Hydraulic system for high-altitude operation machine and high-altitude operation machine

Abstract

The utility model belongs to the technical field of high-altitude operation and provides a hydraulic system for a high-altitude operation machine and the high-altitude operation machine, the hydraulic system comprises a plurality of action execution units, a power unit, a first selection valve and a power generation control unit, the plurality of action execution units comprise a lifting unit, and the lifting unit comprises a lifting oil cylinder; the power unit comprises a two-way pump and a power generation motor which are in transmission connection; the first selection valve is used for selectively communicating a first pumping oil way of the two-way pump with a rodless cavity working oil way of the lifting oil cylinder or other action execution units; the power generation control unit comprises a bypass oil way and a power generation control valve, the bypass oil way is connected between the rodless cavity working oil way and the oil return oil way, and the power generation control valve is used for controlling the on-off of the bypass oil way. According to the system, the scheme that the two-way pump and the generator are combined for energy recovery is organically combined with driving of other action execution units, and after combination, all the units are mutually independent in function.

Description

Technical Field

[0001] This utility model belongs to the field of high-altitude operation technology, specifically relating to a hydraulic system for high-altitude operation machinery and the high-altitude operation machinery itself. Background Technology

[0002] In recent years, there have been explorations into the recovery of potential energy during the descent of aerial work platforms. For example, some technologies convert the potential energy of the boom descent into hydraulic or electrical energy by adding an accumulator or energy conversion device to the hydraulic system. However, such solutions often introduce complex valve groups and redundant components, and the energy recovery efficiency is limited by valve pressure loss. In addition, some existing technologies achieve energy recovery through the combination of a two-way pump and a generator, such as the patent with publication number CN118499293A. However, in aerial work platforms, the hydraulic drive architecture of other action units is still based on an open-loop design. The open-loop design supplies oil through a single-phase pump and controls the oil flow through a solenoid valve. If the existing energy recovery solution combining a two-way pump and a generator is forcibly applied to the hydraulic system of aerial work platforms, it can easily lead to functional conflicts. Utility Model Content

[0003] To address the aforementioned deficiencies or shortcomings, this utility model provides a hydraulic system and aerial work platform for use, aiming to solve the technical problem that the existing energy recovery scheme combining a bidirectional pump and a generator is difficult to apply to aerial work platforms.

[0004] To achieve the above objectives, this utility model provides a hydraulic system for aerial work platforms. The hydraulic system includes several action execution units, a power unit, a first selector valve, and a generator control unit. The action execution units include a lifting unit, which includes a lifting cylinder. The power unit includes a bidirectional pump and a generator motor connected by a transmission connection. The first selector valve is used to selectively connect the first pumping oil circuit of the bidirectional pump to the rodless chamber working oil circuit of the lifting cylinder or other action execution units. The generator control unit includes a bypass oil circuit and a generator control valve. The bypass oil circuit is connected between the rodless chamber working oil circuit and the return oil circuit, and the generator control valve is used to control the on / off state of the bypass oil circuit.

[0005] In an embodiment of this utility model, the lifting unit further includes a lifting control valve group, which is disposed on the rodless chamber working oil circuit and used to control the on / off state of the rodless chamber working oil circuit. One end of the bypass oil circuit is connected between the lifting control valve group and the first selector valve, and the other end of the bypass oil circuit is connected to the return oil circuit.

[0006] In an embodiment of this utility model, the lifting control valve group includes an on / off control valve and a one-way throttle valve. The one-way throttle valve is disposed between the on / off control valve and the first selector valve. The one-way throttle valve is configured to allow unidirectional flow and reverse throttling of hydraulic oil when it flows from the first selector valve to the on / off control valve.

[0007] In an embodiment of this utility model, the power unit includes a first pumping oil circuit and a second pumping oil circuit of a bidirectional pump. A selective return oil valve is provided between the first pumping oil circuit and the second pumping oil circuit. The selective return oil valve is used to control the other circuit to be connected to the return oil circuit when one of the first pumping oil circuit and the second pumping oil circuit is a pressure oil circuit.

[0008] In an embodiment of this utility model, the plurality of action execution units further include a steering unit, the steering unit includes a steering drive cylinder, the working oil port on the first side of the first selector valve is connected to the first pumping oil circuit, and the working oil port on the second side of the first selector valve is connected to the steering drive cylinder and the rodless chamber working oil circuit respectively.

[0009] In an embodiment of this utility model, the working oil port on the second side of the first selector valve is connected to the first working chamber of the steering drive cylinder. The hydraulic system for aerial work machinery also includes a second selector valve, which is used to selectively connect the second pumping oil circuit of the bidirectional pump to the second working chamber of the steering drive cylinder.

[0010] In an embodiment of this utility model, a first high-pressure selection oil circuit is provided between the working oil circuit of the first working chamber and the working oil circuit of the second working chamber. The first high-pressure selection oil circuit is connected to the return oil circuit through a first pressure relief valve, and the pilot pressure tapping end of the first pressure relief valve is connected to the pressure tapping outlet of the first high-pressure selection oil circuit.

[0011] In an embodiment of this utility model, the power unit includes a first pumping oil circuit and a second pumping oil circuit of a bidirectional pump. A second high-pressure selection oil circuit is provided between the first pumping oil circuit and the second pumping oil circuit. The second high-pressure selection oil circuit is connected to the return oil circuit through a second pressure relief valve. The pilot pressure tapping end of the second pressure relief valve is connected to the pressure tapping outlet of the second high-pressure selection oil circuit.

[0012] In an embodiment of this utility model, the power unit includes a first pumping oil passage and a second pumping oil passage of a bidirectional pump. A one-way replenishment oil passage is provided between the first pumping oil passage and the second pumping oil passage. One end of the one-way replenishment oil passage is connected to the oil tank, and the other end is connected one-way to the first pumping oil passage and the second pumping oil passage, respectively.

[0013] To achieve the above objectives, this utility model also provides an aerial work platform, wherein the aerial work platform includes the hydraulic system for aerial work platforms as described above.

[0014] Through the above technical solution, the hydraulic system for aerial work machinery provided by this utility model embodiment has the following beneficial effects:

[0015] This system, through the cooperation of the first selection valve and the generator control valve, requires only one power unit to achieve four operating modes: lifting cylinder extension drive, energy recovery during lifting cylinder retraction, no energy recovery during lifting cylinder retraction, and drive by other motion execution units. This design not only organically combines the energy recovery scheme of combining a bidirectional pump with a generator with the drive of other motion execution units, but also ensures that the four operating modes of the system are independent of each other, effectively avoiding the conflict between functional modules caused by forced functional integration.

[0016] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a hydraulic schematic diagram of the hydraulic system for aerial work machinery according to an embodiment of the present utility model;

[0019] Figure 2 This is a structural schematic diagram of the scissor lift aerial work platform according to an embodiment of the present utility model.

[0020] Explanation of reference numerals in the attached figures

[0021] 1. Lifting unit; 11. Lifting cylinder; 111. Rodless chamber working oil circuit; 12. Lifting control valve assembly; 121. On / off control valve; 122. One-way throttle valve; 21. Two-way pump; 211. First pumping oil circuit; 212. Second pumping oil circuit; 22. Generator motor; 23. Selector return valve; 31. First selector valve; 32. Second selector valve; 41. Bypass oil circuit; 42. Generator control valve; 5. Steering unit; 51. Steering drive cylinder; 61. First high-pressure selector oil circuit; 62. First pressure relief valve; 63. Second high-pressure selector oil circuit; 64. Second pressure relief valve; 65. One-way replenishment oil circuit. Detailed Implementation

[0022] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0023] The hydraulic system for aerial work machinery of this invention is described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, this utility model provides a hydraulic system for aerial work machinery, wherein the hydraulic system for aerial work machinery includes several action execution units, a power unit, a first selection valve 31 and a power generation control unit.

[0025] The plurality of motion execution units include a lifting unit 1 and other motion execution units. The lifting unit 1 includes a lifting cylinder 11 for driving lifting or luffing.

[0026] The power unit includes a bidirectional pump 21 and a generator motor 22 connected by a drive. When the battery supplies power to the generator motor 22, the generator motor 22 drives the bidirectional pump 21 to rotate, so as to provide pressurized oil to the lifting unit 1 or other execution units. When the system performs potential energy recovery, the pressurized oil in the rodless chamber of the lifting cylinder 11 drives the bidirectional pump 21 to drive the generator motor 22 to rotate, so as to generate electricity.

[0027] The first selection valve 31 is used to selectively connect the first pumping oil circuit 211 of the bidirectional pump 21 to the rodless chamber working oil circuit 111 of the lifting cylinder 11 or other actuation units. Through the first selection valve 31, the lifting unit 1 and other actuation units can share a set of power units while ensuring that they can work independently.

[0028] The power generation control unit includes a bypass oil passage 41 and a power generation control valve 42. The bypass oil passage 41 is connected between the rodless chamber working oil passage 111 and the return oil passage. The power generation control valve 42 is used to control the opening and closing of the bypass oil passage 41.

[0029] When the extension drive of the lifting cylinder 11 is required, the first selector valve 31 is switched to the valve position that connects to the rodless chamber working oil passage 111 of the lifting cylinder 11, and the generator control valve 42 is switched to the shut-off valve position. Power is supplied to the generator motor 22 by the battery, which drives the bidirectional pump 21 to pump oil into the first pumping oil passage 211. The pressurized oil flows sequentially through the first selector valve 31 and the rodless chamber working oil passage 111 into the rodless chamber of the lifting cylinder 11, thereby realizing the extension drive of the lifting cylinder 11.

[0030] When the lifting cylinder 11 retracts under the influence of the platform's own weight, if the overall vehicle condition meets the charging requirements, the first selector valve 31 can be controlled to switch to the valve position connected to the rodless chamber working oil circuit 111, and the generator control valve 42 can be controlled to switch to the shut-off valve position. During the retraction process of the lifting cylinder 11, the pressure oil in the rodless chamber will flow sequentially through the rodless chamber working oil circuit 111, the first selector valve 31, the first pumping oil circuit 211, and then to the bidirectional pump 21, ultimately driving the bidirectional pump 21 to drive the generator motor 22 to rotate and generate electricity, realizing the energy conversion and recovery of potential energy into electrical energy.

[0031] When the lifting cylinder 11 retracts under the influence of the platform's own weight, if the overall vehicle condition does not meet the charging requirements, the generator control valve 42 can be switched to the on position. After the generator control valve 42 is turned on, the pressure oil in the rodless chamber of the lifting cylinder will return through the rodless chamber working oil circuit 111 and the bypass oil circuit 41 in sequence.

[0032] When it is necessary to drive other action execution units, simply switch the first selection valve 31 to the valve position connected to the corresponding action execution unit, and the bidirectional pump 21 can supply oil to that action execution unit.

[0033] In summary, this system, through the cooperation of the first selection valve 31 and the generator control valve 42, requires only one power unit to achieve four operating modes: extension drive of the lifting cylinder 11, energy recovery when the lifting cylinder 11 retracts, no energy recovery when the lifting cylinder 11 retracts, and drive by other action execution units. This design not only organically combines the energy recovery scheme of the bidirectional pump 21 combined with the generator with the drive of other action execution units, but also ensures that the four operating modes of the system are independent of each other, effectively avoiding the conflict between functional modules caused by forced functional integration.

[0034] like Figure 1 As shown in the embodiment of this utility model, the lifting unit 1 further includes a lifting control valve group 12. The lifting control valve group 12 is disposed on the rodless chamber working oil passage 111 and is used to control the opening and closing of the rodless chamber working oil passage 111. One end of the bypass oil passage 41 is connected between the lifting control valve group 12 and the first selector valve 31, and the other end of the bypass oil passage 41 is connected to the return oil passage.

[0035] By controlling the on / off state of the lifting control valve group 12, the lifting cylinder 11 can be driven and locked during the lifting process.

[0036] Specifically, in an embodiment of this utility model, the lifting control valve assembly 12 includes an on / off control valve 121 and a one-way throttle valve 122. The one-way throttle valve 122 is disposed between the on / off control valve 121 and the first selector valve 31. The one-way throttle valve 122 is configured to allow hydraulic oil to flow unidirectionally from the first selector valve 31 to the on / off control valve 121 and to throttle in the reverse direction. When the lifting cylinder 11 needs to extend or retract, switching the on / off control valve 121 to the open state allows hydraulic oil to smoothly enter and exit the rodless chamber of the lifting cylinder 11. In addition, when hydraulic oil flows out of the rodless chamber of the lifting cylinder 11, the throttling effect of the one-way throttle valve 122 enables the lifting cylinder 11 to retract slowly and smoothly, ensuring the safe descent of the aerial work platform. When the lifting cylinder 11 extends to a certain length and needs to be locked, the on / off control valve 121 is switched to the off state, which can cause the rodless chamber of the lifting cylinder 11 to be pressurized, effectively preventing the lifting cylinder 11 from retracting.

[0037] like Figure 1 As shown in the embodiment of this utility model, the bidirectional pump 21 is provided with a first pumping oil port and a second pumping oil port. The power unit includes a first pumping oil passage 211 and a second pumping oil passage 212 respectively connected to the first pumping oil port and the second pumping oil port. A selective return oil valve 23 is provided between the first pumping oil passage 211 and the second pumping oil passage 212. The selective return oil valve 23 is used to control the other one to be connected to the return oil passage when one of the first pumping oil passage 211 and the second pumping oil passage 212 is a pressure oil passage.

[0038] Select the return oil valve 23, which has an intermediate shut-off valve position, and the first valve position that connects the first pumping oil circuit 211 with the return oil circuit. Figure 1 The lower valve position), the second valve position that connects the second pump oil circuit 212 to the return oil circuit ( Figure 1 The pilot control terminal corresponding to the first valve position (upper valve position) is connected to the second pumping oil circuit 212, and the pilot control terminal corresponding to the second valve position is connected to the first pumping oil circuit 211. When the first pumping oil circuit 211 is under high pressure, the selector return valve 23 will switch to the second valve position, making the second pumping oil circuit 212 connected to the return oil circuit. When the second pumping oil circuit 212 is under high pressure, the selector return valve 23 will switch to the first valve position, making the first pumping oil circuit 211 connected to the return oil circuit. By setting the selector return valve 23, when the bidirectional pump 21 supplies oil to other action execution units, the direction control of the action execution unit can be achieved by controlling the rotation direction of the bidirectional pump 21.

[0039] Taking the motion execution unit of aerial work machinery, including the steering unit 5, as an example, Figure 1 As shown, the steering unit 5 includes a steering drive cylinder 51. The working port on the first side of the first selector valve 31 is connected to the first pumping oil circuit 211, and the working port on the second side of the first selector valve 31 is connected to both the steering drive cylinder 51 and the rodless chamber working oil circuit 111. Through the first selector valve 31, the hydraulic oil in the first pumping oil circuit 211 can be selectively directed to either the lifting cylinder 11 or the steering drive cylinder 51.

[0040] Furthermore, the steering drive cylinder 51 can be a single-headed cylinder or a double-headed cylinder. The working port on the second side of the first selector valve 31 is connected to the first working chamber of the steering drive cylinder 51. The hydraulic system for aerial work platforms also includes a second selector valve 32, which is used to selectively connect the second pumping oil circuit 212 of the bidirectional pump 21 to the second working chamber of the steering drive cylinder 51. Of course, the second selector valve 32 can also selectively connect the second pumping oil circuit 212 to other oil circuits, such as the return oil circuit.

[0041] When it is necessary to control the aerial work platform to turn in one direction, the bidirectional pump 21 can be controlled to supply oil to the first pumping oil circuit 211, and the first selector valve 31 can be controlled to open the working oil circuit between the first pumping oil circuit 211 and the first working chamber. The second selector valve 32 can be controlled to open the working oil circuit between the second pumping oil circuit 212 and the second working chamber. At this time, the pressurized oil from the first pumping oil circuit 211 will enter the first working chamber of the steering drive cylinder 51 through the first selector valve 31. Simultaneously, the hydraulic oil in the second working chamber of the steering drive cylinder 51 will return through the second selector valve 32, the second pumping oil circuit 212, and the return valve 23. Similarly, when the machine needs to turn in the other direction, the bidirectional pump 21 can be reversed while ensuring that the first selector valve 31 and the second selector valve 32 are in the same state.

[0042] like Figure 1 As shown in the embodiment of this utility model, a first high-pressure selection oil circuit 61 is provided between the working oil circuit of the first working chamber and the working oil circuit of the second working chamber. The first high-pressure selection oil circuit 61 is connected to the return oil circuit through a first pressure relief valve 62, and the pilot pressure tapping end of the first pressure relief valve 62 is connected to the pressure tapping outlet of the first high-pressure selection oil circuit 61. A shuttle valve for pressure tapping is provided on the first high-pressure selection oil circuit 61. When the oil pressure of either the working oil circuit of the first working chamber or the working oil circuit of the second working chamber exceeds the set pressure of the first pressure relief valve 62, the first pressure relief valve 62 will open to relieve pressure, thereby realizing overpressure protection of the steering drive cylinder 51.

[0043] Similarly, in an embodiment of this utility model, the power unit includes a first pumping oil passage 211 and a second pumping oil passage 212 of a bidirectional pump 21. A second high-pressure selection oil passage 63 is provided between the first pumping oil passage 211 and the second pumping oil passage 212. The second high-pressure selection oil passage 63 is connected to the return oil passage through a second pressure relief valve 64, and the pilot pressure tap of the second pressure relief valve 64 is connected to the second high-pressure selection oil passage 63. By setting the second high-pressure selection oil passage 63 and the second pressure relief valve 64, overpressure protection of the power unit is achieved.

[0044] In embodiments of this utility model, other action execution units may also include walking units, etc.

[0045] like Figure 1 As shown in the embodiment of this utility model, the power unit includes a first pumping oil passage 211 and a second pumping oil passage 212 of the bidirectional pump 21. A one-way replenishment oil passage 65 is provided between the first pumping oil passage 211 and the second pumping oil passage 212. One end of the one-way replenishment oil passage 65 is connected to the oil tank, and the other end is connected unidirectionally to the first pumping oil passage 211 and the second pumping oil passage 212 respectively. By setting the one-way replenishment oil passage 65, oil replenishment can be achieved on the suction side of the bidirectional pump 21 when the bidirectional pump 21 rotates forward or reverse.

[0046] In an embodiment of this utility model, the unidirectional oil replenishment circuit 65 is configured such that hydraulic oil can only flow from the oil tank to the first pumping circuit 211 or the second pumping circuit 212.

[0047] like Figure 2 As shown, to achieve the above objectives, this utility model also provides an aerial work platform, which can be a scissor lift, articulated boom lift, telescopic boom lift, etc. The aerial work platform includes the hydraulic system described above. Since the aerial work platform adopts all the technical solutions of the above embodiments, it at least possesses the beneficial effects brought by the above embodiments, and will not be repeated here.

[0048] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] Although embodiments of the present invention have been described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic system for aerial work machinery, characterized in that, The hydraulic system for the aerial work machinery includes: Several action execution units, including a lifting unit (1), wherein the lifting unit (1) includes a lifting cylinder (11); The power unit includes a bidirectional pump (21) and a generator motor (22) connected by a drive. The first selection valve (31) is used to selectively connect the first pumping oil passage (211) of the bidirectional pump (21) to the rodless chamber working oil passage (111) of the lifting cylinder (11) or other action execution units; The power generation control unit includes a bypass oil passage (41) and a power generation control valve (42). The bypass oil passage (41) is connected between the rodless chamber working oil passage (111) and the return oil passage. The power generation control valve (42) is used to control the opening and closing of the bypass oil passage (41).

2. The hydraulic system for aerial work machinery according to claim 1, characterized in that, The lifting unit (1) further includes a lifting control valve assembly (12), which is disposed on the rodless chamber working oil circuit (111) and used to control the opening and closing of the rodless chamber working oil circuit (111). One end of the bypass oil circuit (41) is connected between the lifting control valve assembly (12) and the first selector valve (31), and the other end of the bypass oil circuit (41) is connected to the return oil circuit.

3. The hydraulic system for aerial work machinery according to claim 2, characterized in that, The lifting control valve assembly (12) includes an on / off control valve (121) and a one-way throttle valve (122). The one-way throttle valve (122) is disposed between the on / off control valve (121) and the first selector valve (31). The one-way throttle valve (122) is configured to unidirectionally open and reversely throttle when hydraulic oil flows from the first selector valve (31) to the on / off control valve (121).

4. The hydraulic system for aerial work machinery according to claim 1, characterized in that, The power unit includes a first pumping oil passage (211) and a second pumping oil passage (212) of the bidirectional pump (21). A selective return oil valve (23) is provided between the first pumping oil passage (211) and the second pumping oil passage (212). The selective return oil valve (23) is used to control the other to be connected to the return oil passage when one of the first pumping oil passage (211) and the second pumping oil passage (212) is a pressure oil passage.

5. The hydraulic system for aerial work machinery according to claim 4, characterized in that, The action execution units further include a steering unit (5), which includes a steering drive cylinder (51). The working port on the first side of the first selector valve (31) is connected to the first pumping oil circuit (211), and the working port on the second side of the first selector valve (31) is connected to the steering drive cylinder (51) and the rodless chamber working oil circuit (111), respectively.

6. The hydraulic system for aerial work machinery according to claim 5, characterized in that, The working port on the second side of the first selector valve (31) is connected to the first working chamber of the steering drive cylinder (51). The hydraulic system for the aerial work machinery also includes a second selector valve (32), which is used to selectively connect the second pumping oil circuit (212) of the bidirectional pump (21) to the second working chamber of the steering drive cylinder (51).

7. The hydraulic system for aerial work machinery according to claim 6, characterized in that, A first high-pressure selection oil circuit (61) is provided between the working oil circuit of the first working chamber and the working oil circuit of the second working chamber. The first high-pressure selection oil circuit (61) is connected to the return oil circuit through a first pressure relief valve (62). The pilot pressure tapping end of the first pressure relief valve (62) is connected to the pressure tapping outlet of the first high-pressure selection oil circuit (61).

8. The hydraulic system for aerial work machinery according to any one of claims 1 to 7, characterized in that, The power unit includes a first pumping oil passage (211) and a second pumping oil passage (212) of the bidirectional pump (21). A second high-pressure selection oil passage (63) is provided between the first pumping oil passage (211) and the second pumping oil passage (212). The second high-pressure selection oil passage (63) is connected to the return oil passage through a second pressure relief valve (64). The pilot pressure tap of the second pressure relief valve (64) is connected to the pressure tap outlet of the second high-pressure selection oil passage (63).

9. The hydraulic system for aerial work machinery according to any one of claims 1 to 7, characterized in that, The power unit includes a first pumping oil passage (211) and a second pumping oil passage (212) of the bidirectional pump (21). A one-way replenishment oil passage (65) is provided between the first pumping oil passage (211) and the second pumping oil passage (212). One end of the one-way replenishment oil passage (65) is connected to the oil tank, and the other end is connected unidirectionally to the first pumping oil passage (211) and the second pumping oil passage (212) respectively.

10. An aerial work platform, characterized in that, The aerial work platform includes a hydraulic system for aerial work platforms as described in any one of claims 1 to 9.

Images