Electro-hydraulic multi-actuator flow control system and method

Abstract

An electro-hydraulic multi-actuator flow control system, comprising a power source, a main hydraulic pump, a main safety valve, a main oil path P L , a return oil path T L , a main control valve, a hydraulic actuator, a load sensing proportional valve, a spool displacement sensor, a first pressure sensor, a second pressure sensor, a third pressure sensor and a global controller; the load sensing proportional valve is connected to the main oil path P L ; the spool displacement sensor is installed on the spool of the load sensing proportional valve or integrated on the proportional solenoid; the first pressure sensor is connected to the main oil path P L ; the second pressure sensor and the third pressure sensor are respectively connected to two chambers of the hydraulic actuator; the output signals of the first pressure sensor, the second pressure sensor and the third pressure sensor and the output signal of the spool displacement sensor are connected to the input end of the global controller; the signal output end of the global controller is connected to the proportional solenoid of the load sensing proportional valve and the swing angle control end of the main hydraulic pump.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic technology and relates to a multi-actuator electro-hydraulic control system for engineering machinery, specifically an electro-hydraulic system and method employing closed-loop flow matching technology. Technical Background

[0002] With the rapid development of construction machinery, environmental protection and energy crises have become increasingly prominent. Simultaneously, people's demands for operational comfort are rising. Construction machinery with high reliability, high energy efficiency, and good handling performance has become a hot topic in market demand and research. Currently, construction machinery generally uses an internal combustion engine to drive a hydraulic pump as the power source. Power is distributed and transmitted through multi-way valves and hydraulic pipelines to control the compound actions of multiple actuators in an electro-hydraulic multi-actuator system. This system mainly employs several typical hydraulic control technologies, including negative flow, positive flow, and load-sensitive control.

[0003] Traditional negative flow technology requires detecting the pressure before the throttle orifice to control the pump's displacement, resulting in system response lag and large pressure fluctuations. Traditional positive flow technology uses a shuttle valve assembly to select the highest pilot pressure from each group of actions to control the pump's displacement. With the highest pilot pressure constant, the pump displacement remains constant. However, when a low-load actuator intervenes, the rated pump flow needs to be redistributed, leading to a mismatch between the main pump's output flow and the actuator's required flow, causing fluctuations in actuator pressure and flow. Traditional load-sensitive technology uses variable pump pressure closed-loop control, adaptively controlling the system's pressure and flow. It offers advantages such as good composite operation performance and fine-tuning capabilities and has been widely used in construction machinery. However, due to the long pipeline transmission of the system pressure feedback system, problems such as system oscillation and response lag occur, affecting stability and control performance.

[0004] Existing solutions employ electro-hydraulic flow matching with synchronous pump-valve control, which largely eliminates the pump-valve lag phenomenon in traditional load-sensitive system control. It eliminates the need for pressure feedback closed-loop control, significantly improving dynamic performance and energy efficiency while balancing energy saving and controllability. However, in practice, uncertainties exist in parameters such as system speed, temperature, pump leakage, and valve gain, making precise dynamic matching of hydraulic pump flow difficult. This can easily lead to over-flow matching (resulting in pressure shocks and energy losses) or under-flow matching (reduced speed control accuracy and decreased operability). Therefore, how to precisely control the hydraulic pump to supply oil on demand is a key challenge and research focus of electro-hydraulic flow matching technology, and this is the problem that this invention aims to solve. Summary of the Invention

[0005] To address the aforementioned problems, this invention, based on practical considerations, aims to provide an electro-hydraulic control system and method capable of achieving precise matching of the main pump flow rate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an electro-hydraulic multi-actuator flow control system, comprising a power source, a main hydraulic pump, a main safety valve, and a main oil circuit P. L Return oil circuit T L The main control valve, hydraulic actuator, and power source coaxially drive the main hydraulic pump. The oil outlet of the main hydraulic pump is connected to the main oil circuit P. L The main safety valve inlet is connected to the oil tank, and the main safety valve outlet is connected to the oil tank. The main control valve inlet and outlet are respectively connected to the main oil circuit P. L Return oil circuit T L The main control valve's working oil circuit is connected to both chambers of the hydraulic actuator, and a load detection proportional valve, valve core displacement sensor, pressure sensor I, pressure sensor II, pressure sensor III, and global controller are further added. The load detection proportional valve inlet is connected to the main oil circuit P. L ; The valve core displacement sensor is mounted on the valve core of the load detection proportional valve through a shaft to directly detect the position and speed of the valve core; or it is integrated on the proportional electromagnet to detect the displacement and speed of the valve core by detecting the position of the proportional electromagnet core. The first pressure sensor and the main oil circuit P L The system is connected to detect the outlet pressure of the main hydraulic pump; the second and third pressure sensors are respectively connected to the two chambers of the hydraulic actuator to detect the pressure in the two chambers of the hydraulic actuator. The output signals of the first pressure sensor, the second pressure sensor, and the third pressure sensor, as well as the output signal of the load detection proportional valve core displacement sensor, are connected to the input terminal of the global controller. The global controller signal output terminal is connected to the proportional electromagnet of the load detection proportional valve and the swing angle control terminal of the main hydraulic pump; The global controller signal output terminal is connected to the speed control terminal of the power source.

[0007] A shuttle valve assembly is further added to screen and detect the maximum load pressure of multiple hydraulic actuators. The outlet of the shuttle valve assembly is connected to the spring cavity of the load detection proportional valve core via a hydraulic line. The other cavity of the load detection proportional valve core is connected to the main oil circuit P via a hydraulic line. L The connection is used to detect the outlet pressure of the main hydraulic pump.

[0008] A hydraulic accumulator is further added, and the load detection proportional valve is either a two-position two-way valve or a three-position three-way valve; when the load detection proportional valve is a three-position three-way valve, the oil outlet E of the load detection proportional valve is connected to the oil tank, and the other oil outlet F is connected to the hydraulic accumulator; when the load detection proportional valve is a two-position two-way valve, the oil outlet of the load detection proportional valve is connected to the oil tank.

[0009] A bypass oil replenishment unit is further added; when the load detection proportional valve is a two-position two-way valve or no load detection proportional valve is installed, one end of the oil port of the bypass oil replenishment unit is connected to the hydraulic accumulator, and the other end of the oil port of the bypass oil replenishment unit is connected to the main oil circuit P. L When the load detection proportional valve is a three-position three-way valve, the bypass oil replenishment unit is connected in series with the load detection proportional valve and is added between the oil outlet F of the load detection proportional valve and the accumulator. The oil inlet of the bypass oil replenishment unit is connected to the oil outlet of the accumulator, and the oil outlet of the bypass oil replenishment unit is connected to the oil port F of the load detection proportional valve.

[0010] The bypass replenishment unit includes a bypass replenishment pump and a replenishment power source, with the replenishment power source coaxially driving the bypass replenishment pump. The bypass replenishment pump is either a fixed displacement pump or a proportional variable displacement pump. The replenishment power source is either an electric motor or an internal combustion engine. The control terminal of the bypass replenishment pump or the replenishment power source is connected to the output terminal of the global controller, drawing oil from the accumulator to the main oil circuit P. L fuel supply, or from the main fuel line P L Discharge oil into the hydraulic accumulator.

[0011] The global controller controls the output flow of the main hydraulic pump based on the difference between the output pressure of the main hydraulic pump and the maximum load pressure of each actuator; the global controller receives the deviation between the valve core displacement signal of the load detection proportional valve and the valve core displacement set value, generates a control signal, and controls the flow of the main hydraulic pump; the global controller controls the opening degree of the load detection proportional valve or detects the differential pressure based on the input signal.

[0012] The main control valve is a closed-center multi-way directional valve with a pressure compensator; or an open-center multi-way directional valve with a neutral position oil circuit; or an independent control valve group for inlet and outlet oil ports.

[0013] The power source is either a diesel engine or an electric motor.

[0014] A flow regeneration control valve is further added; the oil inlet of the flow regeneration control valve is connected to the drive chamber of the hydraulic actuator, and the oil outlet of the flow regeneration control valve is connected to the oil inlet of the main hydraulic pump.

[0015] A flow matching control method, characterized by comprising the following steps: Step 1: Input the required flow signals Q1, Q2, Q3, Q4...Q of each main control valve. d The system then sums the required flow rates of each main control valve at the global controller level to calculate the total required flow rate Q of the system. ∑ =Q1 + Q2 + Q3 + Q4 + ... + Q d d is a natural number; Step 2: Compare the total system traffic demand Q ∑ The maximum flow rate Q that the current main hydraulic pump can output. max If the total system demand flow Q ∑ Less than the maximum flow rate Q that the main hydraulic pump can output. max The required flow signals Q1, Q2, Q3, Q4...Q of each main control valve are... d Directly input the corresponding main control valve; If the total system flow demand Q∑ is greater than or equal to the maximum flow rate Q that the main hydraulic pump can output... max The required flow signals Q1, Q2, Q3, Q4...Q of each main control valve are... d Multiply by the gain factor Then, input the corresponding main control valve; Step 3: Based on the flow signal input in Step 2, according to the formula Q = V p ·n calculates the displacement of the main hydraulic pump and the total required flow rate of the output system, where V p n is the displacement of the main hydraulic pump, and n is the speed of the main hydraulic pump. Simultaneously, the opening of each main control valve is controlled, ensuring that the valve with the highest load independently controls the electro-hydraulic valve to its maximum opening. Through flow control methods, the output flow of each valve is precisely controlled to meet the required flow signals Q1, Q2, Q3, Q4...Q input in step one. d ; Step 4: Compare the output pressure of the main hydraulic pump with the maximum working pressure of each actuator in the system in real time, and control the valve opening of the load detection proportional valve by the pressure difference between the two; if the valve core displacement of the load detection proportional valve is less than the theoretical set value, then the output flow of the hydraulic pump is less than the sum of the required flow Q of each main control valve. ∑ If the system is in a state of under-matched flow, increase the displacement of the main hydraulic pump or the speed of the power source, as well as the displacement and speed of the bypass replenishing pump. If the displacement of the load detection proportional valve spool is greater than the theoretical set value, and the output flow of the hydraulic pump is greater than the sum of the required flow of each main control valve, the system is in a state of over-matched flow. Decrease the displacement of the main hydraulic pump or the speed of the power source. Repeat this adjustment until the displacement of the load detection proportional valve spool is equal to the theoretical set value. At this time, the output flow of the hydraulic pump is equal to the sum of the required flow of each control valve, and the output flow of the main hydraulic pump is precisely matched with the required flow of each main control valve.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention adds a load detection proportional valve to the system. The pressure difference between the main hydraulic pump and the highest load is sensed in real time through the hydraulic cylinder pipeline or pressure sensor. The load detection proportional valve is then connected to the oil tank or accumulator to compensate for the system flow status in a timely manner. This solves the problems of pressure shock and energy loss caused by overcurrent matching, as well as poor operability and low control accuracy caused by undercurrent matching, thereby improving system stability and control accuracy.

[0017] 2. This invention adds a load detection proportional valve to the system, integrating a proportional electromagnet and a valve core displacement sensor. The pressure difference between the main hydraulic pump and the highest load is sensed in real time via the hydraulic cylinder pipeline or pressure sensor. The opening of the load detection proportional valve is controlled, and this opening amount is used as the detection quantity to adjust the output flow of the main hydraulic pump. Compared to load sensitivity, the pressure control, which is prone to vibration, is converted into position control of the main hydraulic pump's swing angle or speed control of the power source, thus transforming it into closed-loop control of the pump's output flow. The system achieves high flow matching accuracy and minimal oscillation.

[0018] 3. This invention adds a proportional electromagnet to the load detection proportional valve. By controlling the proportional electromagnet of the load detection proportional valve, the difference between the pump outlet pressure and the maximum load is dynamically adjusted to realize the variable pressure difference control function, meet the high dynamic and low energy consumption requirements of the system, and improve the system load adaptability.

[0019] 4. This invention introduces a low-flow bypass oil replenishment unit. For underflow matching conditions, the displacement or speed of the bypass oil replenishment unit is controlled to replenish the system pressure and flow in a timely manner, thus compensating for the slow response speed of the main hydraulic pump. Attached Figure Description

[0020] Figure 1 This is a system schematic diagram of Embodiment 1 of the present invention; Figure 2 This is a flowchart of the control method of the present invention; Figure 3 This is a system schematic diagram of Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the main control valve of the present invention, which adopts an open-center multi-way valve structure. Figure 5 This is a schematic diagram of the main control valve of the present invention, which is a closed-center multi-way valve with a pressure compensator. Figure 6 This is a system schematic diagram of Embodiment 3 of the present invention; Figure 7 This is the first structure of the present invention, in which the main control valve is an independent control valve group for the inlet and outlet oil ports; Figure 8 This is the second structure of the present invention, in which the main control valve is an independent control valve group for the inlet and outlet oil ports; Figure 9 This is a diagram of the working apparatus of Embodiment 4 of the present invention; Figure 10 This is a system schematic diagram of Embodiment 4 of the present invention; In the diagram: 1-Power source, 2-Main hydraulic pump, 3-Main safety valve, 4-Main control valve, 5-Hydraulic actuator, 6-Load detection proportional valve, 7-Valve core displacement sensor, 8-Bypass replenishment pump, 9-Replenishment power source, 10-Hydraulic accumulator, 11-Pressure sensor I, 12-Pressure sensor II, 13-Pressure sensor III, 14-Global controller, 15-Bypass replenishment unit, 16-Shuttle valve, 17-Flow regeneration control valve, 18-Traveling body, 19-Swing body, 20-Boom, 21-Stick, 22-Bucket, P L -Main oil line, T L - Return oil circuit, 23- Open center multi-way valve, 24- Pressure compensator, 25- First three-position three-way proportional valve, 26- Second three-position three-way proportional valve, 27- First two-way proportional valve, 28- Second two-way proportional valve, 29- Third two-way proportional valve, 30- Fourth two-way proportional valve, 31- Closed center multi-way valve, 32- Pressure compensator, 33- Main directional valve, L- Neutral position oil circuit. Detailed Implementation

[0021] Example 1: like Figure 1 As shown, an electro-hydraulic multi-actuator flow control system includes a power source 1, a main hydraulic pump 2, a main safety valve 3, and a main oil circuit P. L oil return circuit T L The main control valve 4, hydraulic actuator 5, and power source 1 coaxially drive the main hydraulic pump 2. The oil outlet of the main hydraulic pump 2 is connected to the main oil circuit P. L The main safety valve 3 is connected to the oil inlet and the main safety valve 3 is connected to the oil tank. The main control valve 4 is connected to the main oil circuit P through its inlet and outlet ports. L Return oil circuit T L The main control valve 4's working oil circuit is connected to both chambers of the hydraulic actuator 5; The system is also equipped with a load detection proportional valve 6, a hydraulic accumulator 10, a first pressure sensor 11, a second pressure sensor 12, a third pressure sensor 13, a global controller 14, a bypass oil replenishment unit 15, and a shuttle valve group 16. Pressure sensor 11 and main oil circuit P L The connection is used to detect the outlet pressure of the main hydraulic pump 1; the second pressure sensor 12 and the third pressure sensor 13 are respectively connected to the two chambers of the hydraulic actuator 5; The load detection proportional valve 6 is a two-position two-way valve, with an added valve core displacement sensor 7. The oil inlet of the load detection proportional valve 6 is connected to the main oil circuit P. LThe load detection proportional valve 6 is connected to the oil tank via its outlet. The load detection proportional valve 6 uses the shuttle valve assembly 16 to screen and detect the maximum load pressure of multiple hydraulic actuators. The outlet of the shuttle valve assembly 16 is connected to the spring chamber of the load detection proportional valve 6's valve core via a hydraulic line. The other chamber of the load detection proportional valve 6's valve core is connected to the main oil circuit P via a hydraulic line. L Connected, used to detect the outlet pressure of main hydraulic pump 2; The bypass replenishment unit 15 includes a bypass replenishment pump 8 and a replenishment power source 9. The bypass replenishment pump 8 is a variable pump, and the replenishment power source 9 coaxially drives the bypass replenishment pump 8 to draw oil from the hydraulic accumulator 10 to the main oil circuit P. L Oil supply; the control terminal of the bypass replenishment pump 8 is connected to the input terminal of the global controller 14; The bypass oil replenishment unit 15 is connected in parallel with the load detection proportional valve 6. The inlet of the load detection proportional valve 6 is connected to the hydraulic accumulator 10, and the outlet of the load detection proportional valve 6 is connected to the main oil circuit P. L Connected; The signal output terminal of the global controller 14 is connected to the proportional electromagnet of the load detection proportional valve and the swing angle control terminal of the main hydraulic pump; The signal output terminal of the global controller 14 is connected to the swing angle control terminal of the bypass oil replenishment pump.

[0022] When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is greater than the set value, the system is in a state of over-matched flow. Under the action of the control oil at both ends of the load detection proportional valve 6, the valve port of the load detection proportional valve 6 opens, and the excess flow in the system flows back to the oil tank through the load detection proportional valve 6. When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is less than the set value, the system is in a state of under-matched flow. The global controller 14 controls the bypass replenishment unit 6 to supply oil to the main oil circuit P. L The oil replenishment compensates for the slow response of the main hydraulic pump 2 and the insufficient oil replenishment pressure of the hydraulic accumulator 11.

[0023] Figure 2 The diagram illustrates the overall flow control method for the system. When the system is operating, power source 1 starts, driving the main hydraulic pump 2 to run. Based on the execution commands of each hydraulic actuator, the required flow signals Q1, Q2, Q3, Q4... for each main control valve 4 are generated. The required flow signals for each main control valve 4 are summed to calculate the total required flow Q of the system. ∑ =Q1+Q2+Q3+Q4......; Compare the total system demand flow Q ∑ and the maximum flow rate Q that the main hydraulic pump can output max ; If Q ∑ Less than Q max The required flow signal of each main control valve 4 remains unchanged, and Q will be... ∑ Substituting into the formula Q = Vp n calculates the displacement of the main hydraulic pump 2 and the total required flow rate of the output system, where V is... p The main hydraulic pump has a displacement of 2, and n is the main hydraulic pump speed. Since it is matched with a constant speed motor, n is a constant value. If Q ∑ Greater than Q max The required flow signal of each main control valve 4 is multiplied by the gain coefficient β before being input to the corresponding main control valve, thus Q max Substituting into the formula Q = V p ·Calculate the displacement of the main hydraulic pump 2 and the total required flow rate of the output system; The output pressure of the main hydraulic pump 2 is compared with the maximum working pressure of each actuator in the system in real time. The valve opening of the load detection proportional valve 6 is controlled by the pressure difference between the two. If the valve core displacement of the load detection proportional valve 6 is less than the theoretical set value, the output flow of the main hydraulic pump 2 is less than the sum of the required flow Q of each main control valve 4. ∑ If the system is in a state of under-matched flow, increase the displacement of the main hydraulic pump 2 or the speed of the power source 1, as well as the displacement and speed of the bypass replenishing pump 8. If the displacement of the spool of the load detection proportional valve 6 is greater than the theoretical set value, the output flow of the main hydraulic pump 2 is greater than the sum of the required flow of each main control valve 4, and the system is in a state of over-matched flow. The load detection proportional valve 6 opens, and the excess flow of the system flows back to the oil tank through the load detection proportional valve 6. At the same time, reduce the displacement of the main hydraulic pump 2 or the speed of the power source. Repeat this adjustment until the displacement of the spool of the load detection proportional valve 6 is equal to the theoretical set value. At this time, the output flow of the main hydraulic pump 2 is equal to the sum of the required flow of each main control valve 4, and the output flow of the main hydraulic pump 2 is precisely matched with the required flow of each main control valve 4.

[0024] Example 2: like Figure 3 As shown, an electro-hydraulic multi-actuator flow control system includes a power source 1, a main hydraulic pump 2, a main safety valve 3, and a main oil circuit P. L oil return circuit T L The main control valve 4, hydraulic actuator 5, and power source 1 coaxially drive the main hydraulic pump 2. The oil outlet of the main hydraulic pump 2 is connected to the main oil circuit P. L The main safety valve 3 is connected to the oil inlet and the main safety valve 3 is connected to the oil tank. The main control valve 4 is connected to the main oil circuit P through its inlet and outlet ports. L Return oil circuit T L The main control valve 4's working oil circuit is connected to both chambers of the hydraulic actuator 5; The system is also equipped with a load detection proportional valve 6, a first pressure sensor 11, a second pressure sensor 12, a third pressure sensor 13, a global controller 14, and a shuttle valve 16; Pressure sensor 11 and main oil circuit P LThe connection is used to detect the outlet pressure of the main hydraulic pump 1; the second pressure sensor 12 and the third pressure sensor 13 are respectively connected to the two chambers of the hydraulic actuator 5; The load detection proportional valve 6 is a three-position three-way valve, with an added valve core displacement sensor 7. The oil inlet of the load detection proportional valve 6 is connected to the main oil circuit P. L The oil outlet E of the load detection proportional valve 6 is connected to the oil tank, and the other oil outlet F is connected to the hydraulic accumulator 10. The load detection proportional valve 6 has detection ports at both ends. The spring end of the load detection proportional valve 6 is connected to the outlet of the shuttle valve assembly 16 via a hydraulic circuit. The shuttle valve assembly 16 filters and detects the maximum load pressure of multiple hydraulic actuators 5. The other end of the load detection proportional valve 6 is connected to the main oil circuit P via a hydraulic circuit. L The connection is used to detect the outlet pressure of the main hydraulic pump 2. When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is greater than the set value, the system is in a state of over-matched flow. Under the action of the control oil at both ends of the load detection proportional valve 6, the system load detection proportional valve 6 is in the right position, and the excess flow flows back to the oil tank. When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is less than the set value, the system is in a state of under-matched flow. The load detection proportional valve 6 is in the left position, and the insufficient flow is supplemented by the hydraulic accumulator 10.

[0025] The input terminal of the global controller 14 is connected to the pressure sensors 12 and 13 of the two chambers of each hydraulic actuator 5, the displacement sensor 7 of the valve core of the load detection proportional valve 6, and the initial signal input port. The signal output terminal of the global controller 14 is connected to the proportional electromagnet controlling the load detection proportional valve 6 and the control terminal of the main hydraulic pump 2.

[0026] The signal output terminal of the global controller 14 is connected to the proportional electromagnet of the load detection proportional valve and the swing angle control terminal of the main hydraulic pump; The signal output terminal of the global controller 14 is connected to the speed control terminal of the power source.

[0027] like Figure 4 As shown, the main control valve 4 is an open-center multi-way valve 23 with a neutral oil circuit, and the oil inlet P is connected to the main oil circuit P. L Connect the oil outlet T to the return oil path T. L The working ports A and B are connected to the two chambers of the hydraulic actuator 5, respectively. Among them, the inlet F of the open center multi-way valve 23 of the first main control valve 4-1 is connected to the inlet P, and the outlet C is connected to the inlet F of the next open center multi-way valve 23 through the center oil circuit L. The port C of the open center multi-way valve 23 of the tail main control valve 4-3 is connected to the oil tank.

[0028] like Figure 5As shown, the main control valve 4 is a closed-center multi-way valve 31 with a pressure compensator, including a pressure compensator 32 and a main directional valve 33. The oil inlet of the pressure compensator 32 is connected to the main oil circuit P. L The pressure compensator 32 is connected to the oil outlet P of the main directional valve 33, the spring end of the pressure compensator 32 is connected to the oil port LS of the main directional valve 33, the other end of the pressure compensator 32 is connected to the oil inlet of the main directional valve 33, and the oil outlet T of the main directional valve 33 is connected to the return oil circuit T. L The main directional valve's working ports A and B are connected to the two chambers of the hydraulic actuator 5, respectively.

[0029] Example 3: like Figure 6 As shown, an electro-hydraulic multi-actuator flow control system includes a power source 1, a main hydraulic pump 2, a main safety valve 3, and a main oil circuit P. L oil return circuit T L The main control valve 4, hydraulic actuator 5, and power source 1 coaxially drive the main hydraulic pump 2. The oil outlet of the main hydraulic pump 2 is connected to the main oil circuit P. L The main safety valve 3 is connected to the oil inlet and the main safety valve 3 is connected to the oil tank. The main control valve 4 is connected to the main oil circuit P through its inlet and outlet ports. L , return oil circuit T L The main control valve 4's working oil circuit is connected to both chambers of the hydraulic actuator 5; The system is also equipped with a load detection proportional valve 6, a hydraulic accumulator 10, a first pressure sensor 11, a second pressure sensor 12, a third pressure sensor 13, a global controller 14, and a bypass oil replenishment unit 15; This embodiment and Figure 1 The difference in the embodiment shown is that the shuttle valve group 16 is not set in the system. The global controller 14 calculates the maximum load pressure difference between the main hydraulic pump 2 and each hydraulic actuator 5 through the first pressure sensor 11, the second pressure sensor 12, and the third pressure sensor 13, and controls the opening of the load detection proportional valve 6. The bypass replenishing unit 15 is connected in series with the load detection proportional valve 6. The oil inlet of the bypass replenishing unit 15 is connected to the hydraulic accumulator 10, and the oil outlet of the bypass replenishing unit 15 is connected to the oil outlet F of the load detection proportional valve 6. The bypass replenishing unit 15 includes a bypass replenishing pump 8 and a replenishing power source 9. The bypass replenishing pump 8 is a fixed displacement pump, and the replenishing power source 9 coaxially drives the bypass replenishing pump 8 to draw oil from the hydraulic accumulator 10 to the main oil circuit P. L The control terminal of the fuel supply and replenishment power source 9 is connected to the input terminal of the global controller 14; The signal output terminal of the global controller 14 is connected to the proportional electromagnet of the load detection proportional valve and the swing angle control terminal of the main hydraulic pump; The signal output terminal of the global controller 14 is connected to the speed control terminal of the fuel replenishment power source.

[0030] When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is greater than the set value, the system is in a flow over-matching state, the load detection proportional valve 6 is in the right position, and the excess flow flows back to the oil tank; when the difference between the outlet pressure of the main hydraulic pump 2 and the maximum load pressure is less than the set value, the system is in a flow under-matching state, the load detection proportional valve 6 is in the left position, and at the same time, the global controller 14 controls the bypass replenishment unit 6 to supply oil to the main oil circuit P. L The oil replenishment compensates for the slow response of the main hydraulic pump 2 and the insufficient oil replenishment pressure of the hydraulic accumulator 10.

[0031] like Figure 7 As shown, the main control valves 4-1, 4-2, and 4-3 are independent inlet control valve groups, consisting of the first three-position three-way proportional valve 26 and the second three-position three-way proportional valve 27; the inlet C of the first three-position three-way directional valve 26... Ⅰ And the oil inlet C of the second third position three-way directional valve 27 Ⅱ and respectively with the main oil circuit P L Connect, oil outlet D of the third position three-way directional valve 26. Ⅰ and the oil outlet D of the second third position three-way directional valve 27 Ⅱ Respectively connected to return oil circuit T L Connect, working port A of the third position three-way directional valve 26. Ⅰ and the working oil port A of the second third position three-way directional valve 27 Ⅱ It is connected to the two chambers of the hydraulic actuator 5 respectively.

[0032] Figure 8 The diagram shows the second type of inlet / outlet control valve group structure for the main control valves 4-1, 4-2, and 4-3, consisting of a first two-way proportional valve 27, a second two-way proportional valve 28, a third two-way proportional valve 29, and a fourth two-way proportional valve 30; the outlet port A of the first two-way proportional valve 27... Ⅰ , No. IV two-way proportional valve 30 oil outlet A Ⅳ Respectively connected to return oil circuit T L Connect, the second-way proportional valve 28 inlet C Ⅱ , Third 2-way proportional valve 29 oil inlet C Ⅲ Respectively connected to the main oil circuit P L Connect the oil inlet C of the first and second-way proportional valve 27. Ⅰ Oil outlet A of the second-way proportional valve 28 Ⅱ The oil outlet A of the third two-way proportional valve 29 is connected to one chamber of the hydraulic actuator 5. Ⅲ The oil inlet C of the fourth two-way proportional valve 30 Ⅳ Each is connected to another chamber of the hydraulic actuator.

[0033] Example 4: Hydraulic excavators, as the most widely used construction machinery, have working devices such as... Figure 9 As shown, it mainly includes a traveling body 18, a rotating body 19 disposed on the traveling body 18, a boom 20 connected to the rotating body 19 and rotating in the up and down direction, a stick 21 installed at the front end of the boom 20, and a bucket 22 installed in front of the stick 21.

[0034] Figure 10 The present invention is illustrated in the schematic diagram of an excavator hydraulic system, including a power source 1, a main hydraulic pump 2-1, a main hydraulic pump 2-2, a main safety valve 3-1, a main safety valve 3-2, and a main oil circuit P. L1 Main oil circuit P L2 oil return circuit T L Main control valves 4-1, 4-2, 4-3, 4-4, 4-5, 4-6; hydraulic actuators 5-1, 5-2, 5-3, 5-4, 5-5, 5-6.

[0035] Power source 1 coaxially drives main hydraulic pump 2-1 and main hydraulic pump 2-2. The oil outlet of main hydraulic pump 2-1 is connected to the main oil circuit P. L1 The main safety valve 3-1 inlet is connected to the main oil tank, and the main hydraulic pump 2-2 outlet is connected to the main oil circuit P. L2 The oil inlet of the main safety valve 3-2 is connected, and the oil outlet of the main safety valve 3-2 is connected to the oil tank.

[0036] Hydraulic actuators 5-1 and 5-2 are hydraulic motors used to drive the traveling body 22 to move left and right. Both ends of hydraulic actuators 5-1 and 5-2 are connected to the working ports of main control valves 4-1 and 4-2, respectively. The oil inlet P of main control valves 4-1 and 4-2... L1 P L2 Connected, the return oil ports of main control valves 4-1 and 4-2 are respectively connected to the return oil circuit T L For connection, the main control valves 4-1 and 4-2 are closed-center multi-way directional valves with pressure compensators.

[0037] The inlet and outlet ports of the main control valve 4-3 are respectively connected to the main oil circuit P L2 and return oil circuit T L The main control valve 4-3 has one working port connected to the rodless chamber of hydraulic actuator 5-3, and the other working port connected to the rodless chamber of hydraulic actuator 5-5. Hydraulic actuator 5-5 is the bucket hydraulic cylinder, used to drive the excavator bucket 22. The inlet and outlet ports of the main control valve 4-4 are respectively connected to the main oil circuit P. L2 , return oil circuit T LThe main control valve 4-4 is connected to both ends of the hydraulic actuator 5-3, which is the boom hydraulic cylinder used to drive the excavator boom 20. The main control valve 4-3 is primarily used for the combined flow control of the two main hydraulic pumps 2-1 and 2-2. When the main control valve 4-3 is in the left position, both main hydraulic pumps simultaneously supply oil to the hydraulic actuator 5-3; when the main control valve 4-3 is in the right position, both main hydraulic pumps simultaneously supply oil to the hydraulic actuator 5-5. The main control valves 4-3 and 4-4 can be independent inlet and outlet control valves.

[0038] To recover the gravitational potential energy of the excavating boom 20 during operation, the rodless chamber of hydraulic actuator 5-3 is connected to the inlet of flow regeneration control valve 17, and the outlet of flow regeneration control valve 17 is connected to the inlets of main hydraulic pumps 2-1 and 2-2. The inlet and outlet of main control valve 4-5 are respectively connected to the main oil circuit P. L1 Return oil circuit T L The main control valve 4-5's working port is connected to both chambers of the hydraulic actuator 5-4, which is a rotary motor used to drive the rotary body 19. The main control valve 4-5 can be an independent inlet and outlet control valve. The inlets of the main control valves 4-7 and 4-8 are connected to the main oil ports PL1 and PL2 respectively, and their return ports are connected to the return oil circuit T. L The main control valves 4-7 and 4-8 are connected to the two ends of the hydraulic actuator 5-6, which is a boom hydraulic cylinder used to drive the excavator boom 21. The main control valve 4-8 is used for the confluence control of the boom 21. The main control valves 4-7 and 4-8 are independent control valves with independent inlet and outlet ports.

[0039] The system is further equipped with load detection proportional valves 6-1 and 6-2, a global controller 14-1 and 14-2, and bypass replenishment units 15-1 and 15-2. Load detection proportional valves 6-1 and 6-2 are three-position three-way valves, and valve core displacement sensors 7-1 and 7-2 are added. The oil inlets of load detection proportional valves 6-1 and 6-2 are connected to the oil outlets of the main hydraulic pumps 2-1 and 2-2, respectively. The oil outlet E of load detection proportional valves 6-1 and 6-2 is connected to the oil tank, and the other oil outlet F is connected to the hydraulic accumulators 10-1 and 10-2 through the bypass replenishment units 15-1 and 15-2, respectively. The global controller signal output terminal is connected to the proportional electromagnet of the load detection proportional valve and the swing angle control terminal of the main hydraulic pump; the global controller signal output terminal is connected to the speed control terminal of the oil replenishment power source.

[0040] Load detection proportional valves 6-1 and 6-2 are equipped with detection ports at both ends. The spring ends of load detection proportional valves 6-1 and 6-2 are connected to the outlet of shuttle valve assembly 16 via hydraulic oil circuits. The shuttle valve assembly 16 filters and detects the maximum load pressure of multiple hydraulic actuators 5. The other end of load detection proportional valves 6-1 and 6-2 is connected to the main oil circuit P via a hydraulic oil circuit. L The connection is used to detect the outlet pressure of the main hydraulic pumps 2-1 and 2-2. When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is greater than the set value, the system is in a state of over-matched flow. Under the control of the control ports at both ends of the load detection proportional valve 6-1 and 6-2, the load detection proportional valve 6 is in the right position, and the excess flow flows back to the oil tank. When the difference between the outlet pressure of the main hydraulic pump 1 and the maximum load pressure is less than the set value, the system is in a state of under-matched flow. The load detection proportional valve 6 is in the left position, and the insufficient flow is provided by the bypass oil replenishment units 15-1 and 15-2.

Claims

1. An electro-hydraulic multi-actuator flow control system, comprising a power source (1), a main hydraulic pump (2), a main safety valve (3), and a main oil circuit P L , return oil circuit T L The main control valve (4), hydraulic actuator (5), and the power source coaxially drive the main hydraulic pump. The oil outlet of the main hydraulic pump is connected to the main oil circuit P. L The main safety valve inlet is connected to the oil tank, and the main safety valve outlet is connected to the oil tank. The main control valve inlet and outlet are respectively connected to the main oil circuit P. L , return oil circuit T L The main control valve's working oil circuit is connected to both chambers of the hydraulic actuator, characterized in that: Further additions include a load detection proportional valve (6), a valve core displacement sensor (7), a first pressure sensor (11), a second pressure sensor (12), a third pressure sensor (13), and a global controller (14). The load detection proportional valve inlet is connected to the main oil circuit P. L ; The valve core displacement sensor is mounted on the valve core of the load detection proportional valve through a shaft to directly detect the position and speed of the valve core; or it is integrated on the proportional electromagnet to detect the displacement and speed of the valve core by detecting the position of the proportional electromagnet core. The first pressure sensor and the main oil circuit P L The connection is used to detect the outlet pressure of the main hydraulic pump; the second and third pressure sensors are respectively connected to the two chambers of the hydraulic actuator to detect the pressure in the two chambers of the hydraulic actuator; The output signals of the first pressure sensor, the second pressure sensor, and the third pressure sensor, as well as the output signal of the load detection proportional valve core displacement sensor, are connected to the input terminal of the global controller. The global controller signal output terminal is connected to the proportional electromagnet of the load detection proportional valve (6) and the swing angle control terminal of the main hydraulic pump; The global controller signal output terminal is connected to the speed control terminal of the power source; The overall system flow control method includes the following steps: Step 1: Input the required flow signals for each main control valve. Q 1 , Q 2 , Q 3 , Q 4…… Q d The system's total flow demand is calculated by summing the required flow rates of each main control valve at the global controller. Q ∑ = Q 1 + Q 2 + Q 3 + Q 4 ...+ Q d , d It is a natural number; Step 2: Compare the total system traffic demand Q Σ With the current maximum flow rate that the main hydraulic pump can output Q max If the total system demand is Q Σ Less than the maximum flow rate that the main hydraulic pump can output. Q max The required flow signals of each main control valve will be transferred. Q 1 , Q 2 , Q 3 , Q 4…… Q d Directly input the corresponding main control valve; If the total system demand is Q Σ The flow rate is greater than or equal to the maximum output flow rate of the main hydraulic pump. Q max The required flow signals of each main control valve will be transferred. Q 1 , Q 2 , Q 3 , Q 4…… Q d Multiply by the gain coefficient β= Q max / Q Σ Then, input the corresponding main control valve; Step 3: The flow signal input in Step 2 is processed according to the formula... Q = V P · n Calculate the main hydraulic pump displacement and the total required flow rate of the output system, where... V p The displacement of the main hydraulic pump. n The main hydraulic pump speed is controlled; simultaneously, the opening of each main control valve is controlled so that the valve with the highest load independently controls the electro-hydraulic valve to its maximum opening. Through flow control methods, the output flow of each valve is precisely controlled to meet the required flow signal input in step one. Q 1 , Q 2 , Q 3 , Q 4…… Q d ; Step 4: Compare the output pressure of the main hydraulic pump with the maximum working pressure of each actuator in the system in real time. Control the valve opening of the load detection proportional valve by the pressure difference between the two. If the valve core displacement of the load detection proportional valve is less than the theoretical set value, the output flow of the hydraulic pump will be less than the sum of the required flow of each main control valve. Q ∑ If the system is in a state of under-matched flow, increase the displacement of the main hydraulic pump or the speed of the power source, as well as the displacement and speed of the bypass replenishing pump. If the displacement of the load detection proportional valve spool is greater than the theoretical set value, and the output flow of the hydraulic pump is greater than the sum of the required flow of each main control valve, the system is in a state of over-matched flow. Decrease the displacement of the main hydraulic pump or the speed of the power source. Repeat this adjustment until the displacement of the load detection proportional valve spool is equal to the theoretical set value. At this time, the output flow of the hydraulic pump is equal to the sum of the required flow of each control valve, and the output flow of the main hydraulic pump of the system is precisely matched with the required flow of each main control valve.

2. The electro-hydraulic multi-actuator flow control system according to claim 1, characterized in that: A shuttle valve assembly (16) is further added. Multiple shuttle valves are used to screen and detect the maximum load pressure of multiple hydraulic actuators. The outlet of the shuttle valve assembly is connected to the spring chamber of the load detection proportional valve core via a hydraulic line. The other chamber of the load detection proportional valve core is connected to the main oil circuit P via a hydraulic line. L The connection is used to detect the outlet pressure of the main hydraulic pump.

3. The electro-hydraulic multi-actuator flow control system according to claim 1 or 2, characterized in that: A hydraulic accumulator (10) is further added. The load detection proportional valve is either a two-position two-way valve or a three-position three-way valve. When the load detection proportional valve is a three-position three-way valve, the oil outlet E of the load detection proportional valve is connected to the oil tank, and the other oil outlet F is connected to the hydraulic accumulator. When the load detection proportional valve is a two-position two-way valve, the oil outlet of the load detection proportional valve is connected to the oil tank.

4. The electro-hydraulic multi-actuator flow control system according to claim 3, characterized in that: A bypass oil replenishment unit (15) is further added; When the load detection proportional valve is a two-position two-way valve, one end of the bypass oil replenishment unit's oil port is connected to the hydraulic accumulator, and the other end of the bypass oil replenishment unit's oil port is connected to the main oil circuit P. L Connected; When the load detection proportional valve is a three-position three-way valve, the bypass oil replenishment unit is connected in series with the load detection proportional valve and is added between the oil outlet F of the load detection proportional valve and the accumulator. The oil inlet of the bypass oil replenishment unit is connected to the oil outlet of the accumulator, and the oil outlet of the bypass oil replenishment unit is connected to the oil port F of the load detection proportional valve.

5. The electro-hydraulic multi-actuator flow control system according to claim 4, characterized in that: The bypass oil replenishment unit includes a bypass oil replenishment pump (8) and an oil replenishment power source (9), with the oil replenishment power source coaxially driving the bypass oil replenishment pump; The bypass replenishment pump is either a fixed displacement pump or a proportional variable displacement pump. The fuel replenishment power source is either an electric motor or an internal combustion engine; The control terminal of the bypass replenishing pump or replenishing power source is connected to the output terminal of the global controller, drawing oil from the hydraulic accumulator to the main oil circuit P. L fuel supply, or from the main fuel line P L Discharge oil into the hydraulic accumulator.

6. An electro-hydraulic multi-actuator flow control system according to claim 1 or 5, characterized in that: The global controller controls the speed or displacement of the bypass replenishing pump based on the difference between the output pressure of the main hydraulic pump and the maximum load pressure of each actuator. The global controller receives the deviation between the valve core displacement signal of the load detection proportional valve and the valve core displacement set value, generates a control signal, and controls the output flow of the main hydraulic pump. The global controller controls the opening degree of the load detection proportional valve or the detection differential pressure based on the input signal.

7. The electro-hydraulic multi-actuator flow control system according to claim 1, characterized in that: The main control valve is a closed-center multi-way directional valve with a pressure compensator; or an open-center multi-way directional valve with a neutral position oil circuit; or an independent control valve group for inlet and outlet oil ports.

8. The electro-hydraulic multi-actuator flow control system according to claim 1, characterized in that: The power source is either a diesel engine or an electric motor.

9. The electro-hydraulic multi-actuator flow control system according to claim 1, characterized in that: A flow regeneration control valve (17) is further added; the oil inlet of the flow regeneration control valve is connected to the hydraulic actuator drive chamber, and the oil outlet of the flow regeneration control valve is connected to the main hydraulic pump inlet.

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