Construction Machine Back-Pressure Compensation Valve Dynamics
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Solution Overview
Problem
Existing construction machines face issues with cavitation and increased power loss due to fixed or variable back-pressure compensation valves, which generate unnecessary high back pressure regardless of operation conditions, leading to inefficiencies in both cavitation prevention and power consumption.
Innovation Solution
A construction machine with a back-pressure compensation valve that has a switchable setting pressure, controlled by a controller that adjusts the pressure based on traveling operation amounts and slewing conditions, ensuring optimal back pressure for preventing cavitation and minimizing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed back-pressure compensation valve is used with high setting pressure to prevent cavitation, then cavitation prevention is improved, but power loss increases due to unnecessarily high back pressure
Solution Approach 1:
The back-pressure compensation valve is changed from a fixed type to a variable type, allowing the setting pressure to be dynamically adjusted based on operating conditions. The control section modifies the back pressure setting according to the operation state (traveling vs. working), enabling the system to maintain high back pressure when needed for cavitation prevention while reducing back pressure during high-speed traveling to minimize power loss.
2Reliability
If a variable back-pressure compensation valve is used with always high setting pressure during traveling, then cavitation prevention is improved, but power loss increases due to unnecessary back pressure at high speeds
Solution Approach 1:
The control section monitors the operation state of the construction machine (detecting whether traveling or working operations are being performed) and uses this feedback to automatically adjust the back-pressure compensation valve setting. When high-speed traveling is detected, the control section reduces the back pressure setting; when working operations are detected or low-speed traveling occurs, the control section maintains or increases the back pressure setting to prevent cavitation.
3Reliability
If back pressure is increased to prevent cavitation at low traveling speeds, then cavitation prevention is improved, but power loss increases
Solution Approach 1:
The system dynamically changes the back pressure parameter based on the traveling speed and operation conditions. At low traveling speeds where cavitation risk is high, the back pressure is maintained at a higher level. At high traveling speeds where hydraulic oil flow rate increases and circuit pressure loss generates sufficient back pressure, the setting pressure of the back-pressure compensation valve is reduced to minimize power loss while maintaining adequate cavitation protection.
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 effectively reduces power loss during high-speed travel while maintaining cavitation prevention by dynamically adjusting the back-pressure compensation valve's setting pressure, ensuring suitable back pressure for the operating conditions, thus achieving both goals simultaneously.
Implementation Method 1
a back-pressure compensation valve that generates back pressure in a return pipe line connecting each of the control valves to a tank
Implementation Method 2
a hydraulic pump as a hydraulic pressure source that supplies hydraulic oil to a plurality of hydraulic actuators
Data Source
AI summary
A construction machine includes: a lower traveling body; an upper slewing body; a front attachment; a plurality of hydraulic actuators including traveling motors; hydraulic pumps; a plurality of control valves for the hydraulic actuators; a plurality of operation units for the control valves; traveling operation detectors that detect operations for the operation units for the traveling motors of the operation units; a back-pressure compensation valve generating back pressure in a return pipe line connecting each of the control valves and a tank and having a setting pressure switchable between low and high pressure setting values; and a back-pressure control section performing a back-pressure lowering control of making the setting pressure of the back-pressure compensation valve be the low pressure setting value when traveling operation amounts in the traveling operation units are large.