Excavator Hydraulic Flow Control for Overload and Stop States
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Solution Overview
Problem
Conventional work machines, such as hydraulic excavators, face inefficiencies in excavating operations due to inappropriate control of actuators based solely on pre-set maximum excavating power and overload judgments, which do not account for variations in work device posture and operational conditions.
Innovation Solution
A work machine equipped with overload sensors, angle and velocity sensors, and a controller that adjusts the supply of hydraulic fluid to actuators based on sensed overload and stop states, allowing for dynamic correction of operation flow rates to optimize excavating efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed maximum excavating power is set beforehand for overload judgment, then the control system is simple to implement, but the judgment accuracy deteriorates because it does not account for variations in work device posture
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed threshold to a dynamic threshold that varies with work device posture. The maximum excavating power is no longer a constant value but changes according to the current configuration of the boom, arm, and bucket, allowing accurate overload judgment that adapts to real-time operational conditions.
Solution Approach 2:
The patent changes the parameter of maximum excitating power from a fixed constant to a variable parameter that depends on work device posture. By calculating the maximum excavating power based on current joint angles and cylinder thrusts, the system achieves accurate overload detection while accounting for geometric variations in the work device configuration.
2Productivity
If excavation control is performed based on pre-set maximum excitating power, then the control method is simple, but excavating efficiency deteriorates due to unnecessary operation modifications
Solution Approach 1:
The system dynamically calculates the actual maximum excitating power based on current work device posture and cylinder capabilities. This allows the control system to distinguish between genuine overload conditions requiring modification and situations where the fixed threshold would unnecessarily limit operation, thereby improving excavating efficiency while maintaining reasonable control complexity.
Solution Approach 2:
The patent implements feedback by continuously monitoring work device posture (joint angles) and calculating the corresponding maximum excitating power. This feedback loop allows the control system to adjust operation limits in real-time based on actual capabilities, preventing unnecessary modifications while ensuring safety, thus improving productivity without excessive complexity.
3Measurement precision
If the maximum excitating power is calculated based on work device posture, then the overload judgment accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the relationship between work device posture and maximum excitating power through geometric calculations. The system calculates cylinder thrusts and moment arms based on current joint angles before making overload judgments, preparing the necessary computational data in advance to enable accurate real-time decision-making without excessive computational burden during operation.
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
This solution enables more efficient excavating operations by appropriately controlling actuator operations based on the velocity of the work device and load states of the actuators, thereby preventing unnecessary modifications and maintaining excavating force.
Implementation Method 1
controls supply amounts of hydraulic fluid to be supplied to the actuators
Data Source
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AI summary
With respect to a plurality of actuators that drive a plurality of construction elements, respectively, of a work machine, judgements are made whether there are overload states and judgements are also made whether there are stop states, and when among the plurality of actuators, any actuator in the overload state and the stop state is judged, the supply amount of hydraulic fluid to be supplied to the actuator selected based on a result of the judgement is corrected. By appropriately controlling operations of the actuators depending on a velocity of the work device and load states of the actuators, excavating operation can be performed more efficiently.