Hydraulic leveling device and aerial work platform

Abstract

The utility model discloses a hydraulic leveling device and an aerial work platform, and relates to the field of hydraulic control. The device comprises an electromagnetic reversing valve, a first two-way balance valve, a second two-way balance valve, a first leveling oil cylinder, a second leveling oil cylinder, a controller, a shuttle valve, a first electromagnetic unloading valve and a first pressure sensor. A first port and a second port of the shuttle valve are respectively connected with a second port and a third port of the second bidirectional balance valve, and a third port of the shuttle valve is connected with the oil return tank through the first electromagnetic unloading valve; the first pressure sensor is arranged on a pipeline between the shuttle valve and the first electromagnetic unloading valve and is used for detecting first pressure in the pipeline; the controller is used for controlling the first electromagnetic unloading valve to be powered on and powered off according to the first pressure. According to the utility model, the problem that structural parts are damaged due to high pressure between the first leveling oil cylinder and the second leveling oil cylinder is avoided.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic control technology, and in particular relates to a hydraulic leveling device and an aerial work platform. Background Technology

[0002] Currently, aerial work platforms are specialized equipment used to carry workers and equipment to high altitudes for installation, maintenance, and cleaning of equipment located at heights. Compared to traditional methods such as scaffolding and ladders, aerial work platforms offer advantages such as superior performance, higher efficiency, and greater safety, and are widely used in infrastructure industries such as power, transportation, petrochemicals, telecommunications, and landscaping. Currently, the leveling methods for aerial work platforms primarily employ hydraulic and electric leveling to ensure the platform remains horizontal.

[0003] Figure 1 A schematic diagram of an existing hydraulic leveling device is shown, consisting of... Figure 1 It is known that the hydraulic leveling device includes a turntable, a boom, a first leveling cylinder 1, a luffing cylinder 2, a second leveling cylinder 3, and a working platform. The rodless chamber of the first leveling cylinder 1 is connected to the rodless chamber of the second leveling cylinder 3, and the rod chamber of the first leveling cylinder 1 is connected to the rod chamber of the second leveling cylinder 3. When the luffing cylinder 2 pushes the boom to move up or down, the boom drives the first leveling cylinder 1 to move, transferring the oil from the first leveling cylinder 1 to the second leveling cylinder 3. The angle change of the first leveling cylinder 1 is approximately equal to the angle change of the second leveling cylinder 3 (i.e., the second leveling cylinder 3 changes in accordance with the change of the first leveling cylinder 1), thereby keeping the working platform in a horizontal state.

[0004] The schematic diagram of the existing hydraulic leveling device is as follows: Figure 2 and Figure 3 As shown. Figure 2 In this system, the first leveling cylinder 1 and the second leveling cylinder 3 are connected by oil pipes. When the boom moves upward (i.e., the boom cylinder 2 pushes the boom upward), the hydraulic fluid in the rod chamber of the first leveling cylinder 1 is transferred through the oil pipe to the rod chamber of the second leveling cylinder 3, and the hydraulic fluid in the rodless chamber of the second leveling cylinder 3 is transferred through the oil pipe to the rodless chamber of the first leveling cylinder 1, thus achieving the upward movement. The second leveling cylinder 3 retracts to keep the working platform level. The electromagnetic directional valve 4 enables manual leveling of the working platform and the release of gas from the cylinders and oil pipes. The first two-way balance valve 6 prevents cylinder displacement under a certain load. The two-way hydraulic lock 5 ensures that the hydraulic fluid in the first leveling cylinder 1 and the second leveling cylinder 3 does not leak during hydraulic fluid transfer. The first relief valve 7 and the second relief valve 8 prevent the pressure in the first leveling cylinder 1 and the second leveling cylinder 3 from rising indefinitely under abnormal working conditions, protecting the cylinders, oil pipes, and other structural components from damage. Figure 2This hydraulic leveling device uses a two-way hydraulic lock 5 and an overflow valve at the first leveling cylinder 1. The overflow valve leaks, and the opening value of the overflow valve is lower than the set value when the flow rate is low, and higher than the set value when the flow rate is high. Over a long period of time, this will cause the oil in the sealed chambers of the first leveling cylinder 1 and the second leveling cylinder 3 to decrease, resulting in the tilting of the working platform.

[0005] Figure 3 The hydraulic leveling principle and Figure 2 Similarly, the only difference is that the two-way hydraulic lock 5, the first relief valve 7, and the second relief valve 8 are replaced with a second two-way balance valve 9. The function of the second two-way balance valve 9 is the same as that of the two-way hydraulic lock 5, the first relief valve 7, and the second relief valve 8. For Figure 3 This hydraulic leveling device, due to the use of a second bidirectional balance valve 9 at the first leveling cylinder 1, has better pressure-holding performance than... Figure 2 However, under abnormal operating conditions, Figure 3 The overflow performance is lower than Figure 2 This is because the overflow performance of the second bidirectional balance valve 9 is limited, and it cannot limit the pressure value of the sealed chamber of the first leveling cylinder 1 and the second leveling cylinder 3 in time under abnormal working conditions. When the pressure value of the sealed chamber of the first leveling cylinder 1 and the second leveling cylinder 3 exceeds the set value of the second bidirectional balance valve 9 and continues to rise, it will cause damage to structural components such as cylinders, turntables, and booms.

[0006] Figure 4 A schematic diagram of an existing electric leveling device is shown, consisting of... Figure 4 It can be seen that the electric leveling device includes a turntable, boom, luffing cylinder 2, second leveling cylinder 3, working platform, level sensor 10, and leveling control valve 11. The principle of electric leveling is as follows: Figure 5 As shown, during boom luffing, the feedback value from the level sensor 10 is transmitted to the controller. The controller determines the state of the work platform based on the feedback value from the level sensor 10, and energizes the right-hand position of the solenoid directional valve 4 to retract the second leveling cylinder 3. During boom luffing, the controller energizes the left-hand position of the solenoid directional valve 4 to extend the second leveling cylinder 3, keeping the work platform level. Electrical leveling is less reliable than hydraulic leveling, and it is more prone to leveling vibration compared to hydraulic leveling. Utility Model Content

[0007] The purpose of this utility model is to provide a hydraulic leveling device and an aerial work platform to solve the problem that when high pressure occurs between the first leveling cylinder and the second leveling cylinder and the pressure is not released in time, it will cause damage to the cylinder, turntable, boom and other structural components.

[0008] This utility model solves the above-mentioned technical problems through the following technical solution: a hydraulic leveling device applied to an aerial work platform, the leveling device comprising an electromagnetic directional valve, a first bidirectional balance valve, a second bidirectional balance valve, a first leveling cylinder, a second leveling cylinder, and a controller; the first and fourth ports of the electromagnetic directional valve are respectively connected to a hydraulic oil tank and a return oil tank; the second and third ports of the electromagnetic directional valve are respectively connected to the first and fourth ports of the second bidirectional balance valve; the second port of the second bidirectional balance valve is connected to the rodless chamber of the first leveling cylinder and the first port of the first bidirectional balance valve; the third port of the second bidirectional balance valve is connected to the rod chamber of the first leveling cylinder and the fourth port of the first bidirectional balance valve; the second and third ports of the first bidirectional balance valve are respectively connected to the rodless chamber and the rod chamber of the second leveling cylinder.

[0009] The leveling device further includes a shuttle valve, a first electromagnetic unloading valve, and a first pressure sensor; the first port and the second port of the shuttle valve are respectively connected to the second port and the third port of the second bidirectional balancing valve, and the third port of the shuttle valve is connected to the return oil tank through the first electromagnetic unloading valve; the first pressure sensor and the first electromagnetic unloading valve are respectively connected to the controller; the first pressure sensor is located on the pipeline between the shuttle valve and the first electromagnetic unloading valve and is used to detect the first pressure in the pipeline.

[0010] Furthermore, a first throttling element is also provided on the pipeline between the first electromagnetic unloading valve and the return oil tank.

[0011] Furthermore, the first throttling element is a damping orifice.

[0012] Based on the same concept, this utility model also provides a hydraulic leveling device for use on aerial work platforms. The leveling device includes an electromagnetic directional valve, a first bidirectional balance valve, a second bidirectional balance valve, a first leveling cylinder, a second leveling cylinder, and a controller. The first and fourth ports of the electromagnetic directional valve are connected to a hydraulic oil tank and a return oil tank, respectively. The second and third ports of the electromagnetic directional valve are connected to the first and fourth ports of the second bidirectional balance valve, respectively. The second port of the second bidirectional balance valve is connected to the rodless chamber of the first leveling cylinder and the first port of the first bidirectional balance valve. The third port of the second bidirectional balance valve is connected to the rod chamber of the first leveling cylinder and the fourth port of the first bidirectional balance valve. The second and third ports of the first bidirectional balance valve are connected to the rodless chamber and the rod chamber of the second leveling cylinder, respectively.

[0013] The leveling device further includes a second electromagnetic unloading valve, a third electromagnetic unloading valve, a second pressure sensor, and a third pressure sensor; the pipeline between the second port of the second bidirectional balance valve and the rodless chamber of the first leveling cylinder is also connected to the return oil tank through the second electromagnetic unloading valve, and the pipeline between the third port of the second bidirectional balance valve and the rod chamber of the first leveling cylinder is also connected to the return oil tank through the third electromagnetic unloading valve; the second electromagnetic unloading valve, the third electromagnetic unloading valve, the second pressure sensor, and the third pressure sensor are respectively connected to the controller; the second pressure sensor is used to detect the second pressure in the rodless chamber of the first leveling cylinder, and the third pressure sensor is used to detect the third pressure in the rod chamber of the first leveling cylinder.

[0014] Furthermore, a second throttling device is provided on the pipeline between the second electromagnetic unloading valve and the return oil tank, and a third throttling device is provided on the pipeline between the third electromagnetic unloading valve and the return oil tank.

[0015] Furthermore, both the second and third throttling elements are damping orifices.

[0016] Based on the same concept, this utility model also provides an aerial work platform, which includes the hydraulic leveling device described above.

[0017] Beneficial effects

[0018] Compared with the prior art, the advantages of this utility model are:

[0019] This invention utilizes a pressure sensor to detect high pressure between the first and second leveling cylinders. Under high pressure, the electromagnetic unloading valve is energized to release the pressure in time, thus preventing damage to structural components such as cylinders, booms, and turntables caused by high pressure. Attached Figure Description

[0020] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of an existing hydraulic leveling device in the background art of this utility model;

[0022] Figure 2 This is the first existing hydraulic leveling principle diagram in the background technology of this utility model;

[0023] Figure 3 This is the second existing hydraulic leveling principle diagram in the background technology of this utility model;

[0024] Figure 4 This is a schematic diagram of the structure of an existing electric leveling device in the background art of this utility model;

[0025] Figure 5 This is a schematic diagram of an existing electric leveling principle in the background technology of this utility model;

[0026] Figure 6 This is a schematic diagram of the hydraulic leveling device in Embodiment 1 of this utility model;

[0027] Figure 7 This is a schematic diagram of the hydraulic leveling device in Embodiment 2 of this utility model.

[0028] Explanation of reference numerals in the attached drawings: 1-First leveling cylinder, 2-Luffing cylinder, 3-Second leveling cylinder, 4-Solenoid directional valve, 5-Two-way hydraulic lock, 6-First two-way balance valve, 7-First relief valve, 8-Second relief valve, 9-Second two-way balance valve, 10-Level sensor, 11-Leveling control valve, 12-Shuttle valve, 13-First solenoid unloading valve, 14-First pressure sensor, 15-First throttling element, 16-Second solenoid unloading valve, 17-Third solenoid unloading valve, 18-Second throttling element, 19-Third throttling element. Detailed Implementation

[0029] The technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0030] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0031] Example 1

[0032] like Figure 6As shown in the figure, the hydraulic leveling device for aerial work platforms provided in this embodiment includes an electromagnetic directional valve 4, a first bidirectional balance valve 6, a second bidirectional balance valve 9, a first leveling cylinder 1, a second leveling cylinder 3, a controller, a shuttle valve 12, a first electromagnetic unloading valve 13, and a first pressure sensor 14. The first and fourth ports of the electromagnetic directional valve 4 are connected to the hydraulic oil tank and the return oil tank, respectively. The second and third ports of the electromagnetic directional valve 4 are connected to the first and fourth ports of the second bidirectional balance valve 9, respectively. The second port of the second bidirectional balance valve 9 is connected to the rodless chamber of the first leveling cylinder 1 and the first port of the first bidirectional balance valve 6. The third port of the second bidirectional balancing valve 9 is connected to the rod chamber of the first leveling cylinder 1 and the fourth port of the first bidirectional balancing valve 6; the second and third ports of the first bidirectional balancing valve 6 are respectively connected to the rodless chamber and the rod chamber of the second leveling cylinder 3; the first and second ports of the shuttle valve 12 are respectively connected to the second and third ports of the second bidirectional balancing valve 9, and the third port of the shuttle valve 12 is connected to the return oil tank through the first electromagnetic unloading valve 13; the first pressure sensor 14 and the first electromagnetic unloading valve 13 are respectively connected to the controller; the first pressure sensor 14 is located on the pipeline between the shuttle valve 12 and the first electromagnetic unloading valve 13 and is used to detect the first pressure in the pipeline.

[0033] When the boom is in the luffing motion, the solenoid directional valve 4 is energized in the left position, and the hydraulic oil reaches the first leveling cylinder 1 through the second bidirectional balance valve 9. Since the thrust provided by the first leveling cylinder 1 is insufficient to push the boom upward, the hydraulic oil enters the rodless chamber of the second leveling cylinder 3 through the first bidirectional balance valve 6 to push the piston to move, thereby causing the working platform to move upward and realizing the luffing motion. When the boom is in the luffing downward motion, the solenoid directional valve 4 is energized in the right position, thereby realizing the downward movement of the working platform.

[0034] When an aerial work platform needs to be transported, in order to save transportation costs and shorten the transportation distance, the second leveling cylinder 3 is often retracted to its lowest position, so that the work platform is in its lowest position. No oil is transmitted from the rodless chamber of the second leveling cylinder 3 to the rodless chamber of the first leveling cylinder 1 through the pipeline. After transportation to the destination, the aerial work platform needs to be unloaded. If the first step is a boom extension operation, the boom extension will cause the first leveling cylinder 1 to extend. Since the second leveling cylinder 3 is already retracted, with the boom extension movement, the pressure in the rod chambers of the first and second leveling cylinders will increase sharply. At the same time, the pressurized oil pushes the valve core of the shuttle valve 12 to the left. The first pressure sensor 14 detects the first pressure between the first and second leveling cylinders 1 and 3. If the first pressure is higher than a set threshold, the controller sends a signal to the control unit. The proportional valve controlling the boom luffing speed issues a command to reduce the speed of the boom luffing action or stop the boom luffing action. At the same time, it energizes the first electromagnetic unloading valve 13, which opens to relieve the pressure between the first leveling cylinder 1 and the second leveling cylinder 3, thus preventing damage to the cylinders, boom, turntable, and other structural components caused by the high pressure between the first leveling cylinder 1 and the second leveling cylinder 3. If the first pressure is less than or equal to the set threshold, the first electromagnetic unloading valve 13 is de-energized and closes, and the luffing action returns to normal.

[0035] When the working platform is initially tilted, if the second leveling cylinder 3 reaches its stroke limit before the luffing cylinder 2 has reached its limit, a high-pressure situation will occur between the first leveling cylinder 1 and the second leveling cylinder 3. If the pressure is not relieved in time, exceeding the allowable stress of the structural components may damage the cylinders, boom, turntable, and other structural components. Therefore, this invention uses the first pressure sensor 14 to detect the first pressure value to determine whether a high-pressure situation exists between the first leveling cylinder 1 and the second leveling cylinder 3, and then controls the first electromagnetic unloading valve 13 to open in time to relieve the pressure, thus solving the problem of structural component damage caused by high pressure between the first leveling cylinder 1 and the second leveling cylinder 3.

[0036] In a specific embodiment of this utility model, a first throttling element 15 is also provided on the pipeline between the first electromagnetic unloading valve 13 and the return oil tank. The first throttling element 15 limits the unloading flow rate to prevent the oil pressure from being suddenly completely released at the moment the first electromagnetic unloading valve 13 is energized, which would cause a shock. In this embodiment, the first throttling element 15 is a damping orifice.

[0037] The threshold value is set based on the allowable stress of the structural component. In this embodiment, the threshold value is set to 240 Bar.

[0038] Example 2

[0039] like Figure 7As shown in the figure, the hydraulic leveling device for aerial work platforms provided in this embodiment includes an electromagnetic directional valve 4, a first bidirectional balance valve 6, a second bidirectional balance valve 9, a first leveling cylinder 1, a second leveling cylinder 3, a controller, a second electromagnetic unloading valve 16, a third electromagnetic unloading valve 17, a second pressure sensor, and a third pressure sensor. The first and fourth ports of the electromagnetic directional valve 4 are respectively connected to the hydraulic oil tank and the return oil tank. The second and third ports of the electromagnetic directional valve 4 are respectively connected to the first and fourth ports of the second bidirectional balance valve 9. The second port of the second bidirectional balance valve 9 is connected to the rodless chamber of the first leveling cylinder 1 and the first port of the first bidirectional balance valve 6. The third port of the second bidirectional balance valve 9 is connected to the rod chamber of the first leveling cylinder 1 and the first... The fourth port of the bidirectional balancing valve 6 is connected; the second and third ports of the first bidirectional balancing valve 6 are respectively connected to the rodless chamber and the rod chamber of the second leveling cylinder 3; the pipeline between the second port of the second bidirectional balancing valve 9 and the rodless chamber of the first leveling cylinder 1 is also connected to the return oil tank through the second electromagnetic unloading valve 16, and the pipeline between the third port of the second bidirectional balancing valve 9 and the rod chamber of the first leveling cylinder 1 is also connected to the return oil tank through the third electromagnetic unloading valve 17; the second electromagnetic unloading valve 16, the third electromagnetic unloading valve 17, the second pressure sensor, and the third pressure sensor are respectively connected to the controller; the second pressure sensor is used to detect the second pressure in the rodless chamber of the first leveling cylinder 1, and the third pressure sensor is used to detect the third pressure in the rod chamber of the first leveling cylinder 1.

[0040] When the boom is in the luffing motion, the solenoid directional valve 4 is energized in the left position, and the hydraulic oil reaches the first leveling cylinder 1 through the second bidirectional balance valve 9. Since the thrust provided by the first leveling cylinder 1 is insufficient to push the boom upward, the hydraulic oil enters the rodless chamber of the second leveling cylinder 3 through the first bidirectional balance valve 6 to push the piston to move, thereby causing the working platform to move upward and realizing the luffing motion. When the boom is in the luffing downward motion, the solenoid directional valve 4 is energized in the right position, thereby realizing the downward movement of the working platform.

[0041] When an aerial work platform needs to be transported, in order to save on transportation costs and shorten the transport distance, the second leveling cylinder 3 is often retracted to its lowest position, so that the work platform is in its lowest position. No oil is transmitted from the rodless chamber of the second leveling cylinder 3 to the rodless chamber of the first leveling cylinder 1 through the pipeline. After transporting to the destination, the aerial work platform needs to be unloaded. If the first step is a boom extension operation, the boom extension will cause the first leveling cylinder 1 to extend. Since the second leveling cylinder 3 is already retracted, the pressure in the rod chambers of the first and second leveling cylinders will increase sharply with the boom extension operation. The second pressure sensor detects the second pressure in the rodless chamber of the first leveling cylinder 1, and the third pressure sensor detects the third pressure in the rod chamber of the first leveling cylinder 1. If the larger of the second and third pressures is higher than a set threshold, the controller sends a command to the proportional valve controlling the boom luffing speed to reduce the speed of the boom luffing action or to stop the boom luffing action. At the same time, the controller energizes the electromagnetic unloading valve corresponding to the larger pressure, and the corresponding electromagnetic unloading valve opens to relieve the pressure between the first leveling cylinder 1 and the second leveling cylinder 3, thus preventing the high pressure between the first leveling cylinder 1 and the second leveling cylinder 3 from causing damage to the cylinders, boom, turntable and other structural components. If the larger of the second and third pressures is less than or equal to the set threshold, the controller de-energizes the electromagnetic unloading valve corresponding to the larger pressure, and the corresponding electromagnetic unloading valve closes, and the luffing action returns to normal.

[0042] The second pressure corresponds to the second electromagnetic unloading valve 16, and the third pressure corresponds to the third electromagnetic unloading valve 17. If the larger of the second pressure and the third pressure is the second pressure, then the second electromagnetic unloading valve 16 is energized and opens; if the larger of the second pressure and the third pressure is the third pressure, then the third electromagnetic unloading valve 17 is energized and opens.

[0043] In a specific embodiment of this utility model, a second throttling element 18 is further provided on the pipeline between the second electromagnetic unloading valve 16 and the return oil tank, and a third throttling element 19 is further provided on the pipeline between the third electromagnetic unloading valve 17 and the return oil tank. The unloading flow rate is limited by the second throttling element 18 or the third throttling element 19 to prevent the impact caused by the sudden complete pressure release of the oil when the second electromagnetic unloading valve 16 or the third electromagnetic unloading valve 17 is energized. In this embodiment, both the second throttling element 18 and the third throttling element 19 are damping orifices.

[0044] The threshold value is set based on the allowable stress of the structural component. In this embodiment, the threshold value is set to 240 Bar.

[0045] The above description only discloses specific embodiments of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A hydraulic leveling device applied to an aerial work platform, the leveling device comprising an electromagnetic directional valve, a first bidirectional balance valve, a second bidirectional balance valve, a first leveling cylinder, a second leveling cylinder, and a controller; the first and fourth ports of the electromagnetic directional valve are respectively connected to a hydraulic oil tank and a return oil tank; the second and third ports of the electromagnetic directional valve are respectively connected to the first and fourth ports of the second bidirectional balance valve; the second port of the second bidirectional balance valve is connected to the rodless chamber of the first leveling cylinder and the first port of the first bidirectional balance valve; the third port of the second bidirectional balance valve is connected to the rod-end chamber of the first leveling cylinder and the fourth port of the first bidirectional balance valve; the second and third ports of the first bidirectional balance valve are respectively connected to the rodless chamber and the rod-end chamber of the second leveling cylinder; characterized in that: The leveling device further includes a shuttle valve, a first electromagnetic unloading valve, and a first pressure sensor; the first port and the second port of the shuttle valve are respectively connected to the second port and the third port of the second bidirectional balancing valve, and the third port of the shuttle valve is connected to the return oil tank through the first electromagnetic unloading valve; the first pressure sensor and the first electromagnetic unloading valve are respectively connected to the controller; the first pressure sensor is located on the pipeline between the shuttle valve and the first electromagnetic unloading valve and is used to detect the first pressure in the pipeline.

2. The hydraulic leveling device according to claim 1, characterized in that: A first throttling element is also provided on the pipeline between the first electromagnetic unloading valve and the return oil tank.

3. The hydraulic leveling device according to claim 2, characterized in that: The first throttling element is a damping orifice.

4. A hydraulic leveling device applied to an aerial work platform, the leveling device comprising an electromagnetic directional valve, a first bidirectional balance valve, a second bidirectional balance valve, a first leveling cylinder, a second leveling cylinder, and a controller; the first and fourth ports of the electromagnetic directional valve are respectively connected to a hydraulic oil tank and a return oil tank; the second and third ports of the electromagnetic directional valve are respectively connected to the first and fourth ports of the second bidirectional balance valve; the second port of the second bidirectional balance valve is connected to the rodless chamber of the first leveling cylinder and the first port of the first bidirectional balance valve; the third port of the second bidirectional balance valve is connected to the rod-end chamber of the first leveling cylinder and the fourth port of the first bidirectional balance valve; the second and third ports of the first bidirectional balance valve are respectively connected to the rodless chamber and the rod-end chamber of the second leveling cylinder; characterized in that: The leveling device further includes a second electromagnetic unloading valve, a third electromagnetic unloading valve, a second pressure sensor, and a third pressure sensor; the pipeline between the second port of the second bidirectional balance valve and the rodless chamber of the first leveling cylinder is also connected to the return oil tank through the second electromagnetic unloading valve, and the pipeline between the third port of the second bidirectional balance valve and the rod chamber of the first leveling cylinder is also connected to the return oil tank through the third electromagnetic unloading valve; the second electromagnetic unloading valve, the third electromagnetic unloading valve, the second pressure sensor, and the third pressure sensor are respectively connected to the controller; the second pressure sensor is used to detect the second pressure in the rodless chamber of the first leveling cylinder, and the third pressure sensor is used to detect the third pressure in the rod chamber of the first leveling cylinder.

5. The hydraulic leveling device according to claim 4, characterized in that: A second throttling device is provided on the pipeline between the second electromagnetic unloading valve and the return oil tank, and a third throttling device is provided on the pipeline between the third electromagnetic unloading valve and the return oil tank.

6. The hydraulic leveling device according to claim 5, characterized in that: Both the second and third throttling elements are damping orifices.

7. An aerial work platform, characterized in that: The aerial work platform includes a hydraulic leveling device as described in any one of claims 1 to 6.

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