Hydraulic Flow Division Control for Combined Construction Machine Actuators
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Solution Overview
Problem
Existing construction machine control systems face challenges in accurately controlling the flow rate of hydraulic fluid to multiple actuators during combined operations, leading to interference between delivery flow rate control and meter-in valve opening control, resulting in inaccurate flow distribution and reduced performance.
Innovation Solution
A construction machine equipped with a hydraulic pump, regulator, directional control valves, and a controller that adjusts the delivery flow rate and valve openings based on sensed operation velocities and target flow rates, ensuring the delivery flow rate exceeds the total target flow rate during combined operations and minimizing differences between target and actual flow rates across actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the delivery flow rate of the hydraulic pump is corrected on the basis of the estimated inflow flow rate, then the flow rate control accuracy is improved, but flow rate errors different for each actuator section are caused due to leakage, compression, and meter-in valve characteristics
Solution Approach 1:
The patent divides the flow rate control into two independent control levels: (1) delivery flow rate control of the hydraulic pump on the upstream side, and (2) opening amount control of individual meter-in valves for each hydraulic actuator. This segmentation allows each control level to address specific flow rate errors independently, preventing interference between controls and enabling accurate flow distribution to each actuator section.
Solution Approach 2:
The patent adds a new control dimension by introducing individual meter-in valve opening amount control for each hydraulic actuator, in addition to the existing delivery flow rate control of the hydraulic pump. This multi-dimensional control approach enables comprehensive correction of flow rate errors at different levels of the hydraulic circuit.
2Measurement precision
If both the opening amount of the meter-in valve and the delivery flow rate of the hydraulic pump are corrected on the basis of the estimated inflow flow rate, then the flow rate control is enhanced, but interference of the control occurs and hunting occurs in the inflow flow rate
Solution Approach 1:
The patent segments the control functions by assigning delivery flow rate control to the hydraulic pump and opening amount control to individual meter-in valves. This segmentation prevents interference between controls by establishing independent control loops at different levels of the hydraulic circuit, thereby eliminating hunting in the inflow flow rate.
3Measurement precision
If the opening amount of the meter-in valve is directly corrected on the basis of the estimated inflow flow rate, then the flow rate control accuracy is improved, but convergence of the actual inflow flow rate to the target inflow flow rate is delayed if the degree of correction is low
Solution Approach 1:
The patent performs preliminary correction of the delivery flow rate of the hydraulic pump based on the estimated inflow flow rate before the meter-in valve opening correction takes effect. This preliminary action ensures that the hydraulic pump delivers sufficient flow rate, preventing delay in convergence and enabling the meter-in valve correction to achieve accurate flow distribution more quickly.
Data Source
AI summary
A construction machine is provided that can cause each hydraulic actuator to accurately operate according to operation by an operator in combined operation in which a hydraulic fluid of a hydraulic pump is subjected to flow dividing and is supplied to plural hydraulic actuators. A controller 10, in a case of determining that combined operation is being carried out, controls a regulator 7a in such a manner that the delivery flow rate of a hydraulic pump 7 becomes larger than the total target flow rate of plural hydraulic actuators 4a, 5a, and 6a, and controls the respective opening amounts of plural directional control valves 8a1, 8a3, and 8a5 in such a manner that the difference between the respective target flow rates of the plural hydraulic actuators and the respective inflow flow rates of the plural hydraulic actuators sensed by velocity sensors 12 to 14 becomes small.