Excavator Pilot Line Switching for Fast Hydraulic Response
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Solution Overview
Problem
Hydraulic excavators face reduced responsiveness of actuators due to pressure loss from solenoid proportional valves, especially when the front implement control function is not actively limiting operations, affecting efficiency in tasks like rapid shaking and slope tamping.
Innovation Solution
A work machine design that includes a pilot line with a solenoid proportional valve, a selector valve, and a front implement control section, allowing the selector valve to switch between direct and pressure-reduced signal paths to maintain responsiveness and compatibility with the front implement control function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a solenoid proportional valve is provided to the operation signal line to reduce pressure and limit front work implement operation, then front implement control function is achieved, but responsiveness of actuators in response to lever operation decreases due to pressure loss
Solution Approach 1:
The system dynamically switches between two operational modes using a selector valve: a first mode where the operation signal line is directly connected to the control valve for high responsiveness, and a second mode where the solenoid proportional valve is inserted to limit the front work implement operation. This dynamic reconfiguration allows the system to adapt between speed and control function based on operational needs.
Solution Approach 2:
The pilot line is segmented into multiple paths: a first pilot line providing direct connection for high-speed response, and a second pilot line passing through the solenoid proportional valve for controlled operation. The selector valve enables switching between these segmented paths, allowing the system to choose the appropriate signal transmission path based on whether front implement control is required.
2Reliability
If the solenoid proportional valve is always present in the operation signal line, then front implement control can act to limit excavation, but pressure loss occurs even when front implement control does not act, reducing actuator responsiveness
Solution Approach 1:
The solenoid proportional valve is extracted from the main operation signal path and placed in a separate, selectable path. The selector valve enables the system to take the valve out of the signal path when front implement control is not needed, eliminating unnecessary pressure loss and energy waste while maintaining the valve's availability when control function is required.
Solution Approach 2:
The system dynamically reconfigures the pilot line topology based on whether front implement control is active. When control is not needed, the selector valve creates a direct path bypassing the solenoid proportional valve, eliminating pressure loss. When control is activated, the system switches to route the signal through the valve, enabling reliable control function only when necessary.
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
Enhances the responsiveness of actuators during operations by minimizing pressure losses and ensuring compatibility with the front implement control function, improving efficiency and energy efficiency.
Implementation Method 1
at least one solenoid proportional valve provided to the pilot line, the at least one solenoid proportional valve reducing pressure of one of the hydraulic signals generated by a corresponding operation lever device
Implementation Method 2
a hydraulic pump configured to deliver a hydraulic operating oil that drives the actuators
Implementation Method 3
a pilot pump configured to supply a hydraulic operating oil to the operation lever devices
Data Source
AI summary
A work machine includes: control valves that control flows of a hydraulic operating oil supplied to actuators; operation lever devices that generate hydraulic signals to be output to the corresponding control valves according to an operation; solenoid proportional valves that reduce pressure of the hydraulic signals generated by the corresponding operation lever devices; and a front implement control section that controls the solenoid proportional valves. The work machine further includes: operation signal lines connected to the operation lever devices; signal input lines connected to the control valves; pressure reducing lines provided with the solenoid proportional valves; and selector valves that have a first position that interrupts connection of the operation signal lines and the pressure reducing lines and directly connects the operation signal lines to the signal input lines, and a second position that connects the operation signal lines to the signal input lines via the pressure reducing lines.