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

Abstract

The invention discloses a constant pressure and load sensitive switching hydraulic control system and method, and belongs to the technical field of hydraulic control, the constant pressure and load sensitive switching hydraulic control system comprises 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 a shuttle valve, and an electric proportional overflow valve is connected with the variable pump; the electric proportional overflow valve is further connected with a first inlet of the shuttle valve, a P port of the 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; the pressure sensor assembly is used for reading the outlet pressure of the variable pump and transmitting the outlet pressure to the controller. The pressure sensor assembly is further used for reading the load-sensitive feedback pressure and transmitting the load-sensitive feedback pressure to the controller. Constant pressure and negative sensitive switching is automatically carried out along with increase of the load pressure, the load-sensitive system can be prevented from working under the low-pressure condition, and the problems that under the low-pressure condition, an execution element of the load-sensitive system is slow in action, and the system efficiency is low can be effectively solved.

Description

Technical Field

[0001] The present application relates to the field of hydraulic control technology, and in particular, to a constant pressure and load-sensitive switching hydraulic control system and a control method thereof. In addition, the present application also relates to a control method using the constant pressure and load-sensitive switching hydraulic control system. Background Art

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

[0003] In the field of hydraulic control technology, the core of a constant pressure control system is to ensure constant output pressure from the hydraulic pump. When the output pressure falls below the set constant pressure, the variable pump delivers pressurized oil at full capacity, fully powering the system. Once the output oil pressure reaches the set pressure, the variable pump automatically adjusts the pump flow rate, cleverly adjusting the flow rate to maintain a constant pressure to meet system requirements. Constant pressure control systems are ideal for applications requiring extremely stable pressure, such as in high-precision machining equipment, where stable pressure ensures machining accuracy is unaffected by pressure fluctuations.

[0004] Load-sensing control systems focus on the close relationship between hydraulic pump output pressure and load force. The variable displacement pump used in this system is a powerful hydraulic compensator that accurately captures the real-time flow and pressure demands of each actuator in the system and responds quickly and correctly, allowing the plunger pump to flexibly adjust its output. It can adjust pump output according to actual load, avoiding unnecessary energy waste.

[0005] In a constant pressure control system, when the pressure required by the actuator is small, the outlet of the constant pressure pump still needs to maintain a higher pressure (usually the maximum working pressure of the system). Excessive 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] However, in a load sensing system (LS, Load Sensing), 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 sufficient pressure and flow, resulting in slow movement 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 the displacement, but due to the low load, the actual required flow and pressure are small, which causes the pump to operate inefficiently under some working conditions, increasing energy loss.

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

[0008] To address the problems of high energy consumption and high system temperature in existing constant pressure systems, as well as the slow action of actuators and low system efficiency in load-sensitive systems under low load pressure conditions, this application proposes a constant pressure and load-sensitive switching hydraulic control system and control method that is adaptable to multiple working conditions. Summary of the Invention

[0009] In view of at least one of the above technical problems, the present application provides a constant pressure and load sensitive switching hydraulic control system, which can automatically switch between constant pressure and negative sensitivity as the load pressure increases, avoid 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] At the same time, the present 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 the present application, a constant pressure and load sensitive switching hydraulic control system is provided, comprising a variable pump, a shuttle valve, an electric proportional relief valve, a reversing valve and a controller, wherein the variable pump is connected to an actuator via an execution oil circuit, and a load control module is provided on the execution oil circuit;

[0012] The variable pump is provided with a load-sensing valve, the control end of the load-sensing valve is connected to the shuttle valve outlet of the shuttle valve, the P port of the electric proportional relief valve is provided 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 electric proportional relief valve is connected to the T port of the reversing valve, the P port of the reversing valve is connected to the rear end of the load control module, and the A port of the reversing 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 is used to read the outlet pressure and / or load pressure of the variable pump and transmit it to the controller, and the controller is connected to the control end of the electric proportional relief valve.

[0014] In some embodiments of the present application, the constant pressure and load-sensitive switching hydraulic control system also includes a damper arranged between the execution oil circuit and the electric proportional relief valve, and the first inlet of the shuttle valve is connected to the outlet end of the damper. The damper is used to reduce the pressure fluctuation of the variable pump outlet pressure oil flowing to the electric proportional relief valve and the shuttle valve.

[0015] In some embodiments of the present application, the load control module includes a speed regulating valve, which is used to control the flow of hydraulic oil of the variable pump to adjust the movement speed of the actuator.

[0016] In some embodiments of the present 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 the present application, a constant voltage and load sensitive switching control method is provided, which adopts the above-mentioned constant voltage and load sensitive switching control. The constant voltage and load sensitive switching control method is used to control switching of four modes: load sensitive mode, constant voltage mode, electronic negative sensitive mode, and constant voltage and negative sensitive automatic switching mode:

[0018] When load-sensing mode is required: the electric proportional relief valve and the reversing valve are de-energized, the load-sensing feedback pressure oil flows through the P port of the reversing valve to the A port and then acts on the second inlet of the shuttle valve. The load-sensing feedback pressure acts on the load-sensing valve through the shuttle valve outlet. At this time, load-sensing mode is selected.

[0019] When constant pressure mode is required: the electric proportional relief valve is energized and the pressure is set to the system working pressure, the reversing valve is energized, the load-sensing feedback pressure oil flows through the P port of the reversing 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 electric proportional relief valve, and the other end acts on the first inlet of the shuttle valve and then on the shuttle valve outlet, and finally acts on the load-sensing valve. At this time, the constant pressure mode is in effect;

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

[0021] When constant pressure and negative sensitive automatic switching mode is required: the reversing valve shall not be energized, the load sensitive feedback pressure oil flows through the P port of the reversing valve to the A port, and the A port flows to the second inlet of the shuttle valve; one end of the variable pump outlet pressure oil acts on the P port of the electric proportional relief valve, and the other end acts on the first inlet of the shuttle valve. The relief pressure of the electric 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 the present application, in constant pressure mode, electronic negative sensitivity mode and constant pressure and negative sensitivity automatic switching mode, the variable pump outlet pressure oil flows through the damping and reduces the pressure fluctuation through the damping, and then one end acts on the P port of the electric proportional relief valve and the other end acts on the first inlet of the shuttle valve.

[0023] In some embodiments of the present application, in the electronic negative-sensitive mode, the actuator is controlled to act, the load-sensitive feedback pressure is read through the pressure sensor assembly and transmitted to the controller, and the controller controls the electric proportional overflow valve so that the outlet pressure of the variable pump is 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 the present application, when the actuator is controlled in the electronic negative sensing mode, the force on the inlet side of the load sensing valve is the variable pump outlet pressure P P The calculation is shown in Formula 1:

[0025] P P =ΔP+P7 1

[0026] Where ΔP is the spring pressure of the load sensing valve, and P7 is the pressure of the electric proportional relief valve;

[0027] The calculation of the pressure of the electric proportional relief valve is 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 electric proportional relief valve;

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

[0031] P p =ΔP+P7=ΔP+A+B*X 3

[0032] In some embodiments of the present application, when the actuator is controlled in the electronic negative sensitive mode, the electric proportional relief valve and the reversing valve are not energized, the variable pump is started with load, the pressure P7 of the electric proportional relief valve is 0, and the outlet pressure P P The standby pressure; after the preset standby time, the electric proportional relief valve is energized, and the variable pump outlet pressure P is controlled by the electric signal value. p is the maximum working pressure of the system P max When the actuator is working, the pressure sensor component collects the load-sensitive feedback pressure P in real time. LS And transmit it to the controller, which controls the electric proportional relief valve to make the variable pump outlet pressure greater than the load sensitive feedback pressure, and form a pressure difference of Δp. The variable pump outlet pressure P P With load sensing feedback pressure P LS The relationship between is shown in Formula 4:

[0033] P p =ΔP+P7=ΔP+A+B*X=P LS +Δp 4

[0034] In some embodiments of the present application, in the constant pressure and negative sensitive 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 shuttle valve outlet, and finally acts on the load-sensitive valve. At this time, it is a 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 to the A port of the reversing valve, and the A port flows through the second inlet of the shuttle valve to the shuttle valve outlet, and finally acts on the load-sensitive valve. At this time, it is a load-sensitive system mode.

[0035] This application has the following beneficial effects:

[0036] The present application discloses a constant pressure and load-sensitive switching hydraulic control system. When the reversing valve is electrically 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 acts on the load-sensitive valve, forming a constant pressure system. The hydraulic control system of the present application collects the LS load pressure and pump outlet pressure in real time and transmits them to the controller. The controller controls the electric proportional relief valve to perform variable pump outlet pressure follow-up control, that is, the variable pump outlet pressure is always greater than the LS load pressure by a pressure difference. The realization of electric proportional load-sensitive adaptive control can effectively solve the problem of high energy consumption of the constant pressure system. It can meet both the pressure stability characteristics of the constant pressure system and the follow-up energy-saving characteristics of the negative-sensitive system.

[0037] The reversing valve in this application is not powered. At this time, the variable pump outlet pressure acts on the left side of the shuttle valve and ultimately on the load-sensing valve, creating a constant-pressure system. The system pressure is set by the electric proportional relief valve. When the actuator is activated and the load pressure exceeds the set pressure of the electric proportional relief valve, the oil on the right side of the shuttle valve becomes active and ultimately acts on the load-sensing valve, creating a load-sensitive system. That is, 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 problems such as slow actuator action and low system efficiency in load-sensitive systems under low load pressure. The system is simple and reliable to control, energy-efficient, and highly efficient.

[0038] The constant pressure and load-sensitive switching control method of the present application also has the aforementioned beneficial effects. It also includes flexible and convenient switching between the following four operating conditions or modes: load-sensitive mode, constant pressure mode, electronic negative-sensitive mode, and constant pressure and negative-sensitive automatic switching mode, effectively meeting the needs of multiple operating conditions and providing greater adaptability. The electronic load mode, through a controller's preset program and control strategy, controls the electric proportional relief valve so that the variable pump outlet pressure is greater than the LS feedback pressure by a pressure difference of Δp, enabling the variable pump outlet pressure to change in accordance with the LS load feedback pressure. This not only meets the pressure stability characteristics of the constant pressure system, but also meets the follow-up energy-saving characteristics of the negative-sensitive system, and is generally suitable for high-flow rotary or rotational movements. The constant pressure and negative-sensitive automatic switching mode, through the inherent properties of the shuttle valve, enables the system to function as a constant pressure system when the set pressure of the electric proportional relief valve is higher than the LS load feedback pressure, with fast response and good stability. When the set pressure of the electric proportional relief valve is lower than the LS load feedback pressure, the system functions as a load-sensitive system, with energy-saving and high efficiency, and is generally suitable for low-speed, low-load cylinder extension and retraction movements. This application can effectively solve the problems of high energy consumption and high system temperature rise in existing constant pressure systems, and also solve the problems of slow execution of actuators and low system efficiency in load-sensitive systems under low load pressure conditions.

[0039] Of course, any product implementing this application does not necessarily need to achieve all of the advantages described above. In addition to the purposes, features, and advantages described above, this application also has other purposes, features, and advantages. This application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0041] Figure 1 This is an overall schematic diagram of the hydraulic control system of the preferred embodiment of the present application;

[0042] Figure 2 This is a schematic diagram of a two-position three-way electromagnetic reversing valve used in the preferred embodiment of the present application.

[0043] Legend: 1. Power mechanism; 2. Variable pump; 3. Fuel tank; 4. Load-sensing valve; 5. Shuttle valve; 5.1. First inlet; 5.2. Second inlet; 5.3. Shuttle valve outlet; 6. Damping; 7. Electric proportional relief valve; 8. Speed ​​control valve; 9. Reversing valve; 10. First pressure sensor; 11. Second pressure sensor; 12. Controller. DETAILED DESCRIPTION

[0044] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in a variety of different ways defined and covered below.

[0045] Figure 1 This is an overall schematic diagram of the hydraulic control system of the preferred embodiment of the present application; Figure 2 This is a schematic diagram of a two-position three-way electromagnetic reversing valve used in the preferred embodiment of the present application.

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

[0047] The variable pump 2 is provided with a load-sensing valve 4. The control end of the load-sensing valve 4 is connected to the shuttle valve outlet 5.3 of the shuttle valve 5. The P port of the electric 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 electric proportional relief valve 7 is connected to the T port of the reversing valve 9. The P port of the reversing valve 9 is connected to the rear end of the load control module. The A port of the reversing 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. The controller 12 is connected to the control end of the electric proportional relief valve 7.

[0049] Here, the "variable pump 2" refers to a component that provides pressurized oil to the hydraulic system. In some embodiments, the variable pump 2 is a variable piston pump. The variable pump 2 is connected to the power mechanism 1 and is powered by the power mechanism 1. An oil tank 3 for storing hydraulic oil may also be provided.

[0050] Here, the "shuttle valve 5" means a valve component that selects the highest pressure from multiple oil pressure sources connected to it and transmits it to subsequent circuits for load sensing and other control purposes.

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

[0052] Here, the “reversing valve 9” is referred to in some embodiments. Figure 1 , adopts a two-position four-way electromagnetic reversing valve group, and controls the valve core position of the two-position four-way electromagnetic reversing valve group through electromagnetic force 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 electromagnetic reversing valve, which can also realize the on-off of the LS feedback pressure.

[0054] The controller 12 is a PLC controller that receives signals fed back by sensors such as pressure sensor components, performs analysis and processing, and issues control instructions to adjust the operation of various hydraulic components according to preset programs and control strategies.

[0055] The present application discloses a constant pressure and load sensitive switching hydraulic control system. When the reversing valve 9 is electrically 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 finally acts on the load sensitive valve 4, which is a constant pressure system. The hydraulic control system of the present application collects the LS load pressure and pump outlet pressure in real time and transmits them to the controller 12. The controller 12 controls the electric proportional relief valve 7 to perform follow-up control of the outlet pressure of the variable pump 2, that is, the outlet pressure of the variable pump 2 is always greater than the LS load pressure by a pressure difference. The realization of electric proportional load sensitive adaptive control can effectively solve the problem of high energy consumption of the constant pressure system. It can meet both the pressure stability characteristics of the constant pressure system and the follow-up energy-saving characteristics of the negative sensitive system.

[0056] In this application, when the reversing 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-sensing valve 4, creating a constant-pressure system. The system pressure is set by the electro-proportional relief valve 7. When the actuator is activated 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 becomes active, ultimately acting on the load-sensing valve 4, creating a load-sensitive system. That is, when the load pressure is low, the system operates as a constant-pressure system; when the load pressure is high, the system automatically switches to a load-sensitive system. This effectively solves problems such as slow actuator operation and low system efficiency in load-sensitive systems under low load pressure. The system provides simple and reliable control, energy conservation, and high efficiency.

[0057] Preferably, please refer to Figure 1 As shown, the constant pressure and load sensitive switching hydraulic control system further includes a damper 6 arranged between the execution oil circuit and the electric 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 electric proportional relief valve 7 and the shuttle valve 5.

[0058] It's understandable that damper 6 reduces pressure fluctuations in the system's oil circuit, effectively improving system stability. During operation, the pressure oil at the outlet of variable pump 2 flows through damper 6, where pressure fluctuations are reduced. One end of the pressure oil then acts on port P of electric proportional relief valve 7 and the other on first inlet 5.1 of shuttle valve 5, achieving stable transmission of the pressure oil.

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

[0060] It can be understood that by setting up the speed control valve 8 and changing the valve opening thereof, the flow of hydraulic oil in the oil circuit is controlled, thereby adjusting the movement speed of the actuator and ensuring the movement stability 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 can be understood that the outlet pressure of the pump 2 is read in real time by the pressure sensor 10 and the parameters are transmitted to the controller 12 through the control line, and the LS feedback pressure is read in real time by the pressure sensor 11 and the parameters are transmitted to the controller 12 through the control line. Finally, the controller 12 receives the feedback signals from each sensor, analyzes and processes them, and issues control instructions to adjust the operation of each hydraulic component according to the preset program and control strategy of the controller 12, thereby realizing the automatic regulation and operation of the system.

[0063] According to another aspect of the present application, a constant voltage and load sensitive switching control method is provided, which adopts the above-mentioned constant voltage and load sensitive switching control. The constant voltage and load sensitive switching control method is used to control switching of four modes: load sensitive mode, constant voltage mode, electronic negative sensitive mode, and constant voltage and negative sensitive automatic switching mode:

[0064] When load sensing mode is required: the electric proportional relief valve 7 and the reversing valve 9 are de-energized, the load sensing 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 sensing feedback pressure acts on the load sensing valve 4 through the shuttle valve outlet 5.3 of the shuttle valve 5. At this time, load sensing mode is selected;

[0065] When constant pressure mode is required: the electric proportional relief valve 7 is energized and the pressure is set to the system working pressure. The reversing valve 9 is energized, and the load-sensing 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 electric proportional relief valve 7, and the other end acts on the first inlet 5.1 of the shuttle valve 5, and then on the shuttle valve outlet 5.3, and finally acts on the load-sensing valve 4. At this time, the constant pressure mode is in effect;

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

[0067] When the constant pressure and negative-sensitive automatic switching mode is required: the reversing valve 9 is de-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; one end of the outlet pressure oil of the variable pump 2 acts on the P port of the electric 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 electric 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 the present application also has the aforementioned beneficial effects. It also includes flexible and convenient switching between the following four operating conditions or modes: load-sensitive mode, constant pressure mode, electronic negative-sensitive mode, and constant pressure and negative-sensitive automatic switching mode, effectively meeting the needs of multiple operating conditions and providing greater adaptability. In the electronic load mode, the controller 12 uses a preset program and control strategy to control the electric proportional relief valve 7 so that the outlet pressure of the variable pump 2 is greater than the LS feedback pressure by a pressure difference of Δp. This allows the outlet pressure of the variable pump 2 to change in accordance with the LS load feedback pressure. This not only meets the pressure stability characteristics of the constant pressure system, but also meets the follow-up energy-saving characteristics of the negative-sensitive system. It is generally suitable for high-flow rotary or rotational movements. In the constant pressure and negative-sensitive automatic switching mode, the inherent properties of the shuttle valve 5 ensure that when the set pressure of the electric proportional relief valve 7 is higher than the LS load feedback pressure, the system becomes a constant pressure system with fast response and good stability. When the set pressure of the electric proportional relief valve 7 is lower than the LS load feedback pressure, the system becomes a load-sensitive system with energy-saving and high efficiency. It is generally suitable for low-speed and low-load cylinder extension and retraction movements. This application can effectively solve the problems of high energy consumption and high system temperature rise in existing constant pressure systems, and also solve the problems of slow execution of actuators and low system efficiency in load-sensitive systems under low load pressure conditions.

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

[0070] It can be understood that in order to achieve stable transmission of pressure oil to the electric proportional relief valve 7 and the shuttle valve 5, the hydraulic oil flowing from the variable pump 2 to the electric proportional relief valve 7 and the shuttle valve 5 is throttled and regulated through the damper 6 to achieve the effect of pressure filtering, so as to improve the stability of system operation.

[0071] Preferably, in the electronic negative-sensitive mode, the actuator is controlled to act, the load-sensitive feedback pressure is read through the pressure sensor assembly and transmitted to the controller 12, and the controller 12 controls the electric proportional relief valve 7 so that the outlet pressure of the variable pump 2 is 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 the actuator is controlled in the electronic negative sensing mode, the force on the inlet side of the load sensing valve 4 is the pump outlet pressure P P The calculation is shown in Formula 1:

[0073] P P =ΔP+P7 1

[0074] Where ΔP is the spring pressure of the load sensing valve 4, and P7 is the pressure of the electric proportional relief valve 7;

[0075] The pressure calculation of the electric proportional relief valve 7 is shown in Formula 2:

[0076] P7=A+B*X 2

[0077] Where A and B are constants, and X is the electrical signal value of the electric proportional relief valve 7;

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

[0079] P p =ΔP+P7=ΔP+A+B*X 3

[0080] Furthermore, when the actuator is controlled in the electronic negative sensitive mode, the electric proportional relief valve 7 and the reversing valve 9 are both de-energized, the variable pump 2 starts with load, the pressure P7 of the electric proportional relief valve 7 is 0, and the outlet pressure P P After the preset standby time, in some embodiments, the preset standby time is 10s, the electric proportional relief valve 7 is energized, and the variable pump 2 outlet pressure P is controlled by controlling the electric signal value. p is the maximum working pressure of the system P max When the actuator is working, the pressure sensor component collects the load-sensitive feedback pressure P in real time. LS And transmit it to the controller 12, which controls the electric proportional relief valve 7 to make the outlet pressure of the variable pump 2 greater than the load sensitive feedback pressure, and form a pressure difference of Δp. The outlet pressure of the variable pump 2 P P With load sensing feedback pressure P LS The relationship between is shown in Formula 4:

[0081] P p =ΔP+P7=ΔP+A+B*X=P LS +Δp 4

[0082] Usually, Δp is preset to 2.5MPa, and ΔP is preset to 2MPa. According to Formula 4, we can get:

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

[0084] According to formula 5, the controller 12 only needs to collect the load-sensitive feedback pressure P in real time. LS value, we can find the corresponding electrical signal value X.

[0085] It can be understood that according to formula 5, the electric signal value X of the electric proportional relief valve 7 and the LS feedback pressure PLS The controller 12 only needs to calculate the LS feedback pressure P according to the real-time collected LS feedback pressure P. LS The electronic negative-sensing control system is a constant-pressure system, which has the advantages of a constant-pressure system. The outlet pressure of variable pump 2 changes with the LS load feedback pressure, effectively reducing useless power consumption and improving system efficiency. This not only meets the pressure stability characteristics of the constant-pressure system but also meets the follow-up energy-saving characteristics of the negative-sensing system.

[0086] Preferably, in the constant pressure and negative pressure automatic switching modes, when the load-sensing 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 pressure oil at the outlet of the variable pump 2 flows through the first inlet 5.1 of the shuttle valve 5 to the shuttle valve outlet 5.3, ultimately acting on the load-sensing valve 4. This is the constant pressure system mode. When the load-sensing feedback pressure is higher than P1, the pressure at the first inlet 5.1 of the shuttle valve 5 is lower than the pressure at the second inlet 5.2. At this time, the load-sensing feedback pressure oil flows through port P to port A of the reversing valve 9. Port A flows through the second inlet 5.2 of the shuttle valve 5 to the shuttle valve outlet 5.3, ultimately acting on the load-sensing valve 4. This is the load-sensing system mode. It should be noted that the relief pressure of the electric proportional relief valve 7 is P1, which in some embodiments is set to 5 MPa.

[0087] It is understood that when the LS load pressure is low, the system operates as 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 through the shuttle valve oil circuit, making the system energy-efficient and efficient. The hydraulic control system of the present application automatically switches between constant pressure and negative pressure as the load pressure increases, without requiring controller 12 to set programs and control strategies, and only achieves mode switching through the inherent characteristics of shuttle valve 5. This prevents the load-sensitive system from operating under low-pressure conditions, effectively resolving problems such as slow actuator action and low system efficiency in low-pressure conditions. It has the advantages of fast response, good stability, and energy saving.

[0088] In summary, the present application utilizes a pre-set program and control strategy within the controller 12 to control the electric proportional relief valve 7 so that the outlet pressure of the variable pump 2 exceeds the LS feedback pressure by a pressure differential of Δp, thereby achieving an electronic negative-sensing mode in which the outlet pressure of the variable pump 2 follows the LS load feedback pressure. This effectively reduces wasted power consumption, addresses the high energy consumption of constant-pressure systems, and improves system efficiency. This system achieves both the pressure stability characteristics of a constant-pressure system and the energy-saving follow-up characteristics of a negative-sensing system. Through the inherent properties of the shuttle valve 5, when the set pressure of the electric proportional relief valve 7 is higher than the LS load feedback pressure, the system operates as a constant-pressure system, characterized by fast response and excellent stability. When the set pressure of the electric proportional relief valve 7 is lower than the LS load feedback pressure, the system operates as a load-sensing system, characterized by energy efficiency and high efficiency. This system requires no electrical program control and automatically switches modes solely through the inherent properties of the shuttle valve 5. This system effectively addresses the issues of slow actuator operation and low system efficiency often seen in load-sensing systems under low pressure conditions, offering the advantages of fast response, excellent stability, and energy efficiency.

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

[0090] This article uses specific examples to illustrate the principles and implementation methods of this application. The above examples are only used to help understand the method and core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of this application, they can make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as protected by this application.

Claims

1. A constant pressure and load sensitive switching hydraulic control system, characterized in that: The invention comprises a variable pump (2), a shuttle valve (5), an electric proportional relief valve (7), a reversing valve (9) and a controller (12); the variable pump (2) is used to be connected to an actuator through an execution oil circuit, and a load control module is provided on the execution oil circuit; A load-sensing valve (4) is provided on the variable pump (2); a control end of the load-sensing valve (4) is connected to a shuttle valve outlet (5.3) of a shuttle valve (5); a P port of an electric proportional relief valve (7) is provided at a front end of a load control module and is connected to a first inlet (5.1) of the shuttle valve (5); a T port of the electric proportional relief valve (7) is connected to a T port of a reversing valve (9); a P port of the reversing valve (9) is connected to a rear end of the load control module; and an A port of the reversing valve (9) is connected to a second inlet (5.2) of the shuttle valve (5); The constant pressure and load sensitive switching hydraulic control system further comprises a pressure sensor assembly, which is used to read the outlet pressure and / or load pressure of the variable pump (2) and transmit the pressure to a controller (12). The controller (12) is connected to the control end of the electric proportional relief valve (7).

2. A constant pressure and load sensitive switching hydraulic control system according to claim 1, characterized in that: The constant pressure and load sensitive switching hydraulic control system further comprises a damper (6) arranged between an execution oil circuit and an electric proportional relief valve (7); a first inlet (5.1) of the shuttle valve (5) is connected to an outlet end of the damper (6); and the damper (6) is used to reduce pressure fluctuations of the outlet pressure oil of the variable pump (2) flowing to the electric proportional relief valve (7) and the shuttle valve (5).

3. A constant pressure and load sensitive switching hydraulic control system according to claim 1, characterized in that: The load control module comprises a speed regulating valve (8), which is used to control the flow of hydraulic oil of the variable pump (2) to adjust the movement speed of the actuator.

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

5. A constant voltage and load sensitive switching control method, characterized in that: Used to control the constant pressure and load sensitive switching hydraulic control system according to any one of claims 1 to 4, the constant pressure and load sensitive switching control method is used to control the switching of four modes: load sensitive mode, constant pressure mode, electronic negative sensitive mode, constant pressure and negative sensitive automatic switching mode: When the load-sensing mode is required: the electric proportional relief valve (7) and the reversing valve (9) are not energized, the load-sensing 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), and the load-sensing feedback pressure acts on the load-sensing valve (4) through the shuttle valve outlet (5.3) of the shuttle valve (5). At this time, the load-sensing mode is selected. When the constant pressure mode is required: the electric proportional relief valve (7) is energized and the pressure is set to the system working pressure, the reversing valve (9) is energized, the load-sensing 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 electric 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 shuttle valve outlet (5.3), and finally acts on the load-sensing valve (4). At this time, the constant pressure mode is in effect; When the electronic negative sensitive 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 electric 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 shuttle valve outlet (5.3), and finally acts on the load sensitive valve (4). The system pressure is set by the electric proportional relief valve (7), thereby making 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. When the constant pressure and negative sensitive automatic switching mode is 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); one end of the outlet pressure oil of the variable pump (2) acts on the P port of the electric 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 electric 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.

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

7. A constant pressure and load sensitive switching hydraulic control system and control method according to claim 5, characterized in that: In the electronic negative-sensing mode, the actuator is controlled to act, and the load-sensitive feedback pressure is read by the pressure sensor assembly and transmitted to the controller (12). The controller (12) controls the electric proportional relief valve (7) so that the outlet pressure of the variable pump (2) is greater than the load-sensitive feedback pressure, so that the outlet pressure of the variable pump (2) changes with the load-sensitive feedback pressure.

8. A constant pressure and load sensitive switching hydraulic control system and control method according to claim 7, characterized in that: When controlling the actuator in the electronic negative-sensing mode, the force on the inlet side of the load-sensing valve (4) is the outlet pressure P of the variable pump (2). P The calculation is shown in Formula 1: P P =ΔP+P7 1 Where ΔP is the spring pressure of the load sensing valve (4), and P7 is the pressure of the electric proportional relief valve (7). The pressure of the electric proportional relief valve (7) is calculated as shown in Formula 2: P7=A+B*X 2 Where A and B are constants, and X is the electrical signal value of the electric proportional relief valve (7); Variable pump (2) outlet pressure P P It is directly proportional to the electrical signal value X of the electric proportional relief valve (7), as shown in Formula 3: P p =ΔP+P7=ΔP+A+B*X 3。 9. The constant pressure and load sensitive switching hydraulic control method according to claim 8, characterized in that: When the actuator is controlled in the electronic negative sensitive mode, the electric proportional relief valve (7) and the reversing valve (9) are not energized, the variable pump (2) starts with load, the pressure P7 of the electric proportional relief valve (7) is 0, and the outlet pressure P P After the preset standby time, the electric proportional relief valve (7) is energized, and the outlet pressure of the variable pump (2) is P p is the maximum working pressure of the system P max When the actuator is working, the pressure sensor component collects the load-sensitive feedback pressure P in real time. LS The pressure is transmitted to the controller (12), which controls the electric proportional relief valve (7) to make the outlet pressure of the variable pump (2) greater than the load sensitive feedback pressure, and form a pressure difference of Δp. The outlet pressure of the variable pump (2) is P P With load sensing feedback pressure P LS The relationship between is shown in Formula 4: P p =ΔP+P7=ΔP+A+B*X=P LS +Δp 4。 10. The constant pressure and load sensitive switching hydraulic control method according to claim 5, characterized in that: In the constant pressure and negative sensitive automatic switching mode, when the load sensitive feedback pressure is lower than P1, the pressure of the first inlet (5.1) of the shuttle valve (5) is greater than the pressure of 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 shuttle valve outlet (5.3), and finally acts on the load sensitive valve (4). At this time, it is a constant pressure system mode; when the load sensitive feedback pressure is greater than P1, the pressure of the first inlet (5.1) of the shuttle valve (5) is less than the pressure of 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 the A port flows through the second inlet (5.2) of the shuttle valve (5) to the shuttle valve outlet (5.3), and finally acts on the load sensitive valve (4). At this time, it is a load sensitive system mode.

Images