Hydraulic control system for aerial work equipment and aerial work equipment

Abstract

The embodiment of the application provides a hydraulic control system for aerial work equipment and the aerial work equipment. The hydraulic control system comprises: an electro-hydraulic proportional valve installed at an inlet of an upper lifting oil cylinder. A first sensor is installed at the inlet of the upper lifting oil cylinder, and a second sensor is installed at the inlet of a lower lifting oil cylinder. A controller is configured to: determine a target pressure difference between a first target pressure of the upper lifting oil cylinder and a second target pressure of the lower lifting oil cylinder at a current height, determine a current value of the electro-hydraulic proportional valve according to the target pressure difference, and control a valve opening degree of the electro-hydraulic proportional valve according to the current value, so that a difference between an actual pressure difference between the first pressure and the second pressure at the current height and the target pressure difference is within a preset range. The pressures of the two lifting oil cylinders can be adjusted respectively, so that the deformation and internal stress of a scissor arm are reduced, and the energy consumption of the system is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic control, in particular to a hydraulic control system for aerial work equipment and aerial work equipment. BACKGROUND

[0002] At present, the double-cylinder scissors-type aerial work platform controls two hydraulic cylinders through a one-way valve, and the rodless cavities of the two hydraulic cylinders are actually connected. During the lifting or lowering of the scissors-type platform, the pressure of the two cylinders remains consistent. At different heights, the ratio of the driving forces of the upper and lower cylinders is only related to the diameters of the cylinders, and the driving force is determined by the cylinder pressure and the load. Once the structure is determined, the stress between the multi-layer scissors arms is determined by the load, and the hydraulic pressures of the two cylinders cannot be adjusted separately. SUMMARY

[0003] The purpose of the embodiments of the present application is to provide a hydraulic control system for aerial work equipment and aerial work equipment.

[0004] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a hydraulic control system for aerial work equipment, the hydraulic control system comprising:

[0005] a lower lifting cylinder;

[0006] an upper lifting cylinder;

[0007] an electro-hydraulic proportional valve installed at the oil inlet of the upper lifting cylinder, for controlling the flow of hydraulic oil entering the upper lifting cylinder through the valve opening;

[0008] a plurality of sensors, including a first sensor and a second sensor, wherein the first sensor is installed at the oil inlet of the upper lifting cylinder for real-time detection of the first pressure at the oil inlet of the upper lifting cylinder, and the second sensor is installed at the oil inlet of the lower lifting cylinder for real-time detection of the second pressure at the oil inlet of the lower lifting cylinder;

[0009] a controller electrically connected to the plurality of sensors and the electro-hydraulic proportional valve, the controller being configured to:

[0010] determine the first target pressure at the oil inlet of the upper lifting cylinder and the second target pressure at the oil inlet of the lower lifting cylinder at the current height;

[0011] determine the target pressure difference between the first target pressure and the second target pressure;

[0012] determine the current value of the electro-hydraulic proportional valve according to the target pressure difference;

[0013] control the valve opening of the electro-hydraulic proportional valve according to the current value, so that the difference between the actual pressure difference between the first pressure and the second pressure at the current height and the target pressure difference is within a preset range.

[0014] In the embodiments of the present application, the aerial work equipment comprises an inclination sensor for detecting a horizontal inclination of the aerial work equipment, and determining the first target pressure of the upper lifting oil cylinder and the second target pressure of the lower lifting oil cylinder at the current height comprises: obtaining the horizontal inclination of the aerial work equipment at the current height, the first pressure and the second pressure; determining the first target pressure and the second target pressure of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height according to the horizontal inclination at the current height, the first pressure and the second pressure respectively.

[0015] In the embodiments of the present application, determining the first target pressure and the second target pressure of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height according to the horizontal inclination at the current height, the first pressure and the second pressure respectively comprises: determining the first driving force of the upper lifting oil cylinder and the second driving force of the lower lifting oil cylinder at the current height according to the horizontal inclination, the first pressure and the second pressure respectively; determining the first target driving force of the upper lifting oil cylinder and the second target driving force of the lower lifting oil cylinder at the current height according to the first driving force and the second driving force respectively; determining the first target pressure and the second target pressure according to the first target driving force and the second target driving force respectively.

[0016] In the embodiments of the present application, determining the first target pressure and the second target pressure according to the first target driving force and the second target driving force respectively comprises: determining the first oil cylinder size of the upper lifting oil cylinder and the second oil cylinder size of the lower lifting oil cylinder; determining the first target pressure according to the first oil cylinder size and the first target driving force; determining the second target pressure according to the second oil cylinder size and the second target driving force.

[0017] In the embodiments of the present application, the aerial work equipment further comprises a scissors mechanism and a work platform, the third sensor is installed on the upper lifting oil cylinder, and the fourth sensor is installed on the lower lifting oil cylinder; determining the first driving force of the upper lifting oil cylinder and the second driving force of the lower lifting oil cylinder at the current height according to the horizontal inclination, the first pressure and the second pressure respectively comprises: for the current height, determining the working load of the aerial work equipment according to the first pressure, the second pressure and the horizontal inclination, the working load comprising the weight of the scissors mechanism and the work platform; determining the first virtual work corresponding to the working load; determining the second virtual work corresponding to the first driving force and the second driving force according to the first virtual work; determining the first telescopic length and the second telescopic length of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height respectively; determining the driving force ratio of the first driving force to the second driving force according to the length ratio of the first telescopic length to the second telescopic length; determining the first driving force and the second driving force according to the second virtual work and the driving force ratio.

[0018] In the embodiments of the present application, determining the first driving force and the second driving force according to the second virtual work and the driving force ratio comprises: calculating the first driving force and the second driving force according to the following formulas (1) and (2):

[0019]

[0020]

[0021] wherein, m refers to the number of fork arms of the scissor mechanism, w i refers to the weight of the i-th scissor mechanism and the working platform, γ i refers to the first virtual displacement corresponding to the weight, F n refers to the driving force of the n-th lifting oil cylinder at the current height, δ n refers to the second virtual displacement corresponding to the driving force of the n-th lifting oil cylinder in the direction, θ refers to the horizontal inclination angle of the n-th lifting oil cylinder at the current height, F1 refers to the first driving force of the upper lifting oil cylinder at the current height, F2 refers to the second driving force of the lower lifting oil cylinder at the current height, dL1 refers to the first telescopic length of the upper lifting oil cylinder, and dL2 refers to the second telescopic length of the lower lifting oil cylinder.

[0022] In the embodiment of the present application, the controller is further configured to determine a mechanical vibration compensation value of the aerial work equipment and a hydraulic compensation value of the hydraulic control system at the current height; and determine the preset range according to the mechanical vibration compensation value and the hydraulic compensation value.

[0023] The second aspect of the present application provides an aerial work equipment, comprising a hydraulic control system for the aerial work equipment.

[0024] In the embodiment of the present application, the aerial work equipment further comprises an inclination sensor installed on the scissor mechanism, for detecting the horizontal inclination angle of the aerial work equipment.

[0025] In the embodiment of the present application, the scissor mechanism is connected with the upper lifting oil cylinder and the lower lifting oil cylinder respectively, for performing lifting operation according to the telescopic movement of the upper lifting oil cylinder and the lower lifting oil cylinder.

[0026] By the technical solution, the first target pressure of the inlet of the upper lifting oil cylinder and the second target pressure of the inlet of the lower lifting oil cylinder are determined at the current height. The target pressure difference between the first target pressure and the second target pressure is used to determine the current value of the electro-hydraulic proportional valve. The valve opening of the electro-hydraulic proportional valve is controlled according to the current value, so that the actual pressure difference between the first pressure and the second pressure at the current height is within the preset range. The electro-hydraulic proportional valve is installed at the inlet of the upper lifting oil cylinder, and the opening of the electro-hydraulic proportional valve is controlled by the current, so as to control the hydraulic pressure of the two lifting oil cylinders respectively, so that the difference between the actual pressure difference and the target pressure difference can be within the preset range. Therefore, the actual pressure of the upper and lower lifting oil cylinders is detected by the sensor in real time and fed back to the controller. The controller and the driving device form a closed-loop control system, and the minimum target driving force of the lifting oil cylinder output for the aerial work platform is obtained according to different postures of the aerial work equipment. The energy consumption of the hydraulic control system can be reduced, and the endurance of the equipment can be improved. In addition, the deformation and internal stress of the scissor arm can be reduced, the fatigue strength of the scissor arm can be reduced, and the service life of the equipment can be prolonged.

[0027] Other features and advantages of the embodiments of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0029] Figure 1 A schematic diagram of a hydraulic control system for an aerial work equipment according to an embodiment of the present application is schematically shown;

[0030] Figure 2 A flowchart of a hydraulic control method for an aerial work equipment according to an embodiment of the present application is schematically shown;

[0031] Figure 3 A schematic diagram of an aerial work equipment according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0032] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the specific implementation manners described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0033] Figure 1 A schematic diagram of a hydraulic control system for aerial work equipment according to an embodiment of the present application is shown schematically. As Figure 1 shown, in an embodiment of the present application, a hydraulic control system for aerial work equipment is provided, comprising:

[0034] a lower lifting oil cylinder 120;

[0035] an upper lifting oil cylinder 130,

[0036] an electro-hydraulic proportional valve 140 installed at the oil inlet of the upper lifting oil cylinder for controlling the flow of hydraulic oil into the upper lifting oil cylinder through the valve opening;

[0037] a plurality of sensors, including a first sensor 161 and a second sensor 162, wherein the first sensor 161 is installed at the oil inlet of the upper lifting oil cylinder 130 for real-time detection of the first pressure at the oil inlet of the upper lifting oil cylinder 130, and the second sensor 162 is installed at the oil inlet of the lower lifting oil cylinder 120 for real-time detection of the second pressure at the oil inlet of the lower lifting oil cylinder 120;

[0038] a controller electrically connected to the plurality of sensors and the electro-hydraulic proportional valve 140. Figure 2 A flowchart of a hydraulic control method for aerial work equipment according to an embodiment of the present application is shown schematically. As Figure 2 shown, the controller is configured to perform the following steps:

[0039] S202, determining a first target pressure at the oil inlet of the upper lifting oil cylinder and a second target pressure at the oil inlet of the lower lifting oil cylinder at the current height;

[0040] S204, determining a target pressure difference between the first target pressure and the second target pressure;

[0041] S206 determining a current value of the electro-hydraulic proportional valve according to the target pressure difference;

[0042] S208, controlling the valve opening of the electro-hydraulic proportional valve according to the current value, so that the difference between the actual pressure difference between the first pressure and the second pressure at the current height and the target pressure difference is within a preset range.

[0043] like Figure 1 As shown, without the electro-hydraulic proportional valve 140 installed, the rodless chamber ends of the lower lifting cylinder 120 and the upper lifting cylinder 130 are connected. During the ascent or descent of the aerial work platform, the hydraulic pressure at the inlet remains constant. Therefore, the driving force of the two cylinders is also the same. Thus, for a dual-cylinder aerial work platform, the excessive driving force, exceeding the actual requirements of the mechanism, results in greater stress on the scissor arm, reducing the fatigue life of the mechanical structure. Therefore, the electro-hydraulic proportional valve 140 can be installed at the inlet (rodless chamber end) of the upper lifting cylinder 130. The electro-hydraulic proportional valve 140 is connected to the oil pump via an oil circuit. Hydraulic oil from the pump flows from the direction indicated by the arrow in the diagram, with part flowing through the electro-hydraulic proportional valve 140 into the upper lifting cylinder 130 and part directly into the lower lifting cylinder 120. The hydraulic oil then returns to the oil tank 110 via the rod chamber ends of the two lifting cylinders. By controlling the opening of the electro-hydraulic proportional valve 140, the amount of hydraulic oil entering the lifting cylinder 130 is adjusted, thereby changing the hydraulic pressure of the lifting cylinder. The electro-hydraulic proportional valve can also be other hydraulic valves with pressure regulation functions, such as a throttle valve.

[0044] The current height refers to the height of the working platform of the aerial work platform. The controller determines a first target pressure at the inlet of the upper lifting cylinder and a second target pressure at the inlet of the lower lifting cylinder at the current height. The first target pressure is the minimum pressure required to drive the aerial work platform upwards or downwards using the upper lifting cylinder at the current height. The second target pressure is the minimum pressure required to drive the aerial work platform upwards or downwards using the lower lifting cylinder at the current height. Based on the first and second target pressures, the controller can calculate the target pressure difference between them. A first sensor 161 installed at the inlet of the upper lifting cylinder 130 can detect the first pressure at the inlet of the upper lifting cylinder 130 in real time. A second sensor 162 installed at the inlet of the lower lifting cylinder 120 can detect the second pressure at the inlet of the lower lifting cylinder 120 in real time. Both the first and second sensors can be hydraulic gauges. Therefore, the controller can calculate the actual pressure difference between the first and second pressures at the current height. The controller can calculate the current value of the electro-hydraulic proportional valve based on the target pressure difference, thereby controlling the valve opening to ensure that the difference between the actual pressure difference between the first and second pressures at the current height and the target pressure difference is within a preset range. This preset range refers to the system error of the aerial work platform. The electro-hydraulic proportional valve needs to control the difference between the actual pressure difference and the target pressure difference in the lifting cylinders within the system error range. Thus, by controlling the opening of the electro-hydraulic proportional valve, the pressure difference between the upper and lower lifting cylinders can be adjusted, thereby reducing the stress on the scissor arms of the aerial work platform and lowering its energy consumption.

[0045] In one embodiment, the aerial work platform device includes a tilt sensor for detecting a horizontal tilt angle of the aerial work platform device, and determining the first target pressure of the upper lift cylinder inlet and the second target pressure of the lower lift cylinder inlet at the current height includes: obtaining the horizontal tilt angle of the aerial work platform device at the current height, the first pressure and the second pressure; determining the first target pressure and the second target pressure of the upper lift cylinder and the lower lift cylinder at the current height according to the horizontal tilt angle, the first pressure and the second pressure at the current height, respectively.

[0046] The controller can detect the horizontal tilt angle of the aerial work platform device through the tilt sensor. That is, the angle between the scissor arm of the scissor mechanism and the horizontal direction. According to the horizontal tilt angle at the current height, the first pressure of the upper lift cylinder and the second pressure of the lower lift cylinder, the first target pressure of the upper lift cylinder and the second target pressure of the lower lift cylinder can be determined.

[0047] In one embodiment, determining the first target pressure and the second target pressure of the upper lift cylinder and the lower lift cylinder at the current height according to the horizontal tilt angle, the first pressure and the second pressure at the current height, respectively, includes: determining the first driving force of the upper lift cylinder and the second driving force of the lower lift cylinder at the current height according to the horizontal tilt angle, the first pressure and the second pressure, respectively; determining the first target driving force of the upper lift cylinder and the second target driving force of the lower lift cylinder at the current height according to the first driving force and the second driving force, respectively; determining the first target pressure and the second target pressure according to the first target driving force and the second target driving force, respectively.

[0048] In one embodiment, determining the first target pressure and the second target pressure according to the first target driving force and the second target driving force, respectively, includes: determining the first cylinder size of the upper lift cylinder and the second cylinder size of the lower lift cylinder; determining the first target pressure according to the first cylinder size and the first target driving force; determining the second target pressure according to the second cylinder size and the second target driving force.

[0049] The controller can determine, according to the horizontal inclination angle, the first pressure and the second pressure, a first driving force of the upper lifting oil cylinder and a second driving force of the lower lifting oil cylinder at the current height. The first driving force and the second driving force are actual driving forces generated by the lifting oil cylinder based on the hydraulic oil. According to the actual first driving force and the actual second driving force, the controller can calculate, by using the finite element calculation result, a first target driving force of the upper lifting oil cylinder and a second target driving force of the lower lifting oil cylinder. The first target driving force is a minimum driving force of the upper lifting oil cylinder that can meet the lifting operation of the aerial work equipment, and the second target driving force is a minimum driving force of the lower lifting oil cylinder that can meet the lifting operation of the aerial work equipment. Alternatively, the first target driving force and the second target driving force can also be the minimum target driving forces corresponding to the driving forces, which are found by using the experience values of the database based on the first driving force and the second driving force. Then, according to the first cylinder size of the upper lifting oil cylinder and the first target driving force, the controller can determine a minimum first target pressure corresponding to the upper lifting oil cylinder. According to the second cylinder size of the lower lifting oil cylinder and the second target driving force, a minimum second target pressure corresponding to the lower lifting oil cylinder can be determined. The first cylinder size and the second cylinder size refer to the cylinder diameter of the lifting oil cylinder.

[0050] In one embodiment, the aerial work equipment further comprises a scissors mechanism and a work platform, and determining the first driving force of the upper lifting oil cylinder and the second driving force of the lower lifting oil cylinder at the current height according to the horizontal inclination angle, the first pressure and the second pressure comprises: determining, for the current height, a work load of the aerial work equipment according to the first pressure, the second pressure and the horizontal inclination angle, the work load including the weight of the scissors mechanism and the work platform; determining a first virtual work corresponding to the work load; determining a second virtual work corresponding to the first driving force and the second driving force according to the first virtual work; determining a first telescopic length and a second telescopic length of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height, respectively; determining a driving force ratio of the first driving force to the second driving force according to the length ratio of the first telescopic length to the second telescopic length; and determining the first driving force and the second driving force according to the second virtual work and the driving force ratio.

[0051] The aerial work equipment further comprises a scissors mechanism and a work platform. The first telescopic length of the upper lifting cylinder and the second telescopic length of the lower lifting cylinder can be calculated according to the horizontal inclination angle and the equipment parameters of the aerial work equipment. According to the deformation coordination algorithm, the controller can determine the driving force ratio of the first driving force to the second driving force according to the length ratio of the first telescopic length to the second telescopic length for the current height. And the length ratio is equal to the driving force. For the current height, the controller can determine the working load of the aerial work equipment according to the first pressure sum, the second pressure sum and the horizontal inclination angle. The working load includes the weight of the scissors mechanism and the work platform. The processor can first determine the first virtual work of the working load. The first virtual work refers to the virtual work done by the working load in the direction of gravity. Based on the virtual displacement equation, the controller can determine the second virtual work corresponding to the first driving force and the second driving force according to the first virtual work. The second virtual work refers to the virtual work done by the two lifting cylinders in the direction of driving force. According to the virtual work principle, the sum of the first virtual work corresponding to the working load and the second virtual work corresponding to the driving force is 0. Then, the controller can determine the first driving force and the second driving force according to the second virtual work and the driving force ratio.

[0052] In one embodiment, determining the first driving force and the second driving force according to the second virtual work and the driving force ratio comprises calculating the first driving force and the second driving force according to the following formulas (1) and (2):

[0053]

[0054]

[0055] wherein m refers to the number of fork arms of the scissors mechanism, w i refers to the weight of the i-th scissors mechanism and the work platform, γ i refers to the first virtual displacement corresponding to the weight, F n refers to the driving force of the n-th lifting cylinder at the current height, δ n refers to the second virtual displacement corresponding to the driving force of the n-th lifting cylinder in the direction of the cylinder, θ refers to the horizontal inclination angle of the n-th lifting cylinder at the current height, F1 refers to the first driving force of the upper lifting cylinder at the current height, F2 refers to the second driving force of the lower lifting cylinder at the current height, dL1 refers to the first telescopic length of the upper lifting cylinder, and dL2 refers to the second telescopic length of the lower lifting cylinder.

[0056] In one embodiment, the controller is further configured to determine a mechanical vibration compensation value of the aerial work equipment and a hydraulic compensation value of the hydraulic control system at the current height; and determine the preset range according to the mechanical vibration compensation value and the hydraulic compensation value.

[0057] Because the mechanical components of aerial work platforms vibrate during operation, the mechanical vibration compensation value is a compensation value used to compensate for the errors caused by these vibrations. This value is related to the load and mechanical angle of the aerial work platform and can be calculated based on a vibration compensation algorithm. Since the hydraulic oil in the hydraulic control system may cause pressure loss through the relief valve, the hydraulic compensation value compensates for errors such as pressure loss. The controller can determine the preset range corresponding to the difference between the actual pressure difference and the target pressure difference based on the mechanical vibration compensation value and the hydraulic compensation value at the current height. If the difference between the actual and target pressure differences is within the preset range, the driving force of the two lifting cylinders corresponding to that actual pressure difference is calibrated as the driving force output value. If the difference exceeds the preset range, the first and second target driving forces can be re-determined based on the actual pressure and horizontal tilt angle of the two lifting cylinders at the current height to continuously and dynamically adjust the actual pressure difference.

[0058] Figure 3 A schematic diagram of an aerial work platform according to an embodiment of this application is shown. Figure 3 As shown, in one embodiment of this application, a hydraulic control system for aerial work platforms is provided. (Reference) Figure 3 The hydraulic control system includes: a lower lifting cylinder; an upper lifting cylinder 130; an electro-hydraulic proportional valve installed at the inlet of the upper lifting cylinder 130 to control the flow rate of hydraulic oil entering the upper lifting cylinder 130 by adjusting the valve opening; multiple sensors, including a first sensor and a second sensor, wherein the first sensor is installed at the inlet of the upper lifting cylinder 130 to detect the first pressure at the inlet of the upper lifting cylinder 130 in real time, and the second sensor is installed at the inlet of the lower lifting cylinder 120 to detect the second pressure at the inlet of the lower lifting cylinder 120 in real time; and a controller electrically connected to the multiple sensors and the electro-hydraulic proportional valve.

[0059] The controller is configured to: determine a first target pressure at the inlet of the upper lifting cylinder and a second target pressure at the inlet of the lower lifting cylinder at the current height; determine a target pressure difference between the first and second target pressures; determine the current value of the electro-hydraulic proportional valve based on the target pressure difference; and control the valve opening of the electro-hydraulic proportional valve based on the current value, so that the difference between the actual pressure difference between the first and second pressures at the current height and the target pressure difference is within a preset range.

[0060] In one embodiment, reference Figure 3 The aerial work platform also includes a horizontal tilt sensor 310, which is installed on the scissor lift mechanism 320 and is used to detect the horizontal tilt angle of the aerial work platform.

[0061] In one embodiment, referring to Figure 3 The scissor mechanism 320 is connected with the upper lifting oil cylinder 130 and the lower lifting oil cylinder 120 respectively, and is used for lifting operation according to the extension and retraction of the upper lifting oil cylinder 130 and the lower lifting oil cylinder 120.

[0062] In one embodiment, referring to Figure 3 The aerial work equipment includes a horizontal inclination sensor 310 for detecting the horizontal inclination of the aerial work equipment, and the controller determining the first target pressure of the inlet of the upper lifting oil cylinder and the second target pressure of the inlet of the lower lifting oil cylinder at the current height includes: obtaining the horizontal inclination of the aerial work equipment at the current height, the first pressure and the second pressure; determining the first target pressure and the second target pressure of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height according to the horizontal inclination, the first pressure and the second pressure at the current height respectively.

[0063] In one embodiment, the controller determines the first target pressure and the second target pressure of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height according to the horizontal inclination, the first pressure and the second pressure at the current height respectively includes: determining the first driving force and the second driving force of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height according to the horizontal inclination, the first pressure and the second pressure respectively; determining the first target driving force and the second target driving force of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height according to the first driving force and the second driving force respectively; determining the first target pressure and the second target pressure according to the first target driving force and the second target driving force respectively.

[0064] In one embodiment, the controller determines the first target pressure and the second target pressure according to the first target driving force and the second target driving force respectively includes: determining the first cylinder size of the upper lifting oil cylinder and the second cylinder size of the lower lifting oil cylinder; determining the first target pressure according to the first cylinder size and the first target driving force; determining the second target pressure according to the second cylinder size and the second target driving force.

[0065] In one embodiment, referring to Figure 3, the aerial work equipment further comprises a scissors mechanism 320 and a working platform 340. The controller determines the first driving force of the upper lifting oil cylinder and the second driving force of the lower lifting oil cylinder at the current height according to the horizontal inclination angle, the first pressure and the second pressure comprises: determining the working load of the aerial work equipment according to the first pressure, the second pressure and the horizontal inclination angle for the current height, the working load comprises the weight of the scissors mechanism and the working platform; determining the first virtual work corresponding to the working load; determining the second virtual work corresponding to the first driving force and the second driving force according to the first virtual work; determining the first telescopic length and the second telescopic length of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height respectively; determining the driving force ratio of the first driving force and the second driving force according to the length ratio of the first telescopic length and the second telescopic length; determining the first driving force and the second driving force according to the second virtual work and the driving force ratio.

[0066] In one embodiment, the controller determines the first driving force and the second driving force according to the second virtual work and the driving force ratio comprises: calculating the first driving force and the second driving force according to the following formulas (1) and (2):

[0067]

[0068]

[0069] wherein m refers to the number of fork arms of the scissors mechanism, w i refers to the weight of the i-th scissors mechanism and the working platform, γ i refers to the first virtual displacement corresponding to the weight, F n refers to the driving force of the n-th lifting oil cylinder at the current height, δ n refers to the second virtual displacement corresponding to the driving force of the n-th lifting oil cylinder in the x direction, θ refers to the horizontal inclination angle of the n-th lifting oil cylinder of the aerial work equipment at the current height, F1 refers to the first driving force of the upper lifting oil cylinder at the current height, F2 refers to the second driving force of the lower lifting oil cylinder at the current height, dL1 refers to the first telescopic length of the upper lifting oil cylinder, and dL2 refers to the second telescopic length of the lower lifting oil cylinder.

[0070] In one embodiment, the controller is further configured to: determine a mechanical vibration compensation value of the aerial work equipment and a hydraulic compensation value of the hydraulic control system at the current height; and determine the preset range according to the mechanical vibration compensation value and the hydraulic compensation value.

[0071] Using the above technical solution, combined with the virtual displacement equation and deformation coordination algorithm, the driving forces of the upper and lower lifting cylinders are calculated based on the horizontal tilt angle of the aerial work platform at the current height, the first pressure and first extension length of the upper lifting cylinder, and the second pressure and second extension length of the lower lifting cylinder. Then, based on the first and second pressures, the minimum first and second target driving forces corresponding to the two lifting cylinders are obtained using the finite element method or by searching a database. The target pressures of the two lifting cylinders are calculated based on their cylinder dimensions, the first target driving force, and the second target driving force. An electro-hydraulic proportional valve is installed at the inlet of the upper lifting cylinder, and by controlling the opening of the electro-hydraulic proportional valve, the hydraulic pressure of the two lifting cylinders can be adjusted separately, ensuring that the difference between the actual pressure difference and the target pressure difference is within a preset range. Thus, the actual pressure of the upper and lower lifting cylinders is detected in real time by sensors and fed back to the controller. The controller and drive unit form a closed-loop control system, which adjusts the lifting cylinder's output of the minimum target driving force to lift the aerial work platform based on the different postures of the aerial work equipment. This reduces the energy consumption of the hydraulic control system and improves the equipment's endurance. Furthermore, it reduces deformation and internal stress of the scissor arm, decreasing its fatigue strength and thus extending the equipment's service life.

[0072] Figure 2 This is a schematic flowchart of a hydraulic control method for aerial work equipment in one embodiment. It should be understood that, although... Figure 2 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 2 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0073] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart...Figure 1 one or more processes and / or means for carrying out the functions described in one or more of the blocks. Figure 1 one or more blocks or any combination thereof.

[0074] It should also be noted that the terms "comprising," "including," and any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a... " does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0075] The above embodiments of the present application have been described only for clarity's sake and are not intended to limit the present application. The present application can be modified and changed in various ways by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A hydraulic control system for an aerial work platform, said aerial work platform comprising a tilt sensor for detecting a horizontal tilt angle of said aerial work platform, characterized in that, The hydraulic control system comprises: a lower lifting oil cylinder; an upper lifting oil cylinder; an electro-hydraulic proportional valve installed at an oil inlet of the upper lifting oil cylinder, for controlling the flow of hydraulic oil into the upper lifting oil cylinder through valve opening degree; a plurality of sensors, including a first sensor and a second sensor, wherein the first sensor is installed at an oil inlet of the upper lifting oil cylinder, for detecting a first pressure of the oil inlet of the upper lifting oil cylinder in real time, and the second sensor is installed at an oil inlet of the lower lifting oil cylinder, for detecting a second pressure of the oil inlet of the lower lifting oil cylinder in real time; a controller electrically connected with the plurality of sensors and the electro-hydraulic proportional valve, the controller being configured to: determine a first target pressure of the oil inlet of the upper lifting oil cylinder and a second target pressure of the oil inlet of the lower lifting oil cylinder at a current height; determine a target pressure difference between the first target pressure and the second target pressure; determine a current value of the electro-hydraulic proportional valve according to the target pressure difference; control the valve opening degree of the electro-hydraulic proportional valve according to the current value, so that the difference between an actual pressure difference between the first pressure and the second pressure at the current height and the target pressure difference is within a preset range; wherein the determination of the first target pressure of the oil inlet of the upper lifting oil cylinder and the second target pressure of the oil inlet of the lower lifting oil cylinder at the current height comprises: obtaining a horizontal inclination, the first pressure and the second pressure of the aerial work equipment at the current height; determining the first target pressure and the second target pressure of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height, respectively, according to the horizontal inclination, the first pressure and the second pressure at the current height.

2. The hydraulic control system for an aerial device of claim 1, wherein, The determination of the first target pressure and the second target pressure of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height, respectively, according to the horizontal inclination, the first pressure and the second pressure at the current height comprises: determining a first driving force of the upper lifting oil cylinder and a second driving force of the lower lifting oil cylinder at the current height, respectively, according to the horizontal inclination, the first pressure and the second pressure; determining a first target driving force of the upper lifting oil cylinder and a second target driving force of the lower lifting oil cylinder at the current height, respectively, according to the first driving force and the second driving force; determining the first target pressure and the second target pressure, respectively, according to the first target driving force and the second target driving force.

3. The hydraulic control system for an aerial device of claim 2, wherein, The determination of the first target pressure and the second target pressure, respectively, according to the first target driving force and the second target driving force comprises: determining a first oil cylinder size of the upper lifting oil cylinder and a second oil cylinder size of the lower lifting oil cylinder; determining the first target pressure according to the first oil cylinder size and the first target driving force; determining the second target pressure according to the second oil cylinder size and the second target driving force.

4. The hydraulic control system for an aerial device of claim 2, wherein, The aerial work equipment further comprises a scissor mechanism and a working platform, and the determination of the first driving force of the upper lifting oil cylinder and the second driving force of the lower lifting oil cylinder at the current height, respectively, according to the horizontal inclination, the first pressure and the second pressure comprises: determining, according to the first pressure sum, the second pressure sum and the horizontal inclination, a working load of the aerial work equipment at the current height, the working load including weights of the scissor mechanism and the working platform; determining a first virtual work corresponding to the working load; determining a second virtual work corresponding to the first driving force and the second driving force according to the first virtual work; determining a first telescopic length and a second telescopic length of the upper lifting oil cylinder and the lower lifting oil cylinder at the current height, respectively; determining a driving force ratio of the first driving force and the second driving force according to a length ratio of the first telescopic length and the second telescopic length; determining the first driving force and the second driving force according to the second virtual work and the driving force ratio.

5. The hydraulic control system for an aerial device of claim 4, wherein, The determining the first driving force and the second driving force according to the second virtual work and the driving force ratio includes calculating the first driving force and the second driving force according to following formulas (1) and (2): （1） （2） m is the number of fork arms of the scissor mechanism, is the weight of the working platform, is the first virtual displacement corresponding to the weight, is the driving force of the nth lifting oil cylinder at the current height, is the second virtual displacement corresponding to the driving force of the nth lifting oil cylinder, is the horizontal inclination angle of the nth lifting oil cylinder at the current height, is the first driving force of the upper lifting oil cylinder at the current height, is the second driving force of the lower lifting oil cylinder at the current height, is the first telescopic length of the upper lifting oil cylinder, is the second telescopic length of the lower lifting oil cylinder.

6. The hydraulic control system for an aerial device of claim 1, wherein, The controller is further configured to: determining a mechanical vibration compensation value of the aerial work equipment and a hydraulic compensation value of the hydraulic control system at the current height; determining the preset range according to the mechanical vibration compensation value and the hydraulic compensation value.

7. An aerial work platform, characterized in that The aerial work equipment includes the hydraulic control system for aerial work equipment according to any one of claims 1 to 6.

8. Aerial work platform according to claim 7, characterized in that The aerial work equipment further includes: an inclination sensor installed on the scissor mechanism for detecting the horizontal inclination of the aerial work equipment.

9. Aerial work platform according to claim 8, characterized in that The scissor mechanism is connected with the upper lifting oil cylinder and the lower lifting oil cylinder, respectively, for performing lifting operation according to the telescopic movement of the upper lifting oil cylinder and the lower lifting oil cylinder.

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