Electrohydraulic Spool Pressure Feedback for Aging Valve Drift
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Solution Overview
Problem
In construction machinery, electro-hydraulic main control valves with electro proportional pressure reducing valves (EPPRVs) face increased failure risks over time, leading to operating pressures that deviate from design specifications, which deteriorates machine performance.
Innovation Solution
An electro-hydraulic control apparatus and method that includes a control valve, a spool displacement adjusting valve, a pressure sensor, and a controller to detect and correct pressure differences between the secondary pressure and a design pressure using a characteristic function, ensuring the pressure command signal is adjusted to maintain optimal operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electro proportional pressure reducing valve (EPPRV) is used in the electro-hydraulic main control valve, then the control precision and responsiveness are improved, but the reliability deteriorates due to increased failure risks over time
Solution Approach 1:
The patent implements a feedback mechanism where a pressure sensor continuously monitors the secondary pressure output from the EPPRV, and the controller compares the detected pressure with the expected pressure command signal. When deviations are detected, the controller automatically corrects the pressure command signal to maintain accurate control despite EPPRV degradation or failure, thus preserving control precision while compensating for reliability issues.
Solution Approach 2:
The system performs self-diagnosis and self-correction by detecting pressure deviations and automatically adjusting the pressure command signal through the controller. This self-service capability allows the system to maintain reliable operation without external intervention, compensating for the inherent reliability weaknesses of the EPPRV over time.
2Duration of action of moving object
If the usage period of the electro proportional pressure reducing valve increases, then the experience and data accumulation are improved, but the manufacturing precision deteriorates as secondary pressure deviates from design specifications
Solution Approach 1:
The patent dynamically changes the pressure command signal parameter based on detected secondary pressure deviations. The controller adjusts the command signal to compensate for drift in the EPPRV's pressure output over time, maintaining pressure precision despite the aging valve. This involves modifying control parameters (pressure command signal) to counteract degradation effects.
Solution Approach 2:
The continuous feedback loop monitors secondary pressure throughout the usage period and automatically corrects deviations from design specifications. This ensures that even as the EPPRV ages and its characteristics drift, the actual pressure output remains within acceptable tolerances, effectively maintaining manufacturing precision over extended operational periods.
3Adaptability or versatility
If the secondary pressure deviates from the pressure command signal, then the adaptability to actual conditions is improved, but the productivity deteriorates due to pump pressure operating at incorrect pressure
Solution Approach 1:
The feedback mechanism detects when secondary pressure deviates from the pressure command signal and triggers automatic correction. By maintaining accurate pressure control, the system prevents productivity losses that would result from the pump operating at incorrect pressures, while still allowing necessary pressure adaptations to actual operating conditions.
Solution Approach 2:
The patent replaces mechanical pressure regulation mechanisms with an electro-hydraulic control system that uses electrical signals and electronic control to regulate pressure. This substitution enables more precise and responsive pressure control, maintaining productivity by preventing incorrect pump pressure operation while adapting to varying operational requirements.
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 continuously maintains reliable performance of construction machinery by correcting pressure command signals when deviations occur, ensuring the secondary pressure remains within a preset allowable range, even as the usage period elapses.
Implementation Method 1
a pressure sensor to detect the secondary pressure outputted from the spool displacement adjusting valve
Implementation Method 2
a spool displacement adjusting valve configured to output a secondary pressure in proportion to an inputted pressure command signal
Data Source
AI summary
An electro-hydraulic control apparatus for construction machinery includes a control valve installed in a hydraulic line between a hydraulic pump and an actuator to control operations of the actuator according to a displacement amount of a spool therein, a spool displacement adjusting valve configured to output a secondary pressure in proportion to an inputted pressure command signal to the spool of the control valve to control the displacement amount of the spool of the control valve, a pressure sensor to detect the secondary pressure outputted from the spool displacement adjusting valve, and a controller configured to output the pressure command signal to the spool displacement adjusting valve according to a manipulation signal of the construction machinery, and to correct the pressure command signal when a pressure difference between the detected secondary pressure and a design pressure predetermined by the pressure command signal is out of a preset allowable range.