Hydraulic Excavator Valve Control for Rapid Lever Response
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Solution Overview
Problem
Conventional hydraulic circuit systems in work machines, such as hydraulic excavators, experience reduced responsiveness and efficiency when the operation lever changes frequently, leading to decreased work accuracy and efficiency, particularly during tasks like gravel spreading, due to the control methods that restrict fluid flow rates to improve fuel efficiency.
Innovation Solution
A work machine with a hydraulic pump, multijoint front work implement, directional control valves, operation devices, operation amount sensors, and a controller that can switch between a normal mode and a responsiveness priority mode to adjust the flow restriction of the directional control valves, allowing for enhanced fluid flow during rapid operation lever changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the delivery flow rate of the hydraulic pump is reduced to enhance fuel efficiency, then energy consumption is improved, but responsiveness deteriorates when the operation lever changes frequently
Solution Approach 1:
The flow restriction device dynamically adjusts the opening area of the directional control valve based on the operation state. When the operation lever is frequently changed (detected by the operation amount sensor), the device increases the opening area to improve responsiveness. When the lever position is stable, it maintains flow restriction to preserve fuel efficiency. This dynamic adjustment resolves the contradiction between energy efficiency and responsiveness.
Solution Approach 2:
The system changes the flow rate parameter of the hydraulic fluid by adjusting the opening area of the directional control valve. The controller modifies this parameter in real-time based on operation lever changes detected by the operation amount sensor, allowing the system to switch between fuel-efficient mode (restricted flow) and responsive mode (increased flow) to resolve the contradiction.
2Use of energy by moving object
If the opening area of the directional control valve is restricted to reduce supply flow rate, then fuel efficiency is improved, but work accuracy deteriorates during rapid operation lever changes
Solution Approach 1:
The flow restriction device dynamically adjusts the opening area based on real-time detection of operation lever position changes. When rapid changes are detected, the device increases the opening area to maintain work accuracy. When changes are minimal, it maintains restriction for fuel efficiency. This dynamic behavior resolves the contradiction between fuel efficiency and work accuracy.
Solution Approach 2:
The operation amount sensor provides feedback about the operation lever position to the controller. The controller uses this feedback to determine when to adjust the opening area of the directional control valve, ensuring work accuracy is maintained during rapid operations while preserving fuel efficiency during stable operations.
3Ease of operation
If the supply flow rate to the bucket directional control valve is reduced proportionally to boom raising operation amount, then simultaneous movement capability is improved, but responsiveness deteriorates during frequent operation lever changes
Solution Approach 1:
The flow restriction device applies different flow control characteristics to different operating conditions. When the operation lever is frequently changed, the device provides minimal restriction to maintain responsiveness. When the lever position is stable, it applies flow restriction to enable simultaneous movement capability. This localized adaptation to different operational contexts resolves the contradiction.
Solution Approach 2:
The system dynamically adjusts the degree of flow restriction based on the operation state detected by the operation amount sensor. The opening area is increased when rapid lever changes occur to maintain responsiveness, and reduced when stable operation is detected to enable simultaneous movement capability, resolving the contradiction between these two operational requirements.
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 system enhances responsiveness and maintains work efficiency by allowing increased fluid flow during rapid operation lever changes, preventing the decline in work accuracy and efficiency associated with conventional control methods.
Implementation Method 1
a hydraulic pump (41) driven by a prime mover (22)
Implementation Method 2
a plurality of hydraulic actuators (32, 34, 36) each driven by a pressurized fluid delivered from the hydraulic pump (41)
Implementation Method 3
a plurality of directional control valves (43, 44) each controlling a direction and a flow rate of the pressurized fluid supplied from the hydraulic pump (41)
Implementation Method 4
a flow restriction device (45) that can restrict a flow rate of the pressurized fluid in at least one of a meter-in passage and a meter-out passage of one of the directional control valves (44)
Data Source
Figure 1
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AI summary
A work machine includes directional control valves 43 and 44 each controlling a direction and a flow rate of a pressurized fluid supplied to each a boom cylinder 32 and a bucket cylinder 36; operation amount sensors 51a, 52a, and 52b detecting operation amounts of operation devices 51 and 52; a variable flow control valve 45 that can restrict the flow rate of the pressurized fluid in a meter-in passage of the directional control valve 44 related to the bucket cylinder 36; and a controller 60 controlling the variable flow control valve on the basis of the detection results by the operation amounts from the operation amount sensors, and the controller changes over an action mode to any one of a normal mode for restricting the flow rate of the pressurized fluid by the variable flow control valve and a responsiveness priority mode for not restricting the flow rate of the pressurized fluid by the variable flow control valve in response to the detection results of the operation amounts of the plurality of operation devices. It is thereby possible to enhance responsiveness in an action that requires responsiveness such as an action in which an operation amount of an operation lever frequently changes in a short period of time and to suppress a decline in work efficiency.