Back pressure control method for inlet and outlet, control device and engineering machinery equipment

Abstract

This invention discloses a back pressure control method, control device, and engineering machinery equipment for oil inlet and outlet. The back pressure control system includes an actuator cylinder, a drive pump, an oil tank, and a back pressure control component. The inlet control valve and outlet control valve of the back pressure control component are respectively located on the inlet oil line and the return oil line. A first pressure sensor and a second pressure sensor detect the pressure at the inlet and outlet of the actuator cylinder, respectively. The back pressure control method includes controlling the outlet control valve based on a pre-adjusted back pressure determined by real-time flow signal and / or load pressure when the actuator cylinder is determined to be under positive load according to the detection signals of the first and second pressure sensors; and controlling the inlet control valve based on a pre-adjusted back pressure determined by the load pressure change state when the actuator cylinder is determined to be under negative load. This allows for adjustment of the back pressure according to real-time operating conditions, achieving the goal of reducing system energy consumption while maintaining system stability.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic transmission and control technology, specifically relating to a back pressure control method, control device, and engineering machinery equipment for oil inlet and outlet. Background Technology

[0002] Back pressure, as an auxiliary pressure of the system, mainly serves to reduce the oscillation of the system during operation. However, setting the back pressure too high will increase the system's energy consumption.

[0003] Currently, to control back pressure, a throttling orifice is typically added to the oil outlet to throttle the flow, thereby improving system stability. While this method does improve system stability to some extent, the magnitude of the back pressure is related to the design of the throttling orifice. Once the orifice is designed, it cannot be changed, and the back pressure cannot be adjusted in a timely manner according to different operating conditions. If the orifice is too small, the throttling loss is significant, increasing system energy consumption; if the orifice is too large, pressure oscillations are difficult to eliminate under varying load conditions. Summary of the Invention

[0004] To address the aforementioned deficiencies or shortcomings, this invention provides a back pressure control method, control device, and engineering machinery for oil inlet and outlet ports, aiming to solve the technical problem that existing back pressure control methods are difficult to adjust in a timely manner according to different working conditions.

[0005] To achieve the above objectives, the present invention provides a back pressure control method for oil inlet and outlet ports, applied to a back pressure control system for oil inlet and outlet ports. The back pressure control system includes: an actuator cylinder, a drive pump, an oil tank, and a back pressure control assembly. The actuator cylinder, in its working state, forms an oil inlet and an oil outlet. An oil inlet circuit is formed between the drive pump and the oil inlet. A return oil circuit is formed between the oil tank and the oil outlet. The back pressure control assembly includes an inlet control valve, an outlet control valve, a first pressure sensor, and a second pressure sensor. The inlet control valve and the outlet control valve are respectively located on the inlet oil circuit and the return oil circuit. The first pressure sensor and the second pressure sensor are used to detect the pressure at the oil inlet and the oil outlet, respectively.

[0006] Back pressure control methods for inlet and outlet oil ports include:

[0007] Receive detection signals from the first pressure sensor and the second pressure sensor;

[0008] The load pressure of the hydraulic cylinder is determined based on the detection signal;

[0009] When the actuator cylinder is determined to be under positive load based on the load pressure, the oil outlet control valve is controlled based on the pre-adjusted back pressure determined by the real-time flow signal and / or load pressure.

[0010] When the hydraulic cylinder is determined to be under negative load based on the load pressure, the inlet control valve is controlled by the pre-adjusted back pressure determined based on the change in load pressure.

[0011] In this embodiment of the invention, controlling the oil outlet control valve based on the pre-adjusted back pressure determined according to the real-time flow signal and / or load pressure includes:

[0012] Receives real-time flow signals from the control handle;

[0013] Determine the flow signal level based on real-time flow signals;

[0014] Determine the pre-adjusted back pressure based on the flow signal level and load pressure;

[0015] The oil outlet control valve is controlled based on the pre-adjusted back pressure.

[0016] In this embodiment of the invention, determining the pre-adjusted back pressure based on the flow signal level and load pressure includes:

[0017] Determine the load level based on the load pressure;

[0018] The pre-adjusted back pressure is determined based on the flow signal level and load level.

[0019] In this embodiment of the invention, determining the pre-adjusted back pressure based on the flow signal level and the load level includes:

[0020] When the flow signal level reaches the oscillating flow level, the change status of the load pressure is obtained;

[0021] The pre-adjusted back pressure is determined based on the load level and the changes in load pressure.

[0022] In this embodiment of the invention, controlling the oil inlet control valve based on the pre-adjusted back pressure determined according to the load pressure change includes:

[0023] The load pressure change is calculated based on the current load pressure and the previous load pressure.

[0024] When the load pressure change is determined to be in a pressure oscillation state based on the load pressure change value, the oil inlet control valve is controlled according to the pre-adjusted back pressure corresponding to the pressure oscillation state.

[0025] In this embodiment of the invention, when the load pressure change state is determined to be in a pressure oscillation state based on the load pressure change value, controlling the oil inlet control valve according to the pre-adjusted back pressure corresponding to the pressure oscillation state includes:

[0026] If the load pressure change value exceeds the pressure change threshold at least twice consecutively, the load pressure change state is determined to be in a pressure oscillation state.

[0027] The oil inlet control valve is controlled based on the pre-adjusted back pressure corresponding to the pressure oscillation state.

[0028] In this embodiment of the invention, after determining the load pressure of the actuator cylinder based on the detection signal, the method further includes:

[0029] When the actuator cylinder is determined to be under negative load based on the load pressure and is in a rapid start state, the oil inlet control valve is controlled according to the pre-adjusted back pressure corresponding to the rapid start state.

[0030] In this embodiment of the invention, when the actuator is determined to be under negative load based on the load pressure and the actuator is in a rapid start state, controlling the oil inlet control valve based on the pre-adjusted back pressure corresponding to the rapid start state includes:

[0031] If the hydraulic cylinder is determined to be under negative load based on the load pressure, the current flow rate change value is compared with the first flow rate change threshold.

[0032] If the current flow rate change exceeds the first flow rate change threshold, the actuator is determined to be in a rapid start state, and the oil inlet control valve is controlled according to the pre-adjusted back pressure corresponding to the rapid start state.

[0033] In this embodiment of the invention, the method further includes:

[0034] The target valve core position of the target control valve is determined based on the pre-adjusted back pressure. When the actuator cylinder is under positive load, the target control valve is the oil outlet control valve, and when the actuator cylinder is under negative load, the target control valve is the oil inlet control valve.

[0035] The valve core of the target control valve is moved to the target valve core position to perform pressure control on the target control valve.

[0036] In this embodiment of the invention, determining the target valve core position of the target control valve based on the pre-adjusted back pressure includes:

[0037] If the current flow change does not exceed the second flow change threshold, the real-time pressure of the back pressure chamber of the actuator cylinder is determined based on the detection signal of the first pressure sensor or the second pressure sensor, and the displacement proportional coefficient of the target control valve is determined based on the real-time flow signal sent by the control handle.

[0038] The stage valve core displacement is determined based on the displacement proportional coefficient, the pre-adjusted back pressure, and the real-time pressure of the back pressure chamber of the actuator cylinder.

[0039] The valve core position of the target control valve is adjusted according to the valve core displacement of the stage so that the valve core of the target control valve reaches the target valve core position.

[0040] In this embodiment of the invention, the back pressure control assembly further includes a third pressure sensor disposed on the return oil line between the oil tank and the oil outlet control valve. Determining the target valve core position of the target control valve based on the pre-adjusted back pressure further includes:

[0041] Obtain the oil outlet pressure collected by the third pressure sensor;

[0042] If the current flow rate change exceeds the second flow rate change threshold, the flow area will be determined by fitting the flow coefficient, oil density, current flow rate value, pre-adjusted back pressure, and oil outlet pressure.

[0043] The target valve core position is determined based on the flow area.

[0044] In this embodiment of the invention, the back pressure control assembly further includes a third pressure sensor and a fourth pressure sensor. The third pressure sensor is disposed on the return oil line between the oil tank and the oil outlet control valve, and the fourth pressure sensor is disposed on the oil inlet line between the drive pump and the oil inlet control valve. The method further includes:

[0045] When the hydraulic cylinder is determined to be under positive load based on the load pressure, the flow rate of the oil inlet control valve is controlled based on the detection signals of the first pressure sensor and the fourth pressure sensor.

[0046] When the hydraulic cylinder is determined to be under negative load based on the load pressure, the detection signals from the second and third pressure sensors control the flow of the oil outlet control valve.

[0047] In this embodiment of the invention, the back pressure control component further includes a first safety valve and a second installation valve. The first safety valve is connected between the oil inlet and the oil tank, and the second safety valve is connected between the oil outlet and the oil tank.

[0048] To achieve the above objectives, the present invention also provides a control device applied to a back pressure control system for oil inlet and outlet ports, wherein the back pressure control system for oil inlet and outlet ports includes:

[0049] The hydraulic cylinder has an oil inlet and an oil outlet when it is in operation.

[0050] The drive pump forms an oil inlet passage with the oil inlet port;

[0051] The fuel tank forms a return oil path with the fuel outlet; and

[0052] The back pressure control assembly includes an inlet control valve, an outlet control valve, a first pressure sensor, and a second pressure sensor. The inlet control valve and the outlet control valve are respectively located on the inlet oil line and the return oil line. The first pressure sensor and the second pressure sensor are used to detect the pressure at the inlet and outlet oil ports, respectively.

[0053] The control device includes:

[0054] A receiving module is used to receive detection signals from the first pressure sensor and the second pressure sensor;

[0055] The pressure determination module is used to determine the load pressure of the actuator cylinder based on the detection signal;

[0056] The actuation module is used to control the oil outlet control valve based on the real-time flow signal and / or the pre-adjusted back pressure determined by the load pressure when the actuation cylinder is determined to be under positive load based on the load pressure, and to control the oil inlet control valve based on the pre-adjusted back pressure determined by the load pressure change state when the actuation cylinder is determined to be under negative load based on the load pressure.

[0057] To achieve the above objectives, the present invention also provides an engineering machinery device, wherein the engineering machinery device includes a processor and a memory storing computer program instructions, the processor reading and executing the computer program instructions to implement the back pressure control method for the oil inlet and outlet as described above.

[0058] Through the above technical solution, the back pressure control method for oil inlet and outlet provided in this embodiment of the invention has the following beneficial effects:

[0059] When using the aforementioned back pressure control method for the inlet and outlet ports, since an inlet control valve and an outlet control valve are respectively installed on both sides of the inlet and outlet ports of the actuator cylinder, and a first pressure sensor and a second pressure sensor are respectively used to detect the pressure at the inlet and outlet ports, the back pressure formed at the inlet or outlet port of the actuator cylinder can be independently controlled through the inlet control valve or the outlet control valve. The back pressure control method includes, when the actuator cylinder is determined to be under positive load based on the detection signals from the first and second pressure sensors, controlling the outlet control valve based on a pre-adjusted back pressure determined by the real-time flow signal and / or load pressure. When the actuator cylinder is determined to be under positive load, that is, when the force direction of the cylinder rod is opposite to the movement direction, the chamber corresponding to the outlet port on the actuator cylinder is the back pressure chamber. The back pressure is determined based on the real-time flow signal and / or load pressure. The pre-adjusted back pressure, determined by the load pressure, controls the pressure of the outlet control valve, thereby achieving the goal of adjusting the back pressure of the entire system according to real-time operating conditions. Simultaneously, the back pressure control method also includes controlling the inlet control valve based on the pre-adjusted back pressure determined by the load pressure change when the actuator cylinder is determined to be under negative load. When the actuator cylinder is determined to be under negative load, that is, the force direction of the actuator cylinder rod is the same as the movement direction, the chamber corresponding to the inlet port on the actuator cylinder is the back pressure chamber. The pre-adjusted back pressure determined by the load pressure change controls the pressure of the inlet control valve, thus also achieving the goal of adjusting the back pressure of the entire system according to real-time operating conditions. Therefore, the back pressure control method at the inlet and outlet ports can adjust the back pressure according to different operating conditions, achieving the goal of reducing system energy consumption while maintaining system stability.

[0060] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0061] The accompanying drawings are provided to 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:

[0062] Figure 1 This is a schematic diagram of the back pressure control method for oil inlet and outlet ports according to an embodiment of the present invention;

[0063] Figure 2 This is a schematic diagram of the control flow of a control device according to an embodiment of the present invention;

[0064] Figure 3 yes Figure 2 A control flow diagram for step 300 in the diagram;

[0065] Figure 4 yes Figure 2A control flow diagram for step 400 in the diagram;

[0066] Figure 5 This is a schematic diagram of the control device in one embodiment of the present invention.

[0067] Explanation of reference numerals in the attached figures

[0068] 1. Actuate hydraulic cylinder 2. Drive pump

[0069] 3. Oil tank 4. Oil inlet control valve

[0070] 5 Oil outlet control valve 6 First pressure sensor

[0071] 7 Second pressure sensor 8 Third pressure sensor

[0072] 9. Fourth pressure sensor; 10. Control device

[0073] 11 First safety valve 12 Second safety valve Detailed Implementation

[0074] 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.

[0075] The back pressure control method for the oil inlet and outlet of the present invention is described below with reference to the accompanying drawings.

[0076] like Figure 1 and Figure 2 As shown, this invention provides a back pressure control method for oil inlet and outlet ports, applied to a back pressure control system for oil inlet and outlet ports, wherein the back pressure control system for oil inlet and outlet ports includes:

[0077] The hydraulic cylinder 1 has an oil inlet and an oil outlet when it is in operation.

[0078] Drive pump 2 to form an oil inlet passage between it and the oil inlet;

[0079] Oil tank 3 forms a return oil path between itself and the oil outlet;

[0080] The back pressure control assembly includes an inlet control valve 4, an outlet control valve 5, a first pressure sensor 6, and a second pressure sensor 7. The inlet control valve 4 and the outlet control valve 5 are respectively located on the inlet oil line and the return oil line. The first pressure sensor 6 and the second pressure sensor 7 are used to detect the pressure at the inlet and outlet oil respectively.

[0081] Back pressure control methods for inlet and outlet oil ports include:

[0082] Step 100: Receive detection signals from the first pressure sensor 6 and the second pressure sensor 7.

[0083] Specifically, the back pressure chamber of the hydraulic cylinder 1 changes with the operating conditions, so operating condition identification is required first. The first pressure sensor 6 can monitor the pressure at the oil inlet in real time, and the second pressure sensor 7 can monitor the pressure at the oil outlet in real time. The first pressure sensor 6 and the second pressure sensor 7 can send the collected pressure detection signals to the controller 10.

[0084] Step 200: Determine the load pressure of the hydraulic cylinder 1 based on the detection signal.

[0085] Specifically, after receiving the detection signals from the first pressure sensor 6 and the second pressure sensor 7, the controller 10 multiplies the pressure values ​​detected by the first pressure sensor 6 and the second pressure sensor 7 by their respective force-bearing areas and compares the differences to determine whether the force direction and movement direction of the cylinder rod of the actuator 1 are the same. The movement direction of the actuator 1 can be obtained from the control signal of the control handle. Of course, in practical applications, the movement state of the cylinder rod can also be directly monitored through position sensors to obtain the movement direction of the cylinder rod.

[0086] When the direction of force on the cylinder rod is opposite to the direction of movement, the actuator cylinder 1 is determined to be under positive load; when the direction of force on the cylinder rod is the same as the direction of movement, the actuator cylinder 1 is determined to be under negative load. Thus, the working condition of the actuator cylinder 1 can be identified by real-time collection of the pressure at the oil inlet and outlet.

[0087] Step 300: When the load pressure determines that the hydraulic cylinder 1 is under positive load, the oil outlet control valve 5 is controlled according to the pre-adjusted back pressure determined by the real-time flow signal and / or load pressure.

[0088] Furthermore, when the load pressure determines that the hydraulic cylinder 1 is under positive load, the magnitude of the pre-adjusted back pressure can be determined based on the real-time flow signal and / or load pressure, and the valve core position of the oil outlet control valve 5 can be adjusted so that the final back pressure is adjusted to the pre-adjusted back pressure, thereby achieving pressure control of the oil outlet control valve 5. Simultaneously, the real-time flow signal can be sent to the controller 10 via the control handle.

[0089] Step 400: When the load pressure determines that the hydraulic cylinder 1 is under negative load, the oil inlet control valve 4 is controlled by the pre-adjusted back pressure determined by the load pressure change state.

[0090] More specifically, when the load pressure determines that the hydraulic cylinder 1 is under negative load, the magnitude of the pre-adjusted back pressure can be determined according to the change in load pressure, and the valve core position of the oil inlet control valve 4 can be adjusted so that the final back pressure is adjusted to the pre-adjusted back pressure, thereby achieving pressure control of the oil inlet control valve 4.

[0091] When using the aforementioned back pressure control method for the inlet and outlet ports, since an inlet control valve 4 and an outlet control valve 5 are respectively installed on both sides of the inlet and outlet ports of the actuator cylinder 1, and a first pressure sensor 6 and a second pressure sensor 7 are respectively used to detect the pressure at the inlet and outlet ports, the back pressure formed at the inlet or outlet port of the actuator cylinder 1 can be independently controlled by the inlet control valve 4 or the outlet control valve 5. The back pressure control method includes, when the actuator cylinder 1 is determined to be under positive load based on the detection signals from the first pressure sensor 6 and the second pressure sensor 7, controlling the pressure of the outlet control valve 5 based on the pre-adjusted back pressure determined by the real-time flow signal and / or load pressure. When the actuator cylinder 1 is determined to be under positive load, that is, when the force direction of the cylinder rod of the actuator cylinder 1 is opposite to the movement direction, the chamber corresponding to the outlet port on the actuator cylinder 1 is the back pressure chamber. Based on the real-time flow signal and... Alternatively, the pre-adjusted back pressure determined by the load pressure is used to control the pressure of the oil outlet control valve 5, thereby achieving the purpose of adjusting the back pressure of the entire system according to the real-time operating conditions. Simultaneously, the back pressure control method also includes, when the actuator cylinder 1 is determined to be under negative load based on the load pressure, controlling the pressure of the oil inlet control valve 4 based on the pre-adjusted back pressure determined by the load pressure change. When the actuator cylinder 1 is determined to be under negative load, that is, when the force direction of the cylinder rod of the actuator cylinder 1 is the same as the movement direction, the chamber corresponding to the oil inlet on the actuator cylinder 1 is the back pressure chamber. Controlling the pressure of the oil inlet control valve 4 based on the pre-adjusted back pressure determined by the load pressure change value also achieves the purpose of adjusting the back pressure of the entire system according to the real-time operating conditions. Therefore, the back pressure control method through the oil inlet and outlet ports can adjust the back pressure according to different operating conditions, achieving the purpose of reducing system energy consumption while maintaining system stability.

[0092] like Figure 3 As shown, in this embodiment of the invention, step 300, controlling the oil outlet control valve 5 based on the pre-adjusted back pressure determined according to the real-time flow signal and / or load pressure, includes:

[0093] Step 310: Receive the real-time flow signal from the control handle.

[0094] Specifically, the flow rate can be manually adjusted by the control handle according to the working conditions, so that the control handle can send the corresponding real-time flow signal to the controller 10. The controller 10 can control the flow rate of the inlet controller 10 valve based on the real-time flow signal, and can also control the pressure of the outlet control valve 5 based on the real-time flow signal. More specifically, flow control refers to adjusting the position of the valve core to make the flow rate through the valve body a constant value, while pressure control refers to adjusting the position of the valve core to make the pressure at the front end or the rear end a constant value.

[0095] Step 320: Determine the flow signal level based on the real-time flow signal.

[0096] Furthermore, the flow rate can be determined based on the real-time flow signal. For example, when the flow rate Q < 20 L / min, the flow signal level is a low flow signal; when the flow rate 20 L / min ≤ Q < 60 L / min, the flow signal level is a medium flow signal; and when the flow rate Q ≥ 60 L / min, the flow signal level is a high flow signal. Of course, the present invention is not limited to this, and other forms of flow signal level classification are also possible.

[0097] Step 330: Determine the pre-adjusted back pressure based on the flow signal level and load pressure.

[0098] Furthermore, within different flow signal levels, different pre-adjusted back pressures can be determined based on different load pressures.

[0099] Step 340: Control the oil outlet control valve 5 according to the pre-adjusted back pressure.

[0100] When the hydraulic cylinder 1 is under positive load, the pre-adjusted back pressure can be determined based on the flow signal level and load pressure. Different flow signal levels or different load pressures will result in different pre-adjusted back pressures, thus enabling reasonable adjustment of the back pressure according to real-time operating conditions.

[0101] Of course, the present invention is not limited to this. The preset back pressure can also be directly corresponding to the flow signal level or load pressure.

[0102] In this embodiment of the invention, step 330, determining the pre-adjusted back pressure based on the flow signal level and load pressure, includes:

[0103] Determine the load level based on the load pressure.

[0104] Specifically, the currently detected load pressure can be classified into load levels. For example, when the load pressure P FZ When the load pressure is <30 bar, the load rating is light; when the load pressure is 30 bar ≤ P FZ When the load pressure is <60 bar, the load rating is medium; when the load pressure P FZ When the load is >60 bar, the load level is heavy load.

[0105] The pre-adjusted back pressure is determined based on the flow signal level and load level.

[0106] Furthermore, when the flow signal level is a low flow signal and the load level is light load, the pre-adjusted back pressure can be 3 bar; when the load level is medium or heavy load, the pre-adjusted back pressure can be 5 bar. When the flow signal level is a medium flow signal and the load level is light load, the pre-adjusted back pressure can be 8 bar; when the load level is medium load, the pre-adjusted back pressure can be 15 bar; when the load level is heavy load, the pre-adjusted back pressure can be 20 bar. When the flow signal level is a high flow signal and the load level is light load, the pre-adjusted back pressure can be 10 bar; when the load level is medium load, the pre-adjusted back pressure can be 20 bar; when the load level is heavy load, the pre-adjusted back pressure can be 20 bar.

[0107] In this embodiment of the invention, determining the pre-adjusted back pressure based on the flow signal level and the load level includes:

[0108] When the flow signal level reaches the oscillating flow level, the change status of the load pressure is obtained;

[0109] The pre-adjusted back pressure is determined based on the load level and the changes in load pressure.

[0110] Furthermore, first determine whether the flow signal level of the real-time flow signal reaches the oscillating flow level. For example, when the flow signal level reaches the large flow signal, it is determined that the real-time flow signal has reached the oscillating flow level. The large flow signal is the signal generated when the flow is greater than the first flow threshold, which can be used to indicate that the flow is greater than the first flow threshold. The first flow threshold can specifically be 60L / min. Furthermore, when the flow signal level is a high flow signal, it is also necessary to acquire the load pressure change status and determine whether the load pressure is in a pressure oscillation state. Based on the judgment result, the corresponding pre-adjustment back pressure can be determined. Specifically, the pre-adjustment back pressure can be determined as follows: when the flow signal level is a high flow signal, and the load level is light load and not in a pressure oscillation state, the pre-adjustment back pressure can be 10 bar; when the load level is light load and in a pressure oscillation state, the pre-adjustment back pressure can be increased to 30 bar; when the load level is medium load and not in a pressure oscillation state, the pre-adjustment back pressure can be 20 bar; when the load level is medium load and in a pressure oscillation state, the pre-adjustment back pressure can be increased to 35 bar; when the load level is heavy load and not in a pressure oscillation state, the pre-adjustment back pressure can be 20 bar; when the load level is heavy load and in a pressure oscillation state, the pre-adjustment back pressure can be increased to 40 bar. Of course, this invention is not limited to this; the medium flow signal can also be determined as an oscillating flow level, and then the load pressure change status can be judged to determine whether it is in a pressure oscillation state, further refining the pre-adjustment back pressure setting. In this embodiment, the change in load pressure is also taken into account whether it is in a pressure oscillation state. This ensures that the determined pre-adjusted back pressure takes into account the influence of flow signal level, load level and pressure oscillation, thereby enabling further reasonable adjustment of back pressure based on real-time operating conditions.

[0111] In addition, when the load pressure determines that the actuator cylinder 1 is under positive load, it is also possible to directly judge whether the received real-time flow signal reaches the oscillation flow level. If the magnitude of the real-time flow signal reaches the oscillation flow level, it is further judged whether the load pressure change state is in a pressure oscillation state, and the pre-adjustment back pressure is determined based on the judgment result.

[0112] In addition, whether the load pressure change is in a pressure oscillation state can be determined by comparing the load pressure change value with the pressure change threshold. If the load pressure change value exceeds the pressure change threshold at least twice consecutively, it can be determined that it is in a pressure oscillation state. If the above condition is not met, it is determined that it is not in a pressure oscillation state.

[0113] like Figure 4 As shown, in this embodiment of the invention, step 400, controlling the oil inlet control valve 4 based on the pre-adjusted back pressure determined according to the load pressure change state, includes:

[0114] Step 410: Calculate the load pressure change value based on the current load pressure and the previous load pressure.

[0115] Specifically, when it is determined that the hydraulic cylinder 1 is under negative load, and after the flow rate and back pressure remain stable after the rapid start-up state, the current load pressure can be detected by the first pressure sensor 6 and the second pressure sensor 7, and the load pressure change value can be calculated based on the current load pressure and the previous load pressure stored in the controller 10.

[0116] Step 420: If the load pressure change state is determined to be in a pressure oscillation state based on the load pressure change value, the oil inlet control valve 4 is controlled according to the pre-adjusted back pressure corresponding to the pressure oscillation state.

[0117] Specifically, the load pressure change can be used to determine whether the load pressure is in a pressure oscillation state. If it is not in a pressure oscillation state, the current back pressure can be maintained. If it is in a pressure oscillation state, the valve core position of the oil inlet control valve 4 can be adjusted to raise the back pressure to the pre-adjusted back pressure of the pressure oscillation state, so that the back pressure can be reasonably adjusted according to the real-time working conditions.

[0118] In this embodiment of the invention, step 420, when it is determined from the load pressure change value that the load pressure change state is in a pressure oscillation state, controlling the oil inlet control valve 4 according to the pre-adjusted back pressure corresponding to the pressure oscillation state includes:

[0119] Compare the load pressure change value with the pressure change threshold.

[0120] Specifically, a pressure change threshold ΔF can be preset, and ΔF is the pressure oscillation judgment threshold set within a single program cycle, with the threshold range of 0.5 bar to 5 bar within a single cycle.

[0121] If the load pressure change value exceeds the pressure change threshold at least twice consecutively, the load pressure change state is determined to be in a pressure oscillation state.

[0122] That is, if |P FZ -old_P FZ |>ΔF, where P FZ For the current load pressure, old_P FZ If the previous load pressure is given, and ΔF is the pressure change threshold, and the above formula is true at least twice consecutively, then it can be determined that the pressure is in a pressure oscillation state. Specifically, the pressure change threshold can be set to 3 bar.

[0123] The oil inlet control valve 4 is controlled according to the pre-adjusted back pressure corresponding to the pressure oscillation state.

[0124] Specifically, if the load pressure change exceeds the pressure change threshold of 3 bar at least twice consecutively, it is determined to be in a pressure oscillation state. In this case, the valve core position of the inlet control valve 4 can be adjusted to adjust the system back pressure to the pre-adjusted back pressure for the pressure oscillation state. More specifically, the pre-adjusted back pressure for the pressure oscillation state is higher than the back pressure for the stable state. The back pressure for the system in the stable state can be 10 bar. When a pressure oscillation state is determined, since the pre-adjusted back pressure for the pressure oscillation state can be set to 30 bar, the inlet control valve 4 can be controlled to increase the back pressure to 30 bar, thereby eliminating the pressure oscillation.

[0125] In this embodiment of the invention, after determining the load pressure of the hydraulic cylinder based on the detection signal, the method further includes:

[0126] When the load pressure determines that the actuator cylinder 1 is under negative load and the actuator cylinder 1 is in a rapid start state, the oil inlet control valve 4 is controlled according to the pre-adjusted back pressure corresponding to the rapid start state.

[0127] Specifically, when hydraulic cylinder 1 is under negative load and in a rapid start-up state, a large suction pressure oscillation will occur. To eliminate the pressure oscillation caused by rapid start-up, the valve core position of the oil inlet control valve 4 can be adjusted so that the system back pressure reaches the pre-adjusted back pressure for rapid start-up. More specifically, the pre-adjusted back pressure for rapid start-up can be set to 30 bar, so when rapid start-up is detected, the back pressure is increased to 30 bar.

[0128] In this embodiment of the invention, when it is determined that the actuator cylinder 1 is under negative load based on the load pressure, and the actuator cylinder 1 is in a rapid start state, controlling the oil inlet control valve 4 according to the pre-adjusted back pressure corresponding to the rapid start state includes:

[0129] If the load pressure determines that the hydraulic cylinder 1 is under negative load, the current flow rate change value is compared with the first flow rate change threshold.

[0130] If the current flow rate change value exceeds the first flow rate change threshold, it is determined that the hydraulic cylinder 1 is in a rapid start state, and the oil inlet control valve 4 is controlled according to the pre-adjusted back pressure corresponding to the rapid start state.

[0131] Specifically, after determining that hydraulic cylinder 1 is under negative load, it is also necessary to first determine whether hydraulic cylinder 1 is in a rapid start state. This can be determined by comparing the current flow rate change value with a first flow rate change threshold ΔQ_S. The current flow rate change value can be calculated by subtracting the previous flow rate value old_Q from the current flow rate value Q. That is, if the following formula is satisfied: Q - old_Q > ΔQ, then hydraulic cylinder 1 can be determined to be in a rapid start state. More specifically, the flow rate value can be determined based on the real-time flow signal emitted by the control handle, and ΔQ is the rapid start judgment threshold set within a single program cycle. The threshold range for the flow rate change value in a single cycle can be 1L / min to 5L / min.

[0132] Furthermore, when the actuator cylinder 1 is detected to be under negative load or in a rapid start-up state, the back pressure is increased to the pre-adjusted back pressure of 30 bar for rapid start-up to maintain start-up stability. After the flow rate stabilizes, the back pressure is reduced to 10 bar to maintain system stability under stable conditions and reduce system energy consumption. Simultaneously, when the flow signal is stable, changes in load pressure are detected to determine if there is pressure oscillation. If pressure oscillation exists, the back pressure is increased to the pre-adjusted back pressure for pressure oscillation to eliminate it.

[0133] In this embodiment of the invention, the method further includes:

[0134] The target valve core position of the target control valve is determined based on the pre-adjusted back pressure. When the actuator cylinder 1 is under positive load, the target control valve is the oil outlet control valve 5. When the actuator cylinder 1 is under negative load, the target control valve is the oil inlet control valve 4.

[0135] The valve core of the target valve is moved to the target valve core position to perform pressure control on the target control valve.

[0136] Specifically, after determining the pre-adjusted back pressure based on the real-time flow signal in step 300 and the pre-adjusted back pressure based on the load change value in step 400, the valve core position of the target control valve can be adjusted so that the back pressure of the system reaches the pre-adjusted back pressure, thereby achieving pressure control.

[0137] In this embodiment of the invention, determining the target valve core position of the target control valve based on the pre-adjusted back pressure includes:

[0138] If the current flow change does not exceed the second flow change threshold, the real-time pressure of the back pressure chamber of the actuator cylinder 1 is determined based on the detection signal of the first pressure sensor 6 or the second pressure sensor 7, and the displacement proportional coefficient of the target control valve is determined based on the real-time flow signal emitted by the control handle.

[0139] The stage valve core displacement is determined based on the displacement proportional coefficient, the pre-adjusted back pressure, and the real-time pressure of the back pressure chamber of the actuator cylinder 1.

[0140] The valve core position of the target control valve is adjusted according to the valve core displacement of the stage so that the valve core of the target control valve reaches the target valve core position.

[0141] Furthermore, the purpose of pressure control is to maintain the back pressure of the control system at an ideal value. When the actuator cylinder 1 moves slowly, the valve core position can be calculated and adjusted multiple times. After each adjustment, the real-time pressure of the back pressure chamber of the actuator cylinder 1, detected in real time by the first pressure sensor 6 and the second pressure sensor 7, can be compared with the pre-adjusted back pressure. This allows the real-time pressure to gradually approach the pre-adjusted back pressure, and when the valve core reaches the target valve core position, the real-time pressure also reaches the pre-adjusted back pressure, thus achieving closed-loop control of the back pressure. In addition, flow rate changes can be detected to determine whether the actuator cylinder 1 is moving slowly or rapidly. The second flow rate change threshold can be 0.5 L / min.

[0142] Specifically, the initial displacement of the valve core position needs to be set for closed-loop control. After receiving the flow command from the first program run in the start state, the initial valve core displacement corresponding to the back pressure chamber can be set to 1.5mm. In the second program run, upon receiving a new flow command, if the current flow change does not exceed the set second flow change threshold, it can be determined that the actuator cylinder 1 is in slow motion. At this time, closed-loop control of the back pressure can be performed based on the previous valve core displacement. The formula for calculating each valve core displacement is: x = x1 - KP * (P S -P), where x1 is the previous valve core displacement, P S For pre-adjusting pressure, P is the real-time pressure of the back pressure chamber of cylinder 1, and KP is the displacement proportional coefficient. The setting of KP is changed according to the current flow rate Q. When the flow rate is large, the valve core displacement needs to be adjusted quickly, so the KP value should be set slightly larger. When the flow rate is small, the valve core displacement needs to be adjusted slowly, so the KP value should be set slightly smaller. The specific calculation formula for the KP value can be: KP = 0.02 + 0.004 * Q.

[0143] More specifically, the real-time pressure of the back pressure chamber of the actuator cylinder 1 is detected first, and the first valve core displacement x is output through the calculation formula of the valve core displacement. The controller 10 controls the valve core corresponding to the back pressure chamber to move the valve core displacement x. The program is run again, and the valve core displacement of the previous program is used as x1 for the current closed-loop control. Closed-loop iterative control is continuously performed until the actual back pressure reaches the pre-adjusted back pressure.

[0144] In this embodiment of the invention, the back pressure control assembly further includes a third pressure sensor 8 disposed on the return oil line between the oil tank 3 and the oil outlet control valve 5. Determining the target valve core position of the target control valve based on the pre-adjusted back pressure further includes:

[0145] Obtain the oil outlet pressure collected by the third pressure sensor 8.

[0146] If the current flow rate change exceeds the second flow rate change threshold, the flow area will be determined by fitting the flow coefficient, oil density, current flow rate value, pre-adjusted back pressure, and oil outlet pressure.

[0147] The target valve core position is determined based on the flow area.

[0148] Specifically, when the hydraulic cylinder 1 performs a rapid action, the flow rate increases too quickly while the closed-loop adjustment is too slow, which can easily cause pressure buildup. Furthermore, a slight mismatch between the displacement change rate of the closed-loop control valve spool and the displacement change rate of the inlet valve spool can easily cause a sudden pressure change. Therefore, when the current flow rate change is detected to exceed the second flow rate change threshold, the target valve spool position can be directly calculated, thereby allowing for advance control of the opening of the control valve corresponding to the back pressure chamber, avoiding sudden pressure changes. More specifically, the formula for calculating the flow area is:

[0149]

[0150] In the formula, Q is the current flow rate, and P... S To pre-adjust the pressure, P T The oil outlet pressure is determined based on the detection signal from the third sensor, Cd is the fitted flow coefficient, and ρ is the oil density. The current flow rate Q is determined by the controller 10 based on the flow signal input from the control handle, while the fitted flow coefficient Cd is obtained by fitting multiple sets of measured data.

[0151] Furthermore, the formula for calculating the target valve core position is: x = a * A 3 +b*A 2 +c*A+d, where a, b, c, and d are all constants.

[0152] In this embodiment of the invention, the back pressure control assembly further includes a third pressure sensor 8 and a fourth pressure sensor 9. The third pressure sensor 8 is disposed on the return oil line between the oil tank 3 and the oil outlet control valve 5, and the fourth pressure sensor 9 is disposed on the oil inlet line between the drive pump 2 and the oil inlet control valve 4. The method further includes:

[0153] When the load pressure determines that the hydraulic cylinder 1 is under positive load, the flow control valve 4 is controlled according to the detection signals of the first pressure sensor 6 and the fourth pressure sensor 9.

[0154] Specifically, when the load pressure determines that the hydraulic cylinder 1 is under positive load, the oil outlet control valve 5 can be pressure controlled not only based on the pre-adjusted back pressure determined by the real-time flow signal, but also based on the detection signals of the first pressure sensor 6 and the fourth pressure sensor 9 to control the flow of the oil inlet control valve 4.

[0155] When the load pressure determines that the hydraulic cylinder 1 is under negative load, the detection signals of the second pressure sensor 7 and the third pressure sensor 8 control the flow of the oil outlet control valve 5.

[0156] Specifically, when the load pressure determines that the hydraulic cylinder 1 is under negative load, the pressure control valve 4 can be controlled by the pre-adjusted back pressure determined by the load pressure change value, and the flow control valve 5 can be controlled by the detection signals of the second pressure sensor 7 and the third pressure sensor 8.

[0157] In this embodiment of the invention, the back pressure control component further includes a first safety valve 11 and a second safety valve 12. The first safety valve 11 is connected between the oil inlet and the oil tank 3, and the second safety valve 12 is connected between the oil outlet and the oil tank 3. Therefore, when the oil pressure in the system rises above a specified value, the first safety valve 11 and the second safety valve 12 can be used to discharge the oil medium outside the system to prevent the oil pressure in the pipeline or equipment from exceeding the specified value, thus playing an important protective role in equipment operation.

[0158] In addition, such as Figure 1 and Figure 5 As shown, the present invention also provides a control device applied to a back pressure control system for oil inlet and outlet ports, wherein the back pressure control system for oil inlet and outlet ports includes:

[0159] The hydraulic cylinder 1 has an oil inlet and an oil outlet when it is in operation.

[0160] Drive pump 2 to form an oil inlet passage between it and the oil inlet;

[0161] Oil tank 3 forms a return oil circuit with the oil outlet; and

[0162] The back pressure control assembly includes an inlet control valve 4, an outlet control valve 5, a first pressure sensor 6, and a second pressure sensor 7. The inlet control valve 4 and the outlet control valve 5 are respectively located on the inlet oil line and the return oil line. The first pressure sensor 6 and the second pressure sensor 7 are used to detect the pressure at the inlet and outlet oil respectively.

[0163] Control device 10 includes:

[0164] The receiving module is used to receive the detection signals from the first pressure sensor 6 and the second pressure sensor 7.

[0165] The pressure determination module is used to determine the load pressure of the hydraulic cylinder 1 based on the detection signal;

[0166] The actuation module is used to control the oil outlet control valve 5 based on the real-time flow signal and / or the pre-adjusted back pressure determined by the load pressure when the actuation cylinder 1 is determined to be under positive load based on the load pressure, and to control the oil inlet control valve 4 based on the pre-adjusted back pressure determined by the load pressure change state when the actuation cylinder 1 is determined to be under negative load based on the load pressure.

[0167] In this embodiment of the invention, the control device 10 further includes a flow rate determination module and a pre-adjustment back pressure determination module; the receiving module is also used to receive a real-time flow rate signal emitted by the control handle; the flow rate determination module is used to determine the flow rate signal level based on the real-time flow rate signal; the pre-adjustment back pressure determination module is used to determine the pre-adjustment back pressure based on the flow rate signal level and the load pressure; the execution module is also used to control the oil outlet control valve 5 based on the pre-adjustment back pressure.

[0168] In this embodiment of the invention, the pre-adjusted back pressure determination module is further configured to determine the load level based on the load pressure; and to determine the pre-adjusted back pressure based on the flow signal level and the load level.

[0169] In this embodiment of the invention, the pre-adjusted back pressure determination module is further used to obtain the change state of the load pressure when the flow signal level reaches the oscillating flow level; and to determine the pre-adjusted back pressure based on the load level and the change state of the load pressure.

[0170] In this embodiment of the invention, the control device 10 further includes a calculation module; the calculation module is used to calculate the load pressure change value based on the current load pressure and the previous load pressure; the execution module is also used to control the oil inlet control valve 4 according to the pre-adjusted back pressure corresponding to the pressure oscillation state when it is determined from the load pressure change value that the load pressure change state is in a pressure oscillation state.

[0171] In this embodiment of the invention, the control device 10 further includes a comparison module and a load pressure state determination module; the comparison module is used to compare the load pressure change value with the pressure change threshold; the load pressure state determination module is used to determine that the load pressure change state is in a pressure oscillation state when the load pressure change value exceeds the pressure change threshold at least twice consecutively; the execution module is also used to control the oil inlet control valve 4 according to the pre-adjusted back pressure corresponding to the pressure oscillation state.

[0172] In this embodiment of the invention, the execution module is further configured to control the oil inlet control valve 4 according to the pre-adjusted back pressure corresponding to the rapid start state when the execution cylinder 1 is determined to be under negative load based on the load pressure and the execution cylinder 1 is in a rapid start state.

[0173] In this embodiment of the invention, the comparison module is further configured to compare the current flow rate change value with the first flow rate change threshold when the actuator cylinder 1 is determined to be under negative load based on the load pressure; the execution module is further configured to determine that the actuator cylinder 1 is in a rapid start state if the current flow rate change value exceeds the first flow rate change threshold, and control the oil inlet control valve 4 according to the pre-adjusted back pressure corresponding to the rapid start state.

[0174] In this embodiment of the invention, the control device 10 further includes a valve core position determination module; the valve core position determination module is used to determine the target valve core position of the target control valve according to the pre-adjusted back pressure; the execution module is also used to control the target valve core to move to the target valve core position so as to perform pressure control on the target control valve.

[0175] In this embodiment of the invention, the pressure determination module is further configured to determine the real-time pressure of the back pressure chamber of the actuator cylinder 1 based on the detection signal of the first pressure sensor 6 or the second pressure sensor 7 when the current flow change does not exceed the second flow change threshold; the flow determination module is further configured to determine the displacement proportional coefficient of the target control valve based on the real-time flow signal emitted by the control handle when the current flow change does not exceed the second flow change threshold; the valve core position determination module is further configured to determine the stage valve core displacement based on the displacement proportional coefficient, the pre-adjusted back pressure, and the real-time pressure of the back pressure chamber of the actuator cylinder 1; and adjust the valve core position of the target control valve based on the stage valve core displacement so that the valve core of the target control valve reaches the target valve core position.

[0176] In this embodiment of the invention, the pressure determination module is further used to acquire the oil outlet pressure collected by the third pressure sensor 8; the calculation module is further used to determine the flow area by fitting the flow coefficient, oil density, current flow value, pre-adjusted back pressure and oil outlet pressure when the current flow change exceeds the second flow change threshold; the valve core position determination module is further used to determine the target valve core position based on the flow area.

[0177] In this embodiment of the invention, the execution module is further configured to control the flow of the oil inlet control valve 4 based on the detection signals of the first pressure sensor 6 and the fourth pressure sensor 9 when the execution cylinder 1 is determined to be under positive load based on the load pressure; and to control the flow of the oil outlet control valve 5 based on the detection signals of the second pressure sensor 7 and the third pressure sensor 8 when the execution cylinder 1 is determined to be under negative load based on the load pressure.

[0178] To achieve the above objectives, the present invention also provides an engineering machinery device, wherein the engineering machinery device includes a processor and a memory storing computer program instructions, the processor reading and executing the computer program instructions to implement the back pressure control method for the oil inlet and outlet as described above. Since the engineering machinery device adopts all the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated further here.

[0179] In the description of this invention, it should be understood that 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 at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0180] 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, an electrical connection, or a connection that allows communication between them; 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, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0181] 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. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, 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.

[0182] 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 back pressure control method for oil inlet and outlet ports, applied to a back pressure control system for oil inlet and outlet ports, characterized in that, The back pressure control system for the oil inlet and outlet includes: The hydraulic cylinder has an oil inlet and an oil outlet when it is in operation. A drive pump is used to form an oil inlet passage with the oil inlet port; The oil tank forms a return oil passage with the oil outlet; and The back pressure control assembly includes an inlet control valve, an outlet control valve, a first pressure sensor, and a second pressure sensor. The inlet control valve and the outlet control valve are respectively located on the inlet oil line and the return oil line. The first pressure sensor and the second pressure sensor are used to detect the pressure at the inlet and outlet oil respectively. The back pressure control method for the oil inlet and outlet includes: Receive detection signals from the first pressure sensor and the second pressure sensor; The load pressure of the actuator cylinder is determined based on the detection signal; When the actuator cylinder is determined to be under positive load based on the load pressure, the oil outlet control valve is controlled based on the pre-adjusted back pressure determined by the real-time flow signal and / or load pressure. When the actuator cylinder is determined to be under negative load based on the load pressure, the oil inlet control valve is controlled based on the pre-adjusted back pressure determined by the change state of the load pressure. The step of controlling the oil inlet control valve based on the pre-adjusted back pressure determined according to the load pressure change includes: The load pressure change is calculated based on the current load pressure and the previous load pressure. If the load pressure change value exceeds the pressure change threshold at least twice consecutively, it is determined that the load pressure change state is in a pressure oscillation state. If the load pressure change is determined to be in a pressure oscillation state based on the load pressure change value, the oil inlet control valve is controlled according to the pre-adjusted back pressure corresponding to the pressure oscillation state to increase the back pressure to the pre-adjusted back pressure of the pressure oscillation state.

2. The back pressure control method for oil inlet and outlet ports according to claim 1, characterized in that, The control of the oil outlet control valve based on the pre-adjusted back pressure determined according to the real-time flow signal and / or load pressure includes: Receives real-time flow signals from the control handle; The flow signal level is determined based on the real-time flow signal; The pre-adjusted back pressure is determined based on the flow signal level and the load pressure. The oil outlet control valve is controlled according to the pre-adjusted back pressure.

3. The back pressure control method for oil inlet and outlet ports according to claim 2, characterized in that, Determining the pre-adjusted back pressure based on the flow signal level and the load pressure includes: Determine the load level based on the load pressure; The pre-adjusted back pressure is determined based on the flow signal level and the load level.

4. The back pressure control method for oil inlet and outlet ports according to claim 3, characterized in that, Determining the pre-adjusted back pressure based on the flow signal level and the load level includes: When the flow signal level reaches the oscillating flow level, the change state of the load pressure is obtained; The pre-adjusted back pressure is determined based on the load level and the change in load pressure.

5. The back pressure control method for oil inlet and outlet ports according to claim 1, characterized in that, After determining the load pressure of the actuator cylinder based on the detection signal, the method further includes: When the actuator cylinder is determined to be under negative load based on the load pressure and is in a rapid start state, the oil inlet control valve is controlled according to the pre-adjusted back pressure corresponding to the rapid start state.

6. The back pressure control method for oil inlet and outlet ports according to claim 5, characterized in that, When the actuator cylinder is determined to be under negative load based on the load pressure, and the actuator cylinder is in a rapid start state, the pressure control of the oil inlet control valve based on the pre-adjusted back pressure corresponding to the rapid start state includes: If the actuator cylinder is determined to be under negative load based on the load pressure, the current flow rate change value is compared with the first flow rate change threshold. If the current flow rate change value exceeds the first flow rate change threshold, it is determined that the actuator cylinder is in a rapid start state, and the oil inlet control valve is pressure controlled according to the pre-adjusted back pressure corresponding to the rapid start state.

7. The back pressure control method for oil inlet and outlet ports according to any one of claims 1 to 6, characterized in that, The method further includes: The target valve core position of the target control valve is determined based on the pre-adjusted back pressure, wherein, when the actuator cylinder is under positive load, the target control valve is an oil outlet control valve, and when the actuator cylinder is under negative load, the target control valve is an oil inlet control valve. The valve core of the target control valve is moved to the target valve core position to perform pressure control on the target control valve.

8. The back pressure control method for oil inlet and outlet ports according to claim 7, characterized in that, Determining the target valve core position of the target control valve based on the pre-adjusted back pressure includes: If the current flow change does not exceed the second flow change threshold, the real-time pressure of the back pressure chamber of the actuator cylinder is determined based on the detection signal of the first pressure sensor or the second pressure sensor, and the displacement proportional coefficient of the target control valve is determined based on the real-time flow signal sent by the control handle. The stage valve core displacement is determined based on the displacement proportionality coefficient, the pre-adjusted back pressure, and the real-time pressure of the back pressure chamber of the actuator cylinder. The valve core position of the target control valve is adjusted according to the valve core displacement of the stage so that the valve core of the target control valve reaches the target valve core position.

9. The back pressure control method for oil inlet and outlet ports according to claim 7, characterized in that, The back pressure control assembly further includes a third pressure sensor disposed on the return oil line between the oil tank and the oil outlet control valve, and the step of determining the target valve core position of the target control valve based on the pre-adjusted back pressure further includes: Obtain the oil outlet pressure collected by the third pressure sensor; If the current flow rate change exceeds the second flow rate change threshold, the flow area will be determined by fitting the flow coefficient, oil density, current flow rate value, pre-adjusted back pressure, and oil outlet pressure. The target valve core position is determined based on the flow area.

10. The back pressure control method for oil inlet and outlet ports according to any one of claims 1 to 6, characterized in that, The back pressure control assembly further includes a third pressure sensor and a fourth pressure sensor. The third pressure sensor is disposed on the return oil line between the oil tank and the oil outlet control valve, and the fourth pressure sensor is disposed on the oil inlet line between the drive pump and the oil inlet control valve. The method further includes: When the actuator cylinder is determined to be under positive load based on the load pressure, the flow rate of the oil inlet control valve is controlled based on the detection signals of the first pressure sensor and the fourth pressure sensor. When the actuator cylinder is determined to be under negative load based on the load pressure, the detection signals from the second pressure sensor and the third pressure sensor control the flow rate of the oil outlet control valve.

11. The back pressure control method for oil inlet and outlet ports according to any one of claims 1 to 6, characterized in that, The back pressure control assembly further includes a first safety valve and a second safety valve, wherein the first safety valve is connected between the oil inlet and the oil tank, and the second safety valve is connected between the oil outlet and the oil tank.

12. A control device applied to a back pressure control system for oil inlets and outlets, characterized in that, The back pressure control system for the oil inlet and outlet includes: The hydraulic cylinder has an oil inlet and an oil outlet when it is in operation. A drive pump is used to form an oil inlet passage with the oil inlet port; The oil tank forms a return oil passage with the oil outlet; and The back pressure control assembly includes an inlet control valve, an outlet control valve, a first pressure sensor, and a second pressure sensor. The inlet control valve and the outlet control valve are respectively located on the inlet oil line and the return oil line. The first pressure sensor and the second pressure sensor are used to detect the pressure at the inlet and outlet oil respectively. The control device includes: A receiving module is used to receive the detection signals from the first pressure sensor and the second pressure sensor; A pressure determination module is used to determine the load pressure of the actuator cylinder based on the detection signal; An execution module is configured to control the oil outlet control valve based on a pre-adjusted back pressure determined by a real-time flow signal and / or the load pressure when the actuator cylinder is determined to be under positive load based on the load pressure; and to control the oil inlet control valve based on a pre-adjusted back pressure determined by the load pressure change state when the actuator cylinder is determined to be under negative load based on the load pressure. The step of controlling the oil inlet control valve based on the pre-adjusted back pressure determined by the load pressure change state includes: The load pressure change is calculated based on the current load pressure and the previous load pressure. If the load pressure change value exceeds the pressure change threshold at least twice consecutively, it is determined that the load pressure change state is in a pressure oscillation state. If the load pressure change is determined to be in a pressure oscillation state based on the load pressure change value, the oil inlet control valve is controlled according to the pre-adjusted back pressure corresponding to the pressure oscillation state to increase the back pressure to the pre-adjusted back pressure of the pressure oscillation state.

13. An engineering machinery equipment, characterized in that, The engineering machinery equipment includes a processor and a memory storing computer program instructions. The processor reads and executes the computer program instructions to implement the back pressure control method for the oil inlet and outlet as described in any one of claims 1 to 11.

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