Pilot Circuit Bypass Valve for Excavator Actuator Responsiveness
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Solution Overview
Problem
Hydraulic excavators face degraded responsiveness of actuators due to pressure loss from proportional solenoid valves, which affects their ability to perform efficient operations like shaking work and slope taming, where quick boom movements are required.
Innovation Solution
A work machine design that includes a bypass line and valve system to bypass the proportional solenoid valve, allowing for increased hydraulic signal flow and maintaining responsiveness even when the front control function is activated, thereby reducing pressure loss and enhancing energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a proportional solenoid valve is disposed in the pilot line to enable front control functionality, then the front work implement can be limited to operate within a predetermined area, but the responsiveness of the actuator to lever operations is degraded due to pressure loss
Solution Approach 1:
The pilot line is segmented into multiple paths: a main pilot line passing through the proportional solenoid valve for normal front control operations, and a bypass line with a bypass valve that can be activated independently. This segmentation allows the system to selectively use either path based on operational requirements, resolving the contradiction between maintaining front control functionality and preserving actuator responsiveness.
Solution Approach 2:
The bypass valve acts as an intermediary component that provides an alternative pathway for the pilot pressure. When high responsiveness is needed, the bypass valve opens to allow pilot pressure to flow through the bypass line, circumventing the pressure loss caused by the proportional solenoid valve while still enabling front control functionality through the main line when needed.
2Adaptability or versatility
If the proportional solenoid valve is used to restrict operations of the front work implement, then area limiting excavation control is achieved, but pressure loss occurs which reduces hydraulic signal effectiveness
Solution Approach 1:
The hydraulic circuit is divided into two parallel pathways: the main pilot line through the proportional solenoid valve for precise area limiting control, and the bypass line that preserves hydraulic pressure. This allows the system to maintain area limiting functionality while minimizing energy loss by selecting the appropriate path based on operational needs.
Solution Approach 2:
The system dynamically changes the flow path parameter by opening or closing the bypass valve based on operational requirements. When area limiting control is the priority, the proportional solenoid valve is used; when energy efficiency and pressure maintenance are priorities, the bypass valve is opened to alter the flow path and reduce pressure loss.
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 solution achieves both responsiveness of the hydraulic actuators to operator inputs and effective front control functionality, ensuring efficient operations and improved energy efficiency by minimizing pressure loss through the bypass valve system.
Implementation Method 1
a proportional solenoid valve disposed in at least one of the pilot lines, and a front control section configured to calculate a limit command value for restricting operations of the front work implement through control of the proportional solenoid valve
Implementation Method 2
a bypass line configured to connect a portion in the pilot line upstream of the proportional solenoid valve and a portion in the pilot line downstream of the proportional solenoid valve; a bypass valve serving as an open/close valve disposed in the bypass line
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
To achieve both responsiveness of an actuator to an operation and front control functionality, a work machine including a front control section configured to calculate a limit command value for restricting an operation of a front work implement through control of, for example, a proportional solenoid valve 61b disposed in, for example, a pilot line 51b1 includes: for example, a bypass line 81B that bypasses, for example, the proportional solenoid valve 61b in, for example, the pilot line 51b1; for example, a bypass valve 81b disposed in, for example, the bypass line 81B; a switch configured to output a signal to turn on or off control by the front control section; an on/off determining part configured to determine whether the signal from the switch is an on signal that brings front control into an on state or an off signal that brings the front control into an off state; an open/close command part configured to generate an open command signal to open the bypass valve when the signal is determined to be the off signal and generate a close command signal to close the bypass valve when the signal is determined to be the on signal; and an output section configured to output the open command signal or the close command signal to the bypass valve.