Hydraulic Actuator Setpoint Control for Redundant Valve Switching
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Solution Overview
Problem
The existing directional control valve modules for hydraulic actuators face issues such as pressure drops and difficulty in determining if one directional spool valve can take over the function of another during switching, leading to potential actuator malfunction and restricted travel range due to particle deposits, especially during constant operation.
Innovation Solution
A method and control device that vary the position setpoint of electrohydraulic proportional valves to maintain constant hydraulic input pressure, allowing for setpoint manipulation and testing to ensure redundancy and operational reliability, even in the presence of failures, by using redundant valves to compensate for pressure changes and detect malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching between redundant directional control valves is performed, then operational reliability is improved through redundancy, but pressure drops occur and actuator position stability deteriorates
Solution Approach 1:
The control system performs preliminary actions by detecting pressure changes at the hydraulic output before they significantly affect the actuator, and preemptively adjusts the position setpoint to compensate for upcoming pressure drops during valve switching, thereby maintaining actuator position stability
Solution Approach 2:
The system continuously monitors the actual position of the actuator and the pressure at the hydraulic output, using this feedback information to dynamically adjust the position setpoint and maintain stable actuator operation despite valve switching events
2Device complexity
If constant operation of directional control valves is maintained, then system simplicity is preserved, but particle deposits accumulate restricting actuator travel range
Solution Approach 1:
The control system implements periodic action by automatically varying the position setpoint to induce small oscillating movements of the actuator during constant operation, which prevents particle deposits from accumulating and restricting the actuator travel range, while maintaining overall system simplicity
3Length of moving object
If position setpoint is varied to prevent particle deposits, then actuator travel range is maintained, but system complexity increases due to setpoint manipulation
Solution Approach 1:
The control system performs self-service by automatically generating and applying position setpoint variations based on detected operating conditions, eliminating the need for external complex control mechanisms while maintaining actuator travel range through intelligent setpoint manipulation
4Reliability
If redundancy of directional control valves is implemented, then availability is improved, but difficulty in detecting valve malfunction increases
Solution Approach 1:
The system uses feedback by continuously monitoring the pressure at the hydraulic output of each valve and comparing it with expected values, enabling automatic detection of valve malfunctions even in redundant configurations where failure symptoms might be masked by the other valve
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 approach minimizes undesired actuator movement, reduces pressure drops, and ensures quick system reaction, allowing the hydraulic actuator to maintain functionality and availability by compensating for valve failures and particle deposits through setpoint manipulation and pressure balancing.
Implementation Method 1
two electro-hydraulic proportional valves 2, 3... Each directional control valve 2, 3 is designed as an electro-hydraulic proportional valve with an electrical input 4, 5 and a hydraulic output 6, 7
Implementation Method 2
A signal or an electrical current is supplied to the respective electrical input 4, 5, which determines the position of the respective directional control valve 2, 3 and thus the hydraulic pressure delivered by it at the hydraulic output 6, 7
Data Source
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Figure 2
AI summary
The invention relates to a method for activating a hydraulic actuator drive comprising an actuator, the position of which is adjusted by at least one electrohydraulic proportional valve, which has at least one electrical input and at least one hydraulic output, having the following steps: - detecting the position of the actuator and generating therefrom a position actual value; - defining a position target value in dependence upon a specification for a desired position of the actuator and eliminating a target/actual value difference by regulation with the at least one electrohydraulic proportional valve such that the actuator adopts a position corresponding to the position target value. The method according to the invention is characterised in that the position target value is also varied if the specification for a desired position of the actuator is not changed.