Hydraulic Valve Calibration Using Current-Displacement Mapping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for calibrating electrically controlled hydraulic valves rely on assumed constant factors, which can lead to significant errors due to variations in solenoid characteristics and wear, causing performance issues and potential damage to hydraulic systems, especially since on-machine calibration methods require specific components like joysticks and position sensors that may not be available in all systems.
Innovation Solution
A method and system for calibrating electrically controlled hydraulic valves using a known relationship between flow rate and displacement, involving a first and second valve where the second valve is calibrated by pumping hydraulic fluid through both, actuating the valve to specific positions, and correlating current levels with displacements to establish an accurate current-displacement relationship, allowing for on-machine calibration without the need for joysticks or position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a nominal value of factor K is used for all valves of the same type, then calibration time and cost are reduced, but measurement precision and control accuracy deteriorate due to variations in solenoid characteristics and wear
Solution Approach 1:
The calibration system uses the hydraulic circuit's own components (pump, first valve, second valve) to perform calibration without external equipment. The controller actuates the second valve to different positions, measures current and flow rate, and automatically calculates the actual factor K, enabling self-calibration that is both time-efficient and accurate.
Solution Approach 2:
The patent replaces traditional mechanical calibration methods (manual adjustment, external testing equipment) with an automated electronic system. The controller electronically actuates the valve, measures electrical current, calculates flow rate from pressure differential, and computes the calibration factor K through software algorithms, substituting mechanical procedures with electronic and computational methods.
2Measurement precision
If laboratory calibration is performed for each valve, then measurement precision is improved, but productivity and ease of operation worsen due to machine downtime and complex procedures
Solution Approach 1:
The calibration is performed on-machine using the hydraulic circuit's own operational components. The system uses the pump already running, the first valve already in the circuit, and the second valve being calibrated, eliminating the need to remove valves for external laboratory calibration. This self-service approach maintains high machine availability while achieving accurate calibration.
Solution Approach 2:
The calibration procedure is performed proactively during normal operation or scheduled maintenance windows, before performance degradation becomes critical. The controller automatically executes the calibration sequence, determining the actual factor K and updating control parameters in advance, preventing future control inaccuracies without requiring unplanned downtime.
3Device complexity
If the first valve is used to control flow rate through the second valve, then device complexity is reduced by eliminating external equipment, but ease of operation worsens due to the interdependence of valve operations
Solution Approach 1:
The first valve serves multiple functions: it controls flow rate through the second valve during calibration, it can independently control hydraulic circuits during normal operation, and it works in conjunction with the pump to provide the necessary fluid power. This multi-functionality eliminates the need for separate calibration equipment while maintaining operational flexibility through programmable control sequences.
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 accurate characterization and control of hydraulic systems, extending the service life of valves and reducing costs by allowing for on-machine calibration, thereby maintaining precise operation and preventing malfunctions.
Implementation Method 1
When current is applied to the solenoid, the armature will move under electro-magnetic forces generated by the solenoid.
Data Source
AI summary
A method of calibrating an electrically controlled hydraulic valve having a known relationship between flow rate through the valve and displacement of a valve element is disclosed. The method includes ascertaining a first current level for actuating the electrically controlled hydraulic valve to move the valve element to a position adjacent an inlet port, and a first displacement of the valve element responsive to the first current level. The method also includes ascertaining a second current level for actuating the electrically controlled hydraulic valve to move the valve element from the position adjacent the inlet port to a position permitting flow through the inlet port, and ascertaining a second displacement of the valve element responsive to the second current level. The method further includes establishing a relationship between current and displacement associated with the electrically controlled hydraulic valve.