Hydraulic system and method and device for controlling the same

Abstract

The application relates to the technical field of hydraulic control, and provides a hydraulic system and a control method and device thereof, to solve the technical problem of how to realize better hydraulic control effect, the control method comprising the following steps: obtaining a target flow of a hydraulic system; obtaining an actual rotating speed of a motor in real time, obtaining operation parameters of a pump and a valve in real time, and obtaining an actual flow of the hydraulic system in real time; obtaining a control proportion of the motor, and calculating a target flow of motor control according to the control proportion of the motor, the target flow of the hydraulic system and the actual flow of the hydraulic system; calculating a target rotating speed of the motor according to the target flow of motor control, the operation parameters of the pump and the valve; adjusting and controlling the motor according to the target rotating speed and the actual rotating speed; and after the adjustment and control of the motor is ended, adjusting and controlling the pump and / or the valve according to the target flow of the hydraulic system and the actual flow of the hydraulic system.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology, specifically to a hydraulic system and its control method and apparatus. Background Technology

[0002] Hydraulic systems are widely used in industrial and civil fields due to their characteristics of large power transmission, ease of transmission and configuration. For example, in industrial machinery such as aerial work platforms and excavators, hydraulic systems can provide power for the extension, rotation and other movements of the robotic arm.

[0003] Currently, the control of hydraulic systems mainly relies on valve control. In hydraulic systems containing variable displacement pumps, changes in pump displacement can also participate in control. The power source for this type of control is generally a constant-speed rotation, such as an engine running at a high constant speed. Adjusting pipeline pressure through pumps and valves undoubtedly results in energy waste and low efficiency. With the increasing prevalence of electric motors as power sources, the regulation of motor speed and torque is also beginning to be incorporated into effective hydraulic control methods.

[0004] In hydraulic control scenarios that combine motor control, valve control, and pump control, how to achieve a clever combination of various control methods to obtain better hydraulic control results is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a hydraulic system and its control method and apparatus, which can balance control response speed and accuracy, improve energy efficiency, and avoid safety risks caused by motor overshoot, thereby greatly improving the control effect of the hydraulic system.

[0006] The technical solution adopted in this invention is as follows:

[0007] A control method for a hydraulic system, the hydraulic system including a pump, valves, and a motor, the method comprising the following steps: acquiring a target flow rate of the hydraulic system; acquiring the actual rotational speed of the motor in real time, and acquiring the operating parameters of the pump and the valve in real time, and acquiring the actual flow rate of the hydraulic system in real time; acquiring the control ratio of the motor, and calculating the target flow rate controlled by the motor based on the control ratio of the motor, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system; calculating the target rotational speed of the motor based on the target flow rate controlled by the motor, the operating parameters of the pump and the valve; adjusting and controlling the motor based on the target rotational speed and the actual rotational speed until the error between the actual rotational speed and the target rotational speed is less than a first threshold, and ending the adjustment and control of the motor; after ending the adjustment and control of the motor, adjusting and controlling the pump and / or valve based on the target flow rate of the hydraulic system and the actual flow rate of the hydraulic system until the error between the actual flow rate of the hydraulic system and the target flow rate of the hydraulic system is less than a second threshold, and ending the adjustment and control of the pump and / or valve.

[0008] Furthermore, the operating parameters of the pump are the swashplate angle of the pump, the operating parameters of the valve are the opening angle of the valve, and the relationship between the flow rate of the hydraulic system and the operating parameters of the pump and the valve, and the speed of the motor is as follows:

[0009] Q = n * V max *α(S)*β(θ)

[0010] Where Q represents the flow rate of the hydraulic system, n represents the rotational speed of the motor, and V max Let S represent the maximum displacement of the pump, S represent the swashplate angle of the pump, α(S) be the ratio of the actual displacement to the maximum displacement of the pump as a function of S, θ represent the opening angle of the valve, and β(θ) be the flow rate of the valve as a function of θ.

[0011] Further, obtaining the control ratio of the motor specifically includes: obtaining the total response time of the hydraulic system adjustment and control; obtaining the response time of the pump and / or valve; calculating the control time of the motor based on the total response time and the response time of the pump and / or valve; and calculating the control ratio of the motor based on the response time of the pump and / or valve and the control time of the motor.

[0012] Furthermore, the control ratio of the motor is calculated using the following formula:

[0013] λ = 1 - [t2 / (t1 + t2)] 2

[0014] Wherein, λ represents the control ratio of the motor, t1 represents the control time of the motor, and t2 represents the response time of the pump and / or valve.

[0015] Furthermore, the target flow rate controlled by the motor is calculated using the following formula:

[0016] Q motor =Q status +λ*(Q target -Q status )

[0017] Among them, Q motor Q represents the target flow rate controlled by the motor. status Q represents the actual flow rate of the hydraulic system. target This indicates the target flow rate of the hydraulic system.

[0018] Furthermore, after calculating the target flow rate controlled by the motor, the method further includes: determining whether the calculated target flow rate controlled by the motor is less than the motor control margin; if so, the calculated result of the target flow rate controlled by the motor shall be used as the standard; if not, the target flow rate controlled by the motor shall be changed to the actual flow rate of the hydraulic system; obtaining the control ratio of the pump and valve, and calculating the target flow rate controlled by the pump and / or valve based on the control ratio of the pump and valve, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system; determining whether the calculated target flow rate controlled by the pump and / or valve is within the pump and valve control margin; if so, the calculated result of the target flow rate controlled by the motor shall be used as the standard; if not, the target flow rate controlled by the motor shall be changed to the target flow rate of the hydraulic system.

[0019] A control device for a hydraulic system, the hydraulic system including a pump, valves, and a motor, the device comprising: a first acquisition module for acquiring a target flow rate of the hydraulic system; a second acquisition module for acquiring the actual rotational speed of the motor in real time, acquiring the operating parameters of the pump and valves in real time, and acquiring the actual flow rate of the hydraulic system in real time; a first calculation module for acquiring the control ratio of the motor, and calculating the target flow rate controlled by the motor based on the control ratio of the motor, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system; and a second calculation module for calculating the target flow rate controlled by the motor based on the target flow rate controlled by the motor, The operating parameters of the pump and the valve are used to calculate the target speed of the motor; a first control module is used to adjust and control the motor according to the target speed and the actual speed until the error between the actual speed and the target speed is less than a first threshold, and then the adjustment and control of the motor ends; a second control module is used to adjust and control the pump and / or valve according to the target flow rate of the hydraulic system and the actual flow rate of the hydraulic system after the first control module ends the adjustment and control of the motor, until the error between the actual flow rate of the hydraulic system and the target flow rate of the hydraulic system is less than a second threshold, and then the adjustment and control of the pump and / or valve ends.

[0020] Furthermore, the operating parameters of the pump are the swashplate angle of the pump, the operating parameters of the valve are the opening angle of the valve, and the relationship between the flow rate of the hydraulic system and the operating parameters of the pump and the valve, and the speed of the motor is as follows:

[0021] Q = n * V max *α(S)*β(θ)

[0022] Where Q represents the flow rate of the hydraulic system, n represents the rotational speed of the motor, and V max Let S represent the maximum displacement of the pump, S represent the swashplate angle of the pump, α(S) be the ratio of the actual displacement to the maximum displacement of the pump as a function of S, θ represent the opening angle of the valve, and β(θ) be the flow rate of the valve as a function of θ.

[0023] Furthermore, the first calculation module is specifically used for: obtaining the total response time of the hydraulic system adjustment and control; obtaining the response time of the pump and / or valve; calculating the control time of the motor based on the total response time and the response time of the pump and / or valve; and calculating the control ratio of the motor based on the response time of the pump and / or valve and the control time of the motor.

[0024] Furthermore, the first calculation module calculates the control ratio of the motor using the following formula:

[0025] λ = 1 - [t2 / (t1 + t2)] 2

[0026] Wherein, λ represents the control ratio of the motor, t1 represents the control time of the motor, and t2 represents the response time of the pump and / or valve.

[0027] Furthermore, the first calculation module calculates the target flow rate controlled by the motor using the following formula:

[0028] Q motor =Q status +λ*(Q target -Q status )

[0029] Among them, Q motor Q represents the target flow rate controlled by the motor. status Q represents the actual flow rate of the hydraulic system. target This indicates the target flow rate of the hydraulic system.

[0030] Furthermore, after calculating the target flow rate controlled by the motor, the first calculation module is also used to: determine whether the calculated target flow rate controlled by the motor is less than the motor control margin; if so, the calculated result of the target flow rate controlled by the motor shall prevail; if not, the target flow rate controlled by the motor shall be changed to the actual flow rate of the hydraulic system; obtain the control ratio of the pump valve, and calculate the target flow rate controlled by the pump and / or valve based on the control ratio of the pump valve, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system; determine whether the calculated target flow rate controlled by the pump and / or valve is within the pump valve control margin; if so, the calculated result of the target flow rate controlled by the motor shall prevail; if not, the target flow rate controlled by the motor shall be changed to the target flow rate of the hydraulic system.

[0031] A hydraulic system, including a control device for the hydraulic system.

[0032] The beneficial effects of this invention are:

[0033] This invention employs a control strategy that deeply couples the motor ring and the pump-valve ring, enabling the motor to participate more significantly in the control process, thereby improving energy efficiency. Furthermore, the coordinated control of these two components enhances both response speed and precision. By determining the target flow rate corresponding to the motor control based on its control ratio, the safety risks associated with motor overshoot can be mitigated. Thus, the control performance of the hydraulic system is greatly improved. Attached Figure Description

[0034] Figure 1This is a flowchart of a control method for a hydraulic system according to an embodiment of the present invention;

[0035] Figure 2 This is a block diagram of the control device of the hydraulic system according to an embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figure 1 As shown, the control method of the hydraulic system in this embodiment of the invention includes the following steps:

[0038] S1, obtain the target flow rate of the hydraulic system.

[0039] The hydraulic system of this invention includes a pump, a valve, and a motor.

[0040] The target flow rate of a hydraulic system is the required flow rate contained in the control command of the hydraulic system. Taking an aerial work platform as an example, the control command can be input by the vehicle controller or other external controllers. This control command contains the function that the aerial work platform is required to perform, and this function corresponds to the required flow rate, which is the target flow rate of the hydraulic system.

[0041] S2 acquires the actual speed of the motor in real time, as well as the operating parameters of the pump and valve in real time, and the actual flow rate of the hydraulic system in real time.

[0042] In one embodiment of the present invention, the actual speed of the motor and the operating parameters of the pump and valve can be acquired in real time by corresponding sensors, and the data is collected and updated in real time.

[0043] In one embodiment of the present invention, the operating parameters of the pump may be the swashplate angle of the pump, and the operating parameters of the valve may be the opening angle of the valve.

[0044] In one embodiment of the present invention, the relationship between the flow rate of the hydraulic system and the operating parameters of the pump and valve, and the speed of the motor, is as follows:

[0045] Q = n * V max *α(S)*β(θ)

[0046] Where Q represents the flow rate of the hydraulic system, n represents the speed of the motor, and V maxLet represent the pump's maximum displacement, S represent the pump's swashplate angle, α(S) be the ratio of the pump's actual displacement to its maximum displacement as a function of S, θ represent the valve's opening angle, and β(θ) be the valve's flow rate as a function of θ. Both functions α(S) and β(θ) are related to the actual pump and valve structure and other characteristics, and can be obtained through calibration. In one embodiment of this invention, Q can be in L / min, n can be in rpm, and V... max The unit can be ml / r.

[0047] The actual flow rate of the hydraulic system can be calculated based on this formula, taking into account the actual speed of the motor and the operating parameters of the pump and valve.

[0048] In another embodiment of the invention, the actual flow rate of the hydraulic system can also be obtained in real time by a corresponding sensor.

[0049] S3, obtain the control ratio of the motor, and calculate the target flow rate of the motor control based on the control ratio of the motor, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system.

[0050] Specifically, the total response time of the hydraulic system regulation and control can be obtained, as well as the response time of the pump and / or valve. Then, the control time of the motor can be calculated based on the total response time and the response time of the pump and / or valve. Finally, the control ratio of the motor can be calculated based on the response time of the pump and / or valve and the control time of the motor.

[0051] The total response time of the hydraulic system's regulation and control is preset and corresponds to the function to be achieved. In one embodiment of the present invention, the user, calibration department, and design department can jointly pre-determine a correspondence table between function and total response time. After receiving the control command, the corresponding total response time can be obtained by looking up the table according to the corresponding function.

[0052] Taking a 24m aerial work platform as an example, its working mode can be selected by the operator as fast mode or slow mode. Its robotic arm movements can include main arm luffing, main arm extension and retraction, articulated arm luffing, and platform rotation. Based on the above modes and movements as the distinction of functions, the corresponding relationship table is shown in Table 1.

[0053] Table 1

[0054]

[0055] The response time of pumps and / or valves is significantly related to the overall hydraulic system; larger pumps generally respond more slowly, while smaller pumps generally respond more quickly. Additionally, different loads and flow requirements can also result in variations in pump and / or valve response times, but these differences are minor and negligible. Therefore, in one embodiment of this invention, the response time of the pump and / or valves can be calibrated based on the entire hydraulic system, and a calibrated value can be obtained and stored.

[0056] The motor control time is the difference between the total response time and the response time of the pump and / or valve.

[0057] In one embodiment of the present invention, the control ratio of the motor can be calculated by the following formula:

[0058] λ = 1 - [t2 / (t1 + t2)] 2

[0059] Where λ represents the motor control ratio, t1 represents the motor control time, and t2 represents the pump and / or valve response time.

[0060] After calculating the motor control ratio, the target flow rate controlled by the motor can be calculated using the following formula:

[0061] Q motor =Q status +λ*(Q target -Q status )

[0062] Among them, Q motor Q represents the target flow rate for motor control. status Q represents the actual flow rate of the hydraulic system. target This indicates the target flow rate of the hydraulic system.

[0063] It should be understood that the target flow rate of the motor control calculated above is a theoretical value obtained based on time, the target flow rate of the hydraulic system and the actual flow rate. In reality, the motor speed, the pump swashplate angle and the valve opening have upper and lower limits. Therefore, in order to ensure the smooth execution of the control process, it is also necessary to combine the controllable margins of the motor, pump and valve to judge the feasibility of the control and thus formulate a feasible control method.

[0064] Therefore, in one embodiment of the present invention, after calculating the target flow rate of the motor control, it can be determined whether the calculated target flow rate of the motor control is less than the motor control margin. If so, the calculation result of the target flow rate of the motor control shall prevail; if not, the target flow rate of the motor control shall be changed to the actual flow rate of the hydraulic system.

[0065] Furthermore, the control ratio of the pump and valve can be obtained, and the target flow rate controlled by the pump and / or valve can be calculated based on the control ratio of the pump and valve, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system. Then, it is determined whether the calculated target flow rate controlled by the pump and / or valve is within the control margin of the pump and valve. If so, the calculated result of the target flow rate controlled by the motor shall prevail; otherwise, the target flow rate controlled by the motor shall be changed to the target flow rate of the hydraulic system.

[0066] The control ratio of the pump valve is [t2 / (t1+t2)]2 That is, 1-λ. After obtaining the control ratio of the pump and valve, the target flow rate controlled by the pump and / or valve can be calculated using the following formula:

[0067] Q pv =Q status +(1-λ)*(Q target -Q status )

[0068] Among them, Q pv Indicates the target flow rate controlled by the pump and / or valve.

[0069] It should be noted that the target flow rate controlled by the pump and / or valve in this embodiment of the invention is not used as the actual basis for flow control, but only as a measure of whether it is within the control margin of the pump and valve, so as to determine whether the calculated target flow rate controlled by the motor should be used as the standard.

[0070] In summary, the specific strategy for considering control feasibility is as follows: if the target flow rate controlled by the motor is not within the motor control margin, it is considered that the motor cannot complete the control, and the control is switched to be completely controlled by the pump and / or valve, and the motor control ratio λ is set to 0; if the target flow rate controlled by the pump and / or valve is not within the pump and valve control margin, it is considered that the pump and / or valve cannot complete the control, and the control is switched to be completely controlled by the motor, and the motor control ratio λ is set to 1; otherwise, the motor control ratio λ remains as calculated above, and the target flow rate controlled by the motor also remains as calculated above.

[0071] S4 calculates the target speed of the motor based on the target flow rate controlled by the motor and the operating parameters of the pump and valve.

[0072] In one embodiment of the present invention, the relationship between the flow rate of the hydraulic system and the operating parameters of the pump and valve, and the speed of the motor, is as follows:

[0073] Q = n * V max *α(S)*β(θ)

[0074] Where Q represents the flow rate of the hydraulic system, n represents the speed of the motor, and V max Let represent the pump's maximum displacement, S represent the pump's swashplate angle, α(S) be the ratio of the pump's actual displacement to its maximum displacement as a function of S, θ represent the valve's opening angle, and β(θ) be the valve's flow rate as a function of θ. Both functions α(S) and β(θ) are related to the actual pump and valve structure and other characteristics, and can be obtained through calibration. In one embodiment of this invention, Q can be in L / min, n can be in rpm, and V... max The unit can be ml / r.

[0075] Based on this formula, the target flow rate of the motor control obtained in step S3 is substituted into the flow rate of the hydraulic system, and the operating parameters of the pump and valve obtained in step S2 are substituted into them respectively. Combined with the pre-stored maximum displacement of the pump, the target speed of the motor can be calculated.

[0076] Furthermore, the aforementioned motor control margin and pump / valve control margin are also calculated based on this formula. Specifically, by substituting the current pump swashplate angle S and valve opening angle θ, along with the maximum motor speed, the motor control margin for increasing flow rate can be obtained; by substituting the current pump swashplate angle S and valve opening angle θ, along with the minimum motor speed, the motor control margin for decreasing flow rate can be obtained; by substituting the current motor speed n, along with the maximum pump swashplate angle and valve opening angle, the pump / valve control margin for increasing flow rate can be obtained; and by substituting the current motor speed n, along with the minimum pump swashplate angle and valve opening angle, the pump / valve control margin for decreasing flow rate can be obtained.

[0077] S5: Adjust and control the motor according to the target speed and the actual speed until the error between the actual speed and the target speed is less than the first threshold, then end the adjustment and control of the motor.

[0078] S6, after ending the regulation and control of the motor, regulate and control the pump and / or valve according to the target flow rate and the actual flow rate of the hydraulic system until the error between the actual flow rate and the target flow rate of the hydraulic system is less than the second threshold, then end the regulation and control of the pump and / or valve.

[0079] Adjustment control based on target and actual values ​​is existing technology and will not be described in detail here. It should be noted that the adjustment control of the pump and / or valve in the embodiments of the present invention means that either the pump or the valve can be controlled, or both can be controlled.

[0080] In summary, the hydraulic system control method according to embodiments of the present invention, through a control strategy of deep coupling between the motor loop and the pump-valve loop, enables the motor to participate more significantly in the control process, thereby improving energy efficiency. Furthermore, the coordinated control of both improves the control response speed and achieves precise control. By obtaining the target flow rate corresponding to the motor control based on the control ratio of the motor control, the safety risks caused by motor overshoot can be avoided. Therefore, the control effect of the hydraulic system can be greatly improved.

[0081] Furthermore, the flow rate, rotation speed, pump and valve operating parameters, and control commands for the motor and pump / valve obtained in the embodiments of the present invention are all electronic signals. Compared with traditional hydraulic circuit control, the response is faster, the loss is smaller, and the degree of control is higher.

[0082] Corresponding to the control method of the hydraulic system in the above embodiments, the present invention also proposes a control device for a hydraulic system.

[0083] like Figure 2 As shown, the control device of the hydraulic system in this embodiment of the invention includes: a first acquisition module 10, a second acquisition module 20, a first calculation module 30, a second calculation module 40, a first control module 50, and a second control module 60. The system comprises the following modules: a first acquisition module 10 for acquiring the target flow rate of the hydraulic system; a second acquisition module 20 for acquiring the actual speed of the motor, the operating parameters of the pump and valve, and the actual flow rate of the hydraulic system in real time; a first calculation module 30 for acquiring the control ratio of the motor and calculating the target flow rate of the motor control based on the motor control ratio, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system; a second calculation module 40 for calculating the target speed of the motor based on the target flow rate of the motor control and the operating parameters of the pump and valve; a first control module 50 for adjusting and controlling the motor based on the target speed and the actual speed until the error between the actual speed and the target speed is less than a first threshold, at which point the adjustment and control of the motor ends; and a second control module 60 for adjusting and controlling the pump and / or valve based on the target flow rate of the hydraulic system and the actual flow rate of the hydraulic system after the first control module 50 has finished adjusting and controlling the motor, until the error between the actual flow rate of the hydraulic system and the target flow rate of the hydraulic system is less than a second threshold, at which point the adjustment and control of the pump and / or valve ends.

[0084] The hydraulic system of this invention includes a pump, valves, and a motor. The target flow rate of the hydraulic system is the required flow rate contained in the control command of the hydraulic system. Taking an aerial work platform as an example, the control command can be input by the vehicle controller or other external controller. This control command contains the function that the aerial work platform is required to perform, and this function corresponds to the required flow rate, i.e., the target flow rate of the hydraulic system. The first acquisition module 10 can parse the target flow rate of the hydraulic system according to the received control command, or it can directly receive the target flow rate of the hydraulic system parsed by the sender.

[0085] In one embodiment of the present invention, the actual speed of the motor and the operating parameters of the pump and valve can be acquired in real time by corresponding sensors, and the data is collected and updated in real time. The second acquisition module 20 can receive the above data acquired in real time by each sensor.

[0086] In one embodiment of the present invention, the operating parameters of the pump may be the swashplate angle of the pump, and the operating parameters of the valve may be the opening angle of the valve.

[0087] In one embodiment of the present invention, the relationship between the flow rate of the hydraulic system and the operating parameters of the pump and valve, and the speed of the motor, is as follows:

[0088] Q = n * Vmax *α(S)*β(θ)

[0089] Where Q represents the flow rate of the hydraulic system, n represents the speed of the motor, and V max Let represent the pump's maximum displacement, S represent the pump's swashplate angle, α(S) be the ratio of the pump's actual displacement to its maximum displacement as a function of S, θ represent the valve's opening angle, and β(θ) be the valve's flow rate as a function of θ. Both functions α(S) and β(θ) are related to the actual pump and valve structure and other characteristics, and can be obtained through calibration. In one embodiment of this invention, Q can be in L / min, n can be in rpm, and V... max The unit can be ml / r.

[0090] The second acquisition module 20 can calculate the actual flow rate of the hydraulic system based on the formula, according to the actual speed of the motor and the operating parameters of the pump and valve.

[0091] In another embodiment of the present invention, the actual flow rate of the hydraulic system can also be acquired in real time by a corresponding sensor and received in real time by the second acquisition module 20.

[0092] The first calculation module 30 can specifically obtain the total response time of the hydraulic system regulation and control, and obtain the response time of the pump and / or valve. Then, it calculates the control time of the motor based on the total response time and the response time of the pump and / or valve, and then calculates the control ratio of the motor based on the response time of the pump and / or valve and the control time of the motor.

[0093] The total response time of the hydraulic system adjustment and control is preset and can correspond to the function to be achieved. In one embodiment of the present invention, a correspondence table between function and total response time can be jointly formulated by the user, calibration department, and design department. After receiving the control command, the first calculation module 30 can look up the corresponding total response time in the table according to the corresponding function.

[0094] Taking a 24m aerial work platform as an example, its working mode can be selected by the operator as fast mode or slow mode. Its robotic arm movements can include main arm luffing, main arm extension and retraction, articulated arm luffing, and platform rotation. Based on the above modes and movements as the distinction of functions, the corresponding relationship table is shown in Table 1.

[0095] The response time of pumps and / or valves is significantly related to the overall hydraulic system; larger pumps generally respond more slowly, while smaller pumps generally respond more quickly. Additionally, different loads and flow requirements can also result in variations in pump and / or valve response times, but these differences are minor and negligible. Therefore, in one embodiment of the present invention, the response time of the pump and / or valves can be calibrated based on the entire hydraulic system, and a calibrated value can be stored for later retrieval by the first calculation module 30.

[0096] The motor control time is the difference between the total response time and the response time of the pump and / or valve.

[0097] In one embodiment of the present invention, the first calculation module 30 can calculate the control ratio of the motor by the following formula:

[0098] λ = 1 - [t2 / (t1 + t2)] 2

[0099] Where λ represents the motor control ratio, t1 represents the motor control time, and t2 represents the pump and / or valve response time.

[0100] After calculating the control ratio of the motor, the first calculation module 30 can calculate the target flow rate of the motor control using the following formula:

[0101] Q motor =Q status +λ*(Q target -Q status )

[0102] Among them, Q motor Q represents the target flow rate for motor control. status Q represents the actual flow rate of the hydraulic system. target This indicates the target flow rate of the hydraulic system.

[0103] It should be understood that the target flow rate of the motor control calculated above is a theoretical value obtained based on time, the target flow rate of the hydraulic system and the actual flow rate. In reality, the motor speed, the pump swashplate angle and the valve opening have upper and lower limits. Therefore, in order to ensure the smooth execution of the control process, it is also necessary to combine the controllable margins of the motor, pump and valve to judge the feasibility of the control and thus formulate a feasible control method.

[0104] Therefore, in one embodiment of the present invention, after calculating the target flow rate of the motor control, the first calculation module 30 can also determine whether the calculated target flow rate of the motor control is less than the motor control margin. If so, the calculation result of the target flow rate of the motor control shall prevail; if not, the target flow rate of the motor control shall be changed to the actual flow rate of the hydraulic system.

[0105] Furthermore, the first calculation module 30 can obtain the control ratio of the pump and valve, and calculate the target flow rate controlled by the pump and / or valve based on the control ratio of the pump and valve, the target flow rate of the hydraulic system, and the actual flow rate of the hydraulic system. Then, it determines whether the calculated target flow rate controlled by the pump and / or valve is within the control margin of the pump and valve. If so, the calculated result of the target flow rate controlled by the motor shall prevail; otherwise, the target flow rate controlled by the motor shall be changed to the target flow rate of the hydraulic system.

[0106] The control ratio of the pump valve is [t2 / (t1+t2)] 2 That is, 1-λ. After obtaining the control ratio of the pump and valve, the first calculation module 30 can calculate the target flow rate controlled by the pump and / or valve using the following formula:

[0107] Q pv =Q status +(1-λ)*(Q target -Q status )

[0108] Among them, Q pv Indicates the target flow rate controlled by the pump and / or valve.

[0109] It should be noted that the target flow rate controlled by the pump and / or valve in this embodiment of the invention is not used as the actual basis for flow control, but only as a measure of whether it is within the control margin of the pump and valve, so as to determine whether the calculated target flow rate controlled by the motor should be used as the standard.

[0110] In summary, the specific strategy for considering control feasibility is as follows: if the target flow rate controlled by the motor is not within the motor control margin, it is considered that the motor cannot complete the control, and the control is switched to be completely controlled by the pump and / or valve, and the motor control ratio λ is set to 0; if the target flow rate controlled by the pump and / or valve is not within the pump and valve control margin, it is considered that the pump and / or valve cannot complete the control, and the control is switched to be completely controlled by the motor, and the motor control ratio λ is set to 1; otherwise, the motor control ratio λ remains as calculated above, and the target flow rate controlled by the motor also remains as calculated above.

[0111] In one embodiment of the present invention, the relationship between the flow rate of the hydraulic system and the operating parameters of the pump and valve, and the speed of the motor, is as follows:

[0112] Q = n * V max *α(S)*β(θ)

[0113] Where Q represents the flow rate of the hydraulic system, n represents the speed of the motor, and V max Let represent the pump's maximum displacement, S represent the pump's swashplate angle, α(S) be the ratio of the pump's actual displacement to its maximum displacement as a function of S, θ represent the valve's opening angle, and β(θ) be the valve's flow rate as a function of θ. Both functions α(S) and β(θ) are related to the actual pump and valve structure and other characteristics, and can be obtained through calibration. In one embodiment of this invention, Q can be in L / min, n can be in rpm, and V... max The unit can be ml / r.

[0114] Based on this formula, the second calculation module 40 substitutes the target flow rate of the motor control obtained by the first calculation module 30 into the flow rate of the hydraulic system, substitutes the operating parameters of the pump and valve obtained by the second acquisition module 20 into the formula, and combines them with the pre-stored maximum displacement of the pump to calculate the target speed of the motor.

[0115] Furthermore, the aforementioned motor control margin and pump / valve control margin are also calculated based on this formula. Specifically, by substituting the current pump swashplate angle S and valve opening angle θ, along with the maximum motor speed, the motor control margin for increasing flow rate can be obtained; by substituting the current pump swashplate angle S and valve opening angle θ, along with the minimum motor speed, the motor control margin for decreasing flow rate can be obtained; by substituting the current motor speed n, along with the maximum pump swashplate angle and valve opening angle, the pump / valve control margin for increasing flow rate can be obtained; and by substituting the current motor speed n, along with the minimum pump swashplate angle and valve opening angle, the pump / valve control margin for decreasing flow rate can be obtained.

[0116] The adjustment and control by the first control module 50 and the second control module 60 based on the target value and the actual value is prior art and will not be described in detail here. It should be noted that the adjustment and control of the pump and / or valve in the embodiments of the present invention means that either the pump or the valve can be controlled, or both can be controlled.

[0117] In summary, the control device for the hydraulic system according to embodiments of the present invention, through a control strategy of deep coupling between the motor ring and the pump-valve ring, enables the motor to participate more significantly in the control process, thereby improving energy efficiency. Furthermore, the coordinated control of both enhances the control response speed and achieves precise control. By obtaining the target flow rate corresponding to the motor control based on the control ratio of the motor control, the safety risks caused by motor overshoot can be avoided. Therefore, the control effect of the hydraulic system can be greatly improved.

[0118] Furthermore, the flow rate, rotation speed, pump and valve operating parameters, and control commands for the motor and pump / valve obtained in the embodiments of the present invention are all electronic signals. Compared with traditional hydraulic circuit control, the response is faster, the loss is smaller, and the degree of control is higher.

[0119] Based on the control device of the hydraulic system in the above embodiments, the present invention also proposes a hydraulic system.

[0120] The hydraulic system of this invention includes the control device of the hydraulic system of any of the above embodiments of this invention. The specific implementation method can be referred to the above embodiments, and will not be repeated here.

[0121] The hydraulic system according to the embodiments of the present invention has good control performance.

[0122] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0123] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0124] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0125] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0126] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0127] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0128] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0129] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0130] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0131] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A control method of a hydraulic system, characterized by, The hydraulic system comprises a pump, a valve and a motor, and the method comprises the following steps: acquiring a target flow of the hydraulic system; acquiring an actual rotating speed of the motor in real time, acquiring operating parameters of the pump and the valve in real time, and acquiring an actual flow of the hydraulic system in real time; acquiring a control proportion of the motor, and calculating a target flow controlled by the motor according to the control proportion of the motor, the target flow of the hydraulic system and the actual flow of the hydraulic system; calculating a target rotating speed of the motor according to the target flow controlled by the motor and the operating parameters of the pump and the valve; adjusting and controlling the motor according to the target rotating speed and the actual rotating speed, and ending the adjustment and control of the motor until an error between the actual rotating speed and the target rotating speed is less than a first threshold value; after ending the adjustment and control of the motor, adjusting and controlling the pump and / or the valve according to the target flow of the hydraulic system and the actual flow of the hydraulic system, and ending the adjustment and control of the pump and / or the valve until an error between the actual flow of the hydraulic system and the target flow of the hydraulic system is less than a second threshold value, acquiring the control proportion of the motor, specifically comprising: acquiring a total response time of the hydraulic system adjustment and control; acquiring a response time of the pump and / or the valve; calculating a control time of the motor according to the total response time and the response time of the pump and / or the valve; and calculating the control proportion of the motor according to the response time of the pump and / or the valve and the control time of the motor, the control proportion of the motor is calculated by the following formula: λ = 1 - [t2 / (t1+t2)] 2 wherein λ represents the control proportion of the motor, t1 represents the control time of the motor, and t2 represents the response time of the pump and / or the valve.

2. The control method of a hydraulic system according to claim 1, characterized by, The operating parameter of the pump is a swash plate angle of the pump, the operating parameter of the valve is an opening angle of the valve, and the relationship between the flow of the hydraulic system and the operating parameters of the pump and the valve and the rotating speed of the motor is: ， where Q represents a flow rate of the hydraulic system, n represents a rotational speed of the motor, V max represents a maximum displacement of the pump, S represents a swash plate angle of the pump, a(S) is a function of a ratio of an actual displacement of the pump to the maximum displacement with respect to S, θ represents an opening angle of the valve, and β(θ) is a function of a flow rate of the valve with respect to θ.

3. The control method of a hydraulic system according to claim 1, characterized by, the target flow controlled by the motor is calculated by the following formula: ， where Q motor represents the target flow of the motor control, Q status represents the actual flow of the hydraulic system, Q target represents the target flow of the hydraulic system.

4. The control method of a hydraulic system according to claim 3, characterized by, after the target flow controlled by the motor is calculated, the method further comprises: judging whether the calculated target flow controlled by the motor is less than a motor control margin, if yes, taking the calculation result of the target flow controlled by the motor as a reference, and if no, setting the target flow controlled by the motor as the actual flow of the hydraulic system; acquiring a control proportion of the pump and / or the valve, and calculating a target flow controlled by the pump and / or the valve according to the control proportion of the pump and / or the valve, the target flow of the hydraulic system and the actual flow of the hydraulic system; judging whether the calculated target flow controlled by the pump and / or the valve is within a pump and / or valve control margin, if yes, taking the calculation result of the target flow controlled by the motor as a reference, and if no, setting the target flow controlled by the motor as the target flow of the hydraulic system.

5. A control device for a hydraulic system, characterized by The hydraulic system comprises a pump, a valve and a motor, and the device comprises: a first acquiring module, which is used to acquire a target flow of the hydraulic system; The second acquisition module is configured to acquire an actual rotating speed of the motor in real time, acquire operating parameters of the pump and the valve in real time, and acquire an actual flow of the hydraulic system in real time. The first calculation module is configured to acquire a control proportion of the motor, and calculate a target flow controlled by the motor according to the control proportion of the motor, a target flow of the hydraulic system, and the actual flow of the hydraulic system. The second calculation module is configured to calculate a target rotating speed of the motor according to the target flow controlled by the motor and the operating parameters of the pump and the valve. The first control module is configured to adjust and control the motor according to the target rotating speed and the actual rotating speed, and end the adjustment and control of the motor until an error between the actual rotating speed and the target rotating speed is less than a first threshold. The second control module is configured to adjust and control the pump and / or the valve according to the target flow of the hydraulic system and the actual flow of the hydraulic system after the first control module ends the adjustment and control of the motor, and end the adjustment and control of the pump and / or the valve until an error between the actual flow of the hydraulic system and the target flow of the hydraulic system is less than a second threshold. The first calculation module is specifically configured to acquire a total response time of the hydraulic system adjustment and control, acquire a response time of the pump and / or the valve, calculate a control time of the motor according to the total response time and the response time of the pump and / or the valve, and calculate the control proportion of the motor according to the response time of the pump and / or the valve and the control time of the motor. The first calculation module calculates the control proportion of the motor by the following formula: λ = 1 - [t2 / (t1+t2)] 2 Wherein, λ represents the control proportion of the motor, t1 represents the control time of the motor, and t2 represents the response time of the pump and / or the valve.

6. The control device of the hydraulic system according to claim 5, characterized in that The operating parameter of the pump is a swash plate angle of the pump, the operating parameter of the valve is an opening angle of the valve, and a relationship between the flow of the hydraulic system and the operating parameters of the pump and the valve and the rotating speed of the motor is: ， where Q represents a flow rate of the hydraulic system, n represents a rotational speed of the motor, V max represents a maximum displacement of the pump, S represents a swash plate angle of the pump, a(S) is a function of a ratio of an actual displacement of the pump to the maximum displacement with respect to S, θ represents an opening angle of the valve, and β(θ) is a function of a flow rate of the valve with respect to θ.

7. The control device of the hydraulic system according to claim 5, characterized in that, The first calculation module calculates the target flow controlled by the motor by the following formula: ， where Q motor represents the target flow rate of the hydraulic system, Q status represents the actual flow rate of the hydraulic system, Q target represents the target flow rate of the hydraulic system.

8. The control device of the hydraulic system according to claim 7, characterized in that, After calculating the target flow controlled by the motor, the first calculation module is further configured to: determine whether the calculated target flow controlled by the motor is less than a motor control margin, if yes, take the calculation result of the target flow controlled by the motor as a reference, and if no, set the target flow controlled by the motor as the actual flow of the hydraulic system; acquire a control proportion of the pump and the valve, and calculate a target flow controlled by the pump and / or the valve according to the control proportion of the pump and the valve, the target flow of the hydraulic system, and the actual flow of the hydraulic system; determine whether the calculated target flow controlled by the pump and / or the valve is within a pump and valve control margin, if yes, take the calculation result of the target flow controlled by the motor as a reference, and if no, set the target flow controlled by the motor as the target flow of the hydraulic system.

9. A hydraulic system characterized by, A control device comprising a hydraulic system according to any one of claims 5-8.

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