Excavator Float Valve Segmentation for Jack-Up Stability
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Solution Overview
Problem
Conventional hydraulic drive systems for hydraulic excavators fail to prevent the blade from falling during jack-up operations when falsely operated, while also hindering effective leveling work due to incorrect positioning of the blade directional control valve.
Innovation Solution
A hydraulic drive system with a float instruction device, float valve, and float control device that changes the float valve's position based on the blade's operation state, ensuring the blade cylinder's chambers are not communicated with the tank during jack-up operations and are communicated during leveling work, preventing false float states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the blade directional control valve is configured to communicate both rod-side and bottom-side hydraulic chambers with the tank at float position, then the blade can follow ground undulations for leveling work, but the machine body falls when falsely operated during jack-up operation
Solution Approach 1:
The hydraulic control system is segmented into two independent control paths: one for the rod-side chamber and one for the bottom-side chamber. The float valve specifically controls communication of the bottom-side chamber with the tank, while the blade directional control valve controls the rod-side chamber. This segmentation allows independent control of blade float state and jack-up stability.
Solution Approach 2:
The float valve acts as an intermediary component between the bottom-side hydraulic chamber and the tank. It mediates the hydraulic connection, allowing the bottom-side chamber to communicate with the tank only when the float valve is in the float position, thereby enabling controlled float operation without compromising jack-up safety.
2Reliability
If the feeding/discharging hydraulic line leading to the bottom-side hydraulic chamber is closed at float position, then the machine body does not fall during jack-up operation, but the blade cannot follow ground undulations for leveling work
Solution Approach 1:
The hydraulic control system is segmented into two independent control paths: one for the rod-side chamber and one for the bottom-side chamber. The float valve specifically controls communication of the bottom-side chamber with the tank, while the blade directional control valve controls the rod-side chamber. This segmentation allows independent control of blade float state and jack-up stability.
Solution Approach 2:
The float valve dynamically changes position based on operational requirements, transitioning between float position (enabling leveling work) and normal position (ensuring jack-up safety). This dynamic control allows the system to adapt to different operational modes, maintaining both leveling capability and jack-up stability as needed.
3Adaptability or versatility
If a float valve is added to control the rod-side hydraulic chamber, then the blade can be set into float state, but the system complexity increases
Solution Approach 1:
The float valve is integrated into the existing hydraulic control system, sharing common hydraulic lines and control mechanisms with the blade directional control valve. This multi-functional design allows the float valve to perform its specific function of controlling bottom-side chamber communication while utilizing existing system infrastructure, thereby minimizing overall system 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
Enables both effective leveling work and jack-up operations by maintaining the blade in a float state without causing the machine body to fall, even during incorrect operator inputs, by dynamically controlling the float valve's position based on the blade's operational state.
Implementation Method 1
a plurality of actuators driven by a hydraulic fluid delivered from at least one hydraulic pump
Implementation Method 2
the blade falls by a dead weight thereof to come in contact with the ground
Data Source
AI summary
A hydraulic drive system for a hydraulic excavator that enables leveling work and a jack-up operation by a blade in a float state, that can prevent a body from falling even when an operator has falsely operated the hydraulic excavator during the jack-up operation by the blade, and that yet can perform favorable leveling work with the blade turned into the float state is provided. A float switch37, a float valve 38, and a controller 34 are provided, the float valve 38 is changed over to a float position VI upon operating the float switch 37 when the blade is not in a jack-up state, the float valve 38 is changed over from the float position VI to a normal position V when the float valve 38 is in a state of being at the float position VI and an operation lever device 22 has been operated, and the float valve 38 is kept at the normal position V when the float valve 38 is at the normal position V and the float switch 37 has been operated in the jack-up state.