Hydraulic system control method and readable storage medium

Abstract

The application relates to a hydraulic control system, and discloses a hydraulic system control method and a readable storage medium, the hydraulic system comprises at least one working link, the working link comprises a main valve, an actuator and a pressure detection device used for detecting a pressure difference before and after the main valve, the main valve is connected with the actuator; the hydraulic system control method comprises the following steps: receiving an instruction signal of the main valve and the pressure difference detected by the pressure detection device; determining a real-time control signal according to the instruction signal and the pressure difference; and controlling the main valve according to the real-time control signal. The hydraulic system control method can control the speed more accurately and has good universality.

Description

Technical Field

[0001] This invention relates to hydraulic control systems, and more specifically, to a hydraulic system control method. It also relates to a readable storage medium. Background Technology

[0002] For mainframe construction machinery such as cranes and excavators, speed control often involves single or compound actions. Common speed control methods include uniform speed control, stepped uniform speed control, and uniform acceleration control. However, existing speed control methods (such as load-sensitive, positive flow, negative flow, and constant power) cannot achieve satisfactory speed control results. The reasons are as follows:

[0003] Existing speed control methods generally employ pre- or post-valve compensation load-sensitive systems, positive flow control, negative flow control, and constant power control. In load-sensitive systems, when single or compound actions are involved, theoretically, the flow rate in each channel should not change with the load pressure of that channel, nor be affected by the flow rates of other channels. However, in reality, during single or compound actions, due to factors such as the matching relationship between the pressure compensation valve and the main valve, and the constant power characteristics of the pump, the pressure difference before and after the main valve cannot be guaranteed to be an ideal constant value. Therefore, it is difficult to achieve the theoretically required speed curve during single or compound actions, thus affecting the operability and intelligence of the main unit. In contrast, in negative and positive flow control systems, the flow rate allocated to each action depends not only on the main valve opening but also on the load size; lower pressure actions first, and higher pressure actions later.

[0004] Pre-valve compensation refers to a pressure compensation valve positioned between the oil pump and the main valve, while post-valve compensation refers to a pressure compensation valve positioned between the main valve and the actuator. Essentially, both methods maintain a constant load pressure difference between the inlet and outlet ports of each main valve through the pressure compensation valve. Pre-valve compensation lacks anti-load flow saturation capability; when pump supply is insufficient, the flow distribution in the pre-valve compensation system is affected by load differences and cannot be distributed according to the proportion of the main valve's flow area. Post-valve compensation has anti-flow saturation capability; theoretically, the flow rate in each channel is unaffected by changes in the load pressure of that channel or by the flow rates of other channels. In reality, however, pressure losses occur as the oil flows through the pipeline and valve cavity, causing the flow distribution ratio of each channel to not be entirely equivalent to the flow area ratio of the main valve. Furthermore, the design of the flow area of ​​the pressure compensation valve core has a significant impact on the flow distribution characteristics.

[0005] It is evident that when using a pressure compensation valve to control the pressure difference Δp across the main valve's flow area, theoretically, the pressure difference Δp should be constant. However, in practice, due to factors such as pump power limitations (pump power cannot be infinitely large) and improper matching between the main valve and the pressure compensation valve, the pressure difference Δp cannot be constant at a specific value, but rather remains constant within a range. Pre-valve compensation and post-valve compensation load-sensitive systems can only solve the problem of multi-load flow matching and can only meet the coarse distribution of flow under operating conditions. They are not suitable for operating conditions requiring high flow control or flow distribution accuracy, i.e., they cannot meet the needs of precise flow or velocity control. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a hydraulic system control method that can control speed more precisely and has good versatility.

[0007] To address the aforementioned technical problems, the present invention provides a hydraulic system control method. The hydraulic system includes at least one working link, which includes a main valve, an actuator, and a pressure detection device for detecting the pressure difference across the main valve. The main valve is connected to the actuator. The hydraulic system control method includes:

[0008] Receive the command signal to the main valve and the pressure difference detected by the pressure detection device;

[0009] The real-time control signal is determined based on the command signal and the pressure difference;

[0010] The main valve is controlled according to the real-time control signal.

[0011] Optionally, determining the real-time control signal based on the pressure difference detected by the pressure detection device and the command signal includes:

[0012] The flow area of ​​the main valve is determined based on the command signal and the pressure difference across the main valve.

[0013] The real-time control signal is determined based on the correspondence between the current flow area and the preset current flow area-control signal.

[0014] Optionally, the hydraulic system further includes an intermediate variable compensation module for detecting oil state information; controlling the main valve according to the real-time control signal includes:

[0015] The real-time control signal is compensated by the intermediate variable compensation module;

[0016] The main valve is controlled according to the compensated real-time control signal;

[0017] The intermediate variable compensation module is either a temperature compensation module or a viscosity compensation module.

[0018] Optionally, when multiple work links perform compound actions, the speed control coefficient of the command signal of each work link is adjusted according to the actual working conditions; and the real-time control signal of each work link is corrected according to the speed control coefficient.

[0019] Furthermore, the plurality of working links include a first working link and a second working link that perform composite actions and are in a flow saturation condition; the step of adjusting the speed control coefficient of the command signal of each working link according to the actual working condition includes: when the command signal is a command speed and the command speed of the first working link is greater than the command speed of the second working link, setting the speed control coefficient of the first working link to be less than 1 and the speed control coefficient of the second working link to be 1.

[0020] Optionally, when the command signal is a command speed, determining the real-time control signal based on the command signal and the pressure difference includes:

[0021] Obtain the feedback speed obtained by measuring the speed of the actuator;

[0022] The real-time control signal is determined based on the difference between the command speed and the feedback speed and the pressure difference.

[0023] Further, determining the real-time control signal based on the difference between the command speed and the feedback speed and the pressure difference includes:

[0024] When the feedback speed indicates that the actuator is at a constant speed, the real-time control signal is determined based on the difference between the command speed and the feedback speed and the pressure difference.

[0025] Furthermore, determining the real-time control signal based on the command signal and the pressure difference further includes:

[0026] When the feedback speed indicates that the actuator is in a speed change process, a real-time control signal is determined based on the command signal and the pressure difference.

[0027] Specifically, the real-time control signal is current or pilot control pressure.

[0028] In another aspect, the present invention provides a readable storage medium storing executable instructions, which, when executed by a controller, implement the hydraulic system control method described in any of the above technical solutions.

[0029] Through the above technical solution, the present invention adopts a self-compensation technology with real-time differential pressure feedback. During the movement of the main valve core, the differential pressure before and after the main valve is detected in real time, and the differential pressure before and after the main valve is used as the feedback quantity. Based on the differential pressure before and after the main valve and the command signal, a real-time control signal for controlling the main valve is obtained, thereby realizing precise control of the corresponding actuator. It is simple and convenient and has good universality.

[0030] Moreover, it does not require extensive modifications to the hydraulic system. Only a pressure detection device needs to be installed to detect the pressure difference before and after the main valve. This device, along with the command signal, is fed back to the controller, which then determines the real-time control signal to achieve the corresponding control. This method is simple, convenient, and has good versatility.

[0031] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is a hydraulic schematic diagram of the hydraulic system in the first specific embodiment of the present invention;

[0034] Figure 2 This is a block diagram of PID closed-loop control in existing technology;

[0035] Figure 3 This is a control block diagram of the hydraulic system control method in the first specific embodiment of the present invention;

[0036] Figure 4 This is a simplified diagram of the control logic of the hydraulic system control method in a specific embodiment of the present invention;

[0037] Figure 5 This is one of the schematic diagrams of the speed control process in a specific embodiment of the present invention;

[0038] Figure 6 This is the second schematic diagram of the speed control process in a specific embodiment of the present invention;

[0039] Figure 7 This is the third schematic diagram of the speed control process in a specific embodiment of the present invention;

[0040] Figure 8 This is the fourth schematic diagram of the speed control process in a specific embodiment of the present invention;

[0041] Figure 9This is a control block diagram of a hydraulic system control method in a second specific embodiment of the present invention, wherein speed compensation control is added based on the first specific embodiment.

[0042] Figure 10 This is a schematic diagram of the control strategy of the hydraulic system control method in the first specific embodiment of the present invention;

[0043] Figure 11 This is a schematic diagram showing the relationship between the main valve control current and the overcurrent area in a specific embodiment of the present invention;

[0044] Figure 12 This is a hydraulic schematic diagram of the hydraulic system in the third specific embodiment of the present invention;

[0045] Figure 13 This is a schematic diagram of the control strategy of the hydraulic system control method in the third specific embodiment of the present invention;

[0046] Figure 14 This is a schematic diagram of the speed compensation control method in the second specific embodiment of the present invention;

[0047] Figure 15 This is a schematic diagram of the control strategy of the hydraulic system control method in the second specific embodiment of the present invention;

[0048] Figure 16 This is a hydraulic schematic diagram of the hydraulic system in the fourth specific embodiment of the present invention.

[0049] Explanation of reference numerals in the attached figures

[0050] 10 Main valve 20 Actuator

[0051] 30 Controller 40 Pressure Detection Device

[0052] 50 hydraulic pump Detailed Implementation

[0053] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0054] 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 technical features indicated. Therefore, a feature defined as “first” or “second” may explicitly or implicitly include one or more of the stated features.

[0055] It should be noted that the technical solution of this invention belongs to the field of hydraulics, and for those skilled in the art, its essential technical concept lies in the hydraulic connection relationship. Related hydraulic components, such as directional valves, hydraulic cylinders, and hydraulic pumps, are well-known to those skilled in the art and are also commonly used components in existing hydraulic systems; therefore, these hydraulic components will only be briefly described below. After understanding the technical concept of this invention, those skilled in the art can also make simple substitutions to the oil circuits or valves to achieve the corresponding functions of this invention, which also falls within the scope of protection of this invention.

[0056] Reference Figure 1 , Figures 3 to 8 , Figures 11 to 13 This invention provides a hydraulic system control method, wherein the hydraulic system includes at least one working link, the working link including a main valve 10, an actuator 20, and a pressure detection device 40 for detecting the pressure difference across the main valve, the main valve 10 being connected to the actuator 20; the hydraulic system control method includes the following steps:

[0057] Receive the command signal to the main valve 10 and the pressure difference detected by the pressure detection device 40;

[0058] The real-time control signal is determined based on the command signal and the pressure difference;

[0059] The main valve 10 is controlled according to the real-time control signal.

[0060] Typically, various program calculations and controls are performed by the controller 30. This invention detects the pressure difference before and after the main valve in real time, and uses the pressure difference as a feedback quantity, which is input to the controller 30 along with the command signal. Then, after calculation by the control algorithm, the controller 30 outputs a real-time control signal for the main valve 10. In essence, it is a two-input one-output nonlinear model. Generally, the command speed can be used as the command signal to achieve precise speed control of the corresponding actuator.

[0061] Moreover, no excessive modification to the hydraulic system is required. Only a pressure detection device 40 needs to be installed. The pressure detection device 40 is used to detect the pressure difference before and after the main valve. The controller 30 calculates and outputs a real-time control signal according to the corresponding control algorithm. This can achieve good speed control for ordinary hydraulic resistance control, valve pre-compensation, valve post-compensation and other systems. It is simple, convenient, economical and affordable, and has good versatility.

[0062] Reference Figure 1 , Figure 1A specific embodiment of a hydraulic system is provided, wherein a hydraulic pump 50 is connected to the inlet of a main valve 10, the return port of the main valve 10 is connected to an oil tank, and the working port of the main valve 10 is connected to an actuator 20. The actuator 20 can be a hydraulic cylinder, a hydraulic motor, etc. The hydraulic pump 50 can be a variable pump, and the main valve 10 can be a directional flow control valve. Pressure detection devices 40 can be installed in the oil lines between the hydraulic pump 50 and the inlet of the main valve 10, in the oil lines between the return port of the main valve 10 and the oil tank, and in the oil lines between the working port of the main valve 10 and the actuator 20. A controller 30 is connected to the control terminal of the main valve 10, and the controller 30 can also be connected to a variable control structure such as a variable swashplate of the hydraulic pump 50. The pressure detection device 40 can detect the pressure difference across the main valve in real time and feed it back to the controller 30. At the same time, the controller 30 receives the command signal and uses the pressure difference across the main valve and the command signal together as input. After the control algorithm in the controller 30, a real-time control signal is generated to control the flow area of ​​the main valve, thereby achieving precise control of the speed of the actuator 20.

[0063] It should be noted that the hydraulic pump 50 in the hydraulic system is not limited to using a variable pump; it can be replaced with a fixed pump, which will still meet the original system characteristics.

[0064] In a specific embodiment, current can be selected as the control signal to control the movement of the main valve 10. For the sake of brevity, the following description mainly uses current as the control signal. Of course, pilot control pressure can also be selected as the control signal. For those skilled in the art, it is possible to use pilot control pressure instead of current as the control signal based on the technical solution of the present invention, which will not be elaborated further.

[0065] In a specific embodiment, the pressure detection device 40 may be selected from pressure detection electrical components such as differential pressure sensors or pressure sensors.

[0066] Common speed control methods, besides employing pre- or post-valve compensation load-sensitive systems, positive flow control, negative flow control, and constant power control, can be found in [reference needed]. Figure 2 Speed ​​control can also be achieved using closed-loop PID control (proportional-integral-derivative control), fuzzy control, and other methods. These are all closed-loop control methods. A wire displacement sensor detects the speed of the actuator, and this detected speed is fed back to a comparator. The comparator compares this speed with the commanded speed, and the comparison result is fed back to the PID controller. The PID controller then regulates the flow rate of the hydraulic valve, thereby controlling the speed of the actuator. However, PID control struggles to resolve the conflict between overshoot and rapid response. In practical applications, different parameters need to be set for different operating conditions, resulting in a large workload for full-condition parameter tuning and making it difficult to achieve full-condition application of the host machine.

[0067] However, refer to Figure 3 and Figure 10 This invention employs real-time differential pressure feedback and current self-compensation technology, which is an open-loop control method. During the movement of the valve core, the differential pressure across the main valve is fed back in real time and current self-compensation is performed. The overflow area of ​​the main valve is automatically compensated, thereby achieving real-time control of the actual working speed of the actuator. Due to the real-time and precise control of speed, the overshoot is small and the response is fast, which solves the conflict between overshoot and fast response and makes speed fluctuations less likely. Moreover, it can be applied to a variety of working conditions.

[0068] In specific embodiments, the command speed or command flow rate can be used as a command signal and input to the controller 30. Here, the various embodiments of the present invention are mainly described using the command speed as an example. Using the command flow rate as a command signal and inputting it to the controller 30 can achieve essentially the same technical effect as the command speed, and will not be described in detail here.

[0069] Reference Figure 3 The control algorithm within the controller 30 of this invention is essentially a small-orifice throttling formula. During the operation of the hydraulic system, the pressure detection device 40 detects the pressure difference ΔP before and after the main valve in real time, and combines the pressure difference ΔP, the throttling area A under a certain opening of the main valve, the oil density ρ, and the small-orifice throttling constant C. d Hydraulic parameters, such as speed and flow rate, are fed back to controller 30 in real time. These parameters serve as input parameters for the control algorithm. After calculation by the algorithm, the control current I is directly output through the control hardware. U The formula for orifice throttling is as follows:

[0070]

[0071] During the movement of the main valve 10, the pressure difference across the main valve can be automatically detected, thereby automatically compensating the control current, that is, automatically compensating the overflow area of ​​the main valve, which can ensure that the output speed or output flow remains constant, making it very suitable for systems with two inputs and one output.

[0072] Specifically, refer to Figure 10 and Figure 11 Taking an ideal thin-walled orifice as an example, the process of calculating the main valve control current according to the main valve core overcurrent formula is as follows:

[0073]

[0074] Pressure detection device 40 monitors the main valve inlet pressure P in real time. P and the pressure P after the main valve U The difference between the two is the pressure difference P across the main valve. P -P UThe rodless chamber flow area A of the actuator cylinder F Given that the command speed V UD Input to controller 30, command speed V UD The rodless chamber flow area A of the actuator cylinder F The product of these two values ​​is the commanded flow rate, where the oil density ρ and the orifice throttling constant C are also present. d Given the hydraulic parameters, the flow area A of the main valve can be calculated using the formula (2) above. U , refer to Figure 11 , Figure 11 This reflects the correspondence between the flow area and the preset flow area and the control signal, specifically manifested in the main valve control current I. U With flow area A U The relationship diagram stores the main valve control current I within the controller 30. U With flow area A U Relationship diagram, based on the main valve control current I U With flow area A U Interpolation yields the main valve control current I. U This means that the real-time control signal is determined, so that the control hardware can directly output the control current I. U The main valve is controlled to open the corresponding flow area, thereby ensuring that the speed (or flow rate) of the actuator 20 remains constant and achieving precise control.

[0075] Reference Figure 4 When the commanded speed is constant, the pressure difference P across the main valve is detected. P -P U When the current decreases, the control current I of the main valve core increases. U This ensures that the speed (or flow rate) remains constant; when the pressure difference P across the main valve is detected... P -P U When the current increases, the control current I of the main valve core decreases. U This ensures a constant speed (or flow rate). The pressure difference across the main valve is monitored and fed back in real time, and the control current I of the main valve core is automatically adjusted according to the speed control method. U This ensures that the main valve core is always in a dynamic balance process, thereby achieving a more ideal speed control curve.

[0076] Figures 5 to 8It provides the change process of the main physical quantities involved in the automatic control process. Taking the constant power pump system as an example, it is widely used in the main machine of engineering machinery. As the working pressure increases, the actual pressure difference across the main valve decreases. When the pressure difference of the main valve decreases, the control current automatically increases, and when the pressure difference of the main valve increases, the control current automatically decreases. The control current of the main valve is automatically calculated by the control algorithm without manual intervention. The control current or the flow area of ​​the valve core automatically compensates (or automatically cancels) the flow change caused by the pressure difference, so that the measured speed can automatically track the command speed.

[0077] and Figure 2 Unlike traditional PID closed-loop control, the main valve involved in this invention belongs to a physical structure closed-loop control based on the self-adjustment of the hydraulic valve core. Moreover, the technical solution of this invention is not based on the feedback of measured speed for PID adjustment, and does not require a PID controller. The technical solution of this invention obtains automatic compensation for control current or valve core overflow area through commanded speed. Therefore, the hydraulic system control method of this invention belongs to the open-loop control method (that is, the traditional open-loop control refers to electrical control, excluding hydraulic or physical structure closed-loop control).

[0078] Furthermore, in order to improve speed control accuracy, refer to Figure 9 The technical solution of the present invention can also be combined with Figure 2 The existing speed compensation method shown is transformed into an open-loop + speed compensation control method. That is, speed compensation control is added to the open-loop control method of this invention. Specifically, a wire displacement sensor is used to detect the speed of the actuator and feed back the speed V. S Feedback is sent to the comparator, and the comparator also receives the instruction speed V. UD Then the comparator inputs the error v_error between the two into the controller 30. Thus, referring to... Figure 14 During the acceleration or deceleration of actuator 20, the open-loop control method of this invention is used to control the acceleration and deceleration of the actuator, that is, to detect the pressure difference P across the main valve. P -P U The command speed is input to controller 30, and the flow area A of the main valve is calculated through the control algorithm. U According to the main valve control current I U With flow area A U Interpolation yields the main valve control current I. U Thus, the control hardware directly outputs the control current I. UThe main valve opens to the corresponding flow area, thereby ensuring that the speed (or flow rate) of the actuator 20 remains constant, achieving precise control of acceleration and deceleration. This offers advantages such as fast response, small overshoot, and minimal speed fluctuations. During the constant-speed movement of the actuator 20, the actual speed of the actuator 20 is detected in real time by a wire displacement sensor. The actuator 20 can be a hydraulic cylinder, and the actual speed is used as the feedback speed V. S Feedback is sent to the comparator, and the instruction speed V is also given. UD It is also input to the comparator, which will detect the speed error (command speed V) in real time. UD -Feedback speed V S The input is sent to the controller, which can be a PID controller. The controller fine-tunes the control current based on the real-time detected speed error; that is, the control current decreases when the speed is high and increases when the speed is low. Alternatively, the controller can be one used in the open-loop control method described above. The adjustment value (or adjustment range of the control current, etc.) is determined based on the error range of the real-time detected speed error. In this case, the control method is essentially an open-loop control, not a PID closed-loop control, to avoid risks such as overshoot. Alternatively, the actual speed of the actuator 20 can be detected in real time by a cable displacement sensor. The actuator 20 can be a hydraulic cylinder, and the actual speed is used as the feedback speed V. S Feedback is sent to the comparator, and the instruction speed V is also given. UD It is also input to the comparator, which will detect the speed error (command speed V) in real time. UD -Feedback speed V S The input to the controller will also include the detected pressure difference P across the main valve. P -P U Simultaneously, the data is input to the controller, which then fine-tunes the control current based on the real-time detected speed error and the pressure difference across the main valve. Specifically, when the speed is high, the control current decreases; when the speed is low, the control current increases.

[0079] In one specific embodiment, the applicable range of working conditions can be further improved by adding intermediate variable compensation. For example, an intermediate variable compensation module can be added to detect the influencing factors involved in the hydraulic system in real time, thereby compensating for the control current as the input value of the control current of the main valve 10. Specifically, refer to... Figure 15 The intermediate variable compensation module is connected to the comparator in the controller 30. The intermediate variable compensation module can be a temperature compensation module. The pressure detection device 40 feeds back the detected pressure difference across the main valve and the commanded speed to the controller 30. The flow area A of the main valve is obtained through the control algorithm. U Based on the control current and the overcurrent area A UThe control current value is obtained through relational interpolation and input to the comparator. Simultaneously, based on the detected oil temperature, the temperature compensation module outputs a corresponding current value to the comparator. After processing by the comparator, both values ​​serve as the control current I for the main valve 10. U Similarly, the intermediate variable compensation module can also be a viscosity compensation module. That is, the viscosity compensation module detects the viscosity of the oil in real time, and outputs a corresponding current value to the comparator. After processing by the comparator, both values ​​are used as the control current I for controlling the main valve 10. U Alternatively, other elements in the system can be detected and used as intermediate variables to compensate for the control current of the main valve 10, thereby improving the applicable operating conditions. Specifically, the temperature compensation module detects the oil temperature and converts it into a corresponding current value, which is then fed back to the comparator to compensate for the control current of the main valve 10. Similarly, the viscosity compensation module detects the oil viscosity and converts it into a corresponding current value, which is also fed back to the comparator to compensate for the control current of the main valve 10. These are relatively conventional hydraulic components within the technical field. Those skilled in the art, upon learning of the technical solution of this invention, can select specific temperature compensation modules, viscosity compensation modules, and other components; therefore, further details are omitted.

[0080] The hydraulic system control method of the present invention is not limited to speed control of single actions, but can also be applied to speed control of compound actions. The following description takes the compound action of a two-link mechanism as an example.

[0081] Specifically, refer to Figure 12 , Figure 12 An embodiment of a two-link mechanism compound action is provided, wherein the two working links are basically the same in structure. In each working link, the hydraulic pump 50 is connected to the oil inlet of the main valve 10, the oil return port of the main valve 10 is connected to the oil tank, and the working oil port of the main valve 10 is connected to the actuator 20. The actuator 20 can be a hydraulic cylinder, hydraulic motor, etc. The hydraulic pump 50 can be a variable pump, and the main valve 10 can be a directional flow control valve. Pressure detection devices 40 can be set in the oil line between the hydraulic pump 50 and the oil inlet of the main valve 10, in the oil line between the oil return port of the main valve 10 and the oil tank, and in the oil line between the working oil port of the main valve 10 and the actuator 20. The controller 30 is connected to the control terminal of the main valve 10 of the two working links respectively.

[0082] Accordingly, refer to Figure 13 , Figure 13 An embodiment of an open-loop control method for compound operation of a two-link mechanism is provided. The specific open-loop control method is as follows: For the first working link, the pressure detection device 40 detects the pressure P before the main valve in real time. P1 and the pressure P after the main valve U1The detected pressure difference P across the main valve P1 -P U1 and command speed V UD1 Input to controller 30, command speed V UD1 The rodless chamber flow area A of the actuator cylinder F The product of these two values ​​is the command flow rate, and the flow area A of the rodless chamber of the actuator cylinder is the flow area of ​​the rodless chamber. F Oil density ρ, orifice throttling constant C d Given the hydraulic parameters, the flow area A of the main valve can be calculated using formula (2). U1 , refer to Figure 11 The controller 30 stores the main valve control current I. U1 With flow area A U1 Relationship diagram, based on the main valve control current I U1 With flow area A U1 Interpolation yields the main valve control current I. U1 Thus, the control hardware directly outputs the control current I. U1 The main valve is opened to the corresponding flow area, precisely controlling the actual working speed v1 of the actuator in the first working link. Similarly, for the second working link, the pressure detection device 40 detects the pressure P before the main valve in real time. P2 and the pressure P after the main valve U2 The detected pressure difference P across the main valve P2 -P U2 and command speed V UD2 Input to controller 30, command speed V UD2 The rodless chamber flow area A of the actuator cylinder F The product of these two values ​​is the command flow rate, and the flow area A of the rodless chamber of the actuator cylinder is the flow area of ​​the rodless chamber. F Oil density ρ, orifice throttling constant C d Given the hydraulic parameters, the flow area A of the main valve can be calculated using formula (2). U2 , refer to Figure 11 The controller 30 stores the main valve control current I. U2 With flow area A U2 Relationship diagram, based on the main valve control current I U2 With flow area A U2 Interpolation yields the main valve control current I. U2 Thus, the control hardware directly outputs the control current I. U2 The main valve is controlled to open the corresponding flow area, thereby precisely controlling the actual working speed v2 of the actuator in the second working link.

[0083] Furthermore, speed control methods and parameters can be set in controller 30, and the speed control coefficient can be set to a reasonable value. When each working link performs a compound action, the speed control coefficient is used to correct the command speed of each working link, thereby correcting the real-time control signal of each working link. The electronic control system is used to improve the system flow distribution characteristics, and its flow distribution characteristics and degree of automation are higher than those of traditional load-sensitive systems.

[0084] Specifically, refer to Figure 13 Taking a two-link mechanism with compound action as an example, for ease of description, it is divided into a first working link and a second working link. The first working link and the second working link perform compound action and are in a flow saturation condition. For the command speed V in the first working link... UD1 Set the speed control coefficient K U1 For the instruction speed V in the second working link UD2 Set the speed control coefficient K U2 Assuming the command speed V UD1 >Command speed V UD2 Then the speed control coefficient K U1 Set to a fixed value less than 1, which can be adjusted according to actual working conditions; speed control coefficient K U2 Setting it to 1 will result in better traffic distribution characteristics.

[0085] In practical control, to compensate for the impact of oil leakage in the system, the pump output flow rate can be made equal to the flow rate Q required by the first-loop actuator. U1 The second-loop actuator requires flow rate Q. U2 And a fixed value. This can make the pump output pressure equal to the highest combined pressure of each actuator in the compound action plus a fixed value (the fixed value is generally no greater than 3MPa).

[0086] It is understood that the hydraulic system control method of the present invention is not limited to the above-described embodiment of the compound action of two-link mechanisms, but can also be applied to the compound action of three-link or more mechanisms. Its principle is similar to that of the compound action of two-link mechanisms, and will not be described in detail here.

[0087] Regarding the specific form of the main valve 10, various structures can be adopted. In the above embodiments, the main valve 10 is mainly described as a directional flow control valve, such as an electro-hydraulic proportional directional flow control valve; the main valve 10 can also be other hydraulic valves, see [reference]. Figure 16 , Figure 16 Another specific embodiment of the main valve 10 is provided, wherein the main valve 10 can be an electro-proportional throttle valve, that is, the directional flow control valve in each of the above embodiments is replaced by an electro-proportional throttle valve. The hydraulic system control methods involved in the various specific embodiments formed by the formation of the main valve 10 can achieve the same technical effect, which will not be described in detail here.

[0088] Furthermore, the hydraulic system control method of the present invention can also be applied to existing load-sensitive systems. Specifically, the main valve 10 can be a pre-valve compensating load-sensitive valve or a post-valve compensating load-sensitive valve. That is, the directional flow control valve in each of the above embodiments can be replaced by a pre-valve compensating load-sensitive valve or a post-valve compensating load-sensitive valve. The hydraulic system control methods involved in each specific embodiment can achieve basically the same technical effect, which will not be elaborated here.

[0089] To better understand the technical solution of the present invention, the preferred embodiments of the present invention are described below in conjunction with a relatively comprehensive list of preferred technical features.

[0090] Reference Figures 1 to 16 The hydraulic system control method in a preferred embodiment of the present invention includes a hydraulic system comprising at least one working link. Each working link includes a main valve 10, an actuator 20, a controller 30, and a pressure detection device 40. The controller 30 is connected to the control terminal of the main valve 10 in each working link and is used to control the movement of the main valve core of the main valve 10. Pressure detection devices 40 can be installed on the oil lines between the hydraulic pump 50 and the inlet of the main valve 10, between the return port of the main valve 10 and the oil tank, and between the working port of the main valve 10 and the actuator 20. The main valve 10 can be an electro-hydraulic proportional directional flow control valve, an electro-proportional throttle valve, a pre-valve compensating load sensitive valve, or a post-valve compensating load sensitive valve, etc. The actuator 20 can be a hydraulic cylinder or a hydraulic motor, etc., and the pressure detection device 40 can be a differential pressure sensor or a pressure sensor, etc. The hydraulic system control method specifically includes the following steps:

[0091] Pressure detection device 40 monitors the main valve inlet pressure P in real time. P and the pressure P after the main valve U The pressure difference P across the main valve P -P U and command speed V UD The input is sent to controller 30, based on the main valve core overcurrent formula:

[0092]

[0093] Command speed V UD The rodless chamber flow area A of the actuator cylinder F The product of these two values ​​represents the command flow rate, where A is the flow area of ​​the rodless chamber of the actuator cylinder. F Oil density ρ, orifice throttling constant C d Given the hydraulic parameters, the flow area A of the main valve can be calculated using the formula (2) above. U , refer to Figure 11 According to the main valve control current I UWith flow area A U Interpolation yields the main valve control current I. U Thus, the control hardware directly outputs the control current I. U The main valve is controlled to open the corresponding flow area, thereby ensuring that the speed (or flow rate) of the actuator 20 remains constant and achieving precise control.

[0094] For unsaturated flow conditions, whether operating with single or compound actions, or for saturated flow conditions, whether operating with single or compound actions, the hydraulic system control method of this invention is basically the same. However, for saturated flow conditions, when operating with compound actions, taking the compound action of a two-stage mechanism as an example, the principle of compound action for three-stage and above mechanisms is similar, as referred to... Figure 13 Assuming the instruction speed V of the first working link UD1 >Instruction speed V of the second work unit UD2 Then the instruction speed V is given to the first working link. UD1 Speed ​​control coefficient K U1 Set to a fixed value less than 1, which can be adjusted according to actual working conditions, to give the second working link the command speed V. UD2 Speed ​​control coefficient K U2 Setting it to 1 will result in better traffic distribution characteristics.

[0095] The hydraulic system control method of this invention is essentially based on a closed-loop physical structure of self-adjusting hydraulic valve core. It only requires installing differential pressure sensors (or pressure sensors) before and after the main valve and storing the corresponding control algorithm in the controller. The differential pressure before and after the main valve is used as the feedback quantity, and the differential pressure before and after the main valve and the command speed are used as the input quantity. After calculation by the corresponding control algorithm, the control current is obtained by interpolation based on the relationship between the flow area and the control current. The control current of the main valve core is adjusted in real time. It can perform good speed control for ordinary hydraulic resistance control, pre-valve compensation, post-valve compensation and other systems. It belongs to the open-loop control method.

[0096] Compared with load-sensitive flow distribution systems, the flow distribution system of the present invention does not require a pressure compensation valve and does not require much modification to the system.

[0097] Moreover, it can be combined with existing speed compensation methods to form an open-loop + speed compensation control method. During acceleration and deceleration, the open-loop control is used to quickly achieve acceleration and deceleration, which has advantages such as fast response, small overshoot, and less tendency to speed fluctuation. During constant speed, the existing speed compensation method is used to detect speed error (command speed - feedback speed) in real time and fine-tune the control current (the current decreases when the speed is high and increases when the speed is low).

[0098] Furthermore, the detection of intermediate variables such as oil temperature and oil viscosity can be added to further improve the applicability of operating conditions.

[0099] When the flow is saturated and the compound action is working, the flow distribution characteristics of the system can be improved by setting the speed control method and parameters in the controller and setting reasonable values ​​for the control coefficient. The flow distribution characteristics and automation level are higher than those of traditional load-sensitive systems.

[0100] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0101] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0102] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A hydraulic system control method, characterized in that, The hydraulic system includes at least one working link, which includes a main valve (10), an actuator (20), and a pressure detection device (40) for detecting the pressure difference before and after the main valve. The main valve (10) is connected to the actuator (20). The hydraulic system control method includes: Receive the command signal to the main valve (10) and the pressure difference detected by the pressure detection device (40); The real-time control signal is determined based on the command signal and the pressure difference; The main valve (10) is controlled according to the real-time control signal. Wherein, when the command signal is a command speed, determining the real-time control signal based on the command signal and the pressure difference includes: Obtain the feedback speed obtained by measuring the speed of the actuator (20); When the feedback speed indicates that the actuator (20) is at a constant speed, the real-time control signal is determined based on the difference between the command speed and the feedback speed and the pressure difference; When the feedback speed indicates that the actuator (20) is in a speed change process, a real-time control signal is determined based on the command signal and the pressure difference.

2. The hydraulic system control method according to claim 1, characterized in that, The step of determining the real-time control signal based on the pressure difference detected by the command signal and the pressure detection device (40) includes: The flow area of ​​the main valve is determined based on the command signal and the pressure difference across the main valve. The real-time control signal is determined based on the correspondence between the current flow area and the preset current flow area-control signal.

3. The hydraulic system control method according to claim 1, characterized in that, The hydraulic system further includes an intermediate variable compensation module for detecting oil state information; the step of controlling the main valve (10) according to the real-time control signal includes: The real-time control signal is compensated by the intermediate variable compensation module; The main valve (10) is controlled according to the compensated real-time control signal. The intermediate variable compensation module is either a temperature compensation module or a viscosity compensation module.

4. The hydraulic system control method according to claim 1, characterized in that, When multiple working links perform compound actions, the speed control coefficient of the command signal of each working link is adjusted according to the actual working conditions. The real-time control signal of each of the working links is corrected according to the speed control coefficient.

5. The hydraulic system control method according to claim 4, characterized in that, The plurality of working links include a first working link and a second working link that perform a combined action and are in a flow saturation condition; The adjustment of the speed control coefficient of the command signal of each working link according to the actual working conditions includes: When the command signal is a command speed, and the command speed of the first working link is greater than the command speed of the second working link, the speed control coefficient of the first working link is set to be less than 1, and the speed control coefficient of the second working link is set to 1.

6. The hydraulic system control method according to any one of claims 1 to 5, characterized in that, The real-time control signal is either current or pilot control pressure.

7. A readable storage medium storing executable instructions, characterized in that, When the executable instruction is executed by the controller (30), it implements the hydraulic system control method according to any one of claims 1 to 6.

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