Hydraulic Excavator Valve Feedback for Combined Motion Speed Control
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Solution Overview
Problem
Existing construction machines, such as hydraulic excavators, struggle to accurately regulate the actual speed of actuators when there is a significant load imbalance during combined manipulations, leading to inefficiencies in slewing and boom operations.
Innovation Solution
A construction machine equipped with a variable displacement hydraulic pump system, multiple control valves, and a controller that adjusts flow rates and valve openings to compensate for load imbalances between actuators, ensuring accurate speed regulation through feedback controls and pump discharge rate adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a joining valve is used to distribute hydraulic fluid between slewing motor and boom cylinder, then the system can perform combined manipulations, but the actual speed of the first actuator cannot be accurately regulated when its load is larger than the second actuator's load
Solution Approach 1:
The control device receives actual speed information from speed detectors for both actuators and compares it with target speeds. Based on this feedback, the controller adjusts the opening degrees of control valves and discharge rates of pumps to minimize speed errors. This closed-loop feedback mechanism enables accurate speed regulation of the first actuator even when its load exceeds that of the second actuator during combined manipulations.
Solution Approach 2:
The system dynamically adjusts multiple parameters including the opening degrees of first, second, and third control valves, and the discharge rates of first and second pumps. By changing these parameters in response to load conditions and speed deviations, the controller optimizes hydraulic fluid distribution to maintain accurate speed control of the first actuator while supporting combined manipulations.
2Speed
If flow rate distribution is controlled to ensure slewing torque during combined manipulation, then the actual speed of the slewing motor increases, but accurate regulation of actual speed to target speed is not achieved
Solution Approach 1:
The control device continuously monitors the actual speed of the slewing motor through a speed detector and compares it with the target speed. Based on the speed deviation feedback, the controller adjusts the opening degree of the first control valve and the discharge rate of the first pump to accurately regulate the slewing motor speed to the target value, rather than merely ensuring minimum torque.
Solution Approach 2:
The system transitions from static flow rate distribution to dynamic adjustment. The control device continuously modifies the opening degrees of control valves and discharge rates of pumps in real-time based on actual operating conditions and speed feedback, enabling accurate speed regulation that adapts to changing load conditions during combined manipulations.
3Device complexity
If a single hydraulic pump supplies both slewing motor and boom cylinder, then the system structure is simplified, but the load imbalance between actuators causes inaccurate speed control
Solution Approach 1:
The hydraulic system is segmented into two independent pump units: a first pump dedicated to the slewing motor and a second pump dedicated to the boom cylinder. This segmentation allows independent control of hydraulic fluid supply to each actuator, eliminating the load imbalance problem that occurs with a single shared pump while maintaining relatively simple system structure through modular design.
Solution Approach 2:
Each pump unit is designed to be multi-functional, capable of independently adjusting discharge rates and working with corresponding control valves to serve multiple control objectives. The first pump and first control valve combination handles slewing motor control, while the second pump and third control valve combination handles boom cylinder control, providing universal functionality for accurate speed regulation under various load conditions.
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 precise speed control of actuators, even under varying loads, enhancing operational efficiency and accuracy in slewing and boom operations.
Implementation Method 1
a first pump (21) being a variable displacement hydraulic pump for discharging hydraulic fluid
Implementation Method 2
for discharging hydraulic fluid to be supplied to a first actuator (10)
Implementation Method 3
a first control valve (32) that is located between the first pump (21) and the second actuator (7), and opens and closes to change a flow rate of the hydraulic fluid
Implementation Method 4
a speed compensation part (54) that executes a feedback control of regulating an opening degree of the second control valve (32)
Data Source
AI summary
A speed compensation part included in a construction machine executes a feedback control of regulating an opening degree of a second control valve to an opening degree obtained by subtracting a correction amount from a second target opening degree of the second control valve, when a combined manipulation is performed and a preset load determination condition is satisfied. The correction amount is calculated by the speed compensation part so as to be larger as a speed difference between a first target speed and a first actual speed becomes larger, the first target speed being a target speed of a first actuator and determined on the basis of a manipulation amount of a first instructive manipulation, the first actual speed being an actual speed of the first actuator.