Excavator Boom Hydraulic Control for Accurate Bucket Pressing Force
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Solution Overview
Problem
Existing hydraulic drive apparatuses for excavation machines struggle to accurately control the pressing force of the bucket against the construction surface, as the pressing force is influenced by the work device's posture, leading to imprecise control of the compaction force.
Innovation Solution
A hydraulic drive apparatus that includes a boom flow rate control valve, a working posture detection system, a cylinder speed calculation part, a target boom cylinder speed calculation part, a pressing force calculation part, and a correction part to adjust the target boom cylinder speed, ensuring the bucket's pressing force against the construction surface is accurately controlled by considering the work device's posture and self-weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pressing force is calculated only based on boom cylinder thrust, then the control system is simple, but the pressing force measurement is inaccurate because it does not account for work device posture
Solution Approach 1:
The system introduces feedback by detecting the actual pressing force through multiple sensors (boom cylinder pressure, arm cylinder pressure, posture sensors) and comparing it with the target pressing force. The correction part continuously adjusts the target boom cylinder speed based on the deviation between actual and target pressing force, forming a closed-loop control system that improves measurement accuracy while maintaining reasonable complexity.
Solution Approach 2:
The patent introduces intermediary calculation elements (center of gravity position calculation, moment calculation about boom rotation axis) that mediate between the raw sensor data and the final pressing force determination. These intermediaries process the complex relationship between posture, weights, and forces to accurately derive the pressing force without requiring direct measurement.
2Speed
If the target boom cylinder speed is not corrected, then the control response is fast, but the pressing force control accuracy is insufficient
Solution Approach 1:
The system performs preliminary calculation of the correction amount before adjusting the target boom cylinder speed. The correction part calculates the required speed adjustment based on the current pressing force deviation, enabling the system to proactively compensate for errors before they result in significant pressing force inaccuracies, thus maintaining both speed and accuracy.
Solution Approach 2:
The target boom cylinder speed is made dynamic through the correction mechanism. Instead of using a fixed target speed, the system continuously adjusts the target speed based on real-time pressing force feedback, allowing the control parameters to adapt to changing working conditions while maintaining accurate pressing force control.
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
The apparatus achieves high accuracy in controlling the construction surface and pressing force, ensuring the bucket's operation is precise and effective in reaching the target pressing force, enhancing the overall performance of the excavation process.
Implementation Method 1
a hydraulic pump that is driven by a driving source to thereby discharge hydraulic oil; at least one boom cylinder that is expanded and contracted by supply of hydraulic oil from the hydraulic oil supply device
Implementation Method 2
a boom cylinder pressure detector that detects a head pressure and a rod pressure which are respective pressures of a head-side chamber and a rod-side chamber of the at least one boom cylinder
Implementation Method 3
a center-of-gravity position information calculation part that calculates center-of-gravity position information, which is information on a center-of-gravity position of the work device, based on the posture information detected by the working posture detection part
Data Source
AI summary
A hydraulic drive apparatus includes a boom flow rate control valve, a target boom cylinder speed calculation part, a pressing force calculation part, a correction part, and a boom flow rate operation part. The target boom cylinder speed calculation part calculates a target boom cylinder speed for making the construction surface by the bucket closer to the target construction surface. The pressing force calculation part calculates the pressing force by which the bucket is pressed against the construction surface, based on the cylinder thrust of the boom cylinder and the center-of-gravity position information on the center-of-gravity position of the work device. The correction part corrects the target boom cylinder speed to make the deviation between the target pressing force and the calculated pressing force closer to 0. The boom flow rate operation part operates the boom flow rate control valve to provide the corrected target boom cylinder speed.