Open-Center Hydraulic Valve Control With Spool Offset Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Open-center electro-hydraulic control valves require operators to gradually actuate the control lever to balance loads, leading to uncontrolled movements and increased complexity with closed-center valves.
Innovation Solution
Implementing a feedback control system with a position sensor for the hydraulic actuator, which identifies and compensates for the offset of the spool position, allowing the valve to behave like a closed-center valve by manipulating the control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an open center electro-hydraulic control valve is used, then the device complexity is reduced compared to closed center valves, but the ease of operation deteriorates because the operator must gradually actuate the control lever to balance loads
Solution Approach 1:
The system uses a position sensor to detect the actual position of the hydraulic actuator and feeds this information back to the control unit. The control unit calculates the difference between the commanded position (from control lever) and actual position, then adjusts the control signal to the electro-hydraulic valve accordingly. This closed-loop feedback mechanism eliminates the need for gradual manual actuation while maintaining the simplicity of open center valve architecture.
Solution Approach 2:
The patent replaces the manual mechanical balancing operation with an automated electronic control system. Instead of relying on the operator's manual skill to gradually balance loads, the system uses electronic sensors, processors, and actuators to automatically adjust the valve position based on real-time actuator position feedback, thereby improving ease of operation without increasing mechanical complexity.
2Reliability
If the operator acts gradually on the control lever to balance the load, then uncontrolled movements are prevented, but the productivity deteriorates due to the time required to initiate organ movement
Solution Approach 1:
The real-time feedback from the position sensor allows the control system to continuously monitor actuator position and adjust the valve control signal dynamically. This enables the system to safely and rapidly initiate movement by electronically balancing the load without requiring gradual manual actuation, thereby improving productivity while maintaining reliability through automated control.
Solution Approach 2:
The control system performs preliminary automatic load balancing through electronic adjustment of the valve position before the organ actually moves. This preliminary electronic balancing action eliminates the need for gradual manual actuation, allowing the operator to simply position the control lever and have the system automatically prepare and initiate movement rapidly and safely.
3Reliability
If there is no fixed relationship between control lever position and organ movement, then load balancing is achieved, but the ease of operation deteriorates as the operator cannot predict when movement will begin
Solution Approach 1:
The position sensor provides real-time feedback on actuator position, and the control unit uses this information to automatically adjust the valve control signal. This creates a direct, predictable relationship between control lever position and organ movement, as the system electronically compensates for load variations to ensure movement begins at the expected control lever position, thereby improving ease of operation while maintaining load balancing capability.
Solution Approach 2:
The patent replaces the indirect mechanical load-balancing mechanism with a direct electronic control system. Instead of relying on gradual manual adjustment to achieve load balance, the electronic system instantly calculates and applies the necessary valve adjustment based on sensor feedback, creating a predictable and direct relationship between control lever position and organ movement that improves ease of operation.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Method of controlling an electro-hydraulic open center control valve (OCV) for the operation of a hydraulic actuator (ACT) of an organ (A, B) of a working or agricultural vehicle (VHE), powered by a pump (P), wherein a control signal of the control valve is generated proportionally to a position of a control lever (J), the method including a first step (Step 1) of detecting the exceeding of a predetermined position (DB) of the control lever (J) of the hydraulic organ, a second and consequent step (Step 2) of increasing and measuring a control signal value (Offset) at a staring movement of said hydraulic actuator and a third step (Step 3) of setting a positive offset to the control signal (LS) approximately equal to said control signal value, as long as the position of the control lever (J) of the hydraulic organ exceeds said predetermined position (DB).