A hydraulic system and control method comprising an electrically controlled variable pump and an electro-proportional multi-way valve.

Abstract

This invention discloses a hydraulic system and control method incorporating an electronically controlled variable pump and an electro-proportional multi-way valve. Addressing the technical shortcomings of existing pump-controlled volumetric speed regulation systems (poor stability under low-speed and heavy-load conditions) and load-sensitive valve-controlled systems (high energy consumption under high-speed and light-load conditions), this invention adopts an integrated hardware architecture of the electronically controlled variable pump and electro-proportional multi-way valve. It achieves intelligent identification of operating conditions by collecting parameters such as pressure, speed, lever opening, and throttle opening through sensors. Under low-speed and heavy-load conditions, it automatically activates the load-sensitive valve control mode to ensure operational stability and control accuracy. Under medium- and high-speed and light-load conditions, it automatically switches to the pump-controlled volumetric speed regulation mode to minimize energy consumption. Furthermore, it achieves seamless and stepless switching of pump and valve modes through PID compensation, lever dead-zone compensation, and load interference compensation. This invention can accurately adapt to the multi-condition operating requirements of construction machinery, balancing the stability of heavy-load and low-speed control with the energy efficiency of medium- and high-speed and light-load operations, effectively reducing system energy consumption and improving control accuracy and operational smoothness.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology for engineering machinery, specifically to a hydraulic system and control method comprising an electronically controlled variable pump and an electro-proportional multi-way valve. Background Technology

[0002] In the field of construction machinery operations, the hydraulic transmission system, as the core power execution unit, directly determines the energy consumption level and control accuracy of the equipment. Currently, the mainstream hydraulic control systems are mainly divided into two categories: pump-controlled volumetric speed regulation systems and load-sensitive valve-controlled hydraulic systems. Both of them have obvious technical limitations in practical applications. Pump-controlled volumetric speed regulation system: It achieves volumetric speed regulation by directly adjusting the output flow rate of the variable pump. It has the advantages of high flow matching degree, low pressure loss along the flow path and outstanding energy-saving effect under medium and high speed light load conditions. However, under low speed heavy load conditions, it is prone to problems such as flow response lag, large pressure fluctuation and insufficient system stability, which cannot meet the control requirements of heavy load operation.

[0003] Load-sensitive valve-controlled hydraulic system: The output flow is adjusted in real time according to the load pressure through load-sensitive valve group. It has fast response, high control accuracy and strong adaptability under low speed and heavy load conditions, and can stably adapt to the needs of heavy load operation; however, it has the defects of high energy consumption and poor energy saving under high speed and light load conditions.

[0004] The publication number CN121345843A discloses "an integrated energy-saving load-sensitive multi-way valve and hydraulic system". The core is a single valve control mode. Through a segmented valve group structure, integrated stabilization module and pilot control, load-sensitive flow distribution is achieved. Its essence still belongs to the traditional technical framework of "valve control + load sensitivity". It focuses on the integration and maintainability optimization of the multi-way valve itself, and has not broken through the core limitations of traditional hydraulic control.

[0005] Traditional construction machinery mostly adopts a single hydraulic control mode, which can only adapt to some working conditions. It cannot take into account the stability of heavy load and low speed and the energy saving of medium and light load and high speed. At the same time, it has common problems in the industry such as poor adaptability to working conditions, high overall energy consumption and insufficient control precision, which restricts the upgrading of construction machinery towards energy saving, intelligence and precision.

[0006] The current technological shortcomings are mainly reflected in... 1. Difficulty in controlling different working conditions: Construction machinery alternates between low-speed heavy load and medium-to-high-speed light load. Traditional systems rely on a single signal to determine the working condition, without targeted control strategies, and cannot take into account the stability and energy-saving requirements under different working conditions.

[0007] 2. Difficulty in coordinating pump-controlled and valve-controlled modes: The industry generally adopts two technical routes: pump control (electrically controlled variable) and valve control (mechanical feedback), each with obvious shortcomings: pump control has good dynamic performance but poor stability under heavy load; valve control has a stable structure but low energy efficiency.

[0008] 3. There is an urgent need for intelligent operation; users have raised high-level requirements for operation experience: intelligent and precise control, smooth operation under all working conditions, and smooth human-machine collaborative operation. However, the current system has three major pain points in operation: start-stop shock, micro-motion jitter, and lag in complex actions, which restrict the realization of intelligent value. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a hydraulic system and control method comprising an electronically controlled variable pump and an electro-proportional multi-way valve. This system achieves intelligent identification of operating conditions and adaptive collaborative control of the pump and valve in dual modes, balancing the stability of heavy-load low-speed control with the energy efficiency of medium- and high-speed light-load operation, thereby improving the system's control accuracy, operational smoothness, and energy-saving effect.

[0010] A hydraulic system comprising an electrically controlled variable pump and an electro-proportional multi-way valve includes a power unit, an electrically controlled variable pump, an electro-proportional multi-way valve, a sensor group, a PLC controller, and actuators; The power unit is used to provide driving power for the entire hydraulic system and to provide input torque and speed for the electronically controlled variable pump; The electronically controlled variable pump is controlled by an electrical signal to adjust the output displacement and flow rate, providing high-pressure hydraulic oil to the system and realizing pump-controlled volumetric speed regulation. The electro-proportional multi-way valve is used to receive electrical control signals, proportionally control the direction, flow rate and pressure of hydraulic oil, distribute hydraulic oil to the corresponding actuators, and realize valve-controlled throttling speed regulation and load-sensitive control. The sensor group includes a speed sensor, a pressure sensor, and an electric control handle. The speed sensor is used to collect the speed signal of the power unit; the pressure sensor is used to collect the outlet pressure of the electric variable pump and the load pressure signal of the multi-way valve LS port; the electric control handle is used to output operation command signals and provide feedback on the handle opening. The PLC controller is electrically connected to the speed sensor, pressure sensor, electric control handle, electric variable pump, and electric proportional multi-way valve, respectively. It is used to receive sensor and operation signals, perform data processing, working condition identification, control calculation, and output control commands to the electric variable pump and electric proportional multi-way valve to realize the switching and coordinated control of pump control mode and valve control mode. The actuator receives hydraulic oil output from the electro-proportional multi-way valve, converts hydraulic energy into mechanical energy, and drives the construction machinery to perform operational actions.

[0011] A hydraulic control method including an electronically controlled variable pump and an electro-proportional multi-way valve includes the following steps: (1) Data acquisition: The engine speed, hydraulic system pressure, handle opening and throttle opening signals are collected in real time through speed sensor, pressure sensor and electric control handle and transmitted to PLC controller; (2) Automatic identification of working conditions: The PLC controller classifies heavy load, medium load and light load according to the load pressure, and low speed, medium speed and high speed according to the handle opening and throttle opening, and combines them to obtain 9 working conditions; (3) Mode adaptive switching: In low-speed heavy-load conditions, the load-sensitive valve control mode is activated to maintain a constant valve port pressure difference; in medium-speed light-load conditions, the pump control volumetric speed regulation mode is activated to adjust the pump displacement to achieve flow matching. (4) Smooth switching of pump and valve modes: PID closed-loop control and real-time compensation for load disturbance are adopted to eliminate pressure shock during mode switching and achieve stepless switching.

[0012] The technical solution of this invention has the following advantages compared with the prior art: 1. Focusing on electro-hydraulic collaborative innovation, this paper proposes a hardware architecture and hydraulic system schematic diagram of an electro-hydraulic control system containing an electro-hydraulic variable pump and an electro-proportional multi-way valve to address the problems of poor stability of pump control system and large pressure loss of load-sensitive pump throttling system. This provides an application carrier for the "pump control + valve control" composite control technology.

[0013] 2. Automatic identification of product operating conditions. By detecting signals from the handle, throttle, speed, and pressure, the system identifies light load, medium load, and heavy load, as well as low speed, medium speed, and high speed user operation needs, and then combines these to form 9 operating conditions.

[0014] 3. Adaptive control strategy based on operating conditions. The system automatically applies pump control mode and valve control mode based on the operating conditions, and can switch freely between the two, balancing energy saving and stability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the hydraulic system of the present invention, which includes an electrically controlled variable pump and an electro-proportional multi-way valve.

[0016] Figure 2 This is a block diagram of the constant differential pressure control logic under the valve control mode of the present invention.

[0017] The components include: 1. Power unit; 2. Speed ​​sensor; 3. Electro-hydraulic variable pump; 4. Oil tank; 5. Return oil filter; 6. Controller; 7. Multi-way valve; 7.1. Main relief valve; 7.2. Diverter valve; 7.3. Unloading damper; 7.4. First check valve; 7.5. First electro-hydraulic directional valve; 7.6. First check valve; 7.7. Second electro-hydraulic directional valve; 8. First pressure sensor; 9. Second pressure sensor; 10. Third pressure sensor. Detailed Implementation

[0018] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings: like Figure 1As shown, a hydraulic system including an electrically controlled variable pump and an electro-proportional multi-way valve includes a power unit 1, an electrically controlled variable pump 3, an electro-proportional multi-way valve 7, a sensor group, a PLC controller, and actuators.

[0019] The power unit 1 provides driving power for the entire hydraulic system and provides input torque and speed to the electronically controlled variable pump. The power unit of this invention is an engine or an electric motor, used to provide stable speed and torque to drive the electronically controlled variable pump.

[0020] The electrically controlled variable pump 3 is controlled by an electrical signal to adjust its output displacement and flow rate, providing high-pressure hydraulic oil to the system and achieving pump-controlled volumetric speed regulation. The electrically controlled variable pump of this invention is an electrically controlled variable high-pressure plunger pump, which can continuously adjust its displacement according to the control current output by the PLC controller to achieve linear flow output.

[0021] The electro-proportional multi-way valve 7 is used to receive electrical control signals, proportionally control the flow direction, flow rate, and pressure of hydraulic oil, and distribute hydraulic oil to the corresponding actuators to achieve valve-controlled throttling speed regulation and load-sensitive control. The electro-proportional multi-way valve of the present invention includes at least two reversing connections, each of which is equipped with an LS load-sensitive port for feedback of the load pressure of the corresponding actuator.

[0022] The sensor group includes a speed sensor 2, a pressure sensor, and an electric control handle. The speed sensor is used to acquire the speed signal of the power unit; the pressure sensor is used to acquire the outlet pressure of the electronically controlled variable pump and the load pressure signal of the LS port of the multi-way valve; the electric control handle is used to output operation command signals and provide feedback on the handle opening. The pressure sensors of this invention include at least: a first pressure sensor 8 for detecting the outlet pressure of the electronically controlled variable pump, a second pressure sensor 9 for detecting the load pressure of the LS port of the first reversing coupling of the multi-way valve, and a third pressure sensor 10 for detecting the load pressure of the LS port of the second reversing coupling of the multi-way valve. The electric control handle of this invention is a proportional control handle with signal feedback, used to output an electrical signal proportional to the operating angle, representing the operator's speed and direction requirements.

[0023] The PLC controller is electrically connected to a speed sensor, a pressure sensor, an electric control handle, an electric variable pump, and an electro-proportional multi-way valve, respectively. It receives sensor and operation signals, performs data processing, operating condition identification, and control calculations, and outputs control commands to the electric variable pump and electro-proportional multi-way valve to achieve switching and coordinated control between pump control and valve control modes. The PLC controller of this invention integrates a signal acquisition unit, an operating condition identification unit, a mode switching unit, a PID closed-loop control unit, and a signal compensation unit to complete data processing, logical judgment, and precise control.

[0024] The actuator receives hydraulic oil output from the electro-proportional multi-way valve, converts hydraulic energy into mechanical energy, and drives the construction machinery to perform operational actions. The actuator of this invention is a hydraulic cylinder or a hydraulic motor, used to drive the working device of the construction machinery to complete lifting, extension, rotation, and traveling actions.

[0025] The power unit 1 is connected to the electronically controlled variable pump 3. A speed sensor 2 is installed at the connection point to detect the pump's operating speed. The electronically controlled variable pump 3 outputs pressurized oil to the P port of the multi-way valve 7. After being controlled by the first electro-hydraulic directional valve 7.5 and the second electro-hydraulic directional valve 7.7, the oil is output to the A1 / B1 port and supplied to the actuator. Figure 1 The multi-way valve includes: main relief valve 7.1, flow divider valve 7.2, unloading damper 7.3, first check valve 7.4, first electro-hydraulic directional valve 7.5, first check valve 7.6, and second electro-hydraulic directional valve 7.7. -Y1 / -Y2 / -Y3 are the electrical connection symbols for solenoid valves; A1 / B1 / A2 / B2 are the oil port symbols for hydraulic valves.

[0026] A hydraulic control method including an electronically controlled variable pump and an electro-proportional multi-way valve includes the following steps: (1) Data acquisition: The engine speed, hydraulic system pressure, handle opening and throttle opening signals are collected in real time through speed sensor, pressure sensor and electric control handle and transmitted to PLC controller; (2) Automatic identification of working conditions: The PLC controller classifies heavy load, medium load and light load according to the load pressure, and low speed, medium speed and high speed according to the handle opening and throttle opening, and combines them to obtain 9 working conditions; (3) Adaptive mode switching: In low-speed heavy-load conditions, the load-sensitive valve control mode is activated to maintain a constant valve port pressure difference; in medium-speed and light-load conditions, the pump control volumetric speed regulation mode is activated to adjust the pump displacement to achieve flow matching. (4) Smooth switching of pump and valve modes: PID closed-loop control and real-time compensation for load disturbance are adopted to eliminate pressure shock during mode switching and achieve stepless switching.

[0027] like Figure 2 As shown, a hydraulic control method incorporating an electronically controlled variable pump and an electro-proportional multi-way valve comprises the following steps: 1. Data Acquisition Stage: The speed of the power unit is detected in real time through the speed sensor 2 and throttle signal deployed in the product's electro-hydraulic control system; the first pressure sensor 8, the second pressure sensor 9, and the third pressure sensor 10 detect the outlet pressure of the electronically controlled pump 3, the LS port load pressure of the multi-way valve reversing coupling 1, and the LS port load pressure of the reversing valve 2, respectively, to sense the load in real time and calculate the valve port pressure difference value; the electronic control handle has its own signal feedback, and all these sensors and electronic control operation input signals are transmitted to the PLC controller 6 for data processing.

[0028] 2. Automatic operating condition identification process: First, load identification is performed. The steady-state pressure value of the LS port recorded by the PLC controller at the end of the previous action is used as the basis for judgment. If p ≥ 20MPa, it is judged as heavy load; if 10MPa ≤ p < 20MPa, it is judged as medium load; if p < 10MPa, it is judged as light load.

[0029] Next, speed recognition is performed based on the operator's control handle opening (the PLC reads the feedback current signal from the control handle itself) and throttle opening (throttle signal self-check, and speed sensor 2 detects the signal for feedback correction; for example, a detection value of 0 is set to idle speed of 800 rpm, and 1 is set to maximum speed of 2200 rpm). The speed requirement is determined based on the user's control handle and throttle input. Low-speed requirements: Handlebar opening ≤ 50% of maximum operating angle + throttle opening = 0; Medium speed requirement: 50% ≤ handle opening ≤ 80% maximum control angle + 0 ≤ throttle opening ≤ 0.5; High-speed requirements: 80% ≤ handle opening ≤ 100% maximum control angle + 0.5 ≤ throttle opening ≤ 1; Based on the load and speed requirements, the operating conditions can be automatically identified (a total of 3*3=9 items).

[0030] 3. Mode switching process: For the above 9 different working conditions, the control system drives the hydraulic circuit to switch the corresponding control mode.

[0031] Control Mode 1: Pump Control Mode (Volume Speed ​​Regulation), by adjusting the pump control current, the pump displacement changes linearly with the handle; Control Mode 2 (Medium-load low-speed, heavy-load low-speed conditions): Valve control mode (throttling speed regulation), by adjusting the pump current, the pressure difference (ΔP) between valve P port and valve LS port is kept stable at 2MPa. It is the same as the function of the load-sensitive pump.

[0032] Meanwhile, this system also innovatively integrates three core technologies: dead zone compensation for handle signal, constant differential pressure closed-loop PID control, and real-time compensation for load interference.

[0033] Its working logic is as follows: First, the dead zone module of the handle signal compensation effectively compensates the handle operation signal, avoids system malfunctions caused by signal interference, and improves control stability. Second, the system collects the actual pressure difference across the main directional valve in real time, compares it with the set pressure difference to calculate the deviation, and inputs the deviation value into the pressure difference closed-loop PID controller, which outputs a precise control signal through calculation. At the same time, the system introduces real-time load interference compensation technology, collects load change information and compensates and corrects the pump control signal, and drives the pump variable control valve to precisely adjust the output flow of the high-pressure plunger pump.

[0034] Through this series of coordinated controls, the constant pressure difference across the main directional valve is ultimately achieved, ensuring that the movement speed of the actuator matches only the handle operation command, thereby reducing the adverse effects of the handle dead zone.

Claims

1. A hydraulic system comprising an electrically controlled variable pump and an electro-proportional multi-way valve, characterized in that, Includes power unit, electronically controlled variable pump, electro-proportional multi-way valve, sensor group, PLC controller and actuator; The power unit is used to provide driving power for the entire hydraulic system and to provide input torque and speed for the electronically controlled variable pump; The electronically controlled variable pump is controlled by an electrical signal to adjust the output displacement and flow rate, providing high-pressure hydraulic oil to the system and realizing pump-controlled volumetric speed regulation. The electro-proportional multi-way valve is used to receive electrical control signals, proportionally control the direction, flow rate and pressure of hydraulic oil, distribute hydraulic oil to the corresponding actuators, and realize valve-controlled throttling speed regulation and load-sensitive control. The sensor group includes a speed sensor, a pressure sensor, and an electric control handle. The speed sensor is used to collect the speed signal of the power unit; the pressure sensor is used to collect the outlet pressure of the electric variable pump and the load pressure signal of the multi-way valve LS port; the electric control handle is used to output operation command signals and provide feedback on the handle opening. The PLC controller is electrically connected to the speed sensor, pressure sensor, electric control handle, electric variable pump, and electric proportional multi-way valve, respectively. It is used to receive sensor and operation signals, perform data processing, working condition identification, control calculation, and output control commands to the electric variable pump and electric proportional multi-way valve to realize the switching and coordinated control of pump control mode and valve control mode. The actuator receives hydraulic oil output from the electro-proportional multi-way valve, converts hydraulic energy into mechanical energy, and drives the construction machinery to perform operational actions.

2. A hydraulic control method comprising an electrically controlled variable pump and an electro-proportional multi-way valve, characterized in that, Includes the following steps: (1) Data acquisition: The engine speed, hydraulic system pressure, handle opening and throttle opening signals are collected in real time through speed sensor, pressure sensor and electric control handle and transmitted to PLC controller; (2) Automatic identification of working conditions: The PLC controller classifies heavy load, medium load and light load according to the load pressure, and low speed, medium speed and high speed according to the handle opening and throttle opening, and combines them to obtain 9 working conditions; (3) Mode adaptive switching: In low-speed heavy-load conditions, the load-sensitive valve control mode is activated to maintain a constant valve port pressure difference; in medium-speed light-load conditions, the pump control volumetric speed regulation mode is activated to adjust the pump displacement to achieve flow matching. (4) Smooth switching of pump and valve modes: PID closed-loop control and real-time compensation for load disturbance are adopted to eliminate pressure shock during mode switching and achieve stepless switching.

3. The control method according to claim 2, characterized in that, The load pressure determination criteria are as follows: pressure ≥ 20MPa is heavy load, 10MPa ≤ pressure < 20MPa is medium load, and pressure < 10MPa is light load.

4. The control method according to claim 2, characterized in that, The speed determination criteria are as follows: low speed is defined as ≤50% handlebar opening and 0 throttle opening; medium speed is defined as 50%-80% handlebar opening and 0-0.5 throttle opening; and high speed is defined as 80%-100% handlebar opening and 0.5-1 throttle opening.

5. The control method according to claim 2, characterized in that, In valve-controlled mode, the pressure difference between valve P port and LS port is maintained at 2MPa.

6. The control method according to claim 2, characterized in that, It also includes dead-zone compensation for handle signals, constant differential pressure closed-loop PID control, and real-time compensation for load interference.

7. The control method according to claim 2, characterized in that, In pump control mode, the pump displacement changes linearly with the handle opening.

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