Hydraulic leveling device, hydraulic leveling method and aerial work platform

Abstract

The invention discloses a hydraulic leveling device, a hydraulic leveling method 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; and the controller is used for controlling the first electromagnetic unloading valve to be powered on and powered off according to the first pressure when amplitude variation operation is started and the initial state of the working platform is an inclined state. The problem that structural parts are damaged due to high pressure between the first leveling oil cylinder and the second leveling oil cylinder is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic control, and in particular relates to a hydraulic leveling device, a hydraulic leveling method and an aerial work platform. Background Art

[0002] At present, aerial work platforms are special equipment that carry workers and equipment to high altitudes and install, maintain and clean equipment at high altitudes. Compared with traditional working methods such as scaffolding and ladders, aerial work platforms have the advantages of good working performance, high working efficiency and safe working. They are currently widely used in infrastructure industries such as electricity, transportation, petrochemicals, communications, and gardening. At present, the leveling methods of aerial work platforms mainly use hydraulic leveling and electric leveling to ensure that the working platform is in a horizontal state.

[0003] Figure 1 The schematic diagram of the existing hydraulic leveling device is shown. Figure 1 It can be seen 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 upward or downward, the boom drives the first leveling cylinder 1 to move, and the oil in the first leveling cylinder 1 is transferred to the second leveling cylinder 3. The angle change moment of the first leveling cylinder 1 is approximately equal to the angle change moment of the second leveling cylinder 3 (that is, the second leveling cylinder 3 changes 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 shown. Figure 2 In the embodiment, the first leveling cylinder 1 is connected to the second leveling cylinder 3 by an oil pipe. When the boom is in action (i.e., the boom cylinder 2 pushes the boom upward), the oil in the rod chamber of the first leveling cylinder 1 is transferred to the rod chamber of the second leveling cylinder 3 through the oil pipe, and the hydraulic oil in the rodless chamber of the second leveling cylinder 3 is transferred to the rodless chamber of the first leveling cylinder 1 through the oil pipe, so as to realize the upward movement of the boom, and the second leveling cylinder 3 retracts to keep the working platform level; the electromagnetic reversing valve 4 can be used to manually level the working platform and drain the gas in the cylinder and the oil pipe; the first two-way balancing valve 6 can be used to prevent the cylinder from displacement under a certain load; the two-way hydraulic lock 5 can ensure that the oil in the first leveling cylinder 1 and the second leveling cylinder 3 will not leak when the oil is transferred; the first overflow valve 7 and the second overflow valve 8 can prevent the pressure of the first leveling cylinder 1 and the second leveling cylinder 3 from increasing infinitely under abnormal working conditions, so as to protect the cylinders, oil pipes and other structural bodies from damage. Figure 2This hydraulic leveling device uses a two-way hydraulic lock 5 and a relief valve at the first leveling cylinder 1. The relief valve leaks. When the flow rate is small, the opening value of the relief valve is lower than the set value. When the flow rate is large, the opening value of the relief valve is greater than the set value. During long-term movement, the oil in the closed chambers of the first leveling cylinder 1 and the second leveling cylinder 3 will decrease, causing the working platform to tilt.

[0005] Figure 3 Hydraulic leveling principle and Figure 2 Similarly, the two-way hydraulic lock 5, the first relief valve 7 and the second relief valve 8 are replaced by the second two-way balancing valve 9, and the function of the second two-way balancing 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. Figure 3 This hydraulic leveling device has better pressure-maintaining performance than the first leveling cylinder 1 because the second two-way balancing valve 9 is used at the first leveling cylinder 1. Figure 2 , but in abnormal conditions, Figure 3 The overflow performance is lower than Figure 2 This is because the overflow performance of the second two-way balancing valve 9 is limited, and it cannot timely limit the closed chamber pressure value of the first leveling cylinder 1 and the second leveling cylinder 3 under abnormal working conditions. When the closed chamber pressure value of the first leveling cylinder 1 and the second leveling cylinder 3 exceeds the set value of the second two-way balancing valve 9 and continues to rise, it will cause damage to structural components such as the cylinder, turntable, and arm.

[0006] Figure 4 The schematic diagram of the structure of the existing electric leveling device is shown. Figure 4 It can be seen that the electric leveling device includes a turntable, a boom, a variable amplitude cylinder 2, a second leveling cylinder 3, a working platform, a level sensor 10 and a leveling control valve 11. The principle of electric leveling is as follows Figure 5 As shown, when the boom is in action, the feedback value of the level sensor 10 is transmitted to the controller, and the controller judges the state of the working platform according to the feedback value of the level sensor 10, and according to the result of the judgment of the state of the working platform, the electromagnetic reversing valve 4 is energized to the right position, so that the second leveling cylinder 3 is retracted; when the boom is in action, the controller controls the electromagnetic reversing valve 4 to be energized to the left position, so that the second leveling cylinder 3 is extended, so that the working platform is kept horizontal. The reliability of electric leveling is lower than that of hydraulic leveling, and electric leveling is more prone to leveling jitter than hydraulic leveling. Summary of the invention

[0007] The purpose of the present invention is to provide a hydraulic leveling device, a hydraulic leveling method and an aerial work platform to solve the problem that high pressure appears between the first leveling cylinder and the second leveling cylinder, and when the pressure is not released in time, it causes damage to structural parts such as the cylinder, turntable, and arm.

[0008] The present invention solves the above technical problems through the following technical solutions: a hydraulic leveling device, applied to an aerial work platform, the leveling device comprises an electromagnetic reversing valve, a first two-way balancing valve, a second two-way balancing valve, a first leveling oil cylinder, a second leveling oil cylinder and a controller; the first port and the fourth port of the electromagnetic reversing valve are respectively connected to the hydraulic oil tank and the return oil tank, the second port and the third port of the electromagnetic reversing valve are respectively connected to the first port and the fourth port of the second two-way balancing valve, the second port of the second two-way balancing valve is connected to the rodless chamber of the first leveling oil cylinder and the first port of the first two-way balancing valve, the third port of the second two-way balancing valve is connected to the rod chamber of the first leveling oil cylinder and the fourth port of the first two-way balancing valve; the second port and the third port of the first two-way balancing valve are respectively connected to the rodless chamber and the rod chamber of the second leveling oil cylinder;

[0009] The leveling device further comprises 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 two-way balancing valve, and the third port of the shuttle valve is connected to the oil return tank through the first electromagnetic unloading valve;

[0010] The first pressure sensor is arranged on the pipeline between the shuttle valve and the first electromagnetic unloading valve and is used to detect the first pressure in the pipeline; the controller is used to control the power supply and loss supply of the first electromagnetic unloading valve according to the first pressure when the amplitude change operation starts and the initial state of the working platform is an inclined state, so as to avoid damage to structural parts.

[0011] Furthermore, a first throttling element is provided on the pipeline between the first electromagnetic unloading valve and the oil return tank.

[0012] Furthermore, the first throttling member is a damping hole.

[0013] Based on the same concept, the present invention also provides a hydraulic leveling device, which is applied to an aerial work platform. The leveling device includes an electromagnetic reversing valve, a first two-way balancing valve, a second two-way balancing valve, a first leveling cylinder, a second leveling cylinder and a controller; the first port and the fourth port of the electromagnetic reversing valve are respectively connected to the hydraulic oil tank and the return oil tank, the second port and the third port of the electromagnetic reversing valve are respectively connected to the first port and the fourth port of the second two-way balancing valve, the second port of the second two-way balancing valve is connected to the rodless chamber of the first leveling cylinder and the first port of the first two-way balancing valve, the third port of the second two-way balancing valve is connected to the rod chamber of the first leveling cylinder and the fourth port of the first two-way balancing valve; the second port and the third port of the first two-way balancing valve are respectively connected to the rodless chamber and the rod chamber of the second leveling cylinder;

[0014] The leveling device also 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 two-way balancing valve and the rodless chamber of the first leveling oil 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 two-way balancing valve and the rod chamber of the first leveling oil cylinder is also connected to the return oil tank through the third electromagnetic unloading valve;

[0015] 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; the controller is used to control the electromagnetic unloading valve corresponding to the larger of the second pressure and the third pressure to gain or lose power according to the larger of the second pressure and the third pressure when the amplitude change operation starts and the initial state of the working platform is an inclined state, so as to avoid damage to the structural parts; wherein the second pressure corresponds to the second electromagnetic unloading valve, and the third pressure corresponds to the third electromagnetic unloading valve.

[0016] Furthermore, a second throttling element is provided on the pipeline between the second electromagnetic unloading valve and the oil return tank, and a third throttling element is provided on the pipeline between the third electromagnetic unloading valve and the oil return tank.

[0017] Based on the same concept, the present invention also provides an aerial work platform, which includes the hydraulic leveling device as described above.

[0018] Based on the same concept, the present invention also provides a hydraulic leveling method of the hydraulic leveling device as described above, comprising:

[0019] Acquire a pressure detection value; wherein the pressure detection value is a first pressure detected by a first pressure sensor, or the pressure detection value is a larger one of a second pressure and a third pressure;

[0020] When the luffing operation starts and the initial state of the working platform is an inclined state, determining whether the pressure detection value is greater than a first set threshold value;

[0021] If so, the speed of the amplitude change action is controlled to be reduced or the amplitude change action is controlled to be stopped, and at the same time, the electromagnetic unloading valve corresponding to the pressure detection value is controlled to be energized;

[0022] If not, the electromagnetic unloading valve corresponding to the pressure detection value is controlled to lose power.

[0023] Furthermore, before determining whether the pressure detection value is greater than a first set threshold, the hydraulic leveling method further includes:

[0024] Get the actual load of the working platform;

[0025] Determine whether the actual load is less than the second set threshold, and if so, determine whether the pressure detection value is greater than the first set threshold.

[0026] Furthermore, the first set threshold is set according to the allowable stress of the structural component.

[0027] Beneficial Effects

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] The present invention utilizes a pressure sensor to detect the high pressure situation between the first leveling cylinder and the second leveling cylinder. Under the high pressure situation, the amplitude change action is controlled to stop or reduce the speed and the electromagnetic unloading valve is controlled to be energized to release the pressure in time, thereby avoiding the problem of damage to structural parts such as the cylinder, boom, and turntable caused by high pressure.

[0030] Before determining whether a high pressure situation occurs between the first leveling oil cylinder and the second leveling oil cylinder, the present invention also determines whether the working platform is carrying people according to the actual load of the working platform, thereby avoiding the problem of the working platform tilting during the pressure relief process endangering the safety of the operating personnel and protecting the safety of the operating personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a structural schematic diagram of an existing hydraulic leveling device in the background technology of the present invention;

[0033] Figure 2 It is the first existing hydraulic leveling principle diagram in the background technology of the present invention;

[0034] Figure 3 It is the second existing hydraulic leveling principle diagram in the background technology of the present invention;

[0035] Figure 4 It is a schematic diagram of the structure of an existing electric leveling device in the background technology of the present invention;

[0036] Figure 5 It is the existing electric leveling principle diagram in the background technology of the present invention;

[0037] Figure 6 is a schematic diagram of a hydraulic leveling device in Embodiment 1 of the present invention;

[0038] Figure 7 is a flow chart of the hydraulic leveling method in Example 1 of the present invention;

[0039] Figure 8 It is a schematic diagram of the hydraulic leveling device in Example 2 of the present invention.

[0040] Explanation of the accompanying drawings: 1-first leveling cylinder, 2-bending cylinder, 3-second leveling cylinder, 4-electromagnetic reversing valve, 5-bidirectional hydraulic lock, 6-first bidirectional balancing valve, 7-first overflow valve, 8-second overflow valve, 9-second bidirectional balancing valve, 10-level sensor, 11-leveling control valve, 12-shuttle valve, 13-first electromagnetic unloading valve, 14-first pressure sensor, 15-first throttle, 16-second electromagnetic unloading valve, 17-third electromagnetic unloading valve, 18-second throttle, 19-third throttle. DETAILED DESCRIPTION

[0041] The following is a clear and complete description of the technical solutions in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The technical solution of the present application is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0043] Example 1

[0044] like Figure 6 As shown, a hydraulic leveling device for an aerial work platform provided by an embodiment of the present invention includes an electromagnetic reversing valve 4, a first two-way balancing valve 6, a second two-way balancing valve 9, a first leveling oil cylinder 1, a second leveling oil cylinder 3, a controller, a shuttle valve 12, a first electromagnetic unloading valve 13 and a first pressure sensor 14; the first port and the fourth port of the electromagnetic reversing valve 4 are respectively connected to the hydraulic oil tank and the return oil tank, the second port and the third port of the electromagnetic reversing valve 4 are respectively connected to the first port and the fourth port of the second two-way balancing valve 9, the second port of the second two-way balancing valve 9 is connected to the rodless chamber of the first leveling oil cylinder 1, the first The first port of the two-way balancing valve 6 is connected, and the third port of the second two-way balancing valve 9 is connected to the rod chamber of the first leveling cylinder 1 and the fourth port of the first two-way balancing valve 6; the second port and the third port of the first two-way balancing valve 6 are respectively connected to the rodless chamber and the rod chamber of the second leveling cylinder 3; the first port and the second port of the shuttle valve 12 are respectively connected to the second port and the third port of the second two-way 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 is arranged 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.

[0045] When the boom is in upward motion, the left position of the electromagnetic reversing valve 4 is energized, and the hydraulic oil reaches the first leveling cylinder 1 through the second two-way balancing valve 9. Since the thrust provided by the first leveling cylinder 1 cannot push the boom upward, the hydraulic oil enters the rodless chamber of the second leveling cylinder 3 through the first two-way balancing valve 6 to push the piston to move, causing the working platform to move upward and realizing the upward motion of the boom; when the boom is in downward motion, the right position of the electromagnetic reversing valve 4 is energized, realizing the downward motion of the working platform.

[0046] When the aerial work platform needs to be transported, in order to save transportation costs and shorten the transportation length, the second leveling cylinder 3 is often retracted into place so that the work platform is in the lowest position, and no oil in the rodless chamber of the second leveling cylinder 3 is transferred to the rodless chamber of the first leveling cylinder 1 through the pipeline. After being transported to the destination, the aerial work platform needs to be unloaded. At this time, if the first step is the boom up action operation, the boom up action will drive the first leveling cylinder 1 to extend. Since the second leveling cylinder 3 has been retracted into place, with the movement of the boom action, the pressure in the rod chamber of the first leveling cylinder 1 and the rod chamber of the second leveling cylinder 3 will increase sharply. At the same time, the pressure 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 leveling cylinder 1 and the second leveling cylinder 3. If the first pressure is higher than the first set threshold, the controller sends a signal to the control. The proportional valve that controls the boom arm length adjustment speed sends a command to reduce the speed of the boom arm length adjustment action or stop the boom arm length adjustment action. At the same time, the first electromagnetic unloading valve 13 is energized and opened to reduce the pressure between the first leveling cylinder 1 and the second leveling cylinder 3, thereby avoiding the problem of damage to structural parts such as the cylinder, boom, and turntable 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 first set threshold, the first electromagnetic unloading valve 13 is controlled to lose power and close, and the arm length adjustment action returns to normal.

[0047] When the initial state of the working platform is a tilted state, as long as the stroke of the second leveling cylinder 3 is in place first and the stroke of the variable-length cylinder 2 is not in place, 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, it may cause damage to the cylinder, boom, turntable and other structural parts after exceeding the allowable stress of the structural material. Therefore, the present invention determines whether a high pressure situation occurs between the first leveling cylinder 1 and the second leveling cylinder 3 through the first pressure value detected by the first pressure sensor 14, and then controls the first electromagnetic unloading valve 13 to open and unload in time, solving the problem of high pressure between the first leveling cylinder 1 and the second leveling cylinder 3 causing damage to the structural parts.

[0048] In a specific embodiment of the present invention, a first throttle 15 is further provided on the pipeline between the first electromagnetic unloading valve 13 and the oil return tank, and the unloading flow is limited by the first throttle 15 to prevent the impact caused by the sudden release of the pressure of the oil at the moment when the first electromagnetic unloading valve 13 is energized. In this embodiment, the first throttle 15 is a damping hole.

[0049] like Figure 7 As shown, the hydraulic leveling method of the hydraulic leveling device in Example 1 of the present application includes the following steps:

[0050] Step 1: using the first pressure sensor 14 to obtain a pressure detection value, that is, the pressure detection value is a first pressure;

[0051] Step 2: When the amplitude variation operation starts and the initial state of the working platform is an inclined state, the controller determines whether the pressure detection value obtained in step 1 is greater than a first set threshold value;

[0052] If so, the controller controls the speed of the amplitude variation action to decrease or controls the amplitude variation action to stop. At the same time, the controller controls the first electromagnetic unloading valve 13 to be energized, and the first electromagnetic unloading valve 13 is opened to promptly remove the high pressure between the first leveling cylinder 1 and the second leveling cylinder 3 to avoid damage to the structural parts; if not, the controller controls the first electromagnetic unloading valve 13 to lose power, and the first electromagnetic unloading valve 13 is closed.

[0053] In a specific embodiment of the present invention, before determining whether the pressure detection value is greater than the first set threshold, the hydraulic leveling method further includes:

[0054] Obtain the actual load of the working platform; determine whether the actual load is less than the second set threshold value. If so, determine whether the pressure detection value is greater than the first set threshold value; if not, perform the amplitude change action normally without determining whether the pressure detection value is greater than the first set threshold value, thereby avoiding the situation where there are operators on the working platform, causing the working platform to tilt during the pressure relief process and endangering the safety of the operators.

[0055] The first set threshold is set according to the allowable stress of the structural member. In this embodiment, the first set threshold is set to 240 Bar, and the second set threshold is set to 40 kg.

[0056] Example 2

[0057] like Figure 8As shown, a hydraulic leveling device for an aerial work platform provided by an embodiment of the present invention includes an electromagnetic reversing valve 4, a first two-way balancing valve 6, a second two-way balancing 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 port and the fourth port of the electromagnetic reversing valve 4 are respectively connected to the hydraulic oil tank and the return oil tank, the second port and the third port of the electromagnetic reversing valve 4 are respectively connected to the first port and the fourth port of the second two-way balancing valve 9, the second port of the second two-way balancing valve 9 is connected to the rodless chamber of the first leveling cylinder 1 and the first port of the first two-way balancing valve 6, and the second two-way balancing valve 9 is connected to the rodless chamber of the first leveling cylinder 1 and the first port of the first two-way balancing valve 6. The third port of the valve 9 is connected to the rod chamber of the first leveling cylinder 1 and the fourth port of the first two-way balancing valve 6; the second port and the third port of the first two-way 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 two-way 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 two-way 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 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.

[0058] When the boom is in upward motion, the left position of the electromagnetic reversing valve 4 is energized, and the hydraulic oil reaches the first leveling cylinder 1 through the second two-way balancing valve 9. Since the thrust provided by the first leveling cylinder 1 cannot push the boom upward, the hydraulic oil enters the rodless chamber of the second leveling cylinder 3 through the first two-way balancing valve 6 to push the piston to move, causing the working platform to move upward and realizing the upward motion of the boom; when the boom is in downward motion, the right position of the electromagnetic reversing valve 4 is energized, realizing the downward motion of the working platform.

[0059] When the aerial work platform needs to be transported, in order to save transportation costs and shorten the transportation length, the second leveling cylinder 3 is often retracted to the lowest position, so that the working platform is in the lowest position, and no oil is transferred from the rodless chamber of the second leveling cylinder 3 to the rodless chamber of the first leveling cylinder 1 through the pipeline. After being transported to the destination, the aerial work platform needs to be unloaded. At this time, if the first step is the luffing operation, the boom luffing operation will drive the first leveling cylinder 1 to extend. Since the second leveling cylinder 3 has been retracted, the pressure in the rod chamber of the first leveling cylinder 1 and the rod chamber of the second leveling cylinder 3 will rise sharply with the movement of the luffing action. 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 pressure and the third pressure is higher than the first set threshold, the controller sends an instruction to the proportional valve controlling the boom amplitude change speed, controls the boom amplitude change speed to decrease or stops the boom amplitude change action, and at the same time controls the electromagnetic unloading valve corresponding to the larger one to be energized, and the corresponding electromagnetic unloading valve opens to unload the pressure between the first leveling cylinder 1 and the second leveling cylinder 3, thereby avoiding the problem of damage to structural parts such as the cylinder, boom, and turntable caused by the high pressure between the first leveling cylinder 1 and the second leveling cylinder 3; if the larger of the second pressure and the third pressure is less than or equal to the first set threshold, the electromagnetic unloading valve corresponding to the larger one is controlled to lose power, the corresponding electromagnetic unloading valve is closed, and the amplitude change action returns to normal.

[0060] 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, the second electromagnetic unloading valve 16 is controlled to be energized, the second electromagnetic unloading valve 16 is opened, and the pressure between the first leveling cylinder 1 and the second leveling cylinder 3 is unloaded; if the larger of the second pressure and the third pressure is the third pressure, the third electromagnetic unloading valve 17 is controlled to be energized, the third electromagnetic unloading valve 17 is opened, and the pressure between the first leveling cylinder 1 and the second leveling cylinder 3 is unloaded.

[0061] In a specific embodiment of the present invention, a second throttle 18 is provided on the pipeline between the second electromagnetic unloading valve 16 and the oil return tank, and a third throttle 19 is provided on the pipeline between the third electromagnetic unloading valve 17 and the oil return tank. The unloading flow is limited by the second throttle 18 or the third throttle 19 to prevent the impact caused by the sudden release of pressure when the second electromagnetic unloading valve 16 or the third electromagnetic unloading valve 17 is energized.

[0062] The hydraulic leveling method of the hydraulic leveling device in Example 2 of the present application comprises the following steps:

[0063] Step 1: Obtain a pressure detection value; wherein the pressure detection value is the larger of the second pressure and the third pressure;

[0064] Step 2: When the amplitude variation operation starts and the initial state of the working platform is an inclined state, the controller determines whether the pressure detection value obtained in step 1 is greater than a first set threshold value;

[0065] If so, the controller controls the speed of the amplitude variation action to decrease or controls the amplitude variation action to stop. At the same time, the controller controls the electromagnetic unloading valve corresponding to the pressure detection value to be energized, and the corresponding electromagnetic unloading valve opens to promptly remove the high pressure between the first leveling cylinder 1 and the second leveling cylinder 3 to avoid damage to the structural parts; if not, the controller controls the electromagnetic unloading valve corresponding to the pressure detection value to lose power, and the corresponding electromagnetic unloading valve closes.

[0066] In a specific embodiment of the present invention, before determining whether the pressure detection value is greater than the first set threshold, the hydraulic leveling method further includes:

[0067] Obtain the actual load of the working platform; determine whether the actual load is less than the second set threshold value. If so, determine whether the pressure detection value is greater than the first set threshold value; if not, perform the amplitude change action normally without determining whether the pressure detection value is greater than the first set threshold value, thereby avoiding the situation where there are operators on the working platform, causing the working platform to tilt during the pressure relief process and endangering the safety of the operators.

[0068] The first set threshold is set according to the allowable stress of the structural member. In this embodiment, the first set threshold is set to 240 Bar, and the second set threshold is set to 40 kg.

[0069] What is disclosed above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, which should be covered within the protection scope of the present invention.

Claims

1. A hydraulic leveling device, applied to an aerial work platform, the leveling device comprises an electromagnetic reversing valve, a first two-way balancing valve, a second two-way balancing valve, a first leveling oil cylinder, a second leveling oil cylinder and a controller; the first port and the fourth port of the electromagnetic reversing valve are respectively connected to the hydraulic oil tank and the return oil tank, the second port and the third port of the electromagnetic reversing valve are respectively connected to the first port and the fourth port of the second two-way balancing valve, the second port of the second two-way balancing valve is connected to the rodless chamber of the first leveling oil cylinder and the first port of the first two-way balancing valve, the third port of the second two-way balancing valve is connected to the rod chamber of the first leveling oil cylinder and the fourth port of the first two-way balancing valve; the second port and the third port of the first two-way balancing valve are respectively connected to the rodless chamber and the rod chamber of the second leveling oil cylinder; it is characterized in that: The leveling device further comprises 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 two-way balancing valve, and the third port of the shuttle valve is connected to the oil return tank through the first electromagnetic unloading valve; The first pressure sensor is arranged on the pipeline between the shuttle valve and the first electromagnetic unloading valve and is used to detect the first pressure in the pipeline; the controller is used to control the power supply and loss supply of the first electromagnetic unloading valve according to the first pressure when the amplitude change operation starts and the initial state of the working platform is an inclined state, so as to avoid damage to structural parts.

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 oil return tank.

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

4. A hydraulic leveling device, applied to an aerial work platform, the leveling device comprises an electromagnetic reversing valve, a first two-way balancing valve, a second two-way balancing valve, a first leveling oil cylinder, a second leveling oil cylinder and a controller; the first port and the fourth port of the electromagnetic reversing valve are respectively connected to the hydraulic oil tank and the return oil tank, the second port and the third port of the electromagnetic reversing valve are respectively connected to the first port and the fourth port of the second two-way balancing valve, the second port of the second two-way balancing valve is connected to the rodless chamber of the first leveling oil cylinder and the first port of the first two-way balancing valve, the third port of the second two-way balancing valve is connected to the rod chamber of the first leveling oil cylinder and the fourth port of the first two-way balancing valve; the second port and the third port of the first two-way balancing valve are respectively connected to the rodless chamber and the rod chamber of the second leveling oil cylinder; it is characterized in that: The leveling device also 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 two-way balancing valve and the rodless chamber of the first leveling oil 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 two-way balancing valve and the rod chamber of the first leveling oil cylinder is also connected to the return oil tank through the third electromagnetic unloading valve; 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; the controller is used to control the electromagnetic unloading valve corresponding to the larger of the second pressure and the third pressure to gain or lose power according to the larger of the second pressure and the third pressure when the amplitude change operation starts and the initial state of the working platform is an inclined state, so as to avoid damage to the structural parts; wherein the second pressure corresponds to the second electromagnetic unloading valve, and the third pressure corresponds to the third electromagnetic unloading valve.

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

6. An aerial work platform, characterized in that: The aerial work platform comprises a hydraulic leveling device as claimed in any one of claims 1 to 5.

7. A hydraulic leveling method for a hydraulic leveling device according to any one of claims 1 to 5, characterized in that: The hydraulic leveling method comprises: Acquire a pressure detection value; wherein the pressure detection value is a first pressure detected by a first pressure sensor, or the pressure detection value is a larger one of a second pressure and a third pressure; When the luffing operation starts and the initial state of the working platform is an inclined state, determining whether the pressure detection value is greater than a first set threshold value; If so, the speed of the amplitude change action is controlled to be reduced or the amplitude change action is controlled to be stopped, and at the same time, the electromagnetic unloading valve corresponding to the pressure detection value is controlled to be energized; If not, the electromagnetic unloading valve corresponding to the pressure detection value is controlled to lose power.

8. The hydraulic leveling method of the hydraulic leveling device according to claim 7, characterized in that: Before determining whether the pressure detection value is greater than a first set threshold, the hydraulic leveling method further includes: Get the actual load of the working platform; Determine whether the actual load is less than the second set threshold, and if so, determine whether the pressure detection value is greater than the first set threshold.

9. The hydraulic leveling method of the hydraulic leveling device according to claim 7 or 8, characterized in that: The first set threshold is set according to the allowable stress of the structural component.

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