Hydraulic levelling device, hydraulic levelling method and aerial work platform

Abstract

The application 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 bidirectional balance valve, a second bidirectional 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. The first port and the second port of the shuttle valve are connected with the second port and the third port of the second bidirectional balance valve respectively, and the third port of the shuttle valve is connected with an 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 the first pressure in the pipeline. The controller is used for controlling the first electromagnetic unloading valve to be electrified or deenergized according to the first pressure when the initial state of the working platform is an inclined state during the start of the luffing operation. The application avoids the problem that the high pressure between the first leveling oil cylinder and the second leveling oil cylinder causes the damage of structural members.

Description

Technical Field

[0001] The present 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] Aerial work platforms are specialized equipment used to carry workers and equipment to high altitudes for installation, maintenance, and cleaning. Compared to traditional methods like scaffolding and ladders, aerial work platforms offer advantages such as improved performance, high efficiency, and safety. They are widely used in infrastructure industries such as power, transportation, petrochemicals, communications, and gardening. Currently, hydraulic and electric leveling methods are the primary methods used to ensure the platform remains level.

[0003] Figure 1 Shows a schematic diagram of the structure of an existing hydraulic leveling device. Figure 1 As can be seen, 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 work platform. The rodless cavity of the first leveling cylinder 1 is connected to the rodless cavity of the second leveling cylinder 3, and the rod cavity of the first leveling cylinder 1 is connected to the rod cavity of the second leveling cylinder 3. When the luffing cylinder 2 pushes the boom upward or downward, the boom drives the first leveling cylinder 1 to move, transferring the oil in the first leveling cylinder 1 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 changes of the first leveling cylinder 1), thereby keeping the work platform in a horizontal state.

[0004] The principle diagram of the existing hydraulic leveling device is as follows Figure 2 and Figure 3 shown. Figure 2 In the process, the first leveling cylinder 1 and the second leveling cylinder 3 are connected by an oil pipe. When the boom is moved up (i.e. the boom cylinder 2 pushes the boom to move 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, to achieve 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 ensure that the cylinder does not move under a certain load; the two-way hydraulic lock 5 can ensure that the first leveling cylinder 1 and the second leveling cylinder 3 do 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, thereby protecting 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. At a small flow rate, the opening value of the relief valve is lower than the set value, and at a large flow rate, 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 become less, causing the working platform to tilt.

[0005] Figure 3 The hydraulic leveling principle and Figure 2 Similar, only 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 oil cylinder 1 due to the use of the second two-way balancing valve 9. 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 Shows a schematic diagram of the structure of an existing electric leveling device. Figure 4 It can be seen that the electric leveling device includes a turntable, an arm, 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, during boom luffing, the feedback value from level sensor 10 is transmitted to the controller. The controller then determines the working platform's status based on the feedback value and, based on the work platform's status determination, energizes electromagnetic reversing valve 4 to the right position, retracting second leveling cylinder 3. During boom luffing, the controller energizes electromagnetic reversing valve 4 to the left position, extending second leveling cylinder 3 and maintaining a level working platform. Electric leveling is less reliable than hydraulic leveling and is more susceptible to leveling jitter. 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 relieved in time, it causes damage to structural parts such as the cylinder, turntable, and arm.

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

[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 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 power loss of the first electromagnetic unloading valve according to the first pressure when the amplitude variation 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, and the leveling device includes 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 connected to the hydraulic oil tank and the return oil tank respectively, the second port and the third port of the electromagnetic reversing valve are connected to the first port and the fourth port of the second two-way balancing valve respectively, 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 connected to the rodless chamber and the rod chamber of the second leveling oil cylinder respectively;

[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 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 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 power supply and loss of power of the electromagnetic unloading valve corresponding to the larger of the second pressure and the third pressure when the amplitude change operation is started and the initial state of the working platform is an inclined state, so as to avoid damage to 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 the first pressure sensor, or the pressure detection value is the larger of a second pressure and a third pressure;

[0020] When the luffing operation is started 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;

[0021] If so, the speed of the amplitude variation action is controlled to be reduced or the amplitude variation 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 a second set threshold, and if so, determine whether the pressure detection value is greater than a 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 high pressure conditions between the first leveling cylinder and the second leveling cylinder. Under high pressure conditions, the present invention simultaneously controls the boom action to stop or reduce speed and controls the electromagnetic unloading valve to be energized to relieve pressure in a timely manner, thereby avoiding the problem of damage to structural components such as the cylinder, boom, and turntable caused by high pressure.

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

[0031] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 any creative work.

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

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

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

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

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

[0037] Figure 6 is a schematic diagram of a hydraulic leveling device in Example 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 This 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-bend 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 of the present invention in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0042] The following specific embodiments are used to describe the technical solution of the present application in detail. 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 connected to the hydraulic oil tank and the return oil tank respectively, the second port and the third port of the electromagnetic reversing valve 4 are connected to the first port and the fourth port of the second two-way balancing valve 9 respectively, 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 realize 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. 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 transportation 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 an instruction to reduce the speed of the boom arm length adjustment action or stop the boom arm length adjustment action, and at the same time controls the first electromagnetic unloading valve 13 to be energized, and the first electromagnetic unloading valve 13 is opened to relieve the pressure between the first leveling cylinder 1 and the second leveling cylinder 3, thereby avoiding the problem that the high pressure between the first leveling cylinder 1 and the second leveling cylinder 3 causes damage to the cylinders, boom, turntable and other structural parts; if the first pressure is less than or equal to the first set threshold value, the first electromagnetic unloading valve 13 is controlled to lose power, the first electromagnetic unloading valve 13 is closed, and the boom length adjustment action returns to normal.

[0047] When the work platform is initially tilted, as long as the second leveling cylinder 3 reaches its full stroke before the luffing cylinder 2 reaches its full stroke, a high pressure condition will occur between the first and second leveling cylinders 1 and 3. If the pressure is not relieved promptly, the allowable stress of the structural material will be exceeded, potentially causing damage to the cylinders, boom, turntable, and other structural components. Therefore, the present invention uses the first pressure value detected by the first pressure sensor 14 to determine whether a high pressure condition exists between the first and second leveling cylinders 1 and 3, and then controls the first electromagnetic unloading valve 13 to open and unload the pressure in a timely manner, thereby resolving the problem of structural damage caused by the high pressure between the first and second leveling cylinders 1 and 3.

[0048] In a specific embodiment of the present invention, a first throttle member 15 is further provided in the pipeline between the first electromagnetic unloading valve 13 and the oil return tank. This throttle member 15 limits the unloading flow rate to prevent shock caused by a sudden complete pressure release when the first electromagnetic unloading valve 13 is energized. In this embodiment, the first throttle member 15 is a damping orifice.

[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: Obtain a pressure detection value using the first pressure sensor 14, that is, the pressure detection value is a first pressure;

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

[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 workers on the working platform, causing the working platform to tilt during the pressure relief process and endangering the safety of the workers.

[0055] The first threshold value is set according to the allowable stress of the structural component. In this embodiment, the first threshold value is set to 240 Bar, and the second threshold value 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 oil cylinder 1, a second leveling oil 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 oil 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 oil 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 realize 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 work platform is in the lowest position. 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 transportation to the destination, the aerial work platform needs to be unloaded. At this time, if the first step is the boom up operation, the boom up operation will drive 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 leveling cylinder 1 and the second leveling cylinder 3 will increase sharply with the movement of the boom. 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 adjustment speed, controls the boom amplitude adjustment speed to decrease or stops the boom amplitude adjustment 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, avoiding the problem of damage to structural components 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 adjustment action returns to normal.

[0060] The second pressure corresponds to the second solenoid unloading valve 16, and the third pressure corresponds to the third solenoid unloading valve 17. If the larger of the second and third pressures is the second pressure, the second solenoid unloading valve 16 is energized, opening the second solenoid unloading valve 16 and reducing the pressure between the first and second leveling cylinders 1 and 3. If the larger of the second and third pressures is the third pressure, the third solenoid unloading valve 17 is energized, opening the third solenoid unloading valve 17 and reducing the pressure between the first and second leveling cylinders 1 and 3.

[0061] In a specific embodiment of the present invention, a second throttle member 18 is provided on the pipeline between the second electromagnetic unloading valve 16 and the oil return tank, and a third throttle member 19 is provided on the pipeline between the third electromagnetic unloading valve 17 and the oil return tank. The second throttle member 18 or the third throttle member 19 limits the unloading flow rate to prevent a shock caused by a sudden complete pressure release 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 includes 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 luffing operation starts and the initial state of the working platform is the tilted state, the controller determines whether the pressure detection value obtained in step 1 is greater than a first set threshold;

[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 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 electromagnetic unloading valve corresponding to the pressure detection value to lose power, and the corresponding electromagnetic unloading valve is closed.

[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 workers on the working platform, causing the working platform to tilt during the pressure relief process and endangering the safety of the workers.

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

[0069] The above disclosure is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, and they should all be covered by the scope of protection 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 connected to the hydraulic oil tank and the return oil tank respectively, the second port and the third port of the electromagnetic reversing valve are connected to the first port and the fourth port of the second two-way balancing valve respectively, the second port of the second two-way balancing valve is connected to the rodless cavity 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 cavity 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 connected to the rodless cavity and the rod cavity of the second leveling oil cylinder respectively; it is 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 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 power loss of the first electromagnetic unloading valve according to the first pressure when the amplitude variation 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 connected to the hydraulic oil tank and the return oil tank respectively, the second port and the third port of the electromagnetic reversing valve are connected to the first port and the fourth port of the second two-way balancing valve respectively, the second port of the second two-way balancing valve is connected to the rodless cavity 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 cavity 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 connected to the rodless cavity and the rod cavity of the second leveling oil cylinder respectively; 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 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 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 power supply and loss of power of the electromagnetic unloading valve corresponding to the larger of the second pressure and the third pressure when the amplitude change operation is started and the initial state of the working platform is an inclined state, so as to avoid damage to 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 further provided on the pipeline between the second electromagnetic unloading valve and the oil return tank, and a third throttling element is further provided on the pipeline between the third electromagnetic unloading valve and the oil return tank.

6. An aerial work platform, characterized by: The aerial work platform includes the hydraulic leveling device according to 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 the first pressure sensor, or the pressure detection value is the larger of a second pressure and a third pressure; When the luffing operation is started 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; 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 a second set threshold, and if so, determine whether the pressure detection value is greater than a 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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