, the hydraulic systems of existing electric-driven aerial work platforms are overly complex and redundant, resulting in high energy consumption and no longer meeting the energy-saving requirements of electric-driven vehicles. Therefore, this application discloses a new hydraulic system for an electric-driven aerial work platform. As shown in FIG2 , in one embodiment, the new hydraulic system includes:

[0045] The upper vehicle hydraulic system includes the luffing cylinder and telescopic cylinder that drive the boom, and the upper vehicle hydraulic pump that supplies oil to the luffing cylinder and telescopic cylinder; and

[0046] The vehicle disembarkation hydraulic system includes a steering cylinder 7 for driving the vehicle body to steer, a floating cylinder assembly 6, and a vehicle disembarkation hydraulic pump 2 for supplying oil to the steering cylinder 7 and the floating cylinder assembly 6;

[0047] The onboard hydraulic system and the offboard hydraulic system are independent of each other, and the rated displacement of the onboard hydraulic pump is greater than the rated displacement of the offboard hydraulic pump 2.

[0048] In this application, the hydraulic system for getting off the vehicle and the hydraulic system for getting on the vehicle are specifically separated. The two do not share the same oil source and are not connected by oil pipes. This not only simplifies the pipeline wiring, but also greatly reduces the energy consumption of the entire vehicle based on the electric drive characteristics. This will be discussed in detail below.

[0049] As shown in Figure 1, in the hydraulic system of a conventional electric-driven aerial work platform, the lower vehicle's steering and floating movements share the upper vehicle's large-displacement main pump with the upper vehicle's luffing, telescoping, and other movements. A multi-way valve on the upper vehicle controls the lower vehicle's steering and floating. This hydraulic system is not only complex and difficult to route, but also consumes a significant amount of electricity, for unknown reasons.

[0050] Through long-term and unremitting observation and experiments, the inventors of this application have concluded that it is precisely because when the vehicle is loaded, steered and floated in combination, the hydraulic system pressure is at the high pressure required for the vehicle loading action, and the high-pressure hydraulic oil needs to be reduced in pressure when supplied to the steering and floating actions, and the oil circuit needs to pass through the center rotary joint when transferring from loading to unloading. These inevitably lead to large pressure loss and high energy consumption, which makes it difficult to meet the energy consumption requirements of electric vehicles.

[0051] Therefore, the hydraulic system of the present application solves the problem that the steering cylinder and floating cylinder of the vehicle getting off the vehicle need to transmit the high-pressure pumping oil of the vehicle hydraulic pump through the center rotary joint, which causes large pressure loss, and meets the needs of energy conservation and emission reduction.

[0052] In the embodiment of FIG. 2 and FIG. 3 , the vehicle disembarking hydraulic system may include a steering control hydraulic circuit, which includes:

[0053] The steering reversing valve 47 is used for reversing the steering cylinder 7 and includes a first working oil port A1 and a second working oil port A2 connected to the large and small chambers of the steering cylinder 7, respectively. The oil inlet of the steering reversing valve 47 is connected to the main oil inlet line L1, and the oil return port is connected to the main oil return line L0;

[0054] The shuttle valve 46 has two comparison oil ports connected to the first working oil port A1 and the second working oil port A2 respectively;

[0055] The compensator 41 is connected between the main oil inlet line L1 and the main oil return line L0 , and its control oil port is hydraulically connected to the oil outlet of the shuttle valve 46 through the pilot control oil line L′.

[0056] Compensator 41 receives a relatively high-pressure pilot signal from shuttle valve 46 to ensure the desired system flow and pressure output. Specifically, when the steering cylinder 7 is operating under load, compensator 41 is essentially closed, disconnecting the main oil inlet line L1 from the system. When the steering cylinder 7 is not operating, compensator 41's valve can be partially opened, allowing the pressurized oil in the main oil inlet line L1 to be discharged through compensator 41, ensuring the desired system flow and pressure output.

[0057] In Figure 3, as an example, the compensator 41 is a hydraulically controlled stop valve with a continuously adjustable valve opening. The control oil port of the compensator 41 includes a first control end and a second control end at both ends. The first control end is a spring end and is connected to the pilot control oil circuit L', and the second control end is hydraulically connected to the main oil inlet circuit L1. When the disembarkation hydraulic pump 2 is not started, the main oil inlet circuit L1 is at low pressure, and the first control end maintains the compensator 41 in the right stop position shown in the figure under the action of the spring. When the disembarkation hydraulic pump 2 is started and the steering cylinder 7 is working, the pressure is relieved or the oil is replenished according to the load requirements. Of course, those skilled in the art will understand that the compensator 41 may have various other valve body structures and forms, and is not limited to that shown in Figure 3.

[0058] In addition, the steering control hydraulic circuit may also include:

[0059] A one-way valve 49 is provided in the pilot control oil circuit L' of the compensator 41;

[0060] The one-way valve 49 is configured to allow the hydraulic oil to flow from the oil outlet of the shuttle valve 46 to the control oil port of the compensator 41 and to block the flow in the reverse direction.

[0061] The setting of the one-way valve 49 can be used to provide a certain back pressure and make the system have a certain anti-interference ability.

[0062] In addition, the steering control hydraulic circuit may also include:

[0063] The throttle valve 410 is provided in the connecting oil passage between the pilot control oil passage L′ and the main oil return oil passage L0 .

[0064] The purpose of providing the throttle valve 410 here is to remove the signal transmitted by the shuttle valve 46 and maintain the stability of the compensator 41.

[0065] Furthermore, the steering control hydraulic circuit may also include:

[0066] The pressure compensation flow valve 48 is provided in the main oil inlet passage L1 adjacent to the oil inlet of the steering reversing valve 47 .

[0067] The pressure-compensated flow valve 48 provided here can be used to further control and provide a constant flow to the steering mechanism.

[0068] In this embodiment, the vehicle disembarking hydraulic system may further include a floating control hydraulic circuit, which includes:

[0069] The floating control valve 45 is used to control the floating cylinder assembly 6. The oil inlet of the floating control valve 45 is connected to the main oil inlet line L1 through the bypass oil inlet line L1';

[0070] The pressure reducing valve 43 is provided in the bypass oil inlet line L1';

[0071] The bypass oil inlet circuit L1' forms a first hydraulic connection point V1 on the main oil inlet circuit L1, and the compensator 41 forms a second hydraulic connection point V2 on the main oil inlet circuit L1. The first hydraulic connection point V1 is located at the downstream end of the second hydraulic connection point V2.

[0072] As can be seen, the floating control hydraulic circuit is arranged in parallel with the steering control hydraulic circuit. The floating control hydraulic circuit draws pressurized oil from the main oil inlet line L1 via the bypass oil inlet line L1'. After the pressure oil in the main oil inlet line L1 is reduced by the pressure reducing valve 43, most of the oil is supplied to the large and small chambers of the floating cylinder assembly 6, and a small portion is supplied to the floating control valve 45 as pilot hydraulic oil, which is used to pilot control the balancing valve group of the floating cylinder to achieve floating hydraulic locking or cylinder pressure relief of the floating cylinder. The first hydraulic connection point V1 formed by the bypass oil inlet line L1' on the main oil inlet line L1 is located downstream of the second hydraulic connection point V2 formed by the compensator 41 on the main oil inlet line L1. This makes the compensator 41's oil supply compensation control of the steering cylinder 7 less affected by the oil distribution of the floating cylinder assembly 6.

[0073] In addition, the dismounting hydraulic system may also include:

[0074] A floating relief valve 44 is provided between the bypass oil inlet line L1' and the main oil return line L0 between the pressure reducing valve 43 and the floating control valve 45; and

[0075] The main relief valve 42 is provided between the main oil inlet passage L1 and the main oil return passage L0 .

[0076] The main relief valve 42 serves as a safety valve for the entire system, ensuring that the circuit pressure does not exceed the maximum allowable pressure of the off-vehicle hydraulic pump 2 at any time. The float relief valve 44 ensures that the pressure of the float control hydraulic circuit does not exceed a safe range.

[0077] The above valves can be provided separately or in an integrated manner. Therefore, the vehicle disembarking hydraulic system may further include:

[0078] The power unit assembly includes an integrated dismounting hydraulic pump 2, a motor, and a hydraulic oil tank 1;

[0079] The control valve group 4 at least includes an integrated steering reversing valve 47 , a shuttle valve 46 , a compensator 41 , a floating control valve 45 and a pressure reducing valve 43 .

[0080] The lower hydraulic pump 2 can be integrated with the control valve assembly 4 or provided separately. The floating cylinder assembly 6 includes a floating balancing valve and a cylinder to achieve the floating function of the entire unit. The high-pressure filter 3 in Figure 2 filters the oil output by the lower hydraulic pump 2. The pressure tap 5 is used to detect system or circuit pressure. The pressure tap 5 can be replaced with a pressure sensor to implement alternative control logic.

[0081] When the operator operates the vehicle to move, oil pumped from the dismounting hydraulic pump 2 passes through the high-pressure filter 3 and enters the control valve group 4. This oil controls the float of the vehicle via the float control valve 45, and the steering of the vehicle via the steering reversing valve 47. The dismounting hydraulic system utilizes a separate, distributed layout of the dismounting hydraulic pump 2 and the control valve group 4, isolating it from other vehicle operations to achieve energy savings and reduce consumption.

[0082] It should be noted that both the disembarkation hydraulic pump 2 and the onboard hydraulic pump in this embodiment are motor-driven hydraulic pumps. The disembarkation hydraulic system may also include a travel control hydraulic circuit, including multiple travel motors, etc., which may be supplied with oil by the disembarkation hydraulic pump 2 or by an independent pump.

[0083] Specifically, referring to Figure 2 , after the vehicle's hydraulic pump 2 is activated, if the vehicle needs to float, electromagnet Y1 is energized, placing float control valve 45 in the upper cutoff position. The pressure oil in main oil inlet line L1 is reduced in pressure by pressure reducing valve 43, then flows through the check valve in the balancing valve assembly to the floating cylinder assembly 6, where it is locked by the balancing valve assembly. If the vehicle needs to be released from floating, electromagnet Y1 is de-energized, placing float control valve 45 in the lower conduction position. The pressure oil reduced by pressure reducing valve 43 acts as pilot oil to control the opening of the sequence valve in the single balancing valve. The oil in the large chamber of the floating cylinder can then be returned through the sequence valve, releasing the floating state. If the vehicle needs to steer, electromagnet Y3 or Y5 is energized, depending on the steering direction. The pressure oil in main oil inlet line L1 flows through steering reversing valve 47 to steering cylinder 7, controlling vehicle steering.

[0084] This application also discloses a new electric-driven aerial work platform, including the hydraulic system of the electric-driven aerial work platform described above. This new electric-driven aerial work platform better solves the existing problem of requiring the high-pressure pumping oil of the onboard hydraulic pump to be transferred through a central rotary joint for the steering cylinder and floating cylinder of the offboard vehicle, resulting in high pressure loss, and better meets the needs of energy conservation and emission reduction.

[0085] 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.

[0086] 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.

[0087] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean 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.

[0088] 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 an electric drive aerial work platform, characterized in that, The hydraulic system includes: an upper vehicle hydraulic system, including a boom luffing cylinder, a telescopic cylinder for driving the boom, and an upper vehicle hydraulic pump for supplying oil to the luffing cylinder and the telescopic cylinder; and a lower vehicle hydraulic system, including a steering cylinder (7) for driving the vehicle body to steer, a floating cylinder assembly (6), and a lower vehicle hydraulic pump (2) for supplying oil to the steering cylinder (7) and the floating cylinder assembly (6); wherein, the upper vehicle hydraulic system and the lower vehicle hydraulic system are independent of each other, and the rated displacement of the upper vehicle hydraulic pump is greater than the rated displacement of the lower vehicle hydraulic pump (2).

2. The hydraulic system of the electric drive aerial work platform according to claim 1, characterized in that, The lower vehicle hydraulic system includes a steering control hydraulic circuit, and the steering control hydraulic circuit includes: a steering reversing valve (47) for reversing control of the steering cylinder (7) and including a first working oil port (A1) and a second working oil port (A2) respectively connected to the large and small chambers of the steering cylinder (7), an oil inlet of the steering reversing valve (47) is connected with a main inlet oil circuit (L1), and an oil return port is connected with a main oil return circuit (L0); a shuttle valve (46) with two comparison oil ports respectively connected to the first working oil port (A1) and the second working oil port (A2); a compensator (41) connected between the main inlet oil circuit (L1) and the main oil return circuit (L0), and a control oil port is hydraulically connected to the oil outlet of the shuttle valve (46) through a pilot control oil circuit (L').

3. The hydraulic system of the electric drive aerial work platform according to claim 2, characterized in that, The compensator (41) is a liquid-controlled stop valve with continuously adjustable valve opening, and the control oil port of the compensator (41) includes a first control end and a second control end at both ends. The first control end is a spring end and is connected with the pilot control oil circuit (L'), and the second control end is hydraulically connected to the main inlet oil circuit (L1).

4. The hydraulic system of the electric drive aerial work platform according to claim 2, characterized in that, The steering control hydraulic circuit includes: a check valve (49) arranged in the pilot control oil circuit (L') of the compensator (41); wherein, the check valve (49) is arranged to allow hydraulic oil to flow from the oil outlet of the shuttle valve (46) to the control oil port of the compensator (41) and be cut off in the reverse direction.

5. The hydraulic system of the electric drive aerial work platform according to claim 2, characterized in that, The steering control hydraulic circuit includes: a throttle valve (410) arranged in a connecting oil circuit between the pilot control oil circuit (L') and the main oil return circuit (L0).

6. The hydraulic system of the electric drive aerial work platform according to claim 2, characterized in that, The steering control hydraulic circuit includes: a pressure compensating flow valve (48) arranged in the main inlet oil circuit (L1) adjacent to the oil inlet of the steering reversing valve (47).

7. The hydraulic system of the electric drive aerial work platform according to any one of claims 2 to 6, characterized in that, The lower vehicle hydraulic system includes a floating control hydraulic circuit, and the floating control hydraulic circuit includes: a floating control valve (45) for controlling the floating cylinder assembly (6), and an oil inlet of the floating control valve (45) is connected to the main inlet oil circuit (L1) through a bypass inlet oil circuit (L1'); a pressure reducing valve (43) arranged in the bypass inlet oil circuit (L1'); wherein, the bypass inlet oil circuit (L1') forms a first hydraulic connection point (V1) on the main inlet oil circuit (L1), and the compensator (41) forms formed with a second hydraulic connection point (V2), and the first hydraulic connection point (V1) is located at the downstream end of the second hydraulic connection point (V2).

8. The hydraulic system of the electric drive aerial work platform according to claim 7, characterized in that, The lower vehicle hydraulic system includes: a floating relief valve (44) disposed between the bypass inlet oil passage (L1') and the main return oil passage (L0) between the pressure reducing valve (43) and the floating control valve (45); and a main relief valve (42) disposed between the main inlet oil passage (L1) and the main return oil passage (L0).

9. The hydraulic system of the electric drive aerial work platform according to claim 7, characterized in that, The lower vehicle hydraulic system includes: a power unit assembly including the lower vehicle hydraulic pump (2), a motor, and a hydraulic oil tank (1) integrally arranged; a control valve group (4) at least including the steering reversing valve (47), the shuttle valve (46), the compensator (41), the floating control valve (45), and the pressure reducing valve (43) integrally arranged.

10. The hydraulic system of the electric drive aerial work platform according to claim 1, characterized in that, Both the lower vehicle hydraulic pump (2) and the upper vehicle hydraulic pump are motor-driven hydraulic pumps.

11. Electrically-driven aerial work platform, characterized in that, The electric drive aerial work platform includes the hydraulic system of the electric drive aerial work platform according to any one of claims 1 to 10.

Images