Matching method to reduce the pressure shock during the unloading start-up of the bucket arm of an electronically controlled hydraulic excavator

Abstract

The present invention provides a matching method for reducing the pressure shock during the start-up of the boom unloading operation of an electronically controlled hydraulic excavator. The method determines the ideal starting acceleration of the excavator during the start-up of the boom unloading operation based on the hydraulic cylinder force balance equation and big data analysis. The method also adjusts the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure based on the relationship between the bypass valve port flow rate and the main valve control current. Multiple sets of matching data for the main pump displacement current, main valve control current, and bypass valve control current are obtained. The data are then fitted to obtain a specific matching relationship between the main pump displacement current, main valve control current, and bypass valve control current. The present invention constructs an ideal matching method for the handle, main pump, main valve, and bypass valve, enabling the main pump displacement current and bypass valve control current to be regulated based on the main valve control current. This method effectively reduces the pressure shock during the start-up of the boom unloading operation of an electronically controlled hydraulic excavator, thereby improving the operating efficiency, starting stability, and maneuverability of the electronically controlled hydraulic excavator.

Description

Technical Field

[0001] The present invention relates to the technical field of excavators, and in particular to a matching method for reducing the pressure impact of an electronically controlled hydraulic excavator arm during unloading startup. Background Art

[0002] In traditional hydraulic excavator control systems, the coordinated matching of hydraulic components is primarily achieved through logic valves. The hydraulic pump, priority control valve, and main valve limit the flexible control between the hydraulic control components and the hydraulic power unit. With the development of large and medium-sized excavators, the trend towards intelligent control has gradually shifted. The traditional pilot control method of mechanical handles with mechanical pressure reducing valves has been gradually replaced by electronic control handles and electric proportional pressure reducing valves. Furthermore, advances in sensor and controller technology have enabled electrical control to replace the original hardware, laying a solid foundation for the coordinated matching of hydraulic pumps and proportional multi-way valves.

[0003] The electro-hydraulic control system for an electric-hydraulic excavator generally consists of an electric control handle, a proportional multi-way valve, a hydraulic pump, and a controller. The control method is that the control handle sends a flow signal, and the controller calculates and outputs control signals for the proportional multi-way valve opening and the hydraulic pump's swing angle, achieving precise control of the actuator. Currently, research on electric-hydraulic excavators is in its infancy, and there is a lack of research on matching control schemes between pumps and valves in the electro-hydraulic system. The poor matching between the pumps and valves in electric-hydraulic excavators leads to large acceleration of the actuator during startup, ultimately causing a large pressure surge during startup. This pressure surge problem affects the excavator's maneuverability, severely reduces operating efficiency, and cannot meet the operational requirements of current electric-hydraulic excavators under complex working conditions.

[0004] Therefore, there is an urgent need to develop a method for reducing the pressure shock of the boom unloading startup of an electronically controlled hydraulic excavator with strong reliability, smooth startup, good pump-valve matching control, and smooth control. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the technical problem to be solved by the present invention is to provide a matching method for reducing the pressure impact of the boom unloading startup of the electric-controlled hydraulic excavator, so as to improve the operating efficiency and maneuverability of the electric-controlled hydraulic excavator, in view of the poor matching control of the pump and valve of the electric-controlled hydraulic excavator.

[0006] To achieve the above objectives, the present invention discloses the following technical solutions:

[0007] A matching method for reducing the pressure shock of the arm unloading startup of an electronically controlled hydraulic excavator comprises the following steps:

[0008] S1. Determine the ideal starting acceleration of the excavator when the dipper arm unloading action starts based on the hydraulic cylinder force balance equation and big data analysis;

[0009] S11. Establish the hydraulic cylinder force balance equation when the excavator starts the bucket arm unloading action:

[0010] p2A2-p1A1=ma+F l +f

[0011] Among them, p1 is the pressure of the hydraulic cylinder rodless chamber at startup; A1 is the area of the hydraulic cylinder rodless chamber; p2 is the pressure of the hydraulic cylinder rod chamber at startup; A2 is the area of the hydraulic cylinder rod chamber; m is the equivalent mass borne by the excavator arm; a is the acceleration of the arm unloading action at startup; F l is the load force at startup; f is the friction force;

[0012] S12. Calculate the equivalent mass m of the boom hydraulic cylinder based on the angles between the excavator's actuators; and obtain the friction force f by fitting the Stribeck curve.

[0013] S13. When the boom is unloading, the rodless chamber of the hydraulic cylinder is connected to the oil tank and the pressure is 0. The formula for calculating the pressure in the rod chamber of the hydraulic cylinder is as follows:

[0014]

[0015] Among them, p1' is the pressure of the rodless chamber of the hydraulic cylinder before starting; p2' is the pressure of the rod chamber of the hydraulic cylinder before starting;

[0016] S14. The pressure calculation formula above indicates that pressure p2 depends on the acceleration a of the boom unloading action during startup. The excavator performs multiple boom unloading actions, obtaining multiple sets of experimental data. The startup acceleration range corresponding to the pressure shock during the startup phase of the electronically controlled hydraulic excavator is determined when it is less than a threshold value M. The startup pressure here refers to the rod chamber pressure of the hydraulic cylinder. The ideal startup acceleration is then determined from the startup acceleration range.

[0017] S2. Based on the relationship between the bypass valve port flow rate and the main valve control current, adjust the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure;

[0018] S21. Move the handle to the position where the boom hydraulic cylinder is just started. The handle opening at this time is recorded as x by the current sensor. It is known that the handle opening is directly proportional to the main valve control current. The main valve control current is kx, where k is the proportional coefficient.

[0019] In a certain posture, the handle is manipulated to the position where the boom hydraulic cylinder is just started to perform the boom unloading operation. The main valve control current is used as the independent variable, and the main pump displacement current and bypass valve control current are used as dependent variables. The following relationship is satisfied:

[0020] y1=K1·kx

[0021] y2=K2·kx

[0022] Among them, y1 is the main pump displacement current; K1 is the proportional coefficient between the main pump displacement current and the main valve control current; y2 is the bypass valve control current; K2 is the proportional coefficient between the bypass valve control current and the main valve control current;

[0023] S22. Based on the ideal rod chamber starting pressure, the relationship between the bypass valve port flow rate Q and the bypass valve return port flow area A is obtained:

[0024]

[0025] Among them, C d is the valve port flow coefficient; ρ is the oil density;

[0026] During the start-up phase of the boom unloading action, the bypass valve port flow rate is the hydraulic pump output flow rate, and the bypass valve port flow rate Q is expressed as:

[0027] Q=Vn=(K1k1kx+b1)n

[0028] Where n is the speed of the hydraulic pump;

[0029] S23. In the controller, the main pump displacement current and the bypass valve control current are regulated based on the main valve control current, thereby implementing bypass throttling speed regulation of the system through the bypass valve, thereby adjusting the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure under the ideal starting acceleration;

[0030] S3. Acquire multiple sets of matching data of main pump displacement current, main valve control current, and bypass valve control current;

[0031] S31. In a certain posture, manipulate the handle to the position where the boom hydraulic cylinder is just started, and use the flow formula to obtain the relationship between K1, K2 and kx:

[0032]

[0033] Among them, k, k1, k2, k3, b1, b2, and b3 are all controller parameters and are known quantities;

[0034] S32. Under different postures, push the handle to the position where the boom hydraulic cylinder is just started, perform multiple boom unloading actions, and record the handle opening x through the current sensor. n (n=1,2,3…), calculate multiple groups of K through the flow formula 1n , K 2n The relationship between them is as follows:

[0035]

[0036] S4. Perform curve fitting on the matching relationships between multiple groups of kx and K1 and K2, and finally obtain the specific matching relationship between the main pump displacement current, the main valve control current, and the bypass valve control current, so that the main pump, the main valve, and the bypass valve are ideally matched, reducing the pressure shock in the start-up phase of the boom unloading action.

[0037] Furthermore, in step S1, the pressure values of the rod chamber and the rodless chamber of the hydraulic cylinder are obtained based on the pressure sensor. During the startup phase, the displacement of the hydraulic cylinder is very small, that is, F l Before starting F l 'Consistent:

[0038] F l =F l '=p1'A1-p2'A2

[0039] Among them, p1' is the pressure of the hydraulic cylinder rodless cavity before starting; p2' is the pressure of the hydraulic cylinder rod cavity before starting; F l ' is the load force before starting.

[0040] Furthermore, in step S2, the bypass valve pilot pressure causes the bypass valve core to move to form a flow area. The pilot pressure and the oil return port flow area A are approximately simplified to a linear relationship, then:

[0041] A=k3[k2(K2·kx)+b2]+b3

[0042] Among them, k3 is the proportional coefficient between the flow area of the bypass valve return port and the bypass valve pilot pressure; b3 is the offset.

[0043] Furthermore, in step S22, when starting, the engine gear is fixed, the hydraulic pump is in the positive flow stage, and the main pump displacement current and the main pump output displacement are in a linear relationship, then:

[0044] V=k1(K1·kx)+b1

[0045] Where V is the hydraulic pump displacement; k1 is the proportional coefficient between the main pump output displacement and the main pump control current; b1 is the offset.

[0046] Furthermore, in step S22, the output pressure of the electric proportional pressure reducing valve controlling the bypass valve is linearly related to the bypass valve control current, and thus:

[0047] p p =k2(K2·kx)+b2

[0048] Among them, p p is the bypass valve pilot pressure; k2 is the proportional coefficient between the bypass valve pilot pressure and the bypass valve control current; b2 is the offset.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. This invention uses big data analysis to determine the ideal starting acceleration range and the ideal starting pressure. Bypass valve throttling and speed regulation are used to adjust the hydraulic cylinder rod chamber pressure to the ideal starting pressure, minimizing pressure shock during the arm unloading start-up phase.

[0051] 2. The present invention proposes an electro-hydraulic system pump-valve matching control method that uses the main valve control current as a reference to adjust the main pump displacement current and the bypass valve control current. By repeatedly adjusting the posture of the electric-controlled hydraulic excavator boom during the unloading start-up action, multiple sets of matching data of the main pump displacement current, the main valve control current and the bypass valve control current are obtained. The specific matching relationship of the main pump-main valve-bypass valve is obtained through deduction calculation and data fitting, ensuring the coordinated matching of the flow output of the main pump and the distribution of the valve port, thereby reducing the pressure shock during the startup of the actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A flow chart of a matching method for reducing the pressure shock of an electronically controlled hydraulic excavator arm unloading startup according to the present invention;

[0053] Figure 2 This is a hydraulic-control principle diagram of the present invention;

[0054] Figure 3 is a control flow chart of the present invention;

[0055] Figure 4 This is a diagram showing the posture angles of the excavator of the present invention;

[0056] Figure 5 is the friction force fitting curve of the present invention;

[0057] Figure 6 is the Stribeck friction model of the present invention;

[0058] Figure 7 The fitting curve is matched for the pump valve of the present invention. DETAILED DESCRIPTION

[0059] The exemplary embodiments, features, and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0060] The present invention provides a matching method for reducing the pressure impact of the arm unloading start-up of an electronically controlled hydraulic excavator, such as Figure 1 As shown, it is a schematic flow chart of the method of the present invention, comprising the following steps:

[0061] S1. The excavator performs multiple boom unloading actions to obtain multiple sets of experimental data. The ideal starting acceleration range corresponding to the pressure shock during the starting phase is less than a threshold value M is analyzed from the large amount of experimental data; the ideal starting acceleration is obtained from the starting acceleration range.

[0062] The threshold value M is usually taken as the 10th percentile of the pressure shock during the startup phase. Alternatively, threshold conditions such as the mean and median can be used based on different operating conditions and mathematical distributions. The ideal startup acceleration can be selected from any value within the startup acceleration range, but the middle value is usually selected. The acceleration is derived from extensive test data analysis under boom unloading conditions. Generally speaking, the corresponding acceleration range for a small pressure shock during the startup phase is 3 m / s. 2 ~5m / s 2 , take a=4m / s 2 .

[0063] S2. In the controller, the main pump displacement current and the bypass valve control current are regulated based on the main valve control current, so as to realize the bypass throttling speed regulation of the system through the bypass valve, thereby adjusting the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure under the ideal starting acceleration.

[0064] S3. Under different postures, push the handle to the position where the boom hydraulic cylinder just starts, perform multiple boom unloading actions, and obtain multiple sets of matching data of main pump displacement current-main valve control current-bypass valve control current.

[0065] S4. Fit multiple sets of ideal matching data of main pump, main valve and bypass valve into a curve, and finally obtain the specific matching relationship between main pump displacement current, main valve control current and bypass valve control current.

[0066] like Figure 2 As shown, it is a hydraulic control principle diagram of the present invention. Before the excavator operator operates the handle, the main valve port is closed, the bypass valve port is fully open, the system remains in an unloaded state, the hydraulic oil output by the hydraulic pump flows back to the oil tank through the bypass valve, and the boom hydraulic cylinder is not started.

[0067] like Figure 2 and Figure 3 As shown, Figure 3This is the control flow chart of the present invention. The joystick and boom unloading action handle signals are sent to the controller, where they are converted into main valve control currents. The main pump displacement current and bypass valve control currents are then matched and controlled based on the main valve control currents. After the matching operation, the controller outputs the main pump displacement current to the electric proportional pressure reducing valve on the hydraulic pump. This valve outputs pilot pressure to the variable pump displacement adjustment mechanism to adjust the hydraulic pump output to the desired displacement. The controller then outputs the bypass valve control current to the electric proportional pressure reducing valve on the bypass valve. This valve outputs pilot pressure to close the bypass valve spool to the desired valve opening. The system is then throttled and adjusted to the desired starting pressure by the bypass valve. The controller then outputs the main valve control current to the electric proportional pressure reducing valve on the main valve. This valve outputs pilot pressure to open the main valve spool. Hydraulic oil output from the main pump enters the rod chamber of the boom hydraulic cylinder through the main valve, causing the hydraulic rod to retract, completing the boom unloading action. The above steps can achieve a good match between the main pump, main valve and bypass valve, thereby reducing the pressure shock when the excavator starts to unload the bucket arm.

[0068] The method of the present invention mainly uses the main valve control current as a benchmark to calculate the matching relationship between the main valve control current and the main pump displacement current, and the matching relationship between the main valve control current and the bypass valve control current.

[0069] like Figure 2 As shown, in step S1, the hydraulic cylinder force balance equation of the excavator before the bucket arm unloading action is started is:

[0070] p1'A1-p2'A2=F l ' (1)

[0071] Among them, p1' is the pressure of the hydraulic cylinder rodless cavity before starting; A1 is the area of the hydraulic cylinder rodless cavity; p2' is the pressure of the hydraulic cylinder rod cavity before starting; A2 is the area of the hydraulic cylinder rod cavity; F l ' is the load force before starting.

[0072] like Figure 1 As shown, in step S11, when the excavator starts the bucket arm unloading action, the hydraulic cylinder force balance equation is:

[0073] p2A2-p1A1=ma+F l +f (2)

[0074] Among them, p1 is the pressure of the hydraulic cylinder rodless chamber at startup; p2 is the pressure of the hydraulic cylinder rod chamber at startup; m is the equivalent mass borne by the excavator arm hydraulic cylinder; a is the acceleration of the arm unloading action at startup; F l is the load force at startup; f is the friction force.

[0075] Before starting, the pressure sensor can know the pressure values of the rod cavity and rodless cavity of the hydraulic cylinder. The area of the rod cavity of the hydraulic cylinder can be known, and the load force F before starting can be known. l ', and in the starting stage, the displacement of the hydraulic cylinder is very small, and the load force F at the start l Before starting F l 'Approximately equal:

[0076] F l =F l '=p1'A1-p2'A2 (3).

[0077] like Figure 4 As shown, in step S12, it is an excavator posture angle diagram. Before starting, the angles between the excavator's actuators can be known according to the angle sensor, and the equivalent mass m borne by the excavator's boom hydraulic cylinder in the current posture can be known by calculation.

[0078] As a moving body, the bucket arm rotates around the hinge point O2. Assume that the bucket arm is subjected to the resultant force F including the thrust of the hydraulic cylinder and the weight of the bucket arm and bucket in the extension direction of the cylinder body at point A. c , the acceleration in the direction of the resultant force is a c 。 c Decomposed into two components F along the vertical direction of O2A and the direction of O2A c1 and F c2 , a c Decomposed into two accelerations a along the vertical direction of O2A and the direction of O2A c1 and a c2 , then with O2 as the fulcrum, the moment τ and angular acceleration ω acting on the rod are:

[0079]

[0080]

[0081] Where β is the resultant force F c The angle with O2A.

[0082] According to the law of rotation:

[0083] τ=Jω (6)

[0084] Combining the above three equations, we can get the resultant force F c and moment of inertia J c The relationship is:

[0085]

[0086] The above formula and Newton's second law F c =ma c The equivalent mass of the moving point A on the boom can be obtained by connection:

[0087]

[0088] Among them, J c It is the equivalent moment of inertia of the arm, bucket and other parts around the hinge point O2.

[0089] Solve J using the translation method of moment of inertia c :G1, G2, G3 are the center of gravity of the boom, arm and bucket respectively, and their positions are as follows Figure 4 shown.

[0090] J c =I2+m2·O2G2 2 +I3+m3·O2G3 2 (9)

[0091] Among them, I2 is the moment of inertia of the boom relative to its own center of gravity; I3 is the moment of inertia of the bucket relative to its own center of gravity; m2 is the mass of the boom; m3 is the mass of the bucket; O2G2 is the distance from the center of gravity of the boom to O2; O2G3 is the distance from the center of gravity of the bucket to O2.

[0092] In ΔO3G3O4, according to the law of cosines:

[0093]

[0094] ∠O2O3G3=π-∠G3O3O4-θ3 (11)

[0095] In ΔO2O3G3, according to the law of cosines:

[0096] O2G3 2 =O2O3 2 +O3G3 2 -2·O2O3·O3G3·cos∠O2O3G3 (12)

[0097] The equivalent mass borne by the excavator arm hydraulic cylinder in the current posture is:

[0098]

[0099] like Figure 5As shown, in step S12, the friction force fitting curve is obtained. When the excavator performs the bucket arm unloading action, the pressure values of the rod chamber and the rodless chamber of the hydraulic cylinder can be obtained through the pressure sensor. The equivalent mass borne by the bucket arm hydraulic cylinder can be calculated through the angular velocity sensor. The bucket arm hydraulic cylinder piston rod speed can be obtained by derivation of the data collected by the displacement sensor. Then, according to the force balance equation of formula (2), the friction force f corresponding to the current bucket arm hydraulic cylinder piston rod movement speed can be calculated. The excavator performs multiple bucket arm unloading actions, and multiple sets of speed and friction force correspondences can be obtained. The least squares method is used to fit the functional relationship curve between friction force and speed, namely the Stribeck curve.

[0100] like Figure 6 As shown, it is the Stribeck friction model. In step S12, the static friction parameter F is estimated by performing tangent calculation on the Stribeck curve. s 、F c 、v s , and then the friction force during the hydraulic cylinder startup process can be obtained by the Stribeck friction model formula:

[0101]

[0102] Where v is the speed of the hydraulic cylinder; F s is the maximum static friction; F c is Coulomb friction; B v is the viscous friction coefficient; v s is the Stribeck speed.

[0103] In step S13, when the excavator performs the bucket arm unloading action, the rodless chamber of the hydraulic cylinder is connected to the oil tank and the pressure is 0. The pressure of the rod chamber of the hydraulic cylinder can be calculated as follows:

[0104]

[0105] In step S14, the magnitude of the pressure shock p2 depends on the magnitude of the acceleration a of the boom unloading action at startup. Given a suitable startup acceleration range, the ideal pressure required by the boom cavity at startup can be obtained by precalculation.

[0106] In step S2, based on the relationship between the bypass valve port flow rate and the main valve control current, the rod chamber pressure of the boom hydraulic cylinder is adjusted to the ideal starting pressure.

[0107] According to the ideal rod chamber starting pressure, the relationship between the bypass valve port flow and the bypass valve flow area can be obtained:

[0108]

[0109] Wherein, Q is the flow rate of the bypass valve port; C dis the valve port flow coefficient; A is the flow area of the bypass valve return port; ρ is the oil density.

[0110] In step S21, the handle is manipulated to the position where the boom hydraulic cylinder is just started, and the handle opening at this time is recorded as x by the current sensor. It is known that the handle opening is in direct proportion to the main valve control current, so the main valve control current is kx, where k is the proportional coefficient obtained by dividing the handle opening by the main valve control current, k=1300.

[0111] In a certain posture, the handle is manipulated to the position where the boom hydraulic cylinder is just started to perform the boom unloading operation. The main valve control current is used as the independent variable, and the main pump displacement current and bypass valve control current are used as dependent variables. The following relationship is satisfied:

[0112] y1=K1·kx (17)

[0113] y2=K2·kx (18)

[0114] Among them, y1 is the main pump displacement current; K1 is the proportional coefficient obtained by dividing the main pump displacement current by the main valve control current; y2 is the bypass valve control current; K2 is the proportional coefficient obtained by dividing the bypass valve control current by the main valve control current.

[0115] During the start-up phase of the arm unloading action, when the engine gear is fixed, the hydraulic pump is in the positive flow phase, and the main pump displacement current in the controller is linearly related to the main pump output displacement. Therefore:

[0116] V=k1(K1·kx)+b1 (19)

[0117] Among them, V is the hydraulic pump displacement; k1 is the electrical proportional coefficient between the main pump output displacement and the main pump control current, k1 = 0.5; b1 is the offset, b1 = 190.

[0118] There is a linear relationship between the output pressure of the electric proportional pressure reducing valve that controls the bypass valve and the control current of the bypass valve, so:

[0119] p p =k2(K2·kx)+b2 (20)

[0120] Among them, p p is the bypass valve pilot pressure; k2 is the proportional coefficient between the bypass valve pilot pressure and the bypass valve control current, k2 = 0.075; b2 is the offset, b2 = -23.

[0121] In step S21, the bypass valve pilot pressure causes the bypass valve core to move to form a flow area. The bypass valve pilot pressure and the flow area of the bypass valve oil return port are approximately simplified to a linear relationship, then:

[0122] A=k3[k2(K2·kx)+b2]+b3 (21)

[0123] Among them, k3 is the proportional coefficient between the flow area of the bypass valve return port and the bypass valve pilot pressure, k3 = 8.8; b3 is the offset, b3 = -36.

[0124] In step S22, during the start-up phase of the boom unloading action, the bypass valve port flow rate is the hydraulic pump output flow rate. Based on the relationship between the main valve control current, the main pump displacement current, and the bypass valve control current expressed by equations (17) and (18), it can be seen that the bypass valve port flow rate Q and the bypass valve return port flow area A can be expressed as:

[0125] Q=Vn=(K1k1kx+b1)n=650K1xn+190n (22)

[0126] A=K2k2k3kx+k3b2+b3=858K2x-238.4 (23)

[0127] Where n is the speed of the hydraulic pump.

[0128] In step S23, in the controller, the main pump displacement current and the bypass valve control current are regulated based on the main valve control current, so as to realize the bypass throttling speed regulation of the system through the bypass valve, thereby adjusting the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure under the ideal starting acceleration.

[0129] The following is a specific embodiment of the matching method for reducing the pressure impact of the arm unloading startup of the electronically controlled hydraulic excavator according to the present invention:

[0130] Take a 37-ton electric hydraulic excavator as an example. The excavator performs arm unloading in posture 1 (arm angle sensor θ2 = 80°, bucket angle sensor θ3 = 45°). Its equivalent load mass m1 = 18500 kg and the ideal starting acceleration is a = 4 m / s. 2 The pressure sensor detects that before starting, the pressure of the hydraulic cylinder rodless chamber p1'=310bar, the pressure of the rod chamber p2'=5bar, and the area of the rodless chamber A1=0.0227m 2 、Rod cavity area A2=0.0114m 2 , friction force f = 13000N, hydraulic pump speed n = 2000rpm, valve port flow coefficient C d =0.8, hydraulic oil density ρ = 0.8kg / m 3 .

[0131] In step S3, multiple sets of matching data of main pump displacement current, main valve control current, and bypass valve control current are obtained.

[0132] In step S31, in posture 1, the handle is manipulated to the position where the boom hydraulic cylinder is just started. The handle opening at this time is recorded by the current sensor as x1 = 0.5A. The relationship between K1, K2 and kx is calculated by the flow formula:

[0133]

[0134] Among them, K 11 is the proportional coefficient obtained by dividing the main pump displacement current by the main valve control current in posture 1; kx1 is the main valve control current in posture 1; K 21 is the proportional coefficient obtained by dividing the bypass valve control current by the main valve control current in posture 1; m1 is the equivalent mass borne by the boom hydraulic cylinder in posture 1; p 11 ' is the rodless chamber pressure of the hydraulic cylinder before starting in posture 1; p 21 ' is the rod chamber pressure of the hydraulic cylinder before starting in posture 1.

[0135] Based on the above theory, we can quantitatively solve the problem that K 11 With K 21 The relationship:

[0136] K 11 =6.93K 12 -4.4 (25).

[0137] In step S32, under different postures, the handle is manipulated to the position where the boom hydraulic cylinder is just started, and the handle opening x is recorded by the current sensor. n (n=1, 2, 3...), calculate the relationship between multiple groups of K1 and K2 through the flow formula:

[0138]

[0139]

[0140] …

[0141]

[0142] like Figure 7 As shown in the figure, it is a pump-valve matching fitting curve. Under different postures, the handle is pushed to the position when the boom hydraulic cylinder is just started. Different handle openings correspond to different main valve control currents. At the same time, the functional relationship between K1 and K2 also changes. By fitting the relationship between multiple groups of kx and K1 and K2 into a curve, the specific relationship curve between the main pump displacement current, the bypass valve control current and the main valve control current can be obtained.

[0143] In step S4, the calculated relationship between kx and K1 and K2 is finally used to achieve an ideal match between the main pump, the main valve, and the bypass valve, thereby reducing the pressure shock during the start-up phase of the boom unloading action.

[0144] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A matching method for reducing the pressure shock of the arm unloading start-up of an electronically controlled hydraulic excavator, characterized in that: It includes the following steps: S1. Determine the ideal starting acceleration of the excavator when the dipper arm unloading action starts based on the hydraulic cylinder force balance equation and big data analysis; S11. Establish the hydraulic cylinder force balance equation when the excavator starts the bucket arm unloading action: p2A2-p1A1=in+F l +f Among them, p1 is the pressure of the hydraulic cylinder rodless chamber at startup; A1 is the area of the hydraulic cylinder rodless chamber; p2 is the pressure of the hydraulic cylinder rod chamber at startup; A2 is the area of the hydraulic cylinder rod chamber; m is the equivalent mass borne by the excavator arm; a is the acceleration of the arm unloading action at startup; F l is the load force at startup; f is the friction force; S12. Calculate the equivalent mass m of the boom hydraulic cylinder based on the angles between the excavator's actuators; and obtain the friction force f by fitting the Stribeck curve. S13. When the boom is unloading, the rodless chamber of the hydraulic cylinder is connected to the oil tank and the pressure is 0. The formula for calculating the pressure in the rod chamber of the hydraulic cylinder is as follows: Among them, p1' is the pressure of the rodless chamber of the hydraulic cylinder before starting; p2' is the pressure of the rod chamber of the hydraulic cylinder before starting; S14. The pressure calculation formula above indicates that pressure p2 depends on the acceleration a of the boom unloading action during startup. The excavator performs multiple boom unloading actions, obtaining multiple sets of experimental data. The starting acceleration range corresponding to the pressure shock during the startup phase of the electronically controlled hydraulic excavator is obtained when it is less than a threshold value M. The starting pressure here refers to the rod chamber pressure of the hydraulic cylinder. The ideal starting acceleration is then obtained from the starting acceleration range. S2. Based on the relationship between the bypass valve port flow rate and the main valve control current, adjust the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure; S21. Move the handle to the position where the boom hydraulic cylinder is just started. The handle opening at this time is recorded as x by the current sensor. It is known that the handle opening is directly proportional to the main valve control current. The main valve control current is kx, where k is the proportional coefficient. In a certain posture, the handle is manipulated to the position where the boom hydraulic cylinder is just started to perform the boom unloading operation. The main valve control current is used as the independent variable, and the main pump displacement current and bypass valve control current are used as dependent variables. The following relationship is satisfied: y1=K1·kx y2=K2·kx Among them, y1 is the main pump displacement current; K1 is the proportional coefficient between the main pump displacement current and the main valve control current; y2 is the bypass valve control current; K2 is the proportional coefficient between the bypass valve control current and the main valve control current; S22. Based on the ideal rod chamber starting pressure, the relationship between the bypass valve port flow rate Q and the bypass valve return port flow area A is obtained: Among them, C d is the valve port flow coefficient; ρ is the oil density; During the start-up phase of the boom unloading action, the bypass valve port flow rate is the hydraulic pump output flow rate, and the bypass valve port flow rate Q is expressed as: Q=Vn=(K1k1kx+b1)n Wherein, V is the displacement of the hydraulic pump; n is the speed of the hydraulic pump; S23. In the controller, the main pump displacement current and the bypass valve control current are regulated based on the main valve control current, thereby implementing bypass throttling speed regulation of the system through the bypass valve, thereby adjusting the rod chamber pressure of the boom hydraulic cylinder to the ideal starting pressure under the ideal starting acceleration; S3. Acquire multiple sets of matching data of main pump displacement current, main valve control current, and bypass valve control current; S31. In a certain posture, manipulate the handle to the position where the boom hydraulic cylinder is just started, and use the flow formula to obtain the relationship between K1, K2 and kx: Among them, k, k1, k2, k3, b1, b2, and b3 are all controller parameters and are known quantities; S32. Under different postures, push the handle to the position where the boom hydraulic cylinder is just started, perform multiple boom unloading actions, and record the handle opening x through the current sensor. n (n=1,2,3…), calculate multiple groups of K through the flow formula 1n , K 2n The relationship between them is as follows: S4. Perform curve fitting on the matching relationships between multiple groups of kx and K1 and K2, and finally obtain the specific matching relationship between the main pump displacement current, the main valve control current, and the bypass valve control current, so that the main pump, the main valve, and the bypass valve are ideally matched, reducing the pressure shock in the start-up phase of the boom unloading action.

2. The method according to claim 1, characterized in that In step S1, the pressure sensor is used to obtain the pressure values of the rod chamber and the rodless chamber of the hydraulic cylinder. During the startup phase, the displacement of the hydraulic cylinder is very small, that is, F l Before starting F l 'Consistent: F l =F l '=p1'A1-p2'A2 Among them, p1' is the pressure of the hydraulic cylinder rodless cavity before starting; p2' is the pressure of the hydraulic cylinder rod cavity before starting; F l ' is the load force before starting.

3. The method according to claim 1, characterized in that In step S2, the bypass valve pilot pressure causes the bypass valve core to move to form a flow area. The pilot pressure and the oil return port flow area A are approximately simplified to a linear relationship, then: A=k3[k2(K2·kx)+b2]+b3 Among them, k3 is the proportional coefficient between the flow area of the bypass valve return port and the bypass valve pilot pressure; b3 is the offset.

4. The method according to claim 3, characterized in that In step S22, when starting, the engine gear is fixed, the hydraulic pump is in the positive flow stage, and the main pump displacement current and the main pump output displacement are in a linear relationship, then: V=k1(K1·kx)+b1 Where V is the hydraulic pump displacement; k1 is the proportional coefficient between the main pump output displacement and the main pump control current; b1 is the offset.

5. The method according to claim 3, characterized in that In step S22, the output pressure of the electric proportional pressure reducing valve controlling the bypass valve is linearly related to the bypass valve control current, so: p p =k2(K2·kx)+b2 Among them, p p is the bypass valve pilot pressure; k2 is the proportional coefficient between the bypass valve pilot pressure and the bypass valve control current; b2 is the offset.

Images