Excavator Hydraulic Preferential Function Control
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Solution Overview
Problem
The existing hydraulic systems for construction machines, such as excavators, face difficulties in smoothly distributing and supplying hydraulic fluid according to the operator's operation amount, especially during excavation or leveling work, leading to uneven flow rates and reduced workability due to the preferential function's impact on load pressure and flow paths.
Innovation Solution
A hydraulic system with first and second variable displacement pumps, main control valves with spools for actuator control, operation levers, and a control device that allows operators to set or release a preferential function using an on/off switch or cab-mounted cluster, enabling flexible control of flow rates and signal pressures through pressure sensors and electro proportional pressure reducing valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a preferential function is implemented to secure hydraulic fluid supply to high-load actuators, then hydraulic fluid distribution is improved for excavation work, but operability and workability deteriorate during leveling work where smooth distribution according to operation amount is needed
Solution Approach 1:
The patent applies dynamics by making the preferential function switchable rather than fixed. The control unit enables the operator to turn the preferential function on or off based on the work type, allowing the system to adapt its behavior dynamically. During excavation work, the preferential function is activated to ensure reliable hydraulic fluid supply to high-load actuators. During leveling work, the preferential function is deactivated to allow smooth hydraulic fluid distribution according to operation lever movement, thereby resolving the contradiction between reliability and ease of operation.
2Quantity of substance
If the aperture ratio of spool is reduced to prioritize hydraulic fluid flow to high-load actuators, then hydraulic fluid distribution is improved for excavation, but flow rate control precision deteriorates
Solution Approach 1:
The patent makes the aperture ratio of the spool dynamically adjustable based on whether the preferential function is activated. When the preferential function is on, the aperture ratio is reduced to prioritize hydraulic fluid flow to high-load actuators for excavation work. When the preferential function is off, the aperture ratio returns to normal, allowing precise flow rate control according to operation lever movement for leveling work. This dynamic adjustment resolves the contradiction between quantity of hydraulic fluid and flow rate control precision.
3Productivity
If preferential function limits flow paths to ensure hydraulic fluid supply, then workability is improved for excavation tasks, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent applies universality by integrating the preferential function control into the existing hydraulic system through a control unit that can be switched on or off. The same control unit and spool mechanism serve multiple purposes: they enable the preferential function during excavation work to improve workability, and they allow normal operation during leveling work. This multi-functional approach avoids adding separate complex control systems, thereby resolving the contradiction between productivity and device complexity.
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 configuration enhances operability and work efficiency by allowing operators to adjust the preferential function according to work types, ensuring consistent hydraulic fluid supply and reducing operational difficulties during excavation and leveling tasks.
Implementation Method 1
pressure sensors detecting a level of signal pressure
Implementation Method 2
electro proportional pressure reducing valves reducing the signal pressure
Implementation Method 3
first and second variable displacement hydraulic pumps connected to an engine; first and second hydraulic actuators connected to the first and second hydraulic pumps
Implementation Method 4
main control valves installed in flow paths between the first and second hydraulic pumps and the first and second hydraulic actuators, respectively, and having spools shifted to control a start, a stop, and a direction change
Data Source
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AI summary
A hydraulic system for a construction machine is provided, which enables a user to set or release a preferential function when an excavation work or leveling work using an excavator is performed. The hydraulic system for a construction machine includes first and second hydraulic pumps connected to an engine; first and second hydraulic actuators connected to the first and second hydraulic pumps; main control valves (MCV) installed in flow paths between the first and second hydraulic pumps and the first and second hydraulic actuators, respectively, and having spools shifted to control a start, a stop, and a direction change of the first and second hydraulic actuators; first and second operation levers outputting operation signals in proportion to a user's operation amount; a control device limiting a flow rate that is applied to the spool of any one of the first and second hydraulic actuators that share the first and second hydraulic pumps according to a user's operation of the first or second operation lever for a preferential function; and a control unit controlling driving of the control device so as to shift to or release the preferential function according to a user's determination.