Excavator Hydraulic Valve Control for Precise Arm Compaction
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Solution Overview
Problem
Existing hydraulic excavators face challenges in performing compaction work involving arm crowding and arm dumping actions smoothly near an excavation target surface during machine control, due to limitations in velocity control and positional adjustment.
Innovation Solution
A hydraulic excavator system that includes a multi-joint work implement, posture sensors, a hydraulic pump, a control valve unit, solenoid pressure reducing valves, and a controller. The controller calculates velocity limits for the hydraulic actuators based on posture sensor signals and solenoid valve openings, and specifically adjusts the solenoid pressure reducing valves for arm crowding and arm dumping actions to enhance response during machine control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the solenoid pressure reducing valve is opened to allow quick operation of the hydraulic actuator, then the response speed improves, but the work implement may excavate soil beyond the target excavation surface
Solution Approach 1:
The solenoid valve opening is dynamically adjusted based on the work implement's velocity and position relative to the target excavation surface. When the work implement approaches the target surface, the controller reduces the solenoid valve opening to limit velocity, preventing over-excavation while still allowing rapid operation during normal conditions
Solution Approach 2:
The control system changes the opening parameter of the solenoid pressure reducing valve based on real-time feedback from velocity sensors and position data. The opening percentage is adjusted as a control parameter to balance between rapid response and precise excavation control
2Productivity
If the velocity limit for boom lowering operation is eased up to perform compaction work, then the compaction capability improves, but the work implement may still not respond quickly enough for arm crowding and arm dumping actions
Solution Approach 1:
Different velocity limits are applied to different hydraulic actuators based on their specific functions. The boom cylinder receives one velocity limit for compaction, while the arm cylinders receive different velocity limits optimized for their respective actions (crowding and dumping), allowing each to operate at optimal performance levels
Solution Approach 2:
The control system segments the velocity control into separate limits for each hydraulic actuator (boom cylinder, arm cylinders, bucket cylinder). This allows independent optimization of velocity limits for each component, enabling compaction work while maintaining responsive arm movements
3Manufacturing precision
If the solenoid pressure reducing valve opening is restricted to prevent over-excavation, then the excavation precision is maintained, but the adjustment operation of compacting position is delayed
Solution Approach 1:
The control system performs preliminary velocity limit calculations based on predicted work implement trajectories and positions. By anticipating the need for position adjustments during compaction work, the system pre-configures appropriate velocity limits that maintain precision while enabling timely adjustments
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient performance of compaction work and other actions like arm crowding and arm dumping with improved response and accuracy near the excavation target surface, even during machine control operations.
Implementation Method 1
a solenoid valve unit including a plurality of solenoid pressure reducing valves connected between the plurality of control lever devices and the control valve unit
Implementation Method 2
a hydraulic pump that discharges a hydraulic fluid actuating the plurality of hydraulic actuators
Data Source
AI summary
A hydraulic actuator includes a control valve unit that controls a flow of a hydraulic fluid supplied from a hydraulic pump to a plurality of hydraulic actuators, a plurality of control lever devices that output a pilot pressure actuating the control valve unit, with use of a discharged pressure from a pilot pump as a source pressure, a solenoid valve unit including a plurality of solenoid pressure reducing valves connected between the plurality of control lever devices and the control valve unit, and a controller configured to calculate velocity limits for the plurality of hydraulic actuators on the basis of signals from a plurality of posture sensors and control openings of the solenoid pressure reducing valves, in which the controller is configured to control the openings of the solenoid pressure reducing valves for arm crowding and arm dumping to be larger than an opening based on the velocity limits while a boom raising operation signal is being output from the control lever devices.