Hydraulic Circuit Back Pressure for Pilot Line Aeration Control
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Solution Overview
Problem
Current electro-hydraulic circuits experience poor controllability due to low fluid pressures in the pilot lines, leading to aeration of hydraulic fluid and 'spongy' conditions, which result in variable resistance and oscillation of the main spool valve during displacement.
Innovation Solution
The implementation of a hydraulic circuit with fixed minimum back pressures in the pilot lines to maintain dissolved air, preventing aeration and ensuring consistent hydraulic fluid pressure, thereby stabilizing the bulk modulus and resistance on the drain side of the main spool valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If ePRVs are designed with little resistance in the relieving stage to minimize maximum hydraulic fluid pressure, then energy consumption is reduced, but the pilot line pressure becomes low causing aeration and poor controllability
Solution Approach 1:
The patent introduces a back pressure valve that changes the pressure parameter in the pilot line. By maintaining a minimum back pressure (e.g., 5-20 psi) in the pilot line during the relieving stage, the system prevents aeration while still allowing the ePRV to operate with low resistance. This parameter change resolves the contradiction by decoupling the pressure minimization goal from the aeration prevention requirement.
Solution Approach 2:
The back pressure valve acts as an intermediary component between the ePRV and the pilot line. It mediates the conflict between low resistance operation and sufficient pressure maintenance by providing a pressure buffer that prevents air dissolution without significantly increasing the overall system pressure or energy consumption.
2Stress or pressure
If pilot line pressure is kept low to minimize maximum hydraulic fluid pressure, then system pressure requirements are reduced, but dissolved air comes out of solution forming air bubbles
Solution Approach 1:
The back pressure valve changes the pressure parameter locally in the pilot line, maintaining it above the threshold required to keep air dissolved (typically above 5-20 psi). This localized parameter change allows the rest of the system to operate at lower pressures while preventing aeration in the critical pilot line where air dissolution occurs.
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 solution enhances controllability over the displacement of the main spool valve by maintaining a consistent hydraulic fluid pressure in the pilot lines, preventing air bubbles and ensuring precise positioning of hydraulic systems.
Implementation Method 1
a fixed minimum back pressure sufficient to maintain dissolved air in the hydraulic fluid
Data Source
AI summary
A hydraulic circuit is disclosed. The hydraulic circuit may comprise an actuation valve configured to actuate a flow of hydraulic fluid to and from the hydraulic consumer, a first control valve in fluid communication with the actuation valve through a first pilot line and configured to displace the actuation valve to a first position when actuated, and a second control valve in fluid communication with the actuation valve through a second pilot line and configured to displace the actuation valve to a second position when actuated. The first pilot line and the second line may each have a fixed minimum back pressure sufficient to maintain dissolved air in the hydraulic fluid.