Hydraulic Valve Control Switching for Transient Flow Stability
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Solution Overview
Problem
Conventional control devices for hydraulic systems are not effective in maintaining stable flow rate control during transient flow states, as they primarily operate based on steady or quasi-steady flow conditions.
Innovation Solution
A control device that differentiates between transient and non-transient flow states by using a flow rate obtainment unit, a flow state determination unit, an opening command calculation unit, and a valve body control unit to adjust the valve body movement based on the flow state, employing electromagnetic proportional valves to output pilot pressures corresponding to either an opening command or a target flow rate value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional control devices use steady flow state control methods, then control simplicity is maintained, but flow rate control stability deteriorates in transient flow states
Solution Approach 1:
The control device dynamically switches between two control modes based on flow state detection. In transient flow states, it uses target flow rate value-based control to ensure stability, while in steady flow states, it uses opening command-based control for simplicity. This dynamic adaptation resolves the contradiction by making the control system flexible rather than static.
Solution Approach 2:
The invention changes the control parameter based on flow state. When transient flow is detected, the control parameter switches from opening command to target flow rate value. This parameter change allows the system to maintain simplicity in steady states while achieving stability in transient states.
2Device complexity
If a single control method is used for all flow states, then device complexity is reduced, but flow rate control accuracy deteriorates in transient conditions
Solution Approach 1:
The control method is segmented into two distinct modes: target flow rate value-based control for transient states and opening command-based control for steady states. The flow state determination unit divides the operating conditions, allowing each segment to be optimized for its specific flow state, thus improving accuracy without requiring a completely complex new system.
Solution Approach 2:
The control device achieves multi-functionality by using a single system that can operate in two different control modes. The valve body control unit universally handles both control methods, and the electromagnetic proportional valve serves both control strategies, reducing overall system complexity while improving transient state accuracy.
3Ease of operation
If opening command calculation based on pressure loss relationship is used, then control simplicity is maintained, but flow rate control stability worsens when flow state is transient
Solution Approach 1:
The flow state determination unit performs preliminary detection of the flow state before the valve body control unit applies the appropriate control method. This preliminary action allows the system to prepare for transient conditions by switching to target flow rate value-based control before instability occurs, maintaining simplicity in normal operation while ensuring stability when needed.
Solution Approach 2:
The system uses feedback from the flow state determination unit to adjust the control method. By continuously monitoring flow state and providing feedback to the valve body control unit, the system automatically switches between control strategies, maintaining simplicity through automated decision-making rather than complex manual control.
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 enhances the stability of flow rate control in transient flow states, reducing overshoot and improving accuracy by allowing distinct control strategies for steady and transient conditions.
Implementation Method 1
The electromagnetic proportional valve outputs the pilot pressure acting on the spool
Implementation Method 2
The spool travels according to a pilot pressure acting on the spool
Data Source
AI summary
A control device controls movement of a valve body of a valve device and estimates a flow rate of the valve device; determines, on the basis of an input target flow rate value and the flow rate estimate, whether or not the flow of an operating fluid in the valve device is in a transient flow state; calculates an opening command on the basis of the target flow rate value and an upstream-downstream pressure difference of the valve device; and controls the movement of the valve body. When the control device determines that the flow is not in the transient flow state, it controls the movement of the valve body on the basis of the opening command, and when the control determines that the flow is in the transient flow state, it controls the movement of the valve body on the basis of the target flow rate value.