Hydraulic Valve Calibration Using Pilot Pressure and Flow Mapping
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Solution Overview
Problem
The existing control valves in hydraulic systems of working machines like hydraulic excavators suffer from manufacturing tolerances in electromagnetic proportional pressure reducing valves, leading to inconsistent actuator operation speeds, and require costly, specialized structures that occupy valuable space.
Innovation Solution
A calibration system using a spool valve with a pressure compensation valve and electromagnetic proportional valves to maintain consistent pilot pressure, coupled with a controller that adjusts current output based on operator input to calibrate the relationship between operation amount and supply flow rate without a specialized structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an on-off valve structure is integrally formed in the spool valve to enable calibration, then calibration can be performed, but the control valve becomes larger and manufacturing cost increases
Solution Approach 1:
The calibration function is separated from the main control valve body. Instead of integrating an on-off valve structure into the spool valve, the invention uses a separate calibration circuit with a calibration valve that can be independently operated. This segmentation allows calibration functionality to be added without increasing the size of the main control valve components.
Solution Approach 2:
A dedicated calibration valve acts as an intermediary component to enable calibration measurements. This separate calibration valve provides the necessary flow control for calibration purposes without requiring modifications to the spool valve structure, thus avoiding size increase while maintaining calibration capability.
2Measurement precision
If an on-off valve structure is integrally formed in the spool valve to enable calibration, then calibration can be performed, but manufacturing cost increases due to customization
Solution Approach 1:
The calibration function is separated from the main control valve body. Instead of integrating an on-off valve structure into the spool valve, the invention uses a separate calibration circuit with a calibration valve that can be independently operated. This segmentation allows calibration functionality to be added without increasing the size of the main control valve components.
Solution Approach 2:
The calibration valve serves multiple purposes: it enables calibration measurements during manufacturing/testing and can potentially be used for maintenance adjustments. This multi-functionality eliminates the need for specialized integrated structures, allowing standard off-the-shelf components to be used, thereby reducing manufacturing costs.
3Ease of manufacture
If manufacturing tolerance of electromagnetic proportional pressure reducing valve varies, then production cost is reduced, but the relationship between operator operation amount and supply flow rate becomes inconsistent
Solution Approach 1:
The calibration process uses feedback from actual measurements to adjust the control characteristics. By measuring the actual relationship between operator input and supply flow rate, and comparing it with the target relationship, the system generates correction data that compensates for manufacturing tolerances, ensuring consistent performance despite variations in electromagnetic valve characteristics.
Solution Approach 2:
The calibration process modifies operational parameters (current values to the electromagnetic proportional valve) to compensate for manufacturing variations. By adjusting these parameters based on measured deviations, the system achieves the desired flow rate consistency without requiring tighter manufacturing tolerances, thus maintaining low production costs.
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 high-precision calibration efficiently and cost-effectively, reducing the need for specialized structures and minimizing space requirements.
Implementation Method 1
an electromagnetic proportional valve which outputs the pilot pressure to the spool valve according to a current value outputted from the control means
Implementation Method 2
a pressure compensation valve which keeps a differential pressure of the opening for supplying of the spool valve
Data Source
AI summary
Problem: Calibration to make the correspondence relationship between the operation amount of the operator and the supply flow rate to the hydraulic actuator be a preset setting relationship is made easy. Solution: The control valve that controls the supply flow rate to the hydraulic actuator is configured with a spool valve, a pressure compensation valve that maintains a front and rear differential pressure of the spool valve to be constant, and electromagnetic proportional valves that output pilot pressure to the spool valve, and a measured data that actually measures the correspondence between the output pilot pressure from the electromagnetic proportional valves and the supply flow from the control valve before the control valve is installed in the working machine is configured to calibrate the corresponding data of the operation amount of the operator and the output current value to the electromagnetic proportional valves.