Constant pressure and load sensitive switching hydraulic control system and control method

Abstract

The application discloses a constant-pressure and load-sensitive switching hydraulic control system and a control method, and belongs to the technical field of hydraulic control, comprising a power mechanism, a variable pump and an oil tank; the variable pump comprises a load-sensitive valve, the load-sensitive valve is connected with a shuttle valve outlet of the shuttle valve, an electric proportional overflow valve is connected with the variable pump, the electric proportional overflow valve is also connected with a first inlet of the shuttle valve, a P port of a reversing valve is connected with the variable pump, and an A port of the reversing valve is connected with a second inlet of the shuttle valve; a pressure sensor assembly is used for reading outlet pressure of the variable pump and transmitting the outlet pressure to a controller, and the pressure sensor assembly is also used for reading load-sensitive feedback pressure and transmitting the load-sensitive feedback pressure to the controller. The application realizes automatic constant-pressure and load-sensitive switching with the increase of load pressure, can avoid the working of the load-sensitive system under low pressure, and can effectively solve the problems of slow action of an executing element of the load-sensitive system under low pressure and low system efficiency.

Description

Technical Field

[0001] This application relates to the field of hydraulic control technology, and in particular, to a constant pressure and load-sensitive switching hydraulic control system and method. Furthermore, this application also relates to a control method employing the aforementioned constant pressure and load-sensitive switching hydraulic control system. Background Technology

[0002] The information provided in this section is for the purpose of generally presenting the background of this application. To the extent described in this section, the work of the currently named inventors and aspects of the description that may not constitute prior art at the time of filing are neither explicitly nor implicitly considered to be prior art of this application.

[0003] In the field of hydraulic control technology, the core of a constant pressure control system lies in ensuring a constant output pressure from the hydraulic pump. When the output pressure is lower than the set constant pressure, the variable pump outputs pressurized oil at full displacement to provide sufficient power to the system. Once the output oil pressure reaches the set pressure, the variable pump automatically adjusts the pump flow rate, maintaining a constant pressure through clever flow adjustment to meet system requirements. Constant pressure control systems are suitable for scenarios with extremely high pressure stability requirements, such as in high-precision machining equipment, where stable pressure ensures that machining accuracy is not affected by pressure fluctuations.

[0004] The load-sensitive control system focuses on the close correlation between the hydraulic pump output pressure and the load force. The variable displacement pump used in this system is a powerful hydraulic compensator that can accurately capture the real-time flow and pressure requirements of each actuator in the system and respond quickly and correctly. This allows the piston pump to flexibly adjust its output according to the actual load, avoiding unnecessary energy waste.

[0005] In a constant pressure control system, when the pressure required by the actuator is relatively small, the outlet of the constant pressure pump still needs to maintain a relatively high pressure (usually the maximum working pressure of the system). Excess pressure damage often occurs at the multi-way valve or speed control valve. Due to the energy loss caused by the multi-way valve or speed control valve, a large amount of energy is converted into heat energy, which will cause the system oil temperature to rise.

[0006] In load-sensing systems (LS), when the load pressure is low, the control signal fed back to the pump by the load-sensing system may not be sufficient for the pump to quickly build up enough pressure and flow, resulting in sluggish operation of actuators (such as hydraulic cylinders and hydraulic motors). Under low-pressure loads, in order to maintain the control accuracy of the load-sensing system, the pump may continuously adjust its displacement. However, due to the low load, the actual required flow and pressure are small, which causes the pump to operate inefficiently under certain conditions, increasing energy loss.

[0007] For example, Chinese patent publication number CN117072501A discloses a tunnel drilling device and its hydraulic control system and control method. In this scheme, pump 2 is a load-sensitive pump. The pump includes a load-sensitive valve and a control valve connected to the load-sensitive valve. By switching the control valve, the load-sensitive mode operation or constant pressure mode operation can be realized. This method can realize the switching between constant pressure and load-sensitive modes, but it cannot solve the problems of high energy consumption and high system temperature in constant pressure systems. At the same time, it does not mention how to solve the problems of slow action of actuators and low system efficiency in load-sensitive systems under low load and low pressure conditions. Chinese patent CN115388058A discloses a variable pump load-sensitive and constant-pressure switching hydraulic control system and method. In the initial operation, the switching valve is energized to form a constant-pressure system. After the pressure is built up to a certain value (generally ≥40 bar), the switching valve is automatically de-energized to achieve load-sensitive control. This scheme achieves constant-pressure negative-sensitive switching by switching the valve on and off, which can effectively solve the problem of slow action of the actuator in the load-sensitive system under low load pressure. However, it achieves the switching valve on and off through pressure control and feedback, which makes the control logic complex, increases the risk of component failure, and also has problems such as poor stability in the switching process.

[0008] To address the issues of high energy consumption and high system temperature in existing constant pressure systems, and to resolve the problems of sluggish actuator operation and low system efficiency in load-sensitive systems under low-pressure load conditions, this application proposes a constant pressure and load-sensitive switching hydraulic control system and method adaptable to multiple operating conditions. Summary of the Invention

[0009] In view of at least one of the above technical problems, this application provides a constant pressure and load-sensitive switching hydraulic control system, which can automatically switch between constant pressure and load sensitivity as the load pressure increases. This can prevent the load-sensitive system from working under low pressure conditions and effectively solve the problems of slow action of actuators and low system efficiency in the load-sensitive system under low pressure conditions. It has the advantages of fast response, good stability and energy saving.

[0010] This application also provides a control method using the above-mentioned constant pressure and load-sensitive switching hydraulic control system.

[0011] According to one aspect of this application, a constant pressure and load-sensitive switching hydraulic control system is provided, including a variable pump, a shuttle valve, an electro-proportional relief valve, a directional valve, and a controller. The variable pump is used to connect to the actuator through an actuation circuit, and a load control module is provided on the actuation circuit.

[0012] The variable pump is equipped with a load-sensitive valve. The control end of the load-sensitive valve is connected to the shuttle valve outlet. The P port of the electro-proportional relief valve is located at the front end of the load control module and is connected to the first inlet of the shuttle valve. The T port of the electro-proportional relief valve is connected to the T port of the directional valve. The P port of the directional valve is connected to the rear end of the load control module. The A port of the directional valve is connected to the second inlet of the shuttle valve.

[0013] The constant pressure and load-sensitive switching hydraulic control system also includes a pressure sensor assembly, which reads the outlet pressure and / or load pressure of the variable pump and transmits it to the controller, which is connected to the control terminal of the electro-proportional relief valve.

[0014] In some embodiments of this application, the constant pressure and load-sensitive switching hydraulic control system further includes a damper located between the actuation oil circuit and the electro-proportional relief valve. The first inlet of the shuttle valve is connected to the outlet end of the damper. The damper is used to reduce pressure fluctuations in the variable pump outlet pressure oil flowing to the electro-proportional relief valve and the shuttle valve.

[0015] In some embodiments of this application, the load control module includes a speed control valve for controlling the flow rate of hydraulic oil from the variable pump to regulate the movement speed of the actuator.

[0016] In some embodiments of this application, the pressure sensor assembly includes a first pressure sensor connected to the front end of the load control module and a second pressure sensor connected to the rear end of the load control module. The first pressure sensor is used to read the outlet pressure of the variable pump and transmit it to the controller, and the second pressure sensor is used to read the load pressure and transmit it to the controller.

[0017] According to another aspect of this application, a constant voltage and load-sensitive switching control method is also provided, which employs the aforementioned constant voltage and load-sensitive switching control. This method is used to control the switching between four modes: load-sensitive mode, constant voltage mode, electronic negative-sensitive mode, and automatic switching mode between constant voltage and negative-sensitive modes.

[0018] When load-sensitive mode is required: the electro-proportional relief valve and the directional valve are not energized. The load-sensitive feedback pressure oil flows through the P port of the directional valve to the A port and then acts on the second inlet of the shuttle valve. The load-sensitive feedback pressure acts on the load-sensitive valve through the shuttle valve outlet. This is the load-sensitive mode.

[0019] When constant pressure mode is required: the electro-proportional relief valve is energized and the pressure is set to the system working pressure. The directional valve is energized. The load-sensitive feedback pressure oil flows through the P port of the directional valve to the B port and then is blocked. One end of the variable pump outlet pressure oil acts on the P port of the electro-proportional relief valve, and the other end acts on the first inlet of the shuttle valve and then on the outlet of the shuttle valve. Finally, it acts on the load-sensitive valve. At this time, it is constant pressure mode.

[0020] When electronic negative sensing mode is required: the reversing valve is energized, and the load-sensitive feedback pressure oil flows through the P port of the reversing valve to the B port. The B port is blocked. One end of the variable pump outlet pressure oil acts on the P port of the electro-proportional relief valve, and the other end acts on the first inlet of the shuttle valve and then on the outlet of the shuttle valve. Finally, it acts on the load-sensitive valve. The system pressure is set by the electro-proportional relief valve, which makes the outlet pressure of the variable pump greater than the load-sensitive feedback pressure, so that the outlet pressure of the variable pump changes with the load-sensitive feedback pressure.

[0021] When constant pressure and negative pressure automatic switching modes are required: the directional valve is not energized, and the load-sensitive feedback pressure oil flows through the P port of the directional valve to the A port, and the A port flows to the second inlet of the shuttle valve; the outlet pressure oil of the variable pump acts on the P port of the electro-proportional relief valve at one end and on the first inlet of the shuttle valve at the other end. The relief pressure of the electro-proportional relief valve is set to P1. When the load-sensitive load pressure is lower than P1, it is a constant pressure system; when the load-sensitive load pressure is greater than P1, it is a load-sensitive system.

[0022] In some embodiments of this application, in constant pressure mode, electronic negative sensing mode, and constant pressure and negative sensing automatic switching mode, the variable pump outlet pressure oil flows through the damper and reduces pressure fluctuations, then one end acts on the P port of the electro-proportional relief valve, and the other end acts on the first inlet of the shuttle valve.

[0023] In some embodiments of this application, in electronic negative sensing mode, the actuator is controlled to operate, the load-sensitive feedback pressure is read by the pressure sensor assembly and transmitted to the controller, and the controller controls the electro-proportional relief valve to make the outlet pressure of the variable pump greater than the load-sensitive feedback pressure, so that the outlet pressure of the variable pump changes with the load-sensitive feedback pressure.

[0024] In some embodiments of this application, when controlling the actuator in electronic negative sensing mode, the force on the inlet side of the load-sensitive valve is the variable pump outlet pressure P. P The calculation is shown in Formula 1:

[0025] P P =ΔP+P7 1

[0026] In the formula, ΔP is the spring pressure of the load-sensitive valve, and P7 is the pressure of the electro-proportional relief valve.

[0027] The pressure of the electro-proportional relief valve is calculated as shown in Formula 2:

[0028] P7 = A + B * X 2

[0029] In the formula, A and B are constants, and X is the electrical signal value of the electro-proportional relief valve;

[0030] Variable pump outlet pressure P PThe electrical signal value X of the electro-proportional relief valve is directly proportional to the signal value, as shown in Formula 3:

[0031] P p =ΔP + P7 = ΔP + A + B*X 3

[0032] In some embodiments of this application, when controlling the actuator in electronic negative sensitivity mode, neither the electro-proportional relief valve nor the directional valve is energized, the variable pump starts under load, the pressure P7 of the electro-proportional relief valve is 0, and the outlet pressure P of the variable pump is... P This is the standby pressure; after a preset standby time, the electro-proportional relief valve is energized, and the variable pump outlet pressure P is adjusted by controlling the electrical signal value. p The maximum operating pressure P of the system max When the actuator is working, the pressure sensor assembly collects the load-sensitive feedback pressure P in real time. LS The data is transmitted to the controller, which controls the electro-proportional relief valve to make the variable pump outlet pressure greater than the load-sensitive feedback pressure, thus creating a pressure difference Δp. The variable pump outlet pressure P... P With load-sensitive feedback pressure P LS The relationship between them is shown in Formula 4:

[0033] P p =ΔP+P7=ΔP+A+B*X=P LS +Δp 4

[0034] In some embodiments of this application, under the constant pressure and negative sensitivity automatic switching mode, when the load-sensitive feedback pressure is lower than P1, the first inlet pressure of the shuttle valve is greater than the second inlet pressure. At this time, the variable pump outlet pressure oil flows through the first inlet of the shuttle valve to the outlet of the shuttle valve, and finally acts on the load-sensitive valve. This is the constant pressure system mode. When the load-sensitive feedback pressure is greater than P1, the first inlet pressure of the shuttle valve is less than the second inlet pressure. At this time, the load-sensitive feedback pressure oil flows through the P port of the reversing valve to the A port, and the A port flows through the second inlet of the shuttle valve to the outlet of the shuttle valve, and finally acts on the load-sensitive valve. This is the load-sensitive system mode.

[0035] This application has the following beneficial effects:

[0036] This application discloses a constant pressure and load-sensitive switching hydraulic control system. When the directional valve is energized and reversed, the LS (load-sensitive) load feedback oil circuit is cut off to prevent the LS load feedback oil circuit from affecting the constant pressure feedback oil circuit. At this time, the variable pump outlet pressure acts on the left side of the shuttle valve and ultimately on the load-sensitive valve, thus creating a constant pressure system. The hydraulic control system of this application collects the LS load pressure and pump outlet pressure in real time and transmits them to the controller. The controller controls the electro-proportional relief valve to perform follow-up control of the variable pump outlet pressure, ensuring that the variable pump outlet pressure is always greater than the LS load pressure by a pressure difference. This achieves electro-proportional load-sensitive adaptive control, effectively solving the problem of high energy consumption in constant pressure systems. It satisfies both the pressure stability characteristics of constant pressure systems and the follow-up energy-saving characteristics of load-sensitive systems.

[0037] When the directional valve in this application is de-energized, the outlet pressure of the variable pump acts on the left side of the shuttle valve and ultimately on the load-sensitive valve, creating a constant pressure system. The system pressure is set by the electro-proportional relief valve. When the actuator operates and the load pressure exceeds the set pressure of the electro-proportional relief valve, the oil on the right side of the shuttle valve activates and ultimately acts on the load-sensitive valve, creating a load-sensitive system. In other words, when the load pressure is low, the system is a constant pressure system; when the load pressure is high, the system automatically switches to a load-sensitive system. This effectively solves the problems of slow actuator operation and low system efficiency in load-sensitive systems under low load conditions. The system control is simple, reliable, energy-efficient, and highly effective.

[0038] The constant pressure and load-sensitive switching control method of this application also has the aforementioned beneficial effects. It also includes the ability to flexibly and conveniently switch between four operating conditions or modes: load-sensitive mode, constant pressure mode, electronic load-sensitive mode, and automatic switching mode between constant pressure and load sensitivity. This effectively meets the needs of multiple operating conditions and has better adaptability. In the electronic load mode, the controller uses a preset program and control strategy to control the electro-proportional relief valve so that the outlet pressure of the variable pump is greater than the LS feedback pressure by a pressure difference of Δp. This allows the outlet pressure of the variable pump to follow the changes in the LS load feedback pressure, satisfying both the pressure stability characteristics of a constant pressure system and the follow-up energy-saving characteristics of a load-sensitive system. It is generally suitable for high-flow rotary or rotating operations. In the automatic switching mode between constant pressure and load sensitivity, the inherent properties of the shuttle valve ensure that when the set pressure of the electro-proportional relief valve is higher than the LS load feedback pressure, the system is a constant pressure system, characterized by fast response and good stability; when the set pressure of the electro-proportional relief valve is lower than the LS load feedback pressure, the system is a load-sensitive system, characterized by energy saving and high efficiency. It is generally suitable for low-speed, low-load cylinder extension and retraction operations. This application can effectively solve the problems of high energy consumption and high system temperature in existing constant pressure systems, and also solve the problems of slow operation of actuators and low system efficiency in load-sensitive systems under low load and low voltage conditions.

[0039] Of course, any product implementing this application does not necessarily need to achieve all the advantages described above simultaneously. In addition to the purposes, features, and advantages described above, this application also has other purposes, features, and advantages. The following will provide a more detailed description of this application with reference to figures. Attached Figure Description

[0040] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0041] Figure 1 This is a schematic diagram of the overall hydraulic control system according to a preferred embodiment of this application;

[0042] Figure 2 This is a schematic diagram of a preferred embodiment of the present application, showing a two-position three-way solenoid directional valve.

[0043] Legend: 1. Power mechanism; 2. Variable pump; 3. Oil tank; 4. Load-sensitive valve; 5. Shuttle valve; 5.1. First inlet; 5.2. Second inlet; 5.3. Shuttle valve outlet; 6. Damping; 7. Electro-proportional relief valve; 8. Speed ​​control valve; 9. Directional control valve; 10. First pressure sensor; 11. Second pressure sensor; 12. Controller. Detailed Implementation

[0044] The embodiments of this application are described in detail below with reference to the accompanying drawings; however, this application may be implemented in a variety of different ways as defined and covered below.

[0045] Figure 1 This is a schematic diagram of the overall hydraulic control system according to a preferred embodiment of this application; Figure 2 This is a schematic diagram of a preferred embodiment of the present application, showing a two-position three-way solenoid directional valve.

[0046] A constant pressure and load-sensitive switching hydraulic control system includes a variable pump 2, a shuttle valve 5, an electro-proportional relief valve 7, a directional valve 9, and a controller 12. The variable pump 2 is used to connect to the actuator through an actuation circuit, and a load control module is provided on the actuation circuit.

[0047] The variable pump 2 is equipped with a load-sensitive valve 4. The control end of the load-sensitive valve 4 is connected to the shuttle valve outlet 5.3 of the shuttle valve 5. The P port of the electro-proportional relief valve 7 is located at the front end of the load control module and is connected to the first inlet 5.1 of the shuttle valve 5. The T port of the electro-proportional relief valve 7 is connected to the T port of the directional valve 9. The P port of the directional valve 9 is connected to the rear end of the load control module. The A port of the directional valve 9 is connected to the second inlet 5.2 of the shuttle valve 5.

[0048] The constant pressure and load-sensitive switching hydraulic control system also includes a pressure sensor assembly, which is used to read the outlet pressure and / or load pressure of the variable pump 2 and transmit it to the controller 12, which is connected to the control terminal of the electro-proportional relief valve 7.

[0049] Here, "variable pump 2" refers to a component that provides pressurized oil to the hydraulic system. In some embodiments, variable pump 2 is a variable displacement piston pump. Variable pump 2 is connected to power mechanism 1, which provides power to it. A tank 3 for storing hydraulic oil may also be provided.

[0050] Here, "shuttle valve 5" refers to a valve component that selects the highest pressure from multiple connected oil circuit pressure sources and transmits it to subsequent circuits for load-sensitive control.

[0051] It should be noted that the electro-proportional relief valve 7 can adjust the pump outlet pressure, and therefore also functions as a safety valve for the variable pump 2.

[0052] In some embodiments, the term "reversing valve 9" is referred to here. Figure 1 It adopts a two-position four-way solenoid directional valve group, and controls the valve core of the two-position four-way solenoid directional valve group to switch positions through electromagnetic force, so as to realize the on and off of LS feedback pressure.

[0053] In other embodiments, please refer to Figure 2 The reversing valve 9 can be replaced by a two-position three-way solenoid reversing valve, which can also realize the on / off switching of LS feedback pressure.

[0054] Among them, the controller 12 is a PLC controller, which receives the signals fed back by sensors such as pressure sensor components, analyzes and processes them, and issues control commands to adjust the operation of each hydraulic component according to the preset program and control strategy.

[0055] This application discloses a constant pressure and load-sensitive switching hydraulic control system. When the directional valve 9 is energized and reversed, the LS (load-sensitive) load feedback oil circuit is cut off to prevent the LS load feedback oil circuit from affecting the constant pressure feedback oil circuit. At this time, the outlet pressure of the variable pump 2 acts on the left side of the shuttle valve 5 and ultimately on the load-sensitive valve 4, thus creating a constant pressure system. The hydraulic control system of this application collects the LS load pressure and the pump outlet pressure in real time and transmits them to the controller 12. The controller 12 controls the electro-proportional relief valve 7 to perform follow-up control of the outlet pressure of the variable pump 2, ensuring that the outlet pressure of the variable pump 2 is always greater than the LS load pressure by a pressure difference. This achieves electro-proportional load-sensitive adaptive control, which can effectively solve the problem of high energy consumption in constant pressure systems. It can satisfy both the pressure stability characteristics of constant pressure systems and the follow-up energy-saving characteristics of load-sensitive systems.

[0056] When the directional valve 9 is de-energized, the outlet pressure of the variable pump 2 acts on the left side of the shuttle valve 5 and ultimately on the load-sensitive valve 4, creating a constant pressure system. The system pressure is set by the electro-proportional relief valve 7. When the actuator operates and the load pressure exceeds the set pressure of the electro-proportional relief valve 7, the oil on the right side of the shuttle valve 5 is activated and ultimately acts on the load-sensitive valve 4, creating a load-sensitive system. In other words, when the load pressure is low, the system is a constant pressure system; when the load pressure is high, the system automatically switches to a load-sensitive system. This effectively solves the problems of slow actuator operation and low system efficiency in load-sensitive systems under low load conditions. The system control is simple, reliable, energy-saving, and highly efficient.

[0057] Preferably, please refer to Figure 1 As shown, the constant pressure and load-sensitive switching hydraulic control system also includes a damper 6 located between the actuation oil circuit and the electro-proportional relief valve 7. The first inlet 5.1 of the shuttle valve 5 is connected to the outlet end of the damper 6. The damper 6 is used to reduce the pressure fluctuation of the outlet pressure oil of the variable pump 2 flowing to the electro-proportional relief valve 7 and the shuttle valve 5.

[0058] Understandably, reducing pressure fluctuations in the oil circuit through damper 6 can effectively improve system stability. In specific operation, the pressure oil at the outlet of variable pump 2 flows through damper 6 and, after pressure fluctuations are reduced by damper 6, one end acts on port P of electro-proportional relief valve 7, and the other end acts on the first inlet 5.1 of shuttle valve 5, thus achieving stable transmission of pressure oil.

[0059] Preferably, please refer to Figure 1 As shown, the load control module includes a speed control valve 8, which is used to control the flow rate of hydraulic oil in the variable pump 2 to adjust the movement speed of the actuator.

[0060] It is understandable that by setting the speed control valve 8, the valve opening of the speed control valve 8 can be changed, thereby controlling the flow of hydraulic oil in the oil circuit, and thus adjusting the movement speed of the actuator to ensure the smooth movement of the actuator.

[0061] Preferably, please refer to Figure 1 As shown, the pressure sensor assembly includes a first pressure sensor 10 connected to the front end of the load control module and a second pressure sensor 11 connected to the rear end of the load control module. The first pressure sensor 10 is used to read the outlet pressure of the variable pump 2 and transmit it to the controller 12, and the second pressure sensor 11 is used to read the load pressure and transmit it to the controller 12.

[0062] It is understandable that the outlet pressure of pump 2 is read in real time by pressure sensor 10 and transmitted to controller 12 through control line. The LS feedback pressure is read in real time by pressure sensor 11 and transmitted to controller 12 through control line. Finally, controller 12 receives the feedback signals from each sensor, analyzes and processes them, and issues control commands to adjust the operation of each hydraulic component according to the preset program and control strategy of controller 12, so as to realize the automated control operation of the system.

[0063] According to another aspect of this application, a constant voltage and load-sensitive switching control method is also provided, which employs the aforementioned constant voltage and load-sensitive switching control. This method is used to control the switching between four modes: load-sensitive mode, constant voltage mode, electronic negative-sensitive mode, and automatic switching mode between constant voltage and negative-sensitive modes.

[0064] When load-sensitive mode is required: the electro-proportional relief valve 7 and the directional valve 9 are not energized. The load-sensitive feedback pressure oil flows through the P port of the directional valve 9 to the A port and then acts on the second inlet 5.2 of the shuttle valve 5. The load-sensitive feedback pressure acts on the load-sensitive valve 4 through the shuttle valve outlet 5.3 of the shuttle valve 5. At this time, it is the load-sensitive mode.

[0065] When constant pressure mode is required: the electro-proportional relief valve 7 is energized and the pressure is set to the system working pressure. The directional valve 9 is energized. The load-sensitive feedback pressure oil flows through the P port of the directional valve 9 to the B port and then is blocked. One end of the outlet pressure oil of the variable pump 2 acts on the P port of the electro-proportional relief valve 7, and the other end acts on the first inlet 5.1 of the shuttle valve 5, then acts on the outlet 5.3 of the shuttle valve, and finally acts on the load-sensitive valve 4. At this time, it is constant pressure mode.

[0066] When electronic negative sensing mode is required: the reversing valve 9 is energized, and the load-sensitive feedback pressure oil flows through the P port of the reversing valve 9 to the B port. The B port is blocked. One end of the outlet pressure oil of the variable pump 2 acts on the P port of the electro-proportional relief valve 7, and the other end acts on the first inlet 5.1 of the shuttle valve 5, then on the outlet 5.3 of the shuttle valve, and finally on the load-sensitive valve 4. The system pressure is set by the electro-proportional relief valve 7, which makes the outlet pressure of the variable pump 2 greater than the load-sensitive feedback pressure, so that the outlet pressure of the variable pump 2 changes with the load-sensitive feedback pressure.

[0067] When constant pressure and negative pressure automatic switching modes are required: the reversing valve 9 is not energized, and the load-sensitive feedback pressure oil flows through the P port of the reversing valve 9 to the A port, and the A port flows to the second inlet 5.2 of the shuttle valve 5; one end of the outlet pressure oil of the variable pump 2 acts on the P port of the electro-proportional relief valve 7, and the other end acts on the first inlet 5.1 of the shuttle valve 5. The relief pressure of the electro-proportional relief valve 7 is set to P1. When the load-sensitive load pressure is lower than P1, it is a constant pressure system, and when the load-sensitive load pressure is greater than P1, it is a load-sensitive system.

[0068] The constant pressure and load-sensitive switching control method of this application also has the aforementioned beneficial effects. It also includes the ability to flexibly and conveniently switch between four operating conditions or modes: load-sensitive mode, constant pressure mode, electronic load-sensitive mode, and automatic switching mode between constant pressure and load sensitivity, effectively meeting the needs of multiple operating conditions and exhibiting better adaptability. In the electronic load mode, the controller 12, through its preset program and control strategy, controls the electro-proportional relief valve 7 to make the outlet pressure of the variable pump 2 greater than the LS feedback pressure by a pressure difference of Δp, enabling the outlet pressure of the variable pump 2 to change with the LS load feedback pressure. This satisfies both the pressure stability characteristics of a constant pressure system and the follow-up energy-saving characteristics of a load-sensitive system, and is generally suitable for high-flow rotary or rotating operations. In the automatic switching mode between constant pressure and load sensitivity, the inherent properties of the shuttle valve 5 ensure that when the set pressure of the electro-proportional relief valve 7 is higher than the LS load feedback pressure, the system is a constant pressure system, characterized by fast response and good stability; when the set pressure of the electro-proportional relief valve 7 is lower than the LS load feedback pressure, the system is a load-sensitive system, characterized by energy saving and high efficiency, and is generally suitable for low-speed, low-load cylinder extension and retraction operations. This application can effectively solve the problems of high energy consumption and high system temperature in existing constant pressure systems, and also solve the problems of slow operation of actuators and low system efficiency in load-sensitive systems under low load and low voltage conditions.

[0069] Preferably, in constant pressure mode, electronic negative sensitivity mode, and constant pressure and negative sensitivity automatic switching mode, the outlet pressure oil of variable pump 2 flows through damper 6 and reduces pressure fluctuations through damper 6, then one end acts on port P of electro-proportional relief valve 7 and the other end acts on the first inlet 5.1 of shuttle valve 5.

[0070] Understandably, in order to achieve stable transmission of pressurized oil to the electro-proportional relief valve 7 and shuttle valve 5, the hydraulic oil from the variable pump 2 to the electro-proportional relief valve 7 and shuttle valve 5 is throttled and speed-regulated by the damper 6 to achieve the function of pressure filtering, thereby improving the stability of system operation.

[0071] Preferably, in the electronic negative sensing mode, the actuator is controlled to read the load-sensitive feedback pressure through the pressure sensor assembly and transmit it to the controller 12. The controller 12 controls the electro-proportional relief valve 7 to make the outlet pressure of the variable pump 2 greater than the load-sensitive feedback pressure, so that the outlet pressure of the variable pump 2 changes with the load-sensitive feedback pressure.

[0072] Specifically, when controlling the actuator in electronic negative sensing mode, the force on the inlet side of load-sensitive valve 4 is the pump outlet pressure P. P The calculation is shown in Formula 1:

[0073] P P =ΔP+P7 1

[0074] In the formula, ΔP is the spring pressure of the load-sensitive valve 4, and P7 is the pressure of the electro-proportional relief valve 7.

[0075] The pressure of the electro-proportional relief valve 7 is calculated as shown in Formula 2:

[0076] P7 = A + B * X 2

[0077] In the formula, A and B are constants, and X is the electrical signal value of the electro-proportional relief valve 7;

[0078] Variable pump 2 outlet pressure P P The electrical signal value X of the electro-proportional relief valve 7 is directly proportional to the signal value X, as shown in Formula 3:

[0079] P p =ΔP + P7 = ΔP + A + B*X 3

[0080] Furthermore, when controlling the actuator in electronic negative sensitivity mode, neither the electro-proportional relief valve 7 nor the directional valve 9 is energized. The variable pump 2 starts under load, the pressure P7 of the electro-proportional relief valve 7 is 0, and the outlet pressure P of the variable pump 2 is... P The standby pressure is set; after a preset standby time, in some embodiments, a preset standby time of 10 seconds is established, the electro-proportional relief valve 7 is energized, and the outlet pressure P of the variable pump 2 is adjusted by controlling the electrical signal value. p The maximum operating pressure P of the system max When the actuator is working, the pressure sensor assembly collects the load-sensitive feedback pressure P in real time. LS The data is transmitted to controller 12, which controls the electro-proportional relief valve 7 to make the outlet pressure of variable pump 2 greater than the load-sensitive feedback pressure, thus creating a pressure difference Δp. The outlet pressure P of variable pump 2... P With load-sensitive feedback pressure P LS The relationship between them is shown in Formula 4:

[0081] P p =ΔP+P7=ΔP+A+B*X=P LS +Δp 4

[0082] Typically, Δp is preset to 2.5 MPa, and ΔP is preset to 2 MPa. Therefore, according to Formula 4:

[0083] X = (P) LS +0.5-A) / B 5

[0084] According to Formula 5, controller 12 only needs to adjust the load-sensitive feedback pressure P based on the real-time collected data. LS By finding the value, we can find the corresponding electrical signal value X.

[0085] It is understandable that, according to Formula 5, the electrical signal value X of the electro-proportional relief valve 7 and the LS feedback pressure PLS They are directly proportional, and the values ​​correspond one-to-one. Controller 12 only needs to base its response on the real-time collected LS feedback pressure P. LS By finding a single value, a unique electrical signal value X can be found, making the control logic simple and reliable. The electronic negative-sensing control system is a constant-pressure system, possessing the advantages of a constant-pressure system. Simultaneously, the outlet pressure of variable pump 2 changes with the feedback pressure of the LS load, effectively reducing useless power consumption and improving system efficiency. It satisfies both the pressure stability characteristics of a constant-pressure system and the follow-up energy-saving characteristics of a negative-sensing system.

[0086] Preferably, in the constant pressure and negative pressure automatic switching mode, when the load-sensitive feedback pressure is lower than P1, the pressure at the first inlet 5.1 of the shuttle valve 5 is greater than the pressure at the second inlet 5.2. At this time, the outlet pressure oil of the variable pump 2 flows through the first inlet 5.1 of the shuttle valve 5 to the outlet 5.3, and finally acts on the load-sensitive valve 4. This is the constant pressure system mode. When the load-sensitive feedback pressure is greater than P1, the pressure at the first inlet 5.1 of the shuttle valve 5 is less than the pressure at the second inlet 5.2. At this time, the load-sensitive feedback pressure oil flows through the P port of the reversing valve 9 to the A port, and from the A port, it flows through the second inlet 5.2 of the shuttle valve 5 to the outlet 5.3, and finally acts on the load-sensitive valve 4. This is the load-sensitive system mode. It should be noted that the overflow pressure P1 of the electro-proportional relief valve 7 is set to 5 MPa in some embodiments.

[0087] Understandably, when the LS load pressure is low, the system is a constant pressure system, characterized by fast response and good stability. When the load pressure exceeds the set pressure value, the system automatically switches to a load-sensitive system via the shuttle valve oil circuit, resulting in energy-efficient and high-performance systems. The hydraulic control system of this application automatically switches between constant pressure and load-sensitive modes as the load pressure increases, without requiring the controller 12 to set programs and control strategies; mode switching is achieved solely through the inherent characteristics of the shuttle valve 5. This avoids the load-sensitive system operating under low-pressure conditions and effectively solves problems such as slow actuator action and low system efficiency in load-sensitive systems under low-pressure conditions. It offers advantages such as fast response, good stability, and energy saving.

[0088] In summary, this application, through the preset program and control strategy of the controller 12, controls the electro-proportional relief valve 7 to make the outlet pressure of the variable pump 2 greater than the LS feedback pressure by a pressure difference of Δp, thereby realizing the electronic negative-sensitive mode in which the outlet pressure of the variable pump 2 follows the change of the LS load feedback pressure. This effectively reduces useless power consumption, solves the problem of high energy consumption in constant pressure systems, and improves system efficiency. This system can satisfy both the pressure stability characteristics of a constant pressure system and the follow-up energy-saving characteristics of a negative-sensitive system. Through the inherent properties of the shuttle valve 5, when the set pressure of the electro-proportional relief valve 7 is higher than the LS load feedback pressure, the system is a constant pressure system with fast response and good stability; when the set pressure of the electro-proportional relief valve 7 is lower than the LS load feedback pressure, the system is a load-sensitive system with energy-saving and high efficiency. This system does not require electrical program control; it can achieve automatic mode switching solely through the inherent properties of the shuttle valve 5. Furthermore, this system can effectively solve the problems of slow actuator action and low system efficiency in load-sensitive systems under low pressure conditions; it has the advantages of fast response, good stability, and energy saving.

[0089] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0090] This document uses specific examples to illustrate the principles and implementation methods of this application. The examples are merely for the purpose of helping to understand the methods and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, and the existence of an infinite number of specific structures, those skilled in the art can make various improvements, modifications, or variations without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered as protected by this application.

Claims

1. A constant pressure and load-sensitive switching hydraulic control system, characterized in that, Includes a variable pump (2), a shuttle valve (5), an electro-proportional relief valve (7), a directional valve (9), and a controller (12). The variable pump (2) is used to connect to the actuator through the actuator oil circuit, and the actuator oil circuit is equipped with a load control module. The variable pump (2) is equipped with a load-sensitive valve (4). The control end of the load-sensitive valve (4) is connected to the shuttle valve outlet (5.3) of the shuttle valve (5). The P port of the electro-proportional relief valve (7) is located at the front end of the load control module and is connected to the first inlet (5.1) of the shuttle valve (5). The T port of the electro-proportional relief valve (7) is connected to the T port of the directional valve (9). The P port of the directional valve (9) is connected to the rear end of the load control module. The A port of the directional valve (9) is connected to the second inlet (5.2) of the shuttle valve (5). The constant pressure and load-sensitive switching hydraulic control system also includes a pressure sensor assembly, which is used to read the outlet pressure and / or load pressure of the variable pump (2) and transmit it to the controller (12). The controller (12) is connected to the control end of the electro-proportional relief valve (7). The constant pressure and load-sensitive switching hydraulic control system also includes a damper (6) located between the actuation oil circuit and the electro-proportional relief valve (7). The first inlet (5.1) of the shuttle valve (5) is connected to the outlet end of the damper (6). The damper (6) is used to reduce the pressure fluctuation of the outlet pressure oil of the variable pump (2) flowing to the electro-proportional relief valve (7) and the shuttle valve (5).

2. The constant pressure and load-sensitive switching hydraulic control system according to claim 1, characterized in that, The load control module includes a speed control valve (8), which is used to control the flow rate of hydraulic oil in the variable pump (2) to regulate the movement speed of the actuator.

3. The constant pressure and load-sensitive switching hydraulic control system according to claim 1, characterized in that, The pressure sensor assembly includes a first pressure sensor (10) connected to the front end of the load control module and a second pressure sensor (11) connected to the rear end of the load control module. The first pressure sensor (10) is used to read the outlet pressure of the variable pump (2) and transmit it to the controller (12). The second pressure sensor (11) is used to read the load pressure and transmit it to the controller (12).

4. A constant voltage and load-sensitive switching control method, characterized in that, For controlling the constant pressure and load-sensitive switching hydraulic control system as described in any one of claims 1-3, the constant pressure and load-sensitive switching control method is used to control the switching between four modes: load-sensitive mode, constant pressure mode, electronic negative-sensitive mode, and automatic switching mode between constant pressure and negative-sensitive modes. When load-sensitive mode is required: the electro-proportional relief valve (7) and the reversing valve (9) are not energized. The load-sensitive feedback pressure oil flows through the P port of the reversing valve (9) to the A port and then acts on the second inlet (5.2) of the shuttle valve (5). The load-sensitive feedback pressure acts on the load-sensitive valve (4) through the shuttle valve outlet (5.3) of the shuttle valve (5). At this time, it is the load-sensitive mode. When constant pressure mode is required: the electro-proportional relief valve (7) is energized and the pressure is set to the system working pressure. The reversing valve (9) is energized. The load-sensitive feedback pressure oil flows through the P port of the reversing valve (9) to the B port and then is blocked. One end of the outlet pressure oil of the variable pump (2) acts on the P port of the electro-proportional relief valve (7), and the other end acts on the first inlet (5.1) of the shuttle valve (5) and then acts on the outlet (5.3) of the shuttle valve. Finally, it acts on the load-sensitive valve (4). At this time, it is constant pressure mode. When electronic negative sensing mode is required: the reversing valve (9) is energized, the load-sensitive feedback pressure oil flows through the P port of the reversing valve (9) to the B port, the B port is blocked, one end of the outlet pressure oil of the variable pump (2) acts on the P port of the electro-proportional relief valve (7), the other end acts on the first inlet (5.1) of the shuttle valve (5) and then acts on the outlet (5.3) of the shuttle valve, and finally acts on the load-sensitive valve (4). The system pressure is set by the electro-proportional relief valve (7), so that the outlet pressure of the variable pump (2) is greater than the load-sensitive feedback pressure, so as to realize that the outlet pressure of the variable pump (2) changes with the load-sensitive feedback pressure. When constant pressure and negative sensitivity automatic switching mode are required: the reversing valve (9) is not energized, the load-sensitive feedback pressure oil flows through the P port of the reversing valve (9) to the A port, and the A port flows to the second inlet (5.2) of the shuttle valve (5); the outlet pressure oil of the variable pump (2) acts on the P port of the electro-proportional relief valve (7) at one end and on the first inlet (5.1) of the shuttle valve (5) at the other end. The relief pressure of the electro-proportional relief valve (7) is set to P1. When the load-sensitive load pressure is lower than P1, it is a constant pressure system. When the load-sensitive load pressure is greater than P1, it is a load-sensitive system.

5. The constant voltage and load-sensitive switching control method according to claim 4, characterized in that, In constant pressure mode, electronic negative sensitivity mode and constant pressure and negative sensitivity automatic switching mode, the outlet pressure oil of variable pump (2) flows through damper (6) and reduces pressure fluctuation through damper (6), then one end acts on the P port of electro-proportional relief valve (7) and the other end acts on the first inlet (5.1) of shuttle valve (5).

6. The constant pressure and load-sensitive switching hydraulic control method according to claim 4, characterized in that, In electronic negative sensing mode, the control actuator operates, reads the load-sensitive feedback pressure through the pressure sensor assembly and transmits it to the controller (12), and controls the electro-proportional relief valve (7) through the controller (12) to make the outlet pressure of the variable pump (2) greater than the load-sensitive feedback pressure, so as to realize that the outlet pressure of the variable pump (2) changes with the load-sensitive feedback pressure.

7. The constant pressure and load-sensitive switching hydraulic control method according to claim 6, characterized in that, When controlling the actuator in electronic negative sensing mode, the force on the inlet side of the load-sensitive valve (4) is the outlet pressure P of the variable pump (2). P The calculation is shown in the following formula: P P =ΔP+P7 1; In the formula, ΔP is the spring pressure of the load-sensitive valve (4), and P7 is the pressure of the electro-proportional relief valve (7); The pressure of the electro-proportional relief valve (7) is calculated as shown in the following formula: 2; In the formula, A and B are constants, and X is the electrical signal value of the electro-proportional relief valve (7); Variable pump (2) outlet pressure P P The electrical signal value X of the electro-proportional relief valve (7) is directly proportional to the following formula: 3。 8. The constant pressure and load-sensitive switching hydraulic control method according to claim 7, characterized in that, When controlling the actuator in electronic negative sensitive mode, neither the electro-proportional relief valve (7) nor the directional valve (9) is energized. The variable pump (2) starts under load, the pressure P7 of the electro-proportional relief valve (7) is 0, and the outlet pressure P of the variable pump (2) is... P The standby pressure is set; after the standby preset time, the electro-proportional relief valve (7) is energized, and the outlet pressure P of the variable pump (2) is adjusted by controlling the electrical signal value. p The maximum operating pressure P of the system max When the actuator is working, the pressure sensor assembly collects the load-sensitive feedback pressure P in real time. LS The signal is transmitted to the controller (12), which controls the electro-proportional relief valve (7) to make the outlet pressure of the variable pump (2) greater than the load-sensitive feedback pressure, thus forming a pressure difference of Δp. The outlet pressure of the variable pump (2) is P. P With load-sensitive feedback pressure P LS The relationship between them is shown in Formula 4: 4。 9. The constant pressure and load-sensitive switching hydraulic control method according to claim 4, characterized in that, In the constant pressure and negative pressure automatic switching mode, when the load-sensitive feedback pressure is lower than P1, the pressure at the first inlet (5.1) of the shuttle valve (5) is greater than the pressure at the second inlet (5.2). At this time, the outlet pressure oil of the variable pump (2) flows through the first inlet (5.1) of the shuttle valve (5) to the outlet (5.3) of the shuttle valve, and finally acts on the load-sensitive valve (4). This is the constant pressure system mode. When the load-sensitive feedback pressure is greater than P1, the pressure at the first inlet (5.1) of the shuttle valve (5) is less than the pressure at the second inlet (5.2). At this time, the load-sensitive feedback pressure oil flows through the P port of the reversing valve (9) to the A port. The A port flows through the second inlet (5.2) of the shuttle valve (5) to the outlet (5.3) of the shuttle valve, and finally acts on the load-sensitive valve (4). This is the load-sensitive system mode.

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