Flow Rate Control Valve Dual Variable Orifice Overshoot Suppression
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Solution Overview
Problem
Conventional flow rate control valves experience overshoot when upstream fluid pressure is abruptly increased due to a time lag in spool displacement, leading to excessive fluid flow.
Innovation Solution
A pressure compensation type flow rate control valve with a spool that displaces from its initial position as upstream pressure increases, featuring a first variable orifice whose opening is gradually reduced and a second variable orifice whose opening is initially reduced and then gradually increased, allowing for controlled flow rate adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single variable orifice is used for flow rate control, then the structure is simple, but the flow rate overshoots when upstream pressure is abruptly increased due to spool displacement time lag
Solution Approach 1:
The single variable orifice is segmented into two separate variable orifices: a first variable orifice (11) that is gradually reduced as the spool displaces, and a second variable orifice (15) that is previously reduced and then gradually increased. This segmentation allows independent control of flow rate adjustment, eliminating overshoot while maintaining structural simplicity.
Solution Approach 2:
The second variable orifice (15) is configured to be previously reduced before the spool displacement begins, and then gradually increased as the spool moves. This preliminary action compensates for the time lag in spool response, preventing flow rate overshoot by proactively adjusting the flow path area in advance.
2Speed
If the spool displacement speed is increased to respond faster to pressure changes, then the response time is reduced, but the spool may become unstable or require higher force
Solution Approach 1:
The system transitions from a static single orifice to a dynamic dual orifice configuration where both orifices change area simultaneously but in different patterns. The first orifice area is gradually reduced while the second orifice area is previously reduced and then gradually increased, creating a dynamic flow rate control that responds smoothly to pressure changes without requiring excessive spool displacement force.
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 design effectively suppresses flow rate overshoot by reducing the flow rate through the second variable orifice when the first orifice cannot adjust in time, preventing excessive fluid flow and minimizing shocks in applications like hydraulic control circuits.
Implementation Method 1
a spool (3) which is displaced from its initial position by a pressure of fluid entering when an upstream fluid pressure is increased
Implementation Method 2
a spring (4) which resiliently biases the spool (3) in the axial direction
Data Source
AI summary
In a pressure compensation type flow rate control valve, overshoot of a flow rate when an upstream pressure is abruptly increased is suppressed. A first variable orifice 11 is provided on the side of an inflow opening and a second variable orifice 15 is provided on the side of an outflow opening. As the spool 3 is displaced from its initial position by a pressure of fluid entering when the upstream fluid pressure is increased, the opening of the first variable orifice 11 is gradually reduced, and the opening of the second variable orifice 15 is gradually increased. Since the second variable orifice 15 on the side of the outflow opening is previously reduced, even if the upstream pressure is abruptly increased, fluid more than a predetermined amount does not flow out toward the downstream.